SR-71a high speed, high altitude long range reconnaissance aircraft for FSX Deluxe and Acceleration Operation Guide.

Information optimized for Flight Simulator and this model based on the real world SR71 Pilot Manual data.
Primary development was made on FSX Deluxe. Acceleration Pack is now supported with the latest update. FSX Standard is untested but should work. FS9 is not supported.
Model and panel designed to simulate the intense work load of a real world SR71 pilot.
This document is searchable using the standard Control-F browser search feature.

Paul R. Varn
Revised May 18, 2015


SR71a for FSX Operation Guide based on Freeware release AlphaSim SR71a.
Only the AlphaSim 3D model and textures are used. All other files are replaced by this distribution and a panel added which was not included with the AlphaSim freeware release. See the README files which come with this distribution's base installation files and the README included with the current update archive for complete installation and upgrade instructions.
Common First Time Pilot Errors
Hints and Tips
Weather Environment
Special Gauges:
To fly the aircraft effectively, you need to know what these unique gauges and switches do.


Flight Procedures:



Dynamic model replacement for AIR and CFG files for public freeware release of AlphaSim SR71a. Panel with gauges, effects and sounds.

The book "Lockheed SR-71" by Jay Miller provided a wealth of information I didn't have access to before. Thanks to Gary Hall for loaning it to me. Also thanks to Gary Hall for finding the unclassified pilot manual online. This provided massive amounts of information.
Other references include: "Jane's all the World Aircraft."
Boeing Museum of Flight (A12 display and SR71 cockpit.)
"SR-71 Revealed" by Richard Graham.
"Flying the SR-71 Blackbird" by Richard Graham.
"SR-71 Blackbird in action" by Squadron/Signal Publications
Personal interviews with former pilots, RSO's and Crew Chiefs.
Gary Hall FSX Deluxe
Robert Armstrong FSX Acceleration
Johan Uyttewaal FS Acceleration
Marv Thompson FSX Deluxe

- NO CLAIM IS MADE AS TO REAL-WORLD ACCURACY OR AUTHENTICITY although effort was made to get reasonably close.

Typical first time pilot errors include:
- Using a substitute panel. The model only flies correctly with the supplied panel properly installed.
- Using substitute cfg and air files. Only the files provided work properly and will not work in another model.
- Derich: This feature has changed. When clicked, limits throttle to 94% below Mach 1 and 95% above Mach 1 if the EGT reaches 860C.
- EGT Trim: New. Does what Derich used to. Increases/Reduces the rate at which the EGT changes to keep within normal range.
- Do not fly this model like a typical FS airliner. In this model, airspeed and air temperature are more important than mach. This cannot be stressed enough.
- Improper fuel loading on the ground. ALL EIGHT tanks must be configured properly by the pilot. Correct fuel distribution on new flight loading is not automatic.
- Failure to switch Aft Bypass knobs at correct speeds.
- Confusing KEAS with KIAS in operating procedures.
- FS Realism settings too low (must be 100%.)
- Take off from the ground with full fuel. 83% fuel or less is typical. Aircraft is designed to use air refueling for maximum range. Model is underpowered when fueled full on the ground.
- Weather too warm or cold at cruise altitude.
- It is possible to fly too fast. Observe the intake and exhaust temperature gauges and fly within published limits.
- Descending from cruise at too-high rate or EAS speed too slow.
- Inattention to engine and flight specifications and limitations.
- Trying to land at too-low pitch and angle of attack (+9.5 deg typical) or high descent rate.
- Incorrect panel switch settings (see kneeboard checklist.)
- Incompatible gauge add-ons.
- Running out of TEB by cycling the afterburners too often or too many unstarts.
- Trouble stopping after landing due to landing too fast, too heavy and/or forgetting to arm the drag chute. Also forgetting you have two throttles- the AT and the controller.
- Plane will not fly as high or as fast as it is supposed to and/or afterburner effects don't work...
This is most often caused by:
1) Not installing the correct files for your version of Flight Simulator.
2) In FSX Deluxe, not activating the afterbuner(shift-F4) preventing the throttle from advancing past 80%.
3) Effects *.fx files not copied to the FSX effects folder.
4) Unlimited Fuel Cheat will result in improper fuel balance which degrades handling substantially. If the plane cannot burn off the fuel, it cannot climb to published altitude and speed.
- The Sandel gauge has minor bugs one of which is corrected by starting the plane in 2D pit mode. Consult the BUGS section below.

Typical Flight Profile Summary:
Fuel is loaded using one of three standard loads based on mission requirements. Rarely (if ever) is full fuel load used. Take off full power on afterburner with shallow climb while raising gear until 230 KIAS, then full climb. Sub-Mach cruise is Mach 0.9 and 28K ft. If air refueling, this is performed between 28K and 35K ft and Mach 0.8 - 0.85. Mach climb is performed after a "Dipsey Doodle" maneuver where after climbing to 34K ft @ Mach 0.95, shallow dive at full power to 390 KIAS, transitioning to shallow climb until reaching one of two scheduled climb speeds of 400 KEAS or 450 KEAS (normal) where EAS hold is engaged. During climb, the Aft Bypass doors are transitioned through various settings at certain Mach speeds. Climb continues at 3000-3500 ft/min decreasing above 60K ft where the AP/AT is transitioned from EAS hold to Mach hold until reaching Mach 3.0 near 72K feet. Ultimate cruise speed and altitude is determined by air temperature and pressure. Climb continues at decreasing rates until crossing Mach 2.83 where AT hold is transitioned to hold 390 - 410 KIAS for the remainder of the cruise while keeping EAS above 310 minimum (350 recommended.) At speeds near Mach 3.2 or 350 KEAS minimum, descent starts @ 325 miles from landing and Aft Bypass set to closed with EAS hold engaged to initially hold 365 KEAS, then holds scheduled IAS until terminal area procedures. Approach and landing speeds are determined by weight using 175 KIAS and 155 KIAS respectively for 10K lbs fuel and Angle of Attack near 9.5 degrees.
More specific information detailing these procedures along with relevant instrument indications will be found throughout this manual and in the aircraft kneeboards.

How to set Mach Hold over Mach 3.00 in Flight Simulator

Features and images in this document may change without notice.
This model requires an experienced Flight Simulator enthusiast who might enjoy high altitude, high performance aircraft. The flight model is as realistic as my skill and FSX will allow. All FS realism settings must be set to maximum for realistic flight. When using default Jeppeson weather, to prevent some extreme weather effects, "Weather Changes" Tab in the Options->Display should be set to slow which helps reduce the effects of extreme weather server data.
Active Sky Next users will have the best experience possible. No FSX or FSUIPC weather settings are needed with ASN.
The skill level required to fly the aircraft as it was meant to fly is considerable, even within the simplified Flight Simulator limitations. The pilot will be required to unlearn some practices typical with other FS aircraft like setting a static altitude and mach speed. The best sim pilot match would be a person who has the mentality of an Air Force test pilot expecting the challenge of an aircraft flying the knife edge of 1970s technology where automation did not solve all the technical challenges.
I suggest new pilots work up to this aircraft by starting with FS2004(FS9)/FSX training scenarios and up through faster two-engine jets like the Lear or FA-18. When comfortable with the FS interface, flight procedures, and high speed, multi-engine aircraft, you'll be ready to step up to the fastest piloted jet plane in the world.


  • Optimized for Active Sky Next.
  • BECKY real world training sortie with step by step instructions in text file: "BECKY_Training_tutorial.txt" provided in same directory as this manual along with FSX flight plan and ideal weather provided in FSX saved flight start location at Beale AFB (KBAB.)
  • FSX 3D sound. Of course, the pilot is snugly tucked inside a pressure suit and only hears comms and his air supply, so the sound is exaggerated for situational awareness.
  • Realistic after-burner (shift-F4 in Deluxe) tied to throttle position as well as detent shut down.
    Afterburner effect using smoke and flame effect triggered by AB.
  • Nose and Spike thermal glow effect.
  • Built in air refueling. Works with or without AI/multiplayer formation. At 2X and 4X refuel rates are accelerated.
  • Drag Chute (/ spoiler key) is fully implemented.
  • Note: Model will not fly with drag chute activated which is prevented except when opening the canopy in the air which causes the chute to open representing severe drag.
  • The COL has been carefully calibrated to closely follow the trim table in the official SR71 pilot's manual when 450 EAS schedule is applied.
  • Engine Spike position is automatic above Mach 1.6 providing a performance boost. Below that speed, the spike can be positioned manually. Improper spike positioning can cause Un-Starts. Auto (spike knobs straight up) is the default position.
  • Fuel loading is simplified so all tanks can be loaded to the same percentage on the ground. Once loaded, an auto fuel maintenance program keeps the plane properly balanced.
  • Unstarts and compressor stalls are possible. They are not random events and may occur from rapid weather changes, steep banks, too slow, too rapid descent or pilot inattentiveness.
  • Fuel Dump Switch.
  • Oxygen and Pressurization System.
  • Tire and Brake heating. The speed and weight of the aircraft places a strain on the gear. Partial brake failure may result from over-heating.
  • Forward and Aft Inlet Bypass system. The pilot must select the proper Aft Bypass for the speed and mode of flight. There is drag associated with the Forward Bypass door opening which is influenced by the Aft Bypass. See instructions below for correct operation.
  • Comprehensive kneeboard Specifications and Checklist in HTML format which can be viewed in the sim or displayed/printed in a browser.
  • A check ride scorecard which reports on the quality of your flight.
  • Special Master/Slave shared cockpit switch No longer supported at this time.

Weight (the balancing act)
You will read many references to weight and weather in provided documentation.
These two variables affect the performance of the model dramatically. Especially at high altitude 40K to 50K feet higher than typical airliners fly.
You cannot fly at maximum altitude, at max weight in very high or low air pressure where the temperature is excessively cold or warm. Stable flight is a careful balance of flight path planning, altitude, speed, COG, temperature, pressure and fuel load. Considering the aircraft has no flaps or spoilers, it has a 200+ knots air speed range of stability at Mach cruise which is possible due to large delta wing, powerful hybrid ram-jet engines and internal fuel pumping.
The eight segments that make up the seven fuel tanks have been carefully placed to provide the required balance shift during a normal fight through natural attrition and tank switching which should not require pilot intervention except if the pilot loads the tanks incorrectly on the ground. In addition, like the Concorde, an automatic fuel pump provides additional fuel movement.
Air refueling with the provided gauge will maintain this proper balance. A COG warning annunciator gauge and COG readout in the fuel and main panels will assist the pilot in monitoring the balance. Error should only occur in off-nominal fuel loading or flight conditions. There are times late in long refueled flights where the pilot can intervene to provide Aft COG for a longer time by operating the fuel pump manually. Fuel Loading and maintenance is covered in depth later.
Warning: If the tanks are unbalanced left and right which can happen from extended engine out, automated CG errors would occur. For this reason, crossfeed is forced on when CG computer is not switching tanks.
Fuel Balance overview:
On the ground with all tanks set to the same percentage, the fuel is near the normal center of balance for take off (nominally ~20-22%.) If it's too high, rapid rotation causing tail strike may result. Attrition causes COG to shift slowly rearward to a maximum of +25% while over Mach 2.9 cruise and total aircraft weight under 120K lbs. The Annunciator will display "FUEL LOAD" when on the ground and less than 45K lbs fuel is loaded and the Main (number three) tanks are too low.
Near the end of the flight when the fuel load is low, the weight has shifted forward to +21.5% for 10K lbs fuel landing.
An Annunciator "Hi CG" will display if the CG is more than 22.0 under Mach 0.9.
There are forward and rear COG limits of +17 to + 25 in addition to more restrictive limits during certain modes of flight.
In typical flights, weight shift forward of landing COG will not occur.
The annunciator will provide yellow warnings when COG is only slightly out of limits (plane is still flyable) and red when maximum limits are exceeded. A short period of yellow warning during refueling processes or near final approach is normal. If you are flying at high altitude and fast under 8K lbs fuel, you might have trouble getting down to land in time without refueling. Typical descent fuel weight is between 16K - 18K lbs and CG aft of 21.5%. Optimum landing CG is between 21 and 22 percent. OVER-LOADING THE FUEL CAUSES A LETHARGIC CLIMB, SLUGGISH HANDLING AND DIFFICULT DESCENTS SO ATTENTION TO FUEL LOADING FOR THE FLIGHT PLAN WILL INCREASE THE PERFORMANCE, RANGE, AND FLIGHT SATISFACTION.

The Panel is a collection of gauges from other planes which fit the general theme of grey-black high performance aircraft. Many custom gauges unique to the SR-71 were constructed. My emphasis has been on the accuracy and flyability of the flight model. As my elementary gauge making skill improves, I'll replace more of the gauges and add more realistic ones. I invite gauge artists who enjoy high performance aircraft to participate in creating a freeware panel that does justice to this amazing aircraft.
GAUGE BUGS: The "Sandel" HSI supplied with this panel has an error in the "NAV" button which when set to "GPS" causes the autopilot heading bug settings to jump by increments of 10. I suggest not using this mode.
If the model starts up in the sim in 3D cockpit view, the Sandel gauge will not display the button clicks properly nor will it display the data at the top of the gauge (blank grey areas.)
For instance, clicking the BRG button will not display the selected mode or results. To get around this, start all your flights from a saved flight in 2D mode.
In this release, the Autopilot panel has been re-designed. The heading set bug error caused by the former autopilot panel is now gone although the Sandel bug remains.
Some gauges do not display correctly when more than 4X is used. This includes the Checkride score window airborne stats, Refuel feature, Oxygen use rates and Nitrogen rates.

Hints and Tips:

  • Active Sky Next is currently the ONLY download weather generator which provides a suitable environment at very high altitudes. The often too warm and too sudden wind, pressure and temperature changes other generators provide is very disruptive to the SR-71.
  • You will have minimum difficulty learning how to fly the plane if you start the flight from one of the saved flights provided in the distribution.
    Most of the gauges and windows, along with fuel loading are set to go. Beale AFB saved flight while shut down at parking is suggested. Start there and move your plane to desired airfield and runway using the FSX airport menu.
  • 45,000 lbs and 66,000 lbs are the minimum and maximum fuel weights for take off. Consult the Fuel Preparation section for how to load fuel. Incorrect fuel loading causes CG problems and poor flight performance.
  • The Inlet Pressure gauge is your friend. When the needles are lined up, you are flying at the optimum speed for your current altitude, climb, cruise, and descent.
  • The Forward Bypass Door position gauge is your friend. Indications higher than 7% open (above the green) represents increasing drag. Keep the bypass position below 7% at cruise. You will have high drag indications during climb and descent which is normal.
    Speed and Aft Bypass door settings are used to control forward bypass.
  • The KEAS speed hold feature is your friend. It will help you keep the plane at the correct speed while climbing and descending.
  • The ISA temperature guide on the main panel lower right will help you judge performance. If the Static C is colder than ISA, the plane will fly faster and higher. When warmer, the plane's altitude and speed will be lower than specification yo prevent engine heating.
  • If you cycle the AB too often, you will run out of TEB and will not be able to restart the AB or the engine.
  • The plane can fly fast enough to burn out the engines. Keep the Inlet Temperature below the red zone. CIT between 375 and 400 is ideal.
  • Hard banking turns will stall the engine on the inside of the turn. The Autopilot will usually prevent this unless the turbulence is severe.
    In strong turbulence, keep your turns shallow.
  • The Warning Annunciator reports problems which will cause your flight to fail. These should be addressed immediately. Do not take off with red warnings or Master Warning Light illuminated. The only time you should turn off the Master Warning is for warnings you can do nothing about like low fuel or failed engine. All other warnings should be addressed with corrective measures rather than turning off the nag.
  • You will have to change the Aft Bypass Door knob positions while climbing through Mach speeds 1.7, 1.9 and 2.6. Be prepared for this or failures will result.
  • Landing Hot: When landing on hot runways after a long flight, the wheels will heat up quickly. Plan on using a long roll out and let the drag chute do the work of slowing you below 65 knots.
    Note: FS keyboard commands are not pressure sensitive, so use the DURATION of the key held down to represent PRESSURE. PULSING the brakes causes less heating than holding the trigger/key down for long intervals.
  • Cornering: Needless to say, the SR-71 is like a balistic missile at high Mach speeds. If you need to make short distance turns of 30 degrees or more, antitipate the turn by setting the next waypoint 45 miles ahead, descend to 76K feet and slow to just over Mach 3 which will give you about 1 degree per three seconds turn rate at max bank. While in the turn, you will need to set the aft bypass to schedule B to prevent the high drag alarm, then reset back to A when the bank starts to level out.
  • In order to use the Checkride Test effectively, open the test panel (shift-9) while on the ground. This will display "READY" at the top of the panel.
  • Be prepaired to unlearn typical airliner flight procedures like setting an altitude and mach hold speed. The plane is flown at various altitudes and airspeeds which result in correct instrument readings. Weather and weight dictate how high and fast you fly, rather than ideal performance specifications. Don't fixate on the need to obtain a particular mach speed at cruise. Any ground speed near 1750 knots or 2000 MPH or more is normal cruise speed. MACH is relatively unimportant in this plane because of its wide operating range. You can stall or overspeed at Mach 3 depending on weight and altitude. FLY THE INSTRUMENTS, NOT WHAT YOU THINK THE PLANE SHOULD DO!
  • The provided BECKY training sortie along with the checkride gauge will teach you all the fundamental skills needed to be a skilled HABU pilot except air refueling. If you can make it through the BECKY flight plan with a checkride score of 90 or more, you are a skilled Habu. There is a badge for you in the distribution.

SR71-FS2004/FSX Weather environment:
This graphic from NASA illustrates the earth's atmospheric layers. The SR-71 cruises at altitudes between 21 to 27 Km riding the Tropopause boundary. The air temperature reaches a low point near this altitude and warms both descending and climbing. In Flight Simulator the built-in Jeppeson weather simulator includes data only up to around 55K ft (about 25K ft lower than the SR cruises.) Above this limit, the simulation creates steadily warmer temperatures (which mimics the chart above.) Unfortunately, the coldest the sim sets at 55K ft as the top layer is 10 to 15C WARMER than is normal for cruise in the SR. The sim will not create colder temperature than the top layer in the weather data sent to the sim.
Jeppeson emulation in FSX is better than FS9, but still has extreme jumps caused by station proximity interpolation data errors.
When using Jeppeson (or similar emulation like Vatsim) by the time you reach SR cruise altitudes, the air can be as warm as if you were flying at 30K ft. This makes high speed flight impossible without over-heating. What makes high speed flight possible is the thin-cold air at the extreme altitudes of air breathing engines. Another problem with Jeppeson weather is beyond continental and coastal station data, the lack of weather stations causes the sim to load a default profile until new station data arrives. This default data is a fixed temperature and pressure of -56.5C deg and 29.92Mb OR whatever user-created or weather profile was loaded with a saved aircraft flight. This can cause extreme behavior as the sim transitions in and out of this default data when flying in remote areas and over water. The SR-71 spends most of its time in remote areas and over water so this is why a more accurate and comprehensive weather simulator is needed.
I worked with the designers of Active Sky(AS) to encourage them to emulate the Tropopause conditions for high performance aircraft like the SR71 and Concorde. This flight model was specifically designed to operate with Active Sky Next where the stagnant temperature of the tropopause starts at 49K ft and begins to get warmer above 65K ft which is the reverse of what happens below 49K ft.

When ANY program sets the temperature of the highest layer, FS will gradually produce warmer temperatures above the highest defined layer.
In FSX, this flight model has been made as tolerant of the built-in Jeppeson download weather as possible. Most of the time, flights work out OK but there are areas of the world where very bad weather emulation is almost guaranteed. In my experience this includes:
Newfoundland Canada, Coastal BC Canada, Mid Atlantic between Canada and England, South Eastern England and the US Mountain states.
NOTE: When using Jeppeson Weather, make sure The Options->Display->Weather Tab->"Rate at which weather changes..." is set to low which provides some smoothing of weather transitions at the cost of some accuracy. In FS, better the weather transitions slowly than accurately given the extreme diversity of weather station data.

FSrealWX Lite has been briefly tested using this model and so far appears to be superior to the default Jeppeson in many ways, particularly high altitude temperatures.
These are the settings I use:

Update Int: 10
Downloads: Upper air, additional, TAF
Position NM = 300
WX Stations only ahead
Set Global
Dynamic = 1 (this sets the dynamic slider in FSX to none so no internal morphing)
Vis Limit = 190
Turbulence in cumulous
Max Wind Shift = 15
DWC and Interface:
Enable DWC
Degrees/sec = 1, Knots/sec = 1
When using other weather programs besides Active Sky Next, FSUIPC wind smoothing is a must. ASN completely bypasses FSUIPC. All weather settings are ignored.

Weather Planning:
As downloaded data creates weather around the world, it will set the top layer to different altitudes and temperatures. Because of this, you will never have the same flight conditions twice. Sometimes you will get weather warmer or colder than the operating limits. As in the real world, pilots flying the Concorde and SR71 had to ride a range of altitudes and speeds to continually optimize the conditions for maximum range. I call it "Threading the Amospheric Needle." In the sim, the most important indicators are the Exhaust Gas Temperature (EGT), Compressor Inlet Temperature and Pressure (CIP/PSIA), Air Speed Indicator (ASI) and Fuel Flow (FFI.) To prevent structural damage or stalls, the aircraft has to be flown within a 140 knot speed band (370 - 510 KIAS.) To prevent engine failure, the combination of Compressor Inlet Temperature (CIT) and EGT must be kept within their limits which are strongly influenced by the Static Air Temperature (SAT) Engine RPM and air speed.

The tools you will use to juggle the temperature and structural limits are altitude and air speed.
By keeping the IAS setting so the ASI is kept as close to between 390 to 410 KIAS at cruise as possible you will fly right in the middle of the structural limit range between failure and stall.
The CIP gauge helps the pilot fly within the optimum profile at all altitudes and speeds. By keeping the expected (striped) and actual (solid) needles aligned, the aircraft will fly within its operational limits, preventing unstarts and poor fuel economy.
By adjusting the altitude of your flight between 72K and 82K feet to keep the CIT below 427C, you manage the temperature of the air to prevent engine damage. The last of the three tools of the flight management is Fuel Flow (FFI.) By keeping the fuel rate under 20K lbs/hr per engine at cruise, you will get the maximum range the flight model is designed for.

As you read further into this guide, you will see many references to speed and altitude limits. I hope this summary will give you the background to understand why these limits are there and to assure you they are indeed real world. Pilots had to "plan their flight" and "fly their plan" to cooperate with these limits. Unlike airliner flights where you set a altitude and Mach and keep them for the whole cruise, the SR71 "Habu" pilot can rarely enjoy that kind of leisure. Most flights will be relatively calm and uneventful.
Some will have you changing speeds and altitude frequently to stay ahead of the changing weather situation. Configuration for the most trouble-free flight is covered in the flight prep portion of this document.

The following graphic from NASA illustrates the effect of altitude and pressure:
Alt_Press (28K)
As you fly, FS is constantly comparing the distance between the plane's position to the nearest weather stations the weather program has loaded into memory from online weather servers.
FS uses the calculated closest station pressure for the current pressure. In remote areas of the world, these stations may be hundreds or thousands of miles apart with vastly different weather. This strategy can cause large pressure jumps from station-to-station as you get closer to a new station and leave another behind. You may also leave a relatively sparse station area to a dense area where a new station becomes "closer" every few seconds. This character is complicated by the SR's great speed traveling around 1/2 mile per second. Active Sky adopted the unique ability to create temporary "virtual" stations in remote areas between real station data. ASN adds to this real world Airmet, Pirep, and Sigmet reports with baloon data. In earlier versions this helped solve another problem the FS weather simulation causes:
When there isn't enough station data to provide a local weather environment within apprx 60 miles, FS drops all loaded data and sets a local default condition of pressure 29.92 and -55.5 degrees C at 45K ft. When this happens, if the weather you were flying in up to that point was vastly different, you may get a very large altitude transition and engine power spike (because the engines are sensitive to temperature.) ASN completely smooths all temperature, pressure, and wind direction/speed providing this SR with the best possible environment. An attentive pilot will have plenty of time to correct for evolving weather changes with no sudden out of control changes.

2D (282K)

The real plane:
ASM_3D1 (58K)

Mach 3.2 Flight Reference Panel Screenshot:
View Image: Mach 3.2.jpg
When flying at Mach 3.2, 80K ft with a take off fuel weight of 66K lbs, your main 2D panel and the circled gauges should look very close to the above linked image. If not, there is something wrong with fuel loading, flight procedure, installation, gauge or add-on compatibility, simulation options, or simulation version compatibility.

Special Gauges:
This section describes several non-standard FS custom gauges which reflect true real world limitations of the aircraft. As exceptional as it is, it's not a space shuttle. Real world pilots had limitations placed on what they could do. In addition, there were physical limitations to the airframe and engines.
These are discussed again later in this document within relevant sections.
Of particular importance are the many gauges which refelct and control the hybrid ramjet engine. These do not exist on most aircraft.

AutoPilot Master Switch: To the left of the engine gauges is a rotary knob indicating the master mode of the Autopilot.
AP_mode From top to bottom the settings are:
OFF: If the AP master switch is on, this does not turn the AP Master switch off, but it will disable any AP modes currently on.
HDG: Enables Heading mode
NAV: Enables VOR/GPS Mode
ILS: Enables ILS Mode
BC: Enables ILS Backcourse Mode

When you use this knob to change the AP, a click on the label for the mode you want enables that mode and the knob rotates to point to it. Another click on the same spot disables that mode, which functions the same as the OFF position.

If BC mode is enabled, then clicked again to disable it, the switch will move to the ILS mode to indicate ILS is still active. Click again on ILS or OFF mode to disable the ILS after selecting BC.

This gauge does not interfere with the AP Window or any mode set there or using key commands. Doing so, the knob will simply echo your choices.

AIR REFUEL: The top left center of the main panel features a gauge with three functional switches.
REFUEL_D (2K) 1) Fuel Transfer Switch (Top Center- shown off in the center position)
REFUEL_R (2K) 2) READY/DISC: Ready Disconnect Light/Switch (shown enabled when clicked.)
The Ready switch must first be activated by clicking on the light which opens the fuel door and activates the transfer electronics.
Notice also when the Ready witch is enabled, two rows of numbers which were previously hidden also display.
REFUEL_O (3K) When the Transfer switch is enabled by clicking on the switch (shown UP in the ON position) fuel will begin flowing as shown in the top row of numbers as pounds. The bottom row of numbers is the current TARGET REQUESTED amount of transfer fuel in pounds. The requested (bottom) number changes as the engines deplete the tanks and the tanks fill. Because FS2004/FSX Deluxe ADD_FUEL function always transfers fuel in 25% of unused capacity increments, your fuel tank indicators will not show the added fuel until the top number fuel flow indicator matches the bottom number requested fuel. The request estimate is based on FS's tank fill percentage calculation. After each anount is transferred, the request number will re-estimate the amount required for the next update of fuel. As refueling continues, when the top and the bottom numbers match again, the fuel tanks will update again.
The rate at which the top number increments (which controls how fast the request number is matched) is at the realistic rate of 6,000 lbs/hour. Roughly nine and one half minutes are required to fill from 20K lbs to 80K+ lbs. When full capacity is reached, the transfer switch will shut off automatically.
To refuel at a faster rate, use 2x or 4X sim time. Faster than 4X sim time is not supported.
As long as the RDY switch remains enabled, even though the transfer switch is off, the current request amounts and transferred amounts will continue to displaywhich allows you to halt the transfer between updates, check the amount of fuel which is being requested against how much you want, and continue the transfer where you left off. You can also see the total amount transferred for record keeping. When the RDY switch is disabled, the number display will clear and show again as zeros when next activated. If the RDY switch is allowed to turn itself off when refueling parameters are exceeded, reactivating the switch will display the last numbers shown. Cycle the RDY button to clear the numbers to zeros. Warning: Whenever the RDY button is on (lit bright) the pressurization system detects this as refueling stress and will increase the Oxygen usage.
Constraints: Parameters necessary to enable refuel are very forgiving at this time (new for Oct 2014):
o 270 - 350 KIAS
o 10 degrees bank or less
o Between -1000 and +700 ft/min. vertical speed
o 24K ft - 36K ft
Both engine fuel valves must be enabled (engines are operating normally.)
When refueling constrainsts are exceeded, the RDY switch will disable.
High fuel loads at low speeds cause the engines to operate near maximum military power during the last portion of the transfer. It's typical for Habu pilots to enable the AB on one engine and use differential engine throttle to balance the yaw, thus providing more power headroom near the end of the refueling. This condition is commonly observed in the slow tanker refueling profile (Mach 0.8 and 28,000 ft.) At high speed refueling (Mach 0.85 and 35K ft) the AB may on at lower weight.

KEAS Speed Hold Switch (center red to the left of the RDY light) when enabled will capture current EAS and try to hold it until disabled. Optimzed for climb schedules 400 and 450 KEAS and descent schedule 365 KEAS. When set to 450 KEAS, the EAS Bleed schedule above Mach 2.6 gradualy reduces the speed to Mach 3.01 near 74K ft automatically to prevent overspeed.
To use EAS Hold while in IAS mode: Click the KEAS button (will change to brighter color) or Autopilot panel EAS Hold switch while the KEAS display in the Triple gauge displays the desired speed (typically 400 or 450.) The speed will be captured in memory and the AP IAS bug will adjust to hold that speed within a few knots.
Note: The KEAS hold feature is slow to respond to rapid speed changes.

To switch to KEAS Hold from Mach mode: Disable Mach hold and click the KEAS button in the refuel panel (or AP panel switch) when Triple KEAS display matches your desired hold speed. The refuel panel KEAS light will change to a bright color and IAS Hold will operate automatically. You can help the hold through rough weather by adjusting the IAS speed bug manually while hold is still engaged.
To Disable: Click the KEAS Hold light/button again (will darken) or click the AP Mach hold button or the Autopilot panel EAS Hold switch. AP IAS mode will disengage. Steer On is a lamp which brightens when the nose gear makes contact with the ground and the gear is undamaged.
There is no switch or user action associated with Steer On.

CIT<- CIT at normal cruise temperatures
The Compressor Inlet Temperature was not permitted to exceeded 427 degrees Celsius or 125C below mach 2 (with the IGV light on.) If the 427C limit is exceeded for 30 continuous minutes or more an engine will fail.
When failed, the engine cannot be restarted. CIT at 450C or above will fail immediately.
Note: The rapid loss of airspeed and resultant cooling will likely preserve the other engine.
The display includes a red band above 427C and a red mark at 125C which is the limit below mach 2 with inlet guide vanes open.


The Exhaust Gas Temperature displayed as digits above "EGT C" has a built-in electronic "trimming" system (when enabled) to lean the fuel to air mixture and reduce over-heating. If the EGT reaches 860C or more, the de-rich system (if enabled) will engage which shuts off the AT IAS hold function and reduces the throttles (see EGT Trim and Derich for more detail.) This protection mode is usually the result of highly unusual data from an external weather system and in this sim functions as an emergency weather data safeguagrd. The EGT text displays yellow "LIMIT" when the EGT reaches 825-830 C (continuous operating limit) orange and red "hot" indicators for temps above 531 (ground) or 830C (air.) EGT below 400 will indicate "COLD.".
Note: If the EGT Trim system is not engaged, high EG temperatures will result when flown in warmer than normal air temperatures. It is a good idea to always engage EGT Trim when flying faster than Mach 3. At this time, there are no engine failures associated with this gauge though you might be surprised by the throttle-down if the EGT reaches HOT with derich enabled. You will also fail a portion of the checkride test. See EGT Trim for more information

The engine stack gauges from top to bottom are:

  • N2 Percent with digital RPM (changes from white to yellow or red near rated upper and lower limits)
  • EGT readout
  • Temperature range text (COLD, LIMIT, HOT)
  • TRIM (green text when activated)
  • Nozzle Position
  • Derich Lights (flash birght red on/off when activated)
  • Fuel Flow (010 = 10K lbs/hr on digital display) Full Clockwise = 20K lbs on needle
  • IGV lights (yellow when open below Mach 2: See Inlet Temperature Gauge above)
  • Oil Pressure
Note: The exhaust nozzle gauge is displayed realistically based on throttle and Mach3+ speed rather than the position shown on the 3D model which is tied to the throttle position only. In the real plane the turkey feathers do not open below Mach 1.5

Compressor Inlet Pressure under the CIT gauge displays engine inlet pressure Pounds Per Square Inch Atmosphere (PSIA) and has three needles: Left and Right engine "Actual" readings and a striped "Expected" barber pole indication. Unless there is an engine fault, the two actual needles are usually closely overlapped with the striped. The Expected Barber Pole is the theoretical performance when under normal climb, cruise and descent using the three documented schedules (400 EAS climb, 450 EAS climb, and 365 EAS descent) and Cruise. Normally the Barber Pole is hidden behind the actual needles unless the aircraft is being operated outside expected parameters. It's normal for the expected and actual needles to leapfrog each other for a few seconds once in a while. Extended periods where the needles are separated by a needle width or more indicates off-nominal performance caused by flying significantly off schedule.
When this happens, the annunciator will display "INLET" and the Master Warning lamp will light with an associated bell tone. If the expected needle is below the actual needles, the plane is flying slower than expected for the altitude and pressure. Acceleration and/or descent may be required. If the barber pole is higher than the solid, then the plane is too fast or too low in altitude. You should slow and/or climb. The CIP gauge is used as an early indication of an impending engine unstart when flying above Mach 1.5. Below Mach 1.5, indications are not critical. While on the ground, the barber pole indicates the expected take off profile, not the current idle or taxi engine condition. Normal Mach 3+ cruise will produce around 14 - 16 PSI on the gauge. A red flag at the bottom of the gauge indicates invalid gauge operation due to error in the data (usually engine failure, flight performance outside published data or near landing.) On the ground, typical display shows atmospheric pressure with engines stopped.
In flight, pressure peaks near 15 shortly after take off, then drops to lowest reading near Mach 1.6 (around 6.2 using 400 EAS climb, 9.1 using 450 EAS) then increases with speed above Mach 1.6.
Note: At this time, the only failure with the needles not aligning is above Mach 3 and the Forward Bypass Doors are completely closed (zero %.) Setting Aft Bypass to CLOSED is the usual solution to prevent unstart. In normal flight, use the needle positions as an indication of how well you are tracking the climb, cruise, and descent schedules.

Forward Inlet Bypass Doors:
Forward Bypass knobs shown set to manual OPEN.
Forward Bypass Door dual needle gauge to the right of the Spike gauge is part of the inlet bleed system and are slots around the outside of the engine about 1/4 of the distance from the front of the engine nacel. As speed increases above Mach 1.4, doors under these slots gradually open and spill excess inlet pressure out into the air moving past the outside of the engine nacel. Since this spill air collides with the air around the aircraft, the further the doors open, the more drag on the aircraft and a rougher ride. In this respect, the more closed (or close to zero) the indication, the more efficient the aircraft (lower drag and fuel rate.) Additional spill air is directed through the bypass tubes running the length of the engine and out the exhaust nozzle as high pressure RAM air providing up to 80% of the aircraft's thrust at cruise. The forward doors begin to open (above zero percent) accelerating above Mach 1.4. Depending on temperature, peak efficiency is around M 3.14 above which fuel rate increases rapidly. The needle indication is quite dynamic responding to engine duct pressure, intake temperature, air temperature, pitch, yaw, and G loads. The green area between 3 - 6% marks the typical range near Mach 3 cruise above which the aircraft will experience increasing drag.

The Forward Bypass Door position knobs to the right of the Spike Auto-Manual knobs are fully automatic requiring no pilot intervention when the "L" and "R" labels on the knobs are positioned upright as shown in the above Spike Auto-Manual illustration. When the LEFT knob is clicked, the Forward Bypass Doors are positioned to 100% open causing significant drag on the aircraft. The knobs will tilt right as shown in the image above and the bypass needle will rotate to 100% open (full counter-clockwise as shown.) This can be used to assist deceleration on rapid descents. Click again to toggle the doors back to Auto mode. Note: The Bypass Doors will be forced 100% Open when the gear is lowered.
The pilot has additional incremental control over the forward door position above Mach 1.7 by changing the Aft Inlet Door position. See Aft bypass below for Mach3+ unstart conditions. Note: Unusually cold air temperatures (less than -75C) may cause the bypass doors to open too much causing drag warning in the Master Warning. You may have to set Aft Bypass B or Open to halt the warning.

Typical bypass needle values at standard temperatures are:
Wheels Down = 100% Open
Wheels Up below Mach 1.4 = 0% Closed
Mach 1.7 = (A)20%
Mach 1.9 = (B)10%
Mach 2.2 = 12.6%
@-56C OAT:
Mach 3.0 = (A)2-5%
Mach 3.05 = Closed
Mach 3.2 > -65C OAT = 0%
Mach 3.2 < -65C OAT = 0
Above Mach3, the colder the air, the lower the %.
The Aft Bypass below can be used to open or close the forward bypass to obtain desired drag, fuel efficiency, or protection from unstart.

Aft Inlet Bypass Doors:
In the upper left of the main panel above the throttles are the pilot-controlled Aft Inlet Bypass knobs. When the text to the right of the LEFT knob is clicked, BOTH knobs move to the same settings. Default position is CLOSED. Above Mach 1.7, these controls influence the Forward Bypass. The more open (clockwise) the Aft, the more closed (counter-clockwise) the forward. During climb, the annunciator will display the REQUIRED settings in red text. Above mach 3.0 and above 30K lbs fuel, the annunciator will display the SUGGESTED settings in green text.ABPD
Above Mach 3.0 the pilot may want to toggle between A and CLOSED to keep the Forward Doors in the optimum range. As a rule of thumb, the colder the air, and higher the speed, the more likely position CLOSED will be used. A is the standard setting in standard weather. In very dynamic weather, the annunciator text may flicker between A and Closed. In this case, you should retain the A setting, but over time, you will gain judgement over which setting to use. At Mach 3.0, there is an approx. 3-6% difference between the two settings and near Mach 3.2, approx. 1% difference depending on temperature. The importance of these settings is to prevent the high drag caused by the Fwd Doors opening too much (drag) or the potential unstart from being closed too much (high intake pressure.) The aircraft is most sensitive to door position between Mach 1.7 and 2.6 (when the pilot is the most busy) which causes unstarts if set incorrectly. Unstarts over Mach 3.0 due to door position are caused when the Compressor Inlet actual pressure is higher than Expected and the Forward Bypass Doors are fully closed. The Anunciator will assist you in knowing when the forward bypass is fully closed by suggesting the Aft CLOSED position.
The Closed position is used through the entire descent. Note: It takes more time to move the doors the farther they have to change, the result being your adjustments do not take effect immediately.
Correct settings are as follows:
Take-off through M 1.7 = CLOSED
Mach 1.7 - 1.9 = A
Mach 1.9 - 2.6 = B
Mach 2.6 - 3.0 = A
Mach 3.0 - 3.2 = A
Mach 3.2+ = A or CLOSED if A results in FBPD = 0 and Actual CIP over Expected is a possibility.
On Descent, set CLOSED.
The OPEN Aft position will close the Forward Bypass to zero.

System state and failure warning system. Many of the warnings mimic actual plane warning lights although for space and practical purposes some lights are not included. Some warnings will also activate the Master Warning Light on the upper right of the main panel next to the Shaker light. ANNUN (24K)

The systems and warnings are as follows:




Psi drops below 25


Below 15C or above 177C


Below 7 Psi


Below 15%


Below 2000 psi or above 3500 psi


Below 25%


Below 22 Volts


Generator Switch Off


Engine Failed (cannot restart)



ICE will display if ice is forming on Pitot Tube or aircraft structure. INLET will display if the CIT is too high or the CIP error is large above Mach 1.5.



GEAR will display when throttle is low and aircraft below 3000ft. GEAR TR when the gear is in transit.
PITOT H indicates Pitot Heat switch is off below Mach 1.9. GEAR DAMAGED while extended above speed limit.*

SPEED HI and STALL Warnings


SPEED HI and STALL WARN in yellow and red to indicate various levels.
Fuel Low indicates total < 9500 lbs and tank 2 is < 5400 lbs AND tank4 is < 4200 lbs

COG Warnings


COG warning system calculates speed and weight under various conditions and warns when COG is out of config with yellow (minor) and red (beyond limits) alerts. FUEL LOAD while on the ground indicates the fuel quantity or distibution is wrong for take off. Between Mach 1.4 and Mach 3.0, Red text: (CLOSED,A,B) indcates REQUIRED Aft Bypass Doors setting for current speed. Green text will display above Mach 3 and >= 30K lbs fuel suggesting ideal CG ranges based on weight and Aft Bypass Doors "CLOSED" or "A" SUGGESTED settings.
EMER BAT indicates battery is being drained (low gen output vs load.) or APU Power Unit is off while on the ground.



Pitch Trim is too nose down (< -1.5) caused by too fast speed, too low alt, or too aft COG. Canopy Open/Too rapid descent Cabin Pressure or oxygen supply low, Low fuel tank Nitrogen Pressure or Cabin Dump Open. Low Fuel Press due to excessive climb rate.



Surface Limiter (Yaw Damper Off). Anti-Skid Disabled. TIRE Yellow=Cool Down Required. TIRE Red=Tire Temp Limit

    * Gear damage may include:
  • Primary Gear Lever Fail
  • Nose Wheel Steering Fail
  • Breaks Fail
The Damaged indication only lasts until the gear is raised. Once raised, The damage warning is gone until the gear is lowered again.

Drag Chute:
DSSTATES (13K) The drag chute gauge has three states:
-not deployed
-auto-armed (shift-/)
-deployed (shift-/.)
Full chute deploy takes apprx 5 seconds. The drag chute cannot be deployed while in the air but can be armed. If you arm the chute on the ground, the ground contact sensor will deploy the chute. You can arm the chute while in the air. When there is ground contact of the main wheels AND the throttle is lowered to idle, the chute will deploy. Standard procedure requires the chute not be deployed in cross wind until front gear makes contact.
To deploy on the ground, use shift-/ with idle throttle. This is different from the standard FS behavior where only the plain slash is required.
Note: When retracting or "jettisoning" the chute, use / or advance the throttle. It takes 5 seconds for the lever to return to its normal position. The image at the upper right displays these three states. Notice the "normal" un-deployed state has a black center. The armed for auto deployment state shows a bright yellow center but otherwise looks like the un-deployed state. The deployed state has a bright green center and is extended toward the pilot on a red shaft. The gauge cannot be activated by mouse at this time. New Feature as of July 2012: When the canopy is opened in the air, the chute will deploy representing severe drag. Close the canopy to return to normal flight condition with chute retracted. Flight is near impossible with canopy open and there is loss of cabin pressure and oxygen supply.
Note: The 3D panel lever does not display the arming state.
The chute has the following restrictions:
1) Will not auto deploy on the ground unless throttles are idle.
3) 5 seconds are required after deploy for full drag effect.
4) Speed has to be under 210 knots indicated.
5) Pilot cannot deploy chute in the air.

Below the engine throttles are two (Triethylborane) counters, one for each engine. The counters are maintained separately for each engine. Each time an engine is successfully started or the AB is enabled on a fully operating engine, the TEB count for the cycled engine will lower by one. You start out with 16 "shots" of TEB. When the count reaches zero, the affected engine cannot again be restarted or its AB enabled (if off.) The TEB count is only lowered if the engine start is successful or the throttle position is 80% or more for engaging afterburners. An engine which is fully functioning will remain working if the counter reaches zero until another failure occurs. If the fault is an unstart, the engine will not start. If the engine is running but AB is turned off, the AB cannot be reactivated.
The SR71 uses a special fuel which has a very high flash point. Even a match dropped on it will not ignite the fuel. The TEB is what's known as a hypergolic chemical which explodes when exposed to air. When added to the fuel, the flashpoint of the fuel is raised enough to ignite the fuel to a run state or ignite the afterburners.

Engine Spikes:SPIKE (33K) The Spike position gauge is a critical key to the ability of the J-58 engine to obtain Mach 1.5 and more. Together with front and rear bypass doors, they prevent supersonic air from entering the compressor and stalling the engine. In the real SR, the spike is maintained by a computer which is simulated in this model above Mach 1.6. The spike indicator will display positions between 0 inches (moved fully forward and away from the engine intake) to +26 inches (AFT) or fully retracted into the engine. As the spike is retracted, aircraft efficiency improves.
You can move the spike manually while on the ground to confirm its operation, but having it positioned in other than zero while in flight and below mach 1.6 will cause an unstart.

Spike_auto <-- Spike Mode rotary L,R knobs shown in default "Auto Mode" (knobs pointing UP)

Spike_man Spike mode shown in the manual (knobs right) mode.

Manual spike operation requires placing "SPIKE" rotary knobs in the right (non-auto) position. To toggle the auto-manual spike mode, click on the center of the left knob which changes the mode for BOTH engines.
New Pilots should leave the mode in auto.

The default startup switch position is up (auto) which is computer-controlled normal mode.
In manual mode, Adjust the spike position using the flaps keys (F5-F8.)
Beginning at Mach 1.6 and faster, various kinds of failures related to incorrect spike position, high AOA, too-low descent speeds, and high bank angles can cause compressor stalls and unstarts. Please consult the specifications section to order to avoid these problems. USSTATES (2K) Unstarts were a well known problem on the SR-71 and happened most frequently during ascents and descents between mach 1.6 and 2.6. In this simulation, you need to be more attentive to climb/descents than cruise.
Note: Habu pilots refer to various modes of flight where specific procedures or aircraft systems settings and operation are required as "schedules." You will read references to this term elsewhere in this manual.

What's an Unstart?
The "Unstart" term comes from the idea that close to Mach 1.6 and above, supersonic air flow inside part of the inlet has "started" and a shock wave builds behind the spike lowering the intake pressure and diverting excess pressure out through bypass doors, aft tubes and vents in the nacel. The spike and bypass doors follow "scheduled" position changes related to mach speed, pressure, and temperature to preserve the position of the shock and bypass excessive pressure out of the nacel through grills in front of the engine or as high pressure RAM to the nozzle. Loss of the shock wave position control allows the shock to enter the intake and causes similar symptoms as a compressor stall.
When the engine unstarts (loses the "started" shock wave) or stalls above Mach 1.6, the engine RPM will drop suddenly, there will be an extreme yaw moment in the direction of the failed engine, the afterburner will go out, and aircraft speed will drop rapidly while the Autothrottle tries to recover speed with full RPM on the remaining engine. Loss of speed also causes the AP to pitch up trying to maintain altitude which further complicates the impending airodynamic stall. The computer will move the spike position forward to re-capture the shock wave for auto-restarting the engine. Both spikes ALWAYS move together. The computer will keep the spike forward until the failed engine condition is corrected (bank, speed, AOA, Fwd/Aft door positions.) When the engine RPM drops enough to restart, the failed engine will restart itself as long as all dynamic conditions which caused the failure have been corrected. While above mach 3, speed will need to be recovered to above 350 KEAS which usually requires a rapid dive and full power on the remaining engine.
If you react too slowly, you'll have to restart the engine yourself with the starter switch on the panel or Contrl-E key combo. Each successful engine restart will cost you two hits of TEB (one for the start, another for the AB) so it's good to be sure all the conditions allow for a successful manual start or you will waste TEB. If you run out, the engine cannot be restarted or the AB ignited.
In FSX Acceleration, the resulting loss of AB will restict the throttle to 79%.
Restarts are normally performed at Full Military Throttle and above 350 KEAS to prevent another compressor stall.
The Unstart light for the failed engine side should ignite for an unstart, but may not always for a compressor stall. Several engine annunciator lights displaying are a further indication you have an unspooling engine (as well as all the engine stack gauges indicating low.)

Note: Compressor stalls are also simulated which can occur when sub mach. If the pitch is too high for the flight profile, or the mach descent is not maintained above 350 KEAS and/or the RPM drops below 6100 an engine will suddenly lose power and drop to an idle indication. The Unstart lights may not come on. The restart switches may try and fail to ignite the engine. When this happens, level out or start a rapid descent (-7000 FPM or more). The failed engine should ignite once speed is restored above 350 KEAS. A manual restart is necessary if the autostart sequence fails 10 times in a row.

Afterburning Throttle:
This gauge is an enhancement to the main panel throttle. The SR71 has a combined throttle AB control (like most reheat jets.) To activate the AB, the throttle is moved to a hardware stop, then the handle is pulled out-away from the base on a spring and the throttle lifted over the stop into the minimum AB setting. ABSTATES (15K)
Autothrottle control is also available through the autopilot panel which is standard for Flight Simulator except for the "EAS HOLD" feature which is used to hold specific air speeds during climb and descent.
Current Implementation: In Deluxe the throttle will not permit movement past 80% (full military power.) To increase above 80% you have to engage the AB (shift-F4 in FSX Deluxe) which simulates lifting the throttle over the stop. In Acceleration Pack the behavior is different. If you are careful, there is a slight hesitation near 80% and moving the throttle more will push past 80% and engage the AB. Once the AB is engaged, the throttle can be moved at will. If you reduce the throttle below 77%, the AB will disengage automatically. While in AutoThrottle control below 80% with the AB off, the AB is automatically engaged when the throttle is increased near 80.1%. This is to prevent the AutoThrottle from tripping back and forth across the AB boundary using up TEB. You should also keep the EAS hold on as long as possible in the descent which helps prevent AB boundary tripping.
Spooling up on the ground, high speed climb at low weight, and near refueling weight and speed are times when the throttle operates near the boundary and extra care should be taken.
Acceleration Pack users should not pump the throttle up and down across the AB boundary unnecessarily or you will run out of TEB.

Digital readout of the throttle percent setting:
I added this feature for testing other code I was working on and grew to depend on the added position visibility it provided since I do not normally use Tool Tips and like the continuous reading. I decided to make it permanent. Note: The engines operate at near max RPM through climb and cruise. What changes primarily is the fuel sent to the afterburner so don't expect to see the engine RPM needle change much at high speed.

This gauge also provides AB off/on and TO/GA indication. AB ON is indicated by changing the throttle percent number from green for "normal" military power to white for Afterburner. The image above shows these two states with military power (green) on the left and 85% AB engaged on the right. Also shown are the two TEB counters at the bottom.
On the left side just under the throttle percentage readout for engine 1 is an engine selection readout. The purpose is to help confirm you have the correct engine selected for operation when selected individually. Shown in the graphic is both engine 1 and 2 is selected so the digits "12" are shown. When only one engine is selected, the display will show a 1 or a 2 only.
Take Off/Go Round power (new Oct 2014) can be activated by Shift-Control-G or clicking on the small lever under the throttle position numbers. When activated, the throttle selection numbers blank out.
Reducing throttle below idle (apprx -3.1 or lower) will shut off the engine. Restart requires moving throttle lever back to idle position (green) or above (F1 key.) Note: The throttles can only be moved to the detent engine shut-off position when stopped on the ground.

Control Trim:
Three gauges show the degrees of Pitch, Yaw, and Roll trim movement of the aircraft components. Center before take off to make sure the aircraft is configured for controlled flight. Use the keys: Control-numpad 7 and 1 for Pitch, Control-numpad 0 and Enter for Yaw, and Control cursor left and right for Roll. Small digital numbers also assist in displaying small movements. For take off, all three gauges should indicate zero. See specifications section for Pitch/COG limitations.
TRIM (15K)

DERICH (5K) DERICH switch permits operation of the derich feature which instantly limits throttle to 97% below Mach 1 and 90% above Mach 1 if the EGT reaches 860C which also flashes the two large derich lights in the engine stack area.
Unlike previous versions of this panel prior to update 4d, the former derich action is now moved to the EGT Trim switch (see below.) Like the EGT trim, there is no harm in leaving this switch on. This can help save the day when flying in unusually hot weather.
To restore normal throttle control after derich activation and throttle down and stop the lights flashing, switch Derich off, then adjust the throttle manaully or using AP IAS/Mach modes until the desired speed is restored.

EGT Trim switch (below the Derich switch) will reduce the rate at which the EGT increases between 775C and 805C degrees and increase EGT temp when it falls below normal. At cruise, the normal trimmed EGT floats between 800C and 805C. It's usually a good idea to have this switch enabled above Mach 3.0 and on the ground in hot/cold temperatures to protect the engines from over-heat faults during hot take off or extreme weather changes at cruise. You should also use it to correct EGT "COLD" indications. CIT temperatures above 400C represent increasing risk. Near or above 400C, the EGT Trim is no longer effective and EGT temperatures increase steadily above 805C. To return the trim to normal ranges, slow and/or descend to cool the engines.
Note: The trim function is disabled if the CIT is less than 7C.
This function is off or automatic unlike the real plane where the pilot had the ability to manually trim the exhaust.

Behavior: On the ground and in various flight modes below mach 3, the TRIM light will come on if the EGT is too cold for the flight profile. You will sometimes see yellow COLD light come on at the same time if the air temperature is unusually cold.
Above Mach 3, the EGT will vary slowly between 800C and 805C. The TRIM light will come on when the fuel mix needs to be leaned to prevent the EGT from increasing over 805C. If the fuel cannot be leaned any more, the TRIM light will not come on even though the temperature exceeds 805C. In this case, the EGT will continue to increase until the pilots reduces speed and/or changes altitude into colder air. If the temperature rises too much, the DERICH feature will activate (when enabled) and the aircraft will lose speed rapidly. See CIT/EGT for more information.

Anti Skid
Anti-Skid switch decreases stopping distance while at high speed ground roll. The parking brake is disabled until at or below 12 knots. Short toe brake pulses are the most effective rather than holding the brakes for long periods. Anti-Skid ON is normal configuration and the Annunciator will indicate "A-SKID" if Anti-Skid is off. When off, low speed taxi braking will be more grabby and abrupt and excessive braking and heating may result. When ON the same annunciator display doubles as tire temp high indicators.
See section below "Tire Heat" for details.
Note: The known issue when using peddle toe brake controllers which use FSUIPC to reverse the value sent to FS is solved in both Acceleration and Deluxe by the use of the built-in FSX anti-skid feature with the application of update 4d.

Master Warning Light
In addition to the Annunciator Panel, to the right of the Attitude Indicator and below the Stick Shaker Light is the Master Warning Light. The most important alerts from the Annunciator will also light the Master Warning. These include:

  • Battery Discharging
  • Fuel Low
  • Eng Low RPM (under 6100)
  • High COG
  • Engine Failed
  • Canopy Open in Flight
  • Low Cabin Pressure (dump open or excessive descent)
  • Low Fuel Tank Nitrogen Pressure (dump open or excessive descent rate)
  • Low Oxygen Supply (< 2%)
  • Cabin Pressure Dump Open
  • Near Overspeed
  • High CIT (127C or more)
  • Large CIP Error above Mach 1.5
  • High EGT (Hot or higher)
  • Gear Up landing (under 3000 ft AGL)
  • Gear Down in flight Above 320 Knots
  • Tires Hot (above 100C)
  • Near Stall over Mach 1.5 (below 310 EAS)
  • RPM drops near minimum above M 1.5 (below 6200)
  • Ice Forming on Pitot Tube or Structure
  • High drag due to open Fwd Bypass (above 7% at cruise)
Battery power is required for indication. Click the "WARN" switch into the OFF(down) position to disable the Master Warning light. No more warnings will indicate until the switch is clicked again into the up position (default is Up/On) although the Annunciator Panel remains functional. See Qxygen stress factors below which relate to many of these same events.
Since Engine failure and Gear damage are unrecoverable, the Master Warning does not light for these failures. If the Primary Gear lever does not operate, try the backup (Control-G.) This does not repair the gear, just raises/lowers it.
Turning off the Master Warning does not prevent failures or unflyable conditions, but only reduces your awareness these things are occuring.

Altimeter Pressure Trend
Although not a feature of the real SR-71, this addition to the altimeter is provided to help the pilot navigate the digital and often quirky world of FS online weather.
On the left side of the main panel altimeter is a small digital display which shows one of three characters as a pressure trend:
= indicates there has been no atmospheric pressure change in the last 2.5 seconds.
+ indicates the atmospheric pressure has increased in the last 2.5 seconds.
- indicates the atmospheric pressure has dropped in the last 2.5 seconds.
In addition, the letters "H" or "L" will appear for high and low pressure indication:
LL indicates atmospheric pressure is below 1000.0 mb.
L indicates atmospheric pressure is betweem 1000.0(2955in) and 1109.82 mb.
No Letter indicates average atmospheric pressure.
H indicates atmospheric pressure is between 1016.59 and 1025.0 mb.
HH indicates atmospheric pressure is higher than 1025.0 mb.
Flying within average normal pressure (1009.8 - 1016.6 mb) with no recent change.
Flying in low pressure which is dropping below 1009.82 mb.

Rapid cycles through these symbols means the pressure changes are very small.
Although there is no equivalent on the real plane, this feature greatly assists the pilot flying in online weather. If the pressure trend has been up or down for an extended period (30 seconds or more) during (L) indication, the pilot may be encouraged to increase speed and/or decrease altitude to forestall any surprises building up affecting the lift of the plane should the trend continue. Sudden pressure drops affect the aircraft as temprary increases in air speed. After the Autothrottle compensates, the result is reduced power margin as if the plane were flying much higher.
If pressure then increases suddenly, the result is not enough power to compensate, forcing a descent to regain air speed or recover from unstart.
In very low pressure (LL) the pilot should avoid altitudes above 80K ft and may have to fly as low as 74K ft depending on the temperature. In my experience, although high (H) pressure can mean you may fly in the range above 80K ft, these high pressure ridges are often short lived in Jeppeson online. In Active Sky Next, the far superior weather simulation will require little (if any) pilot intervention.
Better to be safe than sorry when making weather decisions. In hundreds of hours in Jeppeson weather flying around the world up to 11 hours at a time, I've had stable flights in the altitude range between 74 - 80 thousand feet. I've also had the most terrible flights possible in certain parts of the world.

The Attitude Indicator features vertical and horizonal Flight Director bars when the "FD" switch on the main panel below the AP mode knob is positioned UP (on.)
Around the inside ring is a ball indicating the pitch trim setting: adi_trim_3 adi_trim_4

Tire Heat:
Hidden gauge: "tire_temp" measures weight, speed on the ground, braking intensity and friction temperature to calculate the effects of taxi and breaking.
In update 4e, the tire/brake temperature (TT) is continiously displayed at the bottom of the control position display in the lower left of the main panel. The brake pressure is displayed at the top (BP).
When Anti-Skid is enabled the annunciator will report when surface temperature, braking temperature, and speed combine to heat the brakes and tires above safe levels. Yellow "TIRE" indication requires a parked hold before take off roll to cool the brakes. Red "TIRE" indicates temperatures are too high on one or both tires for high speed roll (over 100C.) Wait for yellow TIRE inidcation to go out before starting take off roll.
Temperatures over 110C will cause partial brake failure.
If Anti-Skid is disabled, annunciator tire temperature warnings are disabled. Above 50K ft the tire warnings are suppressed. The Anti-Skid switch can toggle between display temp warnings or anti-skid off warning in the annunciator. Anti-skid should always be on for landing/roll or excessive brake pressure and heating could result.
Typically, when stopped and the yellow "TIRE" warning is illuminated, ~120 seconds is required to cool from 90C to below 40C for a safe take off when the surface temperature is near 95 deg F on the ground.
Wind and cold air help cool the tires when gear is deployed. When retracted, the tires assume the ambient temperature of the aircraft internal body.

Fuel and Oxygen Panel:
Oxygen System:
Shift-4 opens up the Fuel and Oxygen panel which should be done as soon as the aircraft is loaded into the sim. There are three gauges and three switches associated with Oxygen and Pressurization.
The upper left "OXY SYS" switch controls which oxygen tanks are being used. The default on startup is "PRI" (UP) which uses the primary Oxygen tanks to pressurize cockpit and suits. Primary consists of 2ea, 10 liter liquid tanks providing 20 hours under normal usage. STB (DOWN) is the standby 10 liter tank providing an additional 10 hours for two crew at normal usage rate. The "PRESS DUMP" switch at the bottom left defaults to off. When ON (UP) the oxygen system is switched off. The suits will use internal oxygen and the Annunciator panel will display "Cabin Psi" until the switch is changed to off. To the right of the PRI/STB switch is the OXYGEN PRESS gauge which always displays the pressure in both systems in pounds. These indicators will display within the upper half until the relevant oxygen quantity is nearly depleated. When depleated, pressurization will fail and Master Warning light will stay on unless forced off or supply is switched to a pressurized tank.
The lower "Liquid Qxygen" displays quantity in the system which is currently in use. To save space, since the Primary tanks 1 and 2 are used together, the same ten liter indicator is used to display both 10 liter Primary tanks.
To prevent unwanted oxygen system usage while on the ground, open the canopy (shift-e) which will automatically position the Cabin Press Dump switch to the ON (UP) position and shut off the oxygen system. The Annunciator panel will display the warning "CANOPY".
On the upper right of the panel, the "PRESS SEL" switch selects between Normal 26K ft (default UP) and 10K ft cabin pressure. The gauge to the left of the switch indicates the current pressurization level. Below the pressure gauge is a digital readout of the current pressure selection. When switching between the two altitudes, about 3.5 minutes is required to fully transition to the new level. NOTE: Switching to the 10K ft pressure causes a large increase in oxygen use rate.
When ready to start engines, close the canopy (shift-e) and click the cabin dump switch to the off (DOWN) position. Careful not to click the Fuel Dump switch by mistake!
The Annunciator "CABIN PSI" warning will stop illuminating.
During use, it's very unlikely you will run low or out of oxygen with between 28 (at worst) and 30 hours of supply unless you have a very stressful flight with a lot of faults or use the 10K ft pressurization.
There are conditions in which oxygen will be used at different rates based on stress factors.
Stressed rates are around 1.4X normal. When there have been no stress factors for 1 hour or more, a relaxed/calm rate of 0.8X is used. Many of these factors are tied to similar Master Warning lights.
IMPORTANT NOTE: With a severe loss of cabin pressure (cabin dump or canopy open) above selected pressurization altitude (10K or 26K ft) the system may not be able to repressurize the cabin in a steep climb. Level off or reduce climb until pressue is nearly equalized. Repressuring the cabin at high altitude after a pressure dump or open canopy will cause a rapid loss of liquid oxygen quantity.

    Increased Anxiety Oxygen usage (1.4x) when:
  • 10K ft pressurization selected
  • Engine Failed
  • Battery Draining
  • Low fuel (under 9500 lbs)
  • Take off or landing
  • Near Overspeed
  • Near Mach Stall
  • Low Speed Stall
  • Eng Unstart, Low RPM
  • High bank low speed, near ground
  • High descent rates over Mach 1.5
  • High Descent Rates close to the ground
  • Refueling (Refuel door open "READY/DISC")
  • High CIT (over 427C)
  • High EGT (Hot or higher >830)
  • High COG (over 25%)
  • Highspeed, high RPM (>M2.6 and > 3200)
  • Excessive hot breaking or ground speed
  • Pilot Pressure Suit temperature above 75F or below 65F
Lower than normal usage when:
No Anxiety for 1 hour

Fuel System:
On the same Fuel and Oxygen panel are various digital indicators of fuel quantity and COG Fuel Pump Switch. The digital COG % indicates the same as on the main panel. The digital fuel level displays are organized roughly in their positions on the aircraft. The previous Concorde fuel pump has been replaced by a custom pump with three positions. Auto (center) is the normal (auto) position for all modes except for minor corrections desired by the pilot. The built-in fuel balancing system will maintain an ideal CG throughout the flight for all but the most unusual conditions. If you need to intervene, a brief click on FORE or AFT (Upper/lower 1/3 of the switch) returning the switch to STOP (click in the center) should do the trick.
If Pump Rel is activated on the Fuel Annunciator, the Fuel Pump Auto mode will be disabled and can only be operated manually which might be desired when you want to over-ride the auto pump.
Note: The fuel pump switch will not return to the auto (center) position automatically.
PUMP_FWD Shown Right: Upper portion of handle clicked, handle positioned forward and forward pump light illuminated.
Fuel supply switches for the Left and Right engines have been provided. If you are having trouble starting the engines, check these switches. They should be in the up position for normal operation. The auto-start feature normally toggles these to ON (up) at ignition.
In the October 2012 update, I added a display under the CG%: TGT% which informs the pilot what the CG fuel system is targeting for an ideal CG. This display normally indicates limits being placed on AFT CG. You can use this information to decide if you want to assist the computer with a small tweak. An indication of zero on this display means the fuel system is not currently targeting a CG limit, but rather letting the default fuel attrition system work its magic. The computer will conflict with your own settings if a large off-nominal condition is created by the pilot and Pump Rel is not enabled.
Note: When descending with fuel loads over 39K lbs, the automatic system will not configure the CG for landing. The pilot will have to manage the CG with the pump switch.
The Fuel Dump switch does not have a safety and is a simple toggle. Its default position is OFF (down.) When clicked, the switch positions up and fuel is purged from all tanks at the rate of 41.6 lbs/sec with a vapor trail behind the aircraft. Another click when enabled stops the fuel dump.
The Fuel Dump switch is inhibited when the center tank four (C2) is 4060 lbs or less.
Note: While fuel dump is in operation, ideal COG is not maintained. The system will attempt to re-establich COG once the dump is concluded which may happen slowly. Manually selecting Crossfeed during the dumb will provide a slightly better CG balance.
The Pilot Pressure Suit Temperature knob (bottom) regulates the comfort zone for the pilot.
In the SR-71, the fuel provides lubrication, cooling and hydraulic pressure. In addition to an air conditioning compressor, the cabin/pressure suit temperature regulator uses fuel and hot engine bypass as sources of cooling and heating.
In the center position (12 oclock) the normal temperature when the fuel supply is above half is around 72 degrees F. As the fuel heats up and depletes, the cooling system loses efficency. When the suit temperature gets too hot or cold, the oxygen usage increases, depleating the supply quicker.
There are three steps of heating and four steps of cooling below and above center. Click on the right side of the knob for heating and left side for cooling.
If the canopy is opened, the temperature change to the outside air is very rapid. If the electrical system is off, the temperature change is even faster.
Notes: It's unlikely this knob will need attention on short flights. Even if you let the temp get too high or low, the oxygen system has a lot of capacity. On longer flights, the pilot will want to look at the the temperature display below the knob and make adjustment if necessary.
Each step is approximately 2.2 degrees F change.
When refueling or descending through cold air, the temperature will slowly drop on its own if the skin temperature drops below the fuel temperature.
Hint: If the pilot has had to lower the temperature knob below center, during periods of outside cooling, the pilot can return the knob to center without causing heating. The advantage of this is if subsequent heating is expected from climb to cruise and fuel depletion, this technique will provide another four steps (9.8 degrees) of cooling later.
Keep in mind that although refueling provides a new charge of cooler fuel to the system, not ALL the fuel gets replaced with the cooler fuel, so there will always be an increased rate of temperature increase as the flight continues. If the heating rate becomes a concern to you, it's best to catch it early before the temperature rises above 75F.
Also, the rate at which the system can reduce the temperature gets slower with time due to loss of the fuel heat sink capacity.

Fuel Annunciator:
On the far right of the main panel, the Fuel Annunciator indicates when a tank is empty by lighting bright and xFEED OPEN when all the tanks are available for both engines. The later is the case when the Auto CG system is in its default non-managed state of fuel attrition balancing in which case the xFEED OPEN lamp is bright. In this state, FS defaults to tank usage based on its own internal logic and BOTH left and right tanks are used for both engines (no isolation.) The "xFeed On" switch lets you over-ride the CG system and force it into xFeed mode all the time, preventing tank switching. You might do this if you dissagree with the CG balance and want to use the pump on the fuel panel to change it without the Auto system over-riding your adjustment.
Pump Rel: When clicked, this lamp will light indicating the CG balancing fuel pump auto mode is disabled. In this mode, the fuel transfer pump between the center tanks can only be operated manually. Enable this if you want to force CG changes without the auto system over-riding.
At the bottom of the set of lamps is a test toggle. When clicked ALL the lamps will light up regardless of their logic state. Click again and the ones which should be in their off state will do so.
See the detailed explanation of this model's fuel balancing system for more explanation.
Defalt all off: F_annun1 Test ALL ON: F_annun2
CG Over-ride/Crossfeed:

The AP OFF light under the nitrogen supply (not shown) will illuminate when the AP main switch is off and the aircraft is airborne.

Nitrogen Fuel Tank intert and pressure quantity:
Nitrogen New for update 4d is Nitrogen pressurization. At the high altitudes the SR flies, the tanks need to be pressurized or the fuel pumps will be drawing against near vacuum. Also, inert gas is used to replace the empty tank space to prevent combustion.
As the tanks deplete, liquid nitrogen is evaporated into the tanks. The tanks leak at low airframe temperatures, so more gas is lost when the aircraft is cool than when at high mach flight.
Master Warning will activate when the gas reaches 2.5 or less capacity. When empty, both engines will shut down and will continue to fail if restarts are attempted.
Under normal flight profiles, there should be over 10 hours of continuous supply. The more time spent at low/cool altitude and speed, the faster the supply depletes.
As with the oxygen depletion, this limited consumable is low impact unless the flight is very long range or unusual.
The level shown on the image reflects a 50 minute take off and land.

Score Card:
Scorecard New for "update4d" is the ability to test your skill and obtain a rating based on 25 test items for a total of 100 points (perfect score.) Most failure points are easily avoidable.
To win a perfect score, start the plane cold and dark, work through the checklist, taxi and take off, climb to at least seventy thousand feet, land to a full stop, and keep all the "PASS" items from failing without using slew or resetting the aircraft. Typically, loading this aircraft in the same flight condition as a previous aircraft is a sure way to cause yourself a lot of trouble.
Alternatively, you can start on the runway with engines fully operating and generators on.
To avoid battery discharge on a cold start, make sure APU is on before enabling the battery. If you start the plane with battery on, but leave the APU or engines/generators off for more than 30 seconds, you will fail the "Battery Discharge" test. Some fail items will be avoided by following the kneeboard checklist, others require skilled piloting and avoiding extreme weather.
Most test items are based on oxygen stress detractors mentioned above in the Fuel Panel Oxygen section.
There is a bonus added which can take the score over 100 or compensate for a few minor missed items when extra effort is detected.

    Some Additional Test Details:
  • "READY" in the panel title indicates conditions are good to start the test. "NOT READY" means the plane is not stopped on the ground before the test, slew was used in the air, or the gear was not fully extended on the ground.
  • The last three items: "Take Off OK", "70K ft", and "Land OK" always start out "FAILED" until you accomplish those things.
  • You must take off from the ground with no slew in the air.
  • Don't forget to reset the Gmeter before take off.
  • 70K ft check might fail if altimeter is not set properly.
  • On longer flights, check the pilot suit temperature.
  • If you complete the flight but fail the take off check, you will get a zero score at the end as well as a Land fail even though you had a good landing.
  • Some items remove a lot of points like: engine fail, unstarts, dynamic stalls, crashes.

As you all well know, faults of any kind are not a normal part of FS simulations. The FS built-in random failure system is so unlikely and unrealistic no one wants to use it. Alternatively, the faults built into these SR-71 gauges take some getting used to, but are an attempt to help wannabe "Habus" appreciate the skill and technical complexity associated with this unique aircraft. Although airliner pilots are known to sleep at the stick from boredom, Habus could not! Go to sleep in this aircraft and you'll find yourself in a reset in short order. These SR-71 faults are not random. The pilot has to fail to react to out-of-limit, off-nominal flight parameters for them to happen. These off-nominal conditions are not forced or random, but are the result of pilot error, fuel loading-balancing, or weather conditions.
If you are an Active Sky Next user, you will appreciate the challenges added to the simulation when the next level of operational weather realism is applied. This model has a similar work load increase.
In a normal flight with switches in correct positions, correct altitude and speed for the temperature and under AP Control you will not have any faults.

How to set Mach Hold over Mach 3.00 in Flight Simulator:
Flight Simulator wasn't designed for aircraft which flew over the speed of the Concorde at the time the autopilot controls were designed, so Mach 3 was considered fast enough I suppose. Up to Mach 3, the Mach speed set window converts the current IAS into Mach but will not over M3.00. If you try to click on the Mach setting window past Mach 3.00, nothing happens. There is a work around which solves this problem. Enable IAS and advance the IAS window setting. Although the Mach display does not change, it will when you click on Mach hold after advancing the IAS bug upwards. With a little practice, it's quite easy to switch back and forth between IAS Hold, advance or decrement the setting, then switch to Mach Hold to see what you get. You will discover one knot is just over one hundreths of a Mach, so changing the IAS one knot will change the Mach by one digit (roughly.) The autopilot panel controls have been arranged to minimize the mouse movement when performing this operation.
Note: If the FSUIPC feature: "Correct IAS Bug in Mach Speed Modes" is checked, this technique will not work and speed will be restricted to Mach 3.0.
Note2: More often than not, holding Mach speeds much over 3 does not work that well over long distances because it's unlikely the weather conditions will always favor a particular mach and altitude. For practical purposes, the pilolt should get used to flying the appropriate air speed for the conditions and accept whatever mach speed results.

Aircraft Specifications:

Length: 103' 10"
Height: 18' 6"
Wing Area: 1,605 sq' (some sources claim 1,800 ft sq)
Wing Span: 55.6 ft
Wing Area (W/Chine): 1750 sqft
Wing Sweep: 52.6 deg
Wing Dihedral: 0 deg
V Stab Area: 70.2 sq'
Gross Weight (MTOW): 135,000 to 140,000+ lbs (Pilot Manual) 170,000 lbs Typical
Zero Fuel Weight: 56,500 to 60,000+ lbs (Pilot Manual)

j58-7eng_stand (60K)
Weight(2): 13,000 lbs (6,500 lbs ea)
20' long, 4',5" wide.
Angle: Pitched -2 degrees down from fuselage angle.
Model: (2ea) P+W JT11D-20B (J-58) Turbo Ramjet.
Static Thrust: 32,500lbs @ sea level
(45,000 lbs with after-burner.)
Single Rotor, 9 stage 8:8:1 ratio compressor.
Note: Rolls-Royce/Snecma Olympus 593 (Concorde) = 15:1:1
General Electric CF6 (747) = 30:5:1
TO_THR (9K)Bleed Air Bypass Transition: CIT 85C to 115C, Mach 1.8 to 2.0
Military Max Thrust sea level: 70% of total
Military Max Thrust high alt: 28% of total
AB Min detent Thrust at sea level: 85% of total
AB Min detent Thrust high alt: 55% of total
Starter Disengage RPM: 3,200
Typical Idle RPM: 3,975
Max Steady RPM @ 350 CIT: 7250
Min RPM above M1.5: 6100
Typical Cruise RPM (350 CIT): 7050-7150
Overspeed RPM: 7450 < 300C CIT, 7300 > 300C CIT
Cruise Inlet/Engine power ratio: 80%/20%
Core Airflow: 450 lb/s
Max Inlet Spike Movement = 26 inches.
Inlet Shock "start" movement: Between Mach 1.6 and 1.8
Inlet Guide Vane (IGV) Transition: Axial/Cambered = apprx CIT 85-115C Mach 1.8 and above.

Fuel Load (JP-7) at 100,000 lbs Gross Weight: 11,570 lbs
Fuel Capacity: (real world) 83,302 lbs JP-7 (12,200 US gal @6.9 lbs/gal)
Fuel Capacity: (this model) 80,653 lbs FS "JetA" (12,038 US gal @6.7 lbs/gal)
Unusable: 32.4 Gal (217 lbs)
Standard temperatures and pressures:
Rated Cruise: Mach 3.20 @80,000ft
Fuel Rate at Ground Idle: 4800 - 6300 lbs/hr
Fuel Rate Max Take Off Full AB: 80,000+ (both engines)
Fuel Rate at refuel speed and alt: 24K lbs/hr
Fuel Rate (rated cruise): 36-41,000lbs/hr
Fuel Rate (Average Climb): 28,500 lbs/hr
Fuel Rate (Average Descent): 16,500 lbs/hr
Full Fuel:
Fuel Temp @ Mach 3: over 300F(149C)
Fuel Dump Rate: 2,500 lbs/minute (42.08/sec) until tank4/6a reaches 4700 lbs, then auto-terminates.

Min Take off Runway length: 9,000ft. (with after-burner)
Min land Runway length: 7000ft (10K lbs or less fuel)
Typical Runway Take off Roll (45K lbs fuel): 4800ft
Max Crosswind landing: 25 knots dry, 20 knots wet.
Caution: 16+ knots @ 55+ degrees
Prohibited: 25+ knots @ 20+ degrees
Gear Extended Limit: 300 KEAS/330 KIAS
Gear Cycle Limit: 10 times per flight
Max Ground Tire Speed: 238 KEAS, 239 KIAS, 275 MPH
Tire Cooling: 9 minutes for every 14,000ft or 2.75 miles of taxi distance at 70 deg F.
Max Taxi Speed (recommended): 40 MPH(35 KIAS)
Typical: 30 MPH (25 KIAS)
TirePressure: 400 Psi
Take off Tire Failure: 10K ft @72 deg F
Max initial braking speed 10K lbs fuel: 209 KIAS @70 deg F
"Brake Walk": Oscillations @ 10 cycles per second.
Anti-Skid Min Speed: 12 knots
Min Ejection Altitude: 15,000ft
Touch Down Vertical Speed: Typical- 50 to 100 fps, Max- 600 fps
Landing Threshold Pitch: 10 deg
Landing Threshold AOA: 9.5 deg>
Pressurization (normal Cruise:) 26K ft:
2ea 10 Liters Oxygen
Standby = 1 ea 10 Liters Oxygen
Tank Pressure 65 - 100 psi
Consumption: 1 Liter/hr for two people
10K ft:
1.4 Liter/Hr

V Speeds (45K lbs fuel):
V1 = 156KIAS (acceleration check speed)
Vr = 180 KIAS, (full weight) = 205KIAS
V2 = 210 KIAS
66K lbs fuel:(full TO Weight) = 220KIAS

Max Speed: Mach 3.45/551 KIAS RANGE_CEILING (176K)
From SR71 flight manual section 5-8 Maximum Mach:
" Mach 3.2 is the design Mach number. Mach 3.17 is the maximum scheduled cruise speed recommended for normal operations. However, when authorized by the commander, speeds up to Mach 3.3 may be flown if the limit CIT of 427C is not exceeded."
Maximum Design Structural Limitation: 500 KEAS (556 KIAS) at 65K ft.
This speed would be exceeded if the plane was flown above Mach 3.0 below 65 thousand feet.
Recommended Operational Ceiling: 85,000ft (model tested stable to standard weather.) Altitudes much higher than this are rare in download weather.
Normal Cruise Altitude: 79K ft westbound, 80K ft Eastbound.
Range: 3,250 miles un-refueled (based on ideal static weather, no wind)
Initial Cruise Speed: M3.0 @ 74K ft.
Mach Cruise Bank Angle Limit: 35 degrees
Max Bank Angle during Climb: 45 degrees
Max Rate of Climb: 11,810 ft/min (60 m/s) - 9999 under AP control
Max Rate of Descent: 1 mach per 3 minutes above Mach 1.8 (roughly exceeding sustained -6200 fpm 75K ft through 60K ft)
Cruise Range Loss from Turn: 2.5 miles per 10 degrees

Minimum Single Engine Approach Speed = 200 KIAS 25,000 lbs fuel.
Minimum Go Around Alt = 300 ft.

From 600 to 900+ degrees Fahrenheit on the airframe.
Temperatures on the J-58 engine exhaust reach 3200 degrees F.

Min Operating Air Temperature = -75 deg C

Sub-Mach Max Climb Speed (no turbulence): 400 KEAS
Max Performance Climb Speed: 450 KEAS
Sub-Mach Max Climb Speed (max turb penetration): 350 KEAS

Minimum Turn Airspeed: 220 KIAS

Landing Speeds:

Fuel lbs

Approach Spd

Touchdown Spd

<= 10K

175 KIAS

155 KIAS













Typical AOA at the above speeds and weights are 9 to 10 degrees, not to exceed 14 degrees (tail strike.)

Flight AOA Limits:
Max below 25K ft = 18 deg
Max Subsonic 25K+ ft = +10 deg
Max Supersonic 25K+ ft to 70K ft = +8 deg
Max Supersonic 70,000+ ft = +6 deg

Drag Chute deploy:
5 seconds full deploy after activated on touch down. 1/2 G decel. Nosewheel contact required before activation with cross wind.
Max Drag Chute Deploy Speed: 210 KIAS
Drag Chute Attachment fail Speed: 30K+ lbs fuel
Min chute Jettison Speed: 55 KIAS

Max Sub-Mach Climb to Cruise:
Full Stop Break Release to 24K ft in three minutes.

Temperatures between -55 to -70 C:
Design Mach Speed = 3.2 (above 35Kft)
Maximum Operational Mach = 3.35
Overspeed Mach =3.45
Maximum Indicated Air Speed = 559 KIAS, 500 KEAS.

Max Safe Altitude = 85Kft (without special auth.)

Max Rated Altitude = 92K ft (can go higher when weather and weight permits.)

Max Pitch at cruise = 7 deg (Speed loss/Stall Instability @ 6.0 deg)
PITCH WARNING!!!: Do not let pitch rise above +7 deg or below level on the Artificial Horizon while above Mach 3.0

Min Supersonic Airspeed = 310 KEAS
Note: Descend rapidly if the weather system causes a sudden drop in EAS to a value near this speed.
Mach 3 stall: Below 240 KIAS

No Power Glide (80K ft Mach 3.2):
375KIAS @ -11,600 ft/min
6 minutes to 10Kft (102nm)

Ground Lift effect: Within 30 ft.

Peak Aerodynamic Pressure: Apprx 670 lbs/sq ft (Dypsey Doodle Climb 450 KEAS through 35K ft.)

Normal Alt- 25K - 35K ft (35K feet with latest tankers.)
AOA 3 deg low fuel
AOA 6 degrees full tanks
Typical distance between tanking: 2000 miles
Refuel Rate: 6,000 lbs/min
Typical Refuel Time: 15 minutes

Max Deceleration above M 1.8 = 1 mach per 3 minutes
Below Mach 1.8 = No limit

MLW: Not Limited (suggested 40K lbs fuel max)
Note: APP AP is very unstable at this weight
Normal Landing weight: 10K lbs fuel or less
Touch and Go Limit: 25K lbs fuel

CIT Compressor Inlet Temperature:

Max Inlet Temperatures (mach 2.8 @85Klbs gross weight)













(mach 3.0 @85Klbs gross weight)-











-53.9 (-52.8 FSX ISA)

338 model calibration



Nominal Inlet Temperatures (Mach 3.2 20K lbs fuel)




350 (typical Cruise)




380/Max: 427C (801F)@ M 3.38







cit_rpm_chart (161K)

Idle: ~430C @ sea level (typical)
Max start temp (idle) = 565 C
Normal Cruise Range: 780 - 820C
Continuous Limit: 830C
Emergency Zone = 825 - 845 C up to 15 minutes
Red Zone: 900 C up to 2 minutes
950 C up to 15 seconds.

egt_cit_chart (167K)

Modeled MAC in FS2004 = 51 ft (wing + forward fuselage chine).
Typical range: Forward- +17% to Aft- + 24%
Ideal Take off: 17 % (Published), Typical: 20%
Max at cruise: +25%
Max Take off and land: +22
Max below Mach 0.9: +24
Min COG above Mach 1.8 and 11,570 lbs fuel: +17
Min below Mach 1.8 and 11,570 lbs fuel: +14.5
Ideal Landing: +21.0 to +22.0
Max at Mach 3.30 = 24.4% MAC

Trim Limits:Subsonic level=-1.5 deg nose down.
Supersonic level: Min=+0.5 @ M2.6 (normal 3.1 at full weight.)
Max=-1.5 @ 25% COG (normal 0 at Mach 3.0 near 24% COG.

Mach 3 Environment Temps:
Interior: 300 deg F
Nose: 800 deg F
Windshield: 600 deg F
Exhaust: 1,200 deg F (649C)

Oil Pressure:
Min safe operating = 35 PSI
Normal = 40-60 PSI

Fuel Pressure: 7-9 Psi

Hydraulic Pressure:
Normal = 2200 - 3000 psi at or above 3000 Engine RPM
Reduced Control = down to 1500 RPM Control Failure = below 1500 RPM

2ea 60KVA direct drive generators. 155/200 volt, 400 cycle.
2ea 28 volt, 25 amp/hour batteries.
Emergency AC buss (supplied by battery 1): 1KVA.
Battery Duration (essential equip only) 40 minutes.
External MD-3 or MD-4 power connector.

G Load Limits:
Mach 2 and Less (below 50K ft): -.2 to +3.5
Mach 2 and less (above 50K ft): -.2 to 2.5
Mach 2 to 2.6: -.1 to +2.0
Mach 2.6 to 3.2: -.1 to 1.5

Min Airspeed Restrictions:
Supersonic: 310 KEAS
Subsonic and >= 25 Kft: 300 KEAS
Subsonic and < 25 Kft: 145 KIAS

Pitch Trim: The model under ordinary fuel and speed operation and auto-pilot control will conform to the following flight trim settings after take off with 66K lbs fuel:
TRIM (32K)

--------------------- FLIGHT PROCEDURES: ----------------------

This general overview of technique for flying this aircraft in FSX is not real-world but based on manipulating the sim to obtain consistent results. Unrealistic weather conditions strongly affect performance. The details here are also provided as checklist and reference items within the panel Kneepad feature. New for sr2012Updt1c are htm checkist and reference files elliminating the problems the previous text files produced.

FLIGHT PLAN loaded into GPS or another navigator that performs turn prediction. FS2004 GPS turns about 2.8 miles prior to the waypoint at high speed. This is JUST enough to maintain control during turns. At cruise, waypoints should be 500 miles apart or more if they have moderate turns, No-turn waypoints can be as close as 100 miles. When flying over water to your destination (ATC hate mach speed in their space) a careful flight plan will include a way point close to the coast (assuming your destination is somewhat inland) for use as a descent calculation target. This is explained in the descent profile later.

Fuel Loading:
To provide a wider performance margin on take off in case of an engine loss, the Air Force flew the SR-71 with one of three fuel loads:
45, 55, or 65K lbs.
If using SFP or NAV3, range and fuel estimating should be close using the following table:

















Fuel Tank Diagram

(EDITED for update sr2012Updt1b) Note: The SR71 is capable of fuel balancing automatically for the entire flight flight and approach. Automatic fuel tank selection and tank attrition schedule built into the model simulates the auto transfer system AS LONG AS you load the tank percentage below on the ground and left and right tanks are balanced.
The balancing system is in auto mode when the FORE AFT pump switch is in the center (AUTO) position and the Fuel Annunciator PUMP REL is off.

Easy Rule of thumb:
To set typical take off weight of 45K lbs, set all the tanks in the FS fuel menu to 56%. This will provide a COG close to 20% for take off. Any COG between 19% and 22% is acceptable for take off or landing.
To set 55.6K load: all tanks 69%
To set 66K load: all tanks 83%
Warning: There are EIGHT(8) fuel tanks in the FS fuel dialog. Failure to set ALL of them to the same percentage may cause the auto balancing system to provide less than optimum performance. This system of setting all the tanks to the same percentage was adopted to make fueling the SR-71 simple for the pilot even though the CG system is very complex.

Detailed explanation of this model's fuel balancing system.
1 hour or less than 1000 miles: Use 45K fuel load.
Up to 2 hours or 1000 to 1500 miles: Use 55K fuel load.
2 to 2.5 hours or 1500 to 2500 miles: Use 66K fuel load.
3200+ miles: Full fuel afer air refeuling
Do not try to take off with full fuel loads. Although it's possible, the potential for problems and the sluggish performance is not worh it. Unless you are flying over 3000 miles, you are not going to use all that fuel anyway.

FS Fuel Dialog:

Ltip = Tanks 1 + 1a
Rtip = Tanks 1 + 1a
Lmain = Tank 3 L
Rmain = Tank 3 R
Cntr = Tank 2 Foward Trim
Cntr2 = Tanks 4 + 6a Rear Trim
Laux = Tank 5 + 6b
Raux = Tank 5 + 6b

Fuel distribution is as follows (rough):

< NOSE to TAIL(111ft)







<  pilot





LRaux >







Min Usable:
1 = 2300 lbs
2 = 3400 lbs
4 = 2400 lbs
5= 1900 lbs
Min Landing Fuel Weight: 5000 lbs.
These tank assignments and positions are based on FS2004/FSX built-in default tank attrition schedule which chooses the order in which tanks deplete until empty. A complex system of tank switching at certain capacities enhance the attrition for optimum CG and trim near Mach 3 and above. Habu pilots considered 60,000+ lbs fuel weight a "heavy" jet. At the typical take off weight of 45K lbs fuel, you'll find the plane nimble and fast-climbing. If you need a fuel load over 70K lbs, it's best to take off with the default loads of 45K, 55.6K or 66K lbs (depending on when you can intercept the tanker) and plan on an air refuel.
Occasionally, near the end of long flights after refueling, the balancing system may allow the CG to move forward prematurely (although it causes no harm.) If the pilot wishes to assist the system to hold 25% longer at cruise, follow these steps:
1) In the Fuel Annunciator, click the "xFEED ON" switch so the xFeed in the Fuel Annunciator lights up. This prevents the system from using tank switching mode and the tanks will empty symmetrically per FS's internal tank logic. Note: Even when the XFeed ON switch is down (off) the system can still use crossfeed, it's just not forced on all the time.
2) At the bottom, click "PUMP REL" so it lights up. This disables the automatic balancing pump so when you operate it, it will not try to correct you and will retain your actions.
3) In the Fuel Panel, operate the fuel pump by clicking the top or bottom (bottom to move fuel aft and increase the COG.) Clicking the center stops the pump. IMPORTANT: You should avoid pumping the center tanks below where the text quantity changes to yellow. At that point, you should stop manipulating the system and change the two items above back to the unlit indications.

The SR71 is sensitive to pressure and temperature more than wind speed because of the high altitude. Near the flight limits large pressure changes can throw the flight model well beyond its operational limits. Pressures over 30.10 inHg are problematic because they force you to fly very high (which can be fun, but increasingly risky.)
Recent retail versions of FSUIPC for FSX provide temperature, wind and pressure smoothing which greatly enhance the flyability of this aircraft when using Jeppeson weather. Very low presure will force the pilot to fly altitudes ~74K ft. Active Sky Next is the preferred weather source and does not require FSUIPC for smoothing.
Note: Active Sky Next uses SimConnect bypassing FSUIPC completely. FSUIPC is not needed at all for weather communication or modification.

Check for strength and direction of prevailing winds. Typically, in the northern hemisphere, you will have mostly head winds traveling West and tail winds heading East. Add 1000 lbs when going West and subtract 1000 from the estimate going East. The exception would be flights more N/S than E/W where I don't modify the estimate.

80,000ft should be used for flights East and 79,000 for west. Although the model supports flights up to 85K ft (normal limit is 82K ft) with pure Jeppeson-only weather source, unstable weather over coastal transition boundaries (300 - 500 miles from land crossing over large bodies of water) may cause highly unstable flight. Engine power is reduced by periods of extreme off axis air flow. The payware version of FSUIPC has a wind smoothing feature which helps reduce rapid wind axis changes but as mentioned, not be used with Active Sky Next.

Weatherset: A useful tool for checking the quality of the weather generation is a free program which comes packaged with FSUIPC called Weatherset. FS2004 and FSX users should use Weatherset2. This program displays all the weather data being sent to FSUIPC by the weather program in a numerical display (rather than the FS weather dialog tabbed graphical display.) This lets you see all the current weather settings at a glance without scrolling or tabbing.

Another useful tool comes with the online multiplayer connection program FSINN. Along with a large package of tools in the main FS menu is the "Pressure" indicator. This places a current pressure display in the sim so you can see what the current pressure is at all times without switching to the desktop. As you get more experienced, you will come to expect certain IAS readings at certain altitudes.
This panel has a special enhancement to the Altimeter to display relative pressure changes.
Higher or lower than normal air speeds at Mach 3.2 are an indication you are flying in unusually low or high pressure. This can help the pilot take pro-active measures to reduce the effects of pressure changes.

Active Sky Next plan and Briefing:
By far the most useful tools in ASN for flight planning are the Flight Plan load, Briefing, and Map Insert waypoint features.
Load a plan into ASN and with these settings in the flight plan aircraft attribute fields, refresh the plan and inspect the briefing screen with TOC/TOD checked:
Climb FPM: 1920 / Climb TAS: 900
Descent FPM: 2900 / Descent TAS: 700
Cruise TAS: 1780

DUSKI: (Calculated flying altitude 68200 feet)
- ETA in 50 minute(s) 43 second(s)
- Expected weather conditions: PKWA 242040Z AUTO 07016KT 10SM SCT020 SCT030 29/23 A2981 RMK AO2 T02860232
- Expected winds: 21/24
- Expected temperature: -79.62 celsius

TOC: (Calculated flying altitude 80000 feet) - ETA in 54 minute(s) 52 second(s) - Expected weather conditions: PKMJ 242051Z 05012KT 10SM VCSH FEW016 SCT050 BKN140 28/25 A2984 - Expected winds: 321/7 - Expected temperature: -68.97 celsius

JMROY: (Calculated flying altitude 80000 feet) - ETA in 1 hour(s) 10 minute(s) 36 second(s) - Expected weather conditions: PHLI 242029Z 05020G26KT 10SM BKN020 OVC029 24/21 A3019 RMK AO2 PK WND 05026/2028 RAB04E14 P0000 $ - Expected winds: 264/23 - Expected temperature: -60.63 celsius

TOD: (Calculated flying altitude 80000 feet) - ETA in 1 hour(s) 32 minute(s) 47 second(s) - Expected weather conditions: PHLI 242029Z 05020G26KT 10SM BKN020 OVC029 24/21 A3019 RMK AO2 PK WND 05026/2028 RAB04E14 P0000 $ - Expected winds: 264/23 - Expected temperature: -60.63 celsius

SYVAD: (Calculated flying altitude 74100 feet) - ETA in 1 hour(s) 33 minute(s) 39 second(s) - Expected weather conditions: PHLI 242029Z 05020G26KT 10SM BKN020 OVC029 24/21 A3019 RMK AO2 PK WND 05026/2028 RAB04E14 P0000 $ - Expected winds: 264/23 - Expected temperature: -65.10 celsius

By using the map and inserting waypoints, you can create additional temperature, wind and pressure checkpoints without changing your navigation program.
Using the above information you can see this flight would provide unusual temperatures for the SR where the air is colder than the recommended -75C during the climb.

In practice, pressures during M3+ flight OVER 1024.4mb (30.25Hg) or UNDER 997.3mb (29.45Hg) are problematic. You can expect to have to climb very high (90K+) to obtain M3 or descend very low (72K ft and under Mach 3) to avoid stall near these pressures.
Avoid IAS over 500 or under 380 at cruise. I cannot stress enough that the most maintenance-free flights will have cruise speeds near 400KIAS/352KEAS (the middle of the model's stability range.)

These procedures are also available in the onboard kneeboard checklist.

PRESET THE AUTOPILOT to have AutoThrottle ENABLED, set initial altitude (usually 10,000 AGL to 28,000) 255 knots IAS on AP bug (for low alt restriction) and 4500 ft/min climb rate. When using normal unrestricted climb, set initial alt to 28K ft and AT IAS bug to 450 KIAS. This will hold close to 400 IAS (350 KEAS.)
Alternatively, use the KEAS HOLD in the Refuel or Autopilot panels to hold climb and decent speeds.

Switch NavGPS switch to GPS (note: GPS mode disables ILS approach so you need to toggle the switch back to NAV during automated ILS approach.)

o Start-up:
With brakes, battery and APU on, click each engine start button until ignition (apprx 22% RPM.) Alternatively, activate the autostart sequence with shift-e. The Chevy V8s will spool up loudly. Once the engine ignites, the TEB counter will lower by one (from 16) to indicate one shot of Triethylborane was used to start the engine.

o Taxi:
Move all control surfaces and visually verify correct operation. When engines have stabilized, start taxi not exceeding 20 knots ground speed or 40 MPH. Avoid rough ground so as not to damage the gear or debris intake damaging the engines.
Frequent breaking will be necessary due to high engine idle RPM.
Warm surface temps and frequent breaking will activate the yellow "TIRE" warning.

o Position and Run-Up:
-Position on the runway into the wind, set the parking breaks and bring up the autopilot.
-Inspect all gauges and switches for correct position for take off. Wait for yellow TIRE warning to extinguish.
-Activate Pitot Heat and also De-Ice if you are passing through freezing clouds on the way up.
-Check Roll, Pitch and Yaw trims for zero position. Operate pitch roll and yaw stick controls and observe they all move to maximum positions (100%) and return to zero.
-Tap the numpad-5 key (with numpad off) to center your control inputs.
-With breaks set, smoothly advance the engines to full military (80% green) for correct operation. IGV lights should illuminate. Return throttle to idle. IGV lights should go out.
-Set decision altitude bug to 350 ft on the radar altimiter.
-Test proper IAS hold operation by briefly clicking on the IAS hold in the AP. The bug should stay where you placed it. If it moves, reset it. Next time you activate it, it will not move. Set throttle back to idle.
-Double check everything.

o Take-off:
Equivalent Air Speed is used for high speed flight. You will see KIAS (Indicated Airpseed) or KEAS used in specifications and procedures depending on documentation available or whether the flight mode is subsonic or supersonic.
Set the AP AT IAS bug to 255 KIAS for restriction or 464 KIAS (to obtain an initial 400 KEAS) non-restricted climb. Preset your desired initial climb rate. This is typically between 7000 and 10,000 ft per min. (The default is 1000.)

-Smoothly advance the throttle to 80% (full military.)
-When bright amber IGV lights come on, release the breaks and after reaching full military power, engage the Afterburner (shift-F4 in standard and Deluxe.)
In AccPack, advance throttle beyond 80%. Throttle position numbers will change from green to white, REHEAT gauge lights and the TEB counter will drop another number to ignite the ABs.
-(optional:) Activate full take-off power (TO/GA) by tapping the key combo Shift-Alt-G or click on the left throttle position number next to the top of the throttle (the numbers will change to orange or dissapear.) Using this feature will help prevent over speed on the engines.
-Passing 156 knots (speed check) you should be over half way through your roll distance. Be prepared to pull the throttle back soon to avoid EGT limits in hot weather or conform to any area speed restriction which might be in place. If your climb is unrestricted, keep the throttle at 100% (or TO/GA mode) through the initial climb.
Observe EGT temperature and do not advance throttle beyond 850C unless absolutely necessary. 900C can only be used for 2 minutes maximum and 950C has a 15 second limit. Normally, the de-rich system will prevent exceeding 960C on take off.
Note: At standard temperatures (50-60 degrees F) full throttle will rarely exceed 850C EGT.
Note: Very warm surface temps will limit climb rate.
-Crossing 156 knots Indicated during roll, reduce throttle to apprx 85% to prevent over-shooting terminal area speed restriction of 250 KIAS when in ATC control. Otherwise, when non-restricted stay in TOGA mode.
-At full weight (66K lbs fuel) rotate the nose steadily at apprx 205 KIAS to 10 degree pitch and hold until lift-off into a 2000 ft/min climb (strong down pressure will be required to prevent nose up.)
-When using 45K lbs fuel (Normal loading) use 180 KIAS rotation speed.
-On positive climb raise gear immediately. Gear will break above 300 KEAS/330 KIAS. Retain AB through climb.
-Engage AP (Z) and tap Contrl-T to temporarily hold climb profile @ 1,500 - 2000 ft/min and click IAS speed hold 255 KIAS in the autopilot (when flying in restricted space.) Closing on 250 KIAS (restricted) disengage AB and click ALT hold in the autopilot with the mouse. This will happen very quickly!!! The 255 bug setting you set earlier will hold close to the 250 KIAS in restricted airspace.
-Tap Cntrl-H to hold current heading.
-Unrestricted, you must first obtain an initial airspeed of 300+ KIAS while at a low climb rate. Continue to climb on TO/GA and set best climb rate to hold as close to 400 EAS through to Mach 0.9.
Note: Clicking the speed hold with the mouse has a different effect than using the key combo Control-R.
When using the keys, the AT will be set to the CURRENT air speed of the plane. The mouse will set the AT to the TARGET speed set in the AP bug control.
At this point the plane will be under stable autopilot control in trimmed flight. Resticted: As the speed reaches 250KIAS increase normal climb to 3500 ft.min.
Unrestricted: Max climb off the runway with gear up can initially be as high as 10,000 ft/min on full throttle/AB after passing 300 KIAS using Autopilot VS. Sustainable climb using 7000 ft/min is possible up to 24K ft in normal temperature conditions.

o Terminal maneuvers:
Use ATC instructions or bring up the navigation aids (GPS etc) and navigate to intercept the 1st flight plan waypoint. Observe the 250KIAS speed restriction when flying near controlled airspace. Engage autopilot NAV mode to start GPS flight plan control. External control programs require staying in HDG mode.

-Engage Yaw Damper (Surface Limiter) above 330 knots Indicated (LIMITER in the annunciator.)
-Crossing 18K ft, reset altimeter to 29.92. Crossing Mach .85 set Mach Hold 0.90 for cruise to tanker circuit. Otherwise, hold M.9 for your cruise-climb to unrestricted Mach climb area.
On long flights where fuel top-off is necessary, intercept the tanker altitude @28 - 35Kft.
Older tankers require 25K - 30K feet. In turbulence, use 350 KEAS for the sub-mach climb, otherwise, use 400KIAS. New tankers modified for the SR71 can use 34K - 35K ft.
Note1: 35,000ft and 350KIAS is the highest and fastest the plane can fly and still remain sub-mach (apprx M.97) 28,000ft and 400 KIAS is more typical providing M.95.
Note2: Max turbulent speed is 350KEAS so only use 400 KEAS in calm conditions.

o Refueling:
Intercept the tanker between 280 and 305 KIAS or Mach 0.85 (whichever is slower.) Under current model configuration, fuel top-off is typically filling ALL available tanks. When refueling with take off COG at 22%, a COG over 24% will result in a warning. The warning will clear as soon as speed in the climb over Mach .9 is obtained. Using the supplied refuel gauge, enable the RDY/DISC button so "0000" is displayed on both top and bottom rows of numbers and click the "Air Refuel" switch.
The rate is @6500 lbs/min, all tanks simul-filled 5-10 minutes at 56-70 psi. The refueling gauge operation is also discussed in the Special Gauges section above.
At typical tanking speed of @280 - 300KIAS, and full fuel, the pitch attitude will be around 10+ degrees.
Note: In reality one tanker could not hold enough fuel for a full SR-71 replenish so required a second tanker to obtain the last 5000 lbs. This is not enforced in the model.
Marginal military power at high pitch can be compensated by enabling AB on one engine and using differential engine control to compensate for yaw.

o Dipsy Doodle (modified for FS9/FSX):
This is the most common technique used to accelerate into the mach climb after refueling to a heavy condition which helps to transition through the high drag of mach 1 at low pitch. After refueling, set AT hold for speed Mach .9, engage AB (or remaining AB if one side already enabled) and set climb rate to 2000 ft/min.
If you have refueled at 35K ft, set Mach hold to 0.95.
Between 30K-32K ft increase AT speed bug to Mach 0.95. Passing M0.95 and 33K ft or above set AT bug initially for 530 (for 450 KEAS climb) or 470 (for 400 KEAS climb) and start a -2000 descent through Mach 1.15. Do not descend below 29,000 ft.
Passing 390 KIAS when using 400 EAS climb increase climb to +2500 fpm. When using 450 "Normal" schedule, set IAS hold to 530 KIAS and when crossing 450 KIAS set climb to +2000. As EAS in the Triple gauge crosses 400 or 450 without blinking, engage EAS hold.
When using 400, set climb rate to +3500. When using 450, set climb rate to +3000.

o Mach Climb:
There are two common climb speed "schedules" used:
450 KEAS which is the "normal" high speed climb into a high risk area after tanking. Fuel burn rates are fairly high reaching 40-44K lbs/hr at Mach 3. On a 1.5 hour flight, around 2000 lbs more fuel will be used than the 400 EAS schedule. This profile gets you over the mission area at high speed, but low altitude again soon for re-tanking. Climb discussions in most books about the SR mention this profile as it's commonly used for incursions close to enemy recon targets.
400 KEAS is used when longer range is needed between refueling. Mach 3 fuel rate is closer to 38K lbs/hr. This profile gets your plane higher sooner, but establishes cruise at a lower initial speed. The world record flights between Beale and Farnborough used a profile similar to the 400 KEAS schedule between refuel tracks.

When flying light (45K lbs fuel or less) and refueling is not used, it's possible to start the climb without the Dipsey Doodle.
Starting from level at Mach .95, engage the AB and set the AT bug to 470 (to obtain 400 KEAS) or 530 (to obtain 450 KEAS) and ease into the desired climb rate starting shallow passing 380 KEAS or 420 respectively. As in the Dipsy Doodle climb, the initial climb target is 74K feet at Mach 3.0.

Adjust Mach speed using this procedure: How to set Mach Hold over 3.00 in FSX

At high fuel loads and 450 KEAS climb speed, climb rate is slowly decreased as follows:
Note: These are guides for 80K ft cruise. Actual operation may vary depending on target altitude, weight and weather conditions.
60Kft = 1500 ft/min
70Kft = 1200 ft/min
75K ft = 1000 ft/min
78K ft = 700 ft/min
Within 2K feet of target = 500 ft/min

Alternatively for more fuel savings, use the Concorde style "Cruise Climb" at 100 ft/min above 60K ft qhwn over 50K lbs fuel. You should cross 74K ft at Mach 3.0. As the fuel rate per engine drops below 19K lbs/hr, gradually increase mach speed until the desired speed and altitude is reached. The 400 KEAS climb profile can use more aggressive climb rates than the 450 KEAS profile. Cruise Climb can also help get through rough weather areas where a slow increase in speed and altitude is much better tolerated than blasting up to target altitude and speed and trying to hold it while encountering extreme weather changes. According to one source, cruise climb was used 99% of the time by SR pilots.

Note: AP initial IAS bug setting for max climb and normal 450 EAS in Auto-Throttle is 530 IAS, then engaging KEAS Hold crossing 450 KEAS.

While in turbulence, Mach Climb will use 350 KEAS.
High Speed Climb:
1) Set required altitude in AP.
2) Set 530 IAS in the AP panel and while climbing ~ +2000 ft/min, click EAS Hold to capture initial speed of 450 KEAS on the triple gauge for the 450 KEAS climb profile. Increase climb rate to +3000 ft/min after capturing the 450 EAS hold.
3) Beale to Farnbourough world record flight uses 400 KEAS and 3500ft/min initially for the first two Mach 3+ cruise legs, then 450 for the last leg after refueling past the Canada East coast.
4) Engage After-Burner (note: AB will stay engaged throughout flight until descent.)

Aft Bypass:
During climb the pilot manually sets the Aft Bypass Door positions to keep the Foward bypass Doors within their correct ranges. The foward doors maintain the correct pressure in the front of the engine by opening up and bypassing air past the intake. If they open up too much, excess nacel drag is created. Move the aft doors on this schedule:
Take off: Closed
Mach 1.7: Position A
Mach 1.9: Position B
Mach 2.6: Position A
Mach 3.05: Closed
There are times during cruise the pilot may need to move the bypass doors between Close, A or B. This is discussed in the section for the Aft Inlet Bypass Doors gauge.

At take-off the plane is fairly evenly balanced. Too high Center of Gravity at take off is more likely to have a tail strike from rapid rotation. During flight the #1 tank fuel burns off first- slowly moving the COG rearward for mach cruise.
During descent, approach and landing, normal fuel attrition and automatic tank switching will result in foward moving COG for landing (unless the pilot applied unusual fuel loading.)
If you want to manage the CG manually, three controls are provided: Pump Release, xFeed, and Fuel pump Fwd, Aft. This is a failrly complex procedure. Auto is recommended.

400 EAS Hold: As you approach Mach 2.83 at near 74K ft, engage Mach hold M 3.0. I use 3.05 in the bug to prevent dropping below M3.0 in slight turns.
Continue shallow climb and watch fuel flow. As flow drops below 20K lbs/engine, slowly advance Mach hold to stay near 20K lbs/hr until desired speed is reached.
Note: When 450 KEAS Hold is used, the EAS Bleed schedule starting at Mach 2.6 will automatically engage reducing the speed gradually to Mach 3.0 near 71K ft without pilot intervention. You can see the current bleed target in the AP panel EASH display.

Cruise Climb:
Nearing 60Kft. reduce climb in a profile called "cruise climb" to around 100ft/min up to the target altitude. It's not unusual to change altitude after reaching cruise to optimize the flight for weather conditions. Crossing Mach 3.0, total initial fuel rate may be near 40K - 44K lbs/hr. Closer to Mach 3.2, rates may drop to 36K-38K lbs/hr or less as fuel depletes. Above Mach 3.2 fuel rate will increase again due to friction. Occasional extreme changes in weather server data may cause much higher or lower fuel rates.

----------------------- WARNINGS FAILURES AND PROCEDURES: -----------------------

Avoid pitches in the AI display over 5 degrees. At apprx 5.5 degrees stall is imminent above Mach 3. WARNING!!!: DO NOT ALLOW PITCH on the Attitude Indicator to drop below zero above Mach 2. Temperatures warmer than -58 deg C and over 72K ft are marginal operation. Climb to cooler temperatures or hold present altitude, or descend to maintain pitch under 5 degrees.
Structural failure will occur @ 520 KIAS.
Static Temperatures of -75 C or lower will reduce engine output to less than max rated power.
Deep Stall will begin above 60K ft and slower than 310 KIAS. It starts as a "twitchy" altitude hold where it appears the AP has trouble holding the altitude and the needle always sits just below the set altitude. I strongly advise not flying under 380 KIAS at or over M3.0. You also risk Unstarts and compressor stalls the closer to 300 KIAS you get.

- Reduce climb rate, level off, disengage heading or nav hold. Descend as conditions require to increase speed as fast as possible. Maintain highest safe mach. Do not exceed M3.45. When pitch attitude drops to stable condition, maintain profile (no matter how long it takes) until a typical pitch of .1 to 4.8 degrees is obtained and 100% throttle is no longer required to stay above stall speed. Only then can climb be re-engaged.
Note: Sometimes conditions combine to limit engine power AND provide excessive pitch. This will seem like a no-win as the temperature limits the engine so you cannot increase speed and lower the pitch. Descend or maintain altitude until stable flight is obtained. If the problem is caused by too-warm temps heating up the CIT and EGT, it's often best to avoid acceleration for a while. This will help the engine cool enough so you can begin a moderate climb into cooler air.
In ASN, the stagnant temperature of the tropopause starts at 49K ft and begins to get warmer above 65K ft.

ENGINE COMPRESSOR STALLS (no unstart lights:)
- Caused by:
1) Excessive AOA during climb (see specs section.) Reduce climb rate, level out, or descend rapidly.
2) Airspeed too low (below 350 KEAS) during descent rates greater than 1500 ft/min. Increase descent until faster than 350 KEAS.
Restart engine. Tap Shift-Cntrl-F4 if the first auto-start sequence fails. The auto-start sequence will usually try three times before giving up.
If you continue to have trouble starting engines, check the Fuel Switches on the Fuel and Oxygen Panel.

- Caused by improper spike position, decelerating too quickly while above Mach 1.5, Hard banking turns, or stalling the aircraft below 300 KIAS while above Mach 3.0.
Place spike in proper position (or return to AUTO [DOWN].) Continue to monitor for correct position during rapid deceleration. Reduce climb, level out, or descend rapidly (-7000 ft/min or more) to build speed above 350 KEAS.
Wait for auto-restart sequence. If auto-start fails, hold start button on main panel until ignition. Alternatively, press the key sequence Contrl-E.
Historically, engines could not be restarted until descending and decelerating below Mach 1.7. This limitation is not emulated at this time but may be in the future. Unstarts will not happen below mach 1.5. but compressor stalls can occur from excessive bank turns at low speed.
If you continue to have trouble starting engines, check the Fuel Switches on the Fuel and Oxygen Panel.

High pitches due to excessive climb rate, severe weather changes, or inattentiveness to power profile may result in loss of power at max throttle.
Too-high pitch may cause power loss.
Temperatures warmer than -55 degrees C or colder than -75 degrees C may cause power loss.
Level out or descend gradually until pitch and temperature permit power recovery. Avoid maintaining flight conditions where The auto-throttle stays at 100% when at mach cruise. In normal mach 3+ cruise, throttle is between 96 and 98%.

!!!! Engine Overheat Warning !!!!
If the CIT temps are permitted to hold or exceed 428C continuously for 30 minutes or more, one engine will be commanded to fail. Each engine has a 50% chance of failure at this temperature. A failed engine cannot be restarted. The non-failed engine will continue to operate. The rapid reduction in speed and temperature will prevent damaging heat in the remaining engine. With one engine operating on AB, you will need an initial descent rate of -3000 ft/min to keep the speed from going below 300 KIAS. When 100% power on the remaining engine to sustain 300+ knots is no longer required you can look for the nearest runway with 7000 ft or more to land. This sustainable power profile should occur around 60K ft and lower. Depending on your fuel load, you should be able to find a runway up to 250 miles away.

Overspeed conditions are very dangerous and you only have seconds to react. When flying near the mach limits very slight changes in weather can bounce you over the edge without warning. M3.2 normally provides a safe buffer zone with 100 knots between both overspeeds and stalls. Overspeeds are caused by very high (non-typical) pressure jumps. The best cruise technique is to hold close to 350 KEAS. 450 KEAS climb schedule is the most likely area where overspeed will occur as the EAS is just over 500 at certain altitudes. The KEAS hold button has the best capability to prevent overspeed on the climb. When flying using normal procedures and schedules, overspeeds are very unlikely uisng the Hold feature.
Disengage AB. Turning off reheat is the fastest way to react to overspeed but will cost you a TEB hit to restart. The result is a large power loss which helps slow down faster. If you don't want to use up TEB, a large manual pull back of the throttle will be necessary. If AB disengage is not enough, Disengage AT (shift-r) and idle the throttle. Avoid descent. Maintain altitude or climb will help prevent acceleration and increase your overspeed margin. Upon slowing to safe speed (do not slow below M 2.8) re-engage AB and/or AT (shift-r). Careful attention to the spike position will be necessary with large speed changes.

!!!! Electrical Power loss and Dead Stick Landing !!!!
Dead stick landing after the loss of two engines has been simulated as well as loss of generator power to the battery. Many successful dead stick landings have been made from 70K ft and up to 200 miles from a runway during testing. Longer distances are possible.
If the load on the battery is reduced to only necessary items, the battery will support the flight through landing.
If the battery fails, vital navigation equipment will remain functional:
Vertical Speed
Radar Altimeter

------------------- END WARNINGS FAILURES AND PROCEDURES -------------------

Engine Spike:
This model is automatically controlled above Mach 1.6 and provides @1+% N1 improvement in efficiency at full retract (full flap deploy) into the engine. These are the settings should you descide to use the spike mode knobs in the Manual switch position (knobs facing right):
Subsonic to Mach 1.69 = spike full forward zero inches (F5)
Mach 1.7 to Mach 2.04 = 1 - 6.4 inches
Mach 2.05 to Mach 2.42 = 6.5 = 12 inches
Mach 2.43 to Mach 2.75 = 13 - 19.4 inches
Mach 2.76 to 3.10 = 19.5 - 25 inches
Mach 3.11+ = 26 inches
(F8 full engine spike retraction)

NOTE: At speeds of Mach 1.6 or greater, leaving the spike out of configuration for an extended time will cause temporary loss of the afterburner and of engine, requiring each to be restarted which costs two shots of TEB.

After switching the AP AT bug to Mach Hold at Mach 3.0, monitor the engine fuel rate. As the rate crosses 19K lbs/engine, slowly advance the mach hold or IAS to obtain the desired cruise speed for the remainder of the flight. Ideal fuel rates should be near 18K lbs/hr per engine. Be prepared to alter the cruise speed and altitude if changes in weather cause the plane to fly near the documented limits of 558 KIAS max or slower than 310 KEAS and/or max 427C intake temperature. You also want to avoid excessive fuel rates which might prevent you from getting the range you need for the mission.
There has been much discussion and speculation about the top speed capability. My opinion as to why we don't yet know the official top speed is because no one inside the program knows. Pilots flew the plane according to strict procedures controlled by the training or mission parameters which dictated fuel rates and altitudes to obtain maximum range between re-fueling assets and turn rates to prevent border or threat area incursions. The few times pilots got to push performance were in official speed record tests where clearly the plane was not being flown to its limits. Other high speed incidents occurred during missions where unexpected things happened. In some cases damage or loss resulted. In terms of raw specifications, the airframe clearly surpassed the design specification of Mach 3.33 or 500 KIAS. In reality, the limitation was not the power of the engine, but the danger of thermal damage beyond the intake temperature of 427C. The plane was never purposely flown above this limit. The limits set in this model provide a generous margin when operated in typical real-world flight profiles and weather.

Ideal Cruise Summary:
  • As close to 400 KIAS/360 KEAS as possible. Above 80K ft, lower airspeed is normal.
  • Above 310 KEAS
  • CIT below 427C
  • EGT below 830C
  • Fuel rates close to 18K lbs/engine (180 on digital readout)
  • Pitch below + 6
  • Pitch trim between 0 and -3

This is the most stable and low-maintenance stage of the flight.
Unless a weather condition causes one of the anomalies above, no action is necessary.
Your task is to manage speed and altitude to keep the pitch bug on the Artificial Horizon between the level and +5 indications. You will monitor the intake spike for proper movement CIT for temperature, CIP for needle aligment, and foward bypass for drag and unstart protection. If fuel loading procedures were followed carefully, the fuel balance and attrition system will maintain controlled flight and balance within operational limits without intervention. The auto system will most closely track ideal when fueled to the medium range profile of 66K lbs on the ground.
Panel warnings will activate if COG or speed is out of limits for the flight profile. You can correct small imbalances with the fuel pump switch in the fuel panel.
Above Mach 3, a green annunciator panel indication will light showing the ideal COG range for the current weight and AFt Bypass setting. Ideal pitch trim for best fuel efficiency will be between zero and minus 3. Positive trim is normal early in the cruise at high fuel loads. Speeds of Mach 3.18+ where spike is fully retracked is best efficiency.

Keep this in mind:
- Higher, colder air provides higher mach indications and more fuel efficiency at a cost of reduced total engine power. Stalls are more likely.
- Lower, warmer air uses more fuel and heats the engine and surfaces. Over-speeds are more likely.

o Descent:
Note: High mach speeds procedures use KEAS (available in the main panel "Triple" gauge.) rather than IAS.

Descent Profile:
Descents are the most challenging part of flying the SR-71. A lot goes on in a short time and the performance constraints are tight. The pilot needs to be alert and have all the activities planed out ahead of time.

Note: The angle at which the air enters the engine at supersonic speeds is critical. Notice the engines are pitched down compared to the airframe so while the airframe is pitched up slightly at cruise, the engines remain close to on-axis to the air flow. When descending supersonic, there is a limit to how much off axis the air flow can get without stalling the engines.

The object is to approach the descent point as close to 400 KIAS and 350 EAS or more as possible to make holding 365 KEAS in the descent as easy as possible. 365 KEAS is used because it keeps the plane well above 350 EAS below which unstarts are likely.
If you start the descent under 350 KIAS, you risk an unstart, so you must accellerate while at a shallow descent (no more then -1500 ft/min) until the plane is fast snough to engage EAS Hold safely.
If possible, try to obtain and lock in 365 KEAS hold just before or shortly after starting descent.
The easiest way to do this is when starting the decent and EAS is between 350 and 360, swith to IAS hold (if not already) and set your descent altitude target bug to a very low value (10 - 20K ft) and -4500 ft/min descent rate. This will give you time while the aircraft slowly accelerates to 365 EAS in the Triple gauge.
As the EAS display in the Triple gauge crosses 365 with a solid display, immediately click the KEAS Hold button on the refuel panel above the Drag Chute Lever or within Autopilot panel. The EASH display in the Autopilot panel will indicate the speed you have captured. Don't worry if your captured speed is a knot or two off.
Note: The EAS hold will not hold perfectly, but close enough to take the workload of managing the descent speed off the pilot. Most importantly, set properly, will prevent the EAS from going below critical 350. The new EASH display in the AP panel will indicate the current hold speed you have captured.
Soon after starting descent, close to the time of 365 EAS hold, the throttle will back off enough to force the afterburners to disengage. The hold will now transition to holding the documented *IAS* for the remainder of the descent. This helps insure the engine RPM will not fall below critical speed.
The engine spikes will start to extend. Power is now limited to full military, so you need to manage descent rates to stay near mile/altitude targets and keep the plane from flying too slow.
You can now concentrate on managing the descent rate with two objectives:
1) Crossing various altitude targets at set distances from the landing or refueling target.
2) Preventing the engine RPM from spooling below 6100.
Note: Static temperatures colder than -74C will cause more difficulty keeping the RPM over 6100, so make sure the Aft Bypass Doors are set to CLOSED which adds some drag from the engines. When close to mimimum RPM, the EAS Hold will increase speed to try to keep the RPMs from dropping too low. In VERY cold descent temperatures, you may need to use the forward bypass knobs set to full open to add additional drag. You can also reduce the descent rate. Don't forget to close the aft bypass again below Mach 1.5.
Use the "friendly" descent target chart below and adjust descent rate (typically settings start around -4000 to -6000 near the end.)
When the aircraft speed is below Mach 1.5 you can relax a bit as unstarts from descent rates are no longer possible which means you cen set any speed and descent rate you want.

Mach 0.90 and 5500-6100 RPM is the standard cruise speed below Mach 1. Descent angle is typically between 1 degree at the start to near -7 degrees around Mach 1. AOA gauge should never go below zero degrees.
If decent rates exceed -6200 ft/min, "CAB/N PSI will display on the Annunciator indicating the cabin pressure and fuel tank Nitrogen pressures are affected. Reduce descent rate or switch pressure to 10K ft temporarily. 10K cabin pressure will increase H2O usage considerably.
Higher descent rates risk engine RPM falling below 6100 causing compressor stall. KEAS hold has both minimum and maximum hold values built into it to restrict overspeeds and stalls. The Master Warning light and RPM digital readout changing from white, to yelllow, to red indicates the pilot must take action to avoid minimum RPM stall.
The chart graphic above is converted into more FS friendly table and is also displayed in the simulator kneeboard:







M3.2/365 KEAS



M3.2/365 KEAS



M3.2/365 KEAS




M3.2/365 KEAS



M3.2/438 IAS




M2.8/437 IAS


69K ft

Mach 2.5 and below 6900 RPM by this altitude.



M2.1/428 IAS




M1.65/416 IAS



M1.5/365 EAS/408 IAS



401 IAS




391 KIAS/M0.78
Opt: Disable EAS Hold. Set 388 IAS, maintain
400-410 IAS for landing target until restriction speed.

Under 150 miles:

If Hold still engaged, AP will continue to
slow to 379 IAS by 25K ft.
Set desc rate per desc calc gauge with approach target altitude set in AP alt.
Mote: Descentometer supplied with panel is most useful below 20K ft.



379 KIAS

* Suggested descent rate may vary greatly based on altitude, speed, weight and weather.

(Edited for sr2012Updt1c):
Slowing below Mach 0.90 "CG HI" in yellow could display on the Annunciator. This is an awarness status and normally does not require action. Fuel Low indicates tanks 2 or 4 are below minimums which is unlikely to occur in a normal flight with proper ground fuel loading.
At 18K ft, set IAS bug to 340, and 16K ft, set 320 KIAS. At 14k ft AGL, set 280 KIAS. At 12K ft AGL, slow to 250 KIAS by setting IAS bug to initially to 240 then adjust upward to hold 250. Within 30 miles of landing slow to 220 KIAS minimum turn speed (10K lbs fuel.) Faster if heavier than 10K lbs total fuel.

o Terminal maneuvers and approach:
APP1 (21K)
At light weight and slow, the model turns and changes speed rapidly. The pilot manual describes the sub-sonic handling as "adequate" and interviews with crew describe it this way in "SR-71 In Action":

"Subsonic, it feels like a big, heavy airplane, and you have to horse the stick around a bit to get the airplane to move."

Final approach should use speeds as suggested by weight and approach chart near the top of this document. Typical terminal speed for base turns is 220 KIAS minimum.)

Normal landing weight is 10K lbs and base turn should be made @16 miles (manual control) to 20 miles (AP/APP mode) and 220 KIAS. Higher fuel loads and or turbulence require higher speed.
When lined up reduce speed to 175 KIAS.
At max weight, decel to threshold speed should be made at least 9 miles out. 10K lbs fuel can decelerate in @7.5 miles. Threshold AOA is 9.5 degrees. Pitch is 10 degrees (not to exceed 14.)
Use shift-enter(FS9) Cntrol-Q(FSX) key sequence to lower the view to see the runway. In this model, the 3D panel provides the best undistorted view
shift-backspace(FS9) Control-shift-Q(FSX) to pitch up or SPACE key(FS9) to recenter view to default.
Note: Many pilots remap the FSX shift-num-0 back to FS9's spacebar.
The Approach Auto-pilot will hold a steady glideslope with fuel weights up to 22,000 lbs down to around 600 feet.

Observe the AOA gauge to keep the threshold attitude under around 9.5 degrees.
Note: Fuel weight over 40K lbs requires 275 knots IAS above 10K ft. keeping RPM over 6400 and land around 250 knots IAS and 10.5 degrees pitch.
- Upon GS capture (when using AP APP mode) lower the gear passing - 5 ft/minute.
- Arm drag chute if there is little or no crosswind. An armed chute is indicated by the lever center changing from black to orange. If there is significant crosswind, operate the chute manually after the front wheels touch down using shift-/.
- Between 500ft and 600ft take manual control (z key) of pitch, roll, and yaw while targeting the threshold with between 700-1000 ft/min descent.
- At apprx 150ft AGL, flare to obtain minus 50ft/min or less and reduce throttle to idle at 10 ft altitude after the key sequence control-r (to disengage AT control.)
On touchdown, chute will deploy on wheel contact WITH THROTTLE IDLE and AUTO-DEPLOY ENABLED.
Use stick back pressure to lower the nose slowly until front gear contact at 100 knots. On cross wind landing, deploy the chute manually AFTER front wheel contact.
-Begin gradual breaking ~65 knots ground speed. Anti Skid will prevent full breaking until speed passes below 12 knots. Expect siginificant breaking effectiveness with rain, ice and snow.
- Around 30 knots jettison drag chute (/) or increase engine speed slightly for a few moments. Increasing speed resets the auto-spoiler logic.
- Taxi to parking not exceeding 20 knots ground speed or 30 MPH. Shut down engines using contrl-shift-F1, reducing throttle(s) below zero (typcially -3.1) or fuel panel switches.
Note: The high RPM of the idle engines may result in nearly constant breaking at low weight typical at landing. If breaking is a problem, one engine can be shut down. However, this causes a lot of steering to compensate for the induced yaw as a trade off.

Real world tanker descent (assumes M3.2 80Kft):
Speed and settings are similar to landing descent.
-Start descent 328 miles from runway. Tanker is expected 100 miles this side of runway.
-Set descent alt (target) in AP for 29K-35K ft in IAS hold mode.
-Gradually set initial dec rate to 4500.
-Crossing 365 EAS click EAS Hold and increase descent rate to -5000 ft/min and follow tanking descent chart.
- At 40K ft, set AT bug to obtain 400 KIAS and target crossing 30K by 150 miles.
- At 30K target crossing 25K by 140 miles. Set AT to obtain 370 KIAS.
- Within 100 miles of runway, adjust dec rate so calc display is 20 miles lower than distance to runway. Maintain this difference for remainder of approach to runway.
- At 30K ft, set AT bug to obtain 370 KIAS.
--- If using tanker, start rendezvous operations. ----
- At 25K ft, set target alt to runway approach altitude.
- @50 miles from runway and/or 14K ft, set AT bug
to obtain 300 KIAS crossing 12K ft.
- At 12K ft, set AT bug to obtain 250 KIAS by 10K ft.
- by 30 miles from runway, be slowed to 220-230 KIAS minimum maneuvering speed.


For those interested, a more complete explanation of the Fuel Balancing System:
When the standard loads of 45K, 55K, and 65K lbs fuel are used, the resulting CG should be between 20% and 22% while on the ground. By the end of taxi, CG around +-21% is normal.
There are two modes of CG control: Passive and Active.
The position, quantity, and tank selection by normal FS attrition contributes largely to CG during climb and early cruise. Passive mode is indicated by zeros in the TGT: display and by the xFeed Open lamp lit bright in the Fuel Annunciator. If the pilot clicks on the xFeed ON switch, the Auto CG system will be disabled and xFeed forced on all the time. Note: It is not a good idea to click this switch to On (forced on) unless necessary which is why it defaults to off.
There are two active modes: Tank Selection and Tank Pumping.
Active is used largely to maintain high speed cruise CG, descent and landing CG. When in Active Mode, the xFeed Open lamp in the Fuel annunciator will not be lit and there will be a non-zero number displayed in the Fuel Panel "TGT:".
When the CG error is low but a correction necessary, individual tanks are selected which affect the balance in the desired direction. If the error grows beyond a certain limit (which could happen if the tank switching does not affect the CG fast enough) tanks 2 and 4 (centers) will pump fore and aft until the error is within tank selection or passive system effectiveness. Active pumping is indicated by the green lamps lit bright in on the Fuel Panel Pump switch. If these two tanks are full or near empty, the active pump is suppressed, but the active switching continues. Below 8000 pouds total fuel, all active correction is suppressed and passive only is in effect. Active mode is indicated by a target CG number in the "TGT:" display and the Fuel Annunciator xFeed Open not lit (unless the pilot clicked to over-ride.) The TGT percent is the CG the Active mode is trying to enforce an upper or lower limit on.
For Active/Auto pumping to operate, the pump switch has to be in the Center position and the Pump Rel light in the Fuel Annunciator must not be illuminated. If Pump Rel is activated, the auto pump system is disabled and the pump must be operated manually.

During the climb, tanks 1 and 4 deplete together providing a slow CG transfer to rear. At heavy weights, the rear tank 6 engages to prevent excessive rear CG for the weight. As speed increases above mach 3.05 and below 120K lbs gross weight, the CG will gradually move rearward based on speed to the maximum of 24.97%. If the pilot attemps to intervene for CG greater than 25%, the tank 6 will again engage to attempt to prevent this. Active pumping will engage if active switching is ineffective.
When tank 1 is empty, tank 2 will take over maintaining rear CG until it reaches the minimum of ~5400 lbs. This is just enough weight to provide some pilot intervention when landing near or below 10,000 lbs fuel weight. Your flight plan should always allow for landing as close to 10,000 lbs fuel as possible.
Below 30,000 lbs total fuel weight, CG is gradually lowered in favor of setting up descent and landing. Below 30K lbs fuel the influence on balance error is much reduced and the Annunciator no longer displays the suggested CG hint. This is not a problem.

As the aircraft approaches the terminal area and 21.5% CG, the remaining tank levels will work together to hold this CG as long as possible. Active CG control may not work well or at all with fuel levels under 8,000 lbs. Keep in mind 21.5% is the ideal CG for a 10,000 lbs fuel landing, so low CG and under 10K lbs fuel is not a big problem. It's quite easy to perform a good landing below this weight when proper AOA and speeds are used. The closer to 10,000 lbs fuel, the less the pilot has to be concerned with fuel balance maintenance and the landing is the easiest. Heavier weight also makes stopping a little easier when at low speed, but harder whan at high speed.
Note: If the tanks are unbalanced left and right automated CG errors would occur. To prevent this, crossfeed is on for all tanks in passive mode, meaning there is no Left and Right engine isolation.
Passive mode is also engaged in an engine stall or unstart where the crossfeed will minimize L and R inbalance while only one engine is operating.

Some interesting facts:
The SR is composed of Titanium and Composite (plastic/carbon) materials. The landing gear is the largest piece of titanium ever forged in the world. The United States did not have enough titanium to build the fleet and ironically, we bought the needed titanium from Russia.

50 Blackbird airframes of various designations were built. The nose section can be removed and swapped with various configurations in radar and sensors and different shapes to the nose.

Speed/Altitude Limits: The highest speeds and altitudes claimed by verifyable sources are Mach 3.5 above which center window frame heats to the point of damaging the windows and a reported accidental altitude of 87,000 ft. The world record of 85,000 ft is considered the maximum safe altitude above which the engines start to become starved for oxygen. Conditions at which 85K ft and above can be obtained are not always available (ideal temperatures, pressure and weight.)

Costs to operate have been difficult to estimate due to the large variation in missions.
In my opinion, the most believable figure is $27,000 to $32,000 per hour exluding tankers, training, and various logistical support.

The A-12s were never called "blackbirds" and were referred to by their program name "CYGNUS" or "CYG".

The SR-71's fly at 33+ miles per minute (1,980 MPH/1,722+ knts) or 3,000 feet per second, faster than a 30-06 bullet.

Each SR-71 cost 33 million to build.

At Mach 3.0 the air flowing into the engine intake has to slow down to Mach .6 to prevent compressor stall. This is the equivalent of slowing from 2100 MPH to 600 MPH in 20 feet.

Aircraft skin temperature can reach 800+ deg F.

Refueling was not performed primarily because of high fuel loss from leakage, but to have a larger performance margin on take off in case of an engine flameout. At full fuel load above 35 ft, the minimum dyamic control speed with one engine on full military power is over 280 knots indicated!

On average, an unstart would occur about 1 out of 5 flights. Some planes more often than others.

Sonic Boom transmission time 75K ft: 1 min, 20 sec.

AB in Flight:

J58_AB_standT3 (12K)Full AB thrust test stand exhaust flame apprx 30ft long
producing 311 deg F temp and 150 knot winds 100 yards behind the engine.
Another jet engine is used to push hot, super sonic air into the intake. These shots were taken after closing the SR-71 program while burning off the last of the stored fuel.

J58_AB_standT1 (20K) J58_AB_standT2 (14K)

The cameras can photograph a golf ball on the green from 80,000 feet. They can survey 110,000 square miles of the Earth's surface per hour.

Ben Rich of Lockheed announced that the SR-71 had over 1,000 missile launches against it, but none successful. In 1981 a confirmed missle launch of two SA-2 missiles on an SR-71 occured near the Korean DMZ. The typical evasion technique was to keep flying straight so as not to slow down. Then existing communist computer technology was not fast enough to calculate an intercept from 16 miles away at closest point.

Pilots in a pressure suit can lose up to 5 pounds in a four hour flight.

Because of the sleek "hooded" appearance of the Blackbird caused by the chine, the Okinawans claimed it looked like a Habu cobra snake. Thus the nickname.
Apparently it's not normally aggressive to humans but has a nasty bite.
SR-71 Crew members are also called "Habus."
RODN is famous for the "Habu Hill" where friends, familly and local fanatics would gather to watch and photograph a take off. Pilots would rate each other on how large a crowd they could attract.

The SR-71 flew for 17 straight years (1972-1989) by the US Air Force without a loss of plane or crew. Of the 50 variants produced, 19 crashed with no loss of US Air Force crew.
One CIA crew was lost launching a drone in an M-21. The recon officer drowned in his chute on landing in water.
Another accident related to right engine unstart during turn at cruise causing a breakup and loss of the RSO during a Lockheed test flight.
The Seattle Museum of Flight in addition to the drone-mounted M-21 has the nose of a
crashed SR71 on landing at Kadena when the front gear collapsed in a storm.
The rest of the plane burned, RSO ejected and pilot rode it out until it stopped.
Visitors can sit in this cockpit.

Last Flight documented by NASA Dryden Edwards AFB web site:
"NASA's SR-71A served as a research platform from 1992 until its final flight flown by Smith and Meyer on Oct. 9, 1999, the last flight by any SR-71. It remains on display at NASA Dryden today. NASA's SR-71B served as both a research platform and for crew training and pilot proficiency until its final flight in October 1997."

478 total people have flown the Blackbirds. More people have climbed to the top of Mount Everest in that time.
- The first test flight of A-12 was made on 26 April 1962 by Lockheed Test Pilot Lou Schalk from Area 51.
- 29 October 1964: SR-71 prototype (#61-7950) delivered to Palmdale.
- 22 December 1964: First flight of the SR-71 with Lockheed test pilot Bob Gilliland at AF Plant #42.
- 5 February 1968: Lockheed ordered to destroy A-12, YF-12, and SR-71 tooling.
- 21 March 1968: First SR-71 (#61-7976) operational mission flown from Kadena Airbase over Vietnam.
- Sept 1, 1974: Beale to Farnborough World record flight.
- Sept 13, 1974: Mildenhall to Beale World record flight.
- 15 January 1982: SR-71B #61-7956 flies its 1,000th sortie.
- 22 November 1989: Air Force SR-71 program officially terminated.
- 21 January 1990: Last SR-71 (#61-7962) left Kadena AB.
- March 6, 1990: Last official Flight Palmdale to Dulles setting new world records delivering to Smithsonian Museum.
- Last flight of a military SR71 into Beale AFB for display: 1997
- NASA used one of its two SR aircraft for research on the LASRE aerospike engine project as late as 1998:

Program Info:(as of Jan 1990) Source:

* Total Flight Hours:...........53,490
* Total Mach 3+ Time:........11,675
* Total Sorties:.....................17,300
* Total Operational Sorties:....3,551
* Total Operational Hours:...11,008
*Total Air Refuelings..........25,862
* Total Crew Members:............284 (includes NASA and USAF Crews checked out in AC)
* Cumulative Hours by Crews:
o 300 Hours.....163
o 600 Hours.......69
o 900 Hours.......18
o 1000 Hours.......8
o 1392.7 Hours.....1

Some historic SR71 bases or refuel/repair/training sites:
EGUN Mildenhall England (Det 1.)
EGUL Lakenheath England (temporary during Mildenhall runway repairs.)
RODN Kadena Okinawa Japan (Det 4.)
KBAB Beale Air Force Base Marysville California USA (9th Reconnaisance Wing US Air Force.)
KHIF Hill AFB Utah.
KEDW Edwards Air Force Base California USA (Dryden.)
KPMD Palmdale (Lockheed Martin Skunkworks Palmdale, CA)
Note: Most flights out of Palmdale were operated by CIA or Lockheed test pilots
and had differing procedures from the USAF including no air refueling.
KSKA Fairchild AFB Spokane WA USA (training.)
KOFF Offutt AFB Nebraska USA:
One brief landing was during the Sunday Mt. St. Helens eruption.
VTUD Udon Tailand.
Utapao Tailand.
KGSB Seymour Johnson AFB North Carolina (1973 Israeli War)
KNFL Fallon AFB Nevada (one emergency landing)
KRDR Grand Forks AFB North Dakota (one emergency night landing Gen/Hyd/ADS failure flying E over Canada) FJDG Diego Garcia Navy Base (one landing)
Carswell AFB, Texas (KNFW Frt Worth NAS?): One landing. Hydraulic pump failure with ground refueling from a parked tanker aircraft.
AR51 Area 51 Groom Lake "The Farm"

Paul R. Varn