SR71 for FS2004(FS9) Operation Guide

Paul R. Varn
Revised Nov 22, 2008

SR71 for FS2004(FS9) Operation Guide based on Freeware release AlphaSim SR71a
Credits
Attributes
Weather Environment
Special Gauges
Specifications

Flight Procedures
• Fuel Preparation
• Weather Preparation
• Ground Operations
• Take Off
• Refueling
• Mach Climb
• Warnings and Procedures
• Mach Climb
• Spike Settings
• Cruise
• Descent
• Approach and Landing

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: "Janes all the World Aircraft."
Boeing Museum of Flight (A12 display and SR71 cockpit.)
"SR-71 Revealed" by Richard Graham. Personal interviews with former pilots, RSO's and Crew Chiefs.
Testers:
Gary Hall (Habu lover)
Marv Thompson who devoted a huge number of hours providing quality feedback and tremendous assistance with assembling/testing gauges for the panel. A truly tireless tester.

IMPORTANT!!! USE AT YOUR OWN RISK! THIS AUTHOR WILL NOT ASSUME ANY RESPONSIBILITY FOR ANY FAILURE WHATSOEVER, IN HARDWARE or SOFTWARE.
NO CLAIM IS MADE AS TO REAL-WORLD ACCURACY OR AUTHENTICITY.
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 FS2004 will allow. All FS realism settings should be set to maximum for realistic flight. The skill level required to fly the aircraft as it was meant to fly is considerable. I suggest new pilots work up to this aircraft by starting with FS2004 training scenarios and up through faster two-engine jets like the Lear. When comfortable with the FS interface, flight procedures, and high speed, multi-engine aircraft, you'll be ready to step up to the fastest plane in the world.

Added REAL after-burner (shift-F4.)
Afterburner effect using smoke effect triggered by AB key.
Added Drag Chute (/ spoiler key - Panel indicator needed)
Note: Model will not fly with drag chute activated!
The COL has been carefully calibrated to closely follow the trim table in the official SR71 pilots manual.
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 also cause Un-Starts.
Compressor stalls during excessive climbs and descents are now possible.
COG now conforms to real world specs.
Fuel loading is simplified so all tanks can be loaded to the same percentage on the ground.
As of May 2008, a dramatic improvement to the speed limit. Raised from 457 KIAS to over 500.
With reality gauges installed (explained below) unstarts and compressor stalls are now possible. They are not random events and may occur from rapid weather changes, steep banks, too slow, too rapid descent or pilot in-attentiveness.

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. Stable flight is a careful balance of flight path planning, altitude, speed, COG and fuel load. Considering the aircraft has no flaps or spoilers, it has a 200+ knots air speed range of stability at Mach cruise.
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 which should not require pilot intervention except if the pilot loads the tanks incorrectly on the ground. Air refueling will maintain this proper balance. A COG warning annunciator gauge and COG readout in the fuel and main panels will assist the pilot in correcting the balance which should be minimal. Fuel loading and maintenance is covered in depth later.
Fuel Balance overview: In short, the fuel is near the normal center of balance for take off (nominally 20%.) If it's too high, rapid rotation causing tail strike may result. Attirition causes COG to shift slowly rearward to a mximum of +23.95 near mach 3.2 cruise.
Near the end of the flight when the fuel load is low, the weight has shifted forward to a minimum of +18.5, then slowly shifts rear again to near +20% for 10K lbs fuel landing. The less fuel on landing, the more rear the COG. There are forward and rear COG limits of +17 to + 25 in addition to more restrictive limits during certain modes of flight. The annunciator will provide yellow warnings when COG is only slightly out of limits (plane is still flyable) and red when maximum limits are exceded. A short period of yellow warning during refueling processes is normal. If you are still high 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 20%. Optimum landing CG is between 21 and 22 percent. Manual pumping nearing the terminal approach area may be necessary.

The Panel is a collection of gauges from other planes which fit the general theme of grey-black high performance aircraft. Some gauges are not accurate. In some cases where accuracy was absolutely necessary, I constructed primitive text-based and graphical XML gauges so the pilot could fly the plane to real-world procedures and specifications. It's not pretty, but functional. 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.

SR71-FS2004 Weather environment:

This graphic from NASA illustrates the earth's atmospheric layers. The SR71 cruises at altitudes between 21 to 27 Km riding the Tropopause. The air temperature reaches its coldest near this point and warms both descending and climbing. In Flight Simulator 2004 (FS) the built-in Jeppeson weather simulator includes data only up to around 45K ft (about 40-50K 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 45K ft is 10-15C WARMER than is normal for 60 to 80K ft.
When using Jeppeson (or similar emulation like Vatsim) by the time you reach SR cruise altitudes, the air is 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. This is why a more accurate weather simulator is needed like Active Sky(AS.) I worked with the designers of this program to encourage them to emulate the Tropopause conditions for high performance aircraft like the SR71 and Concorde. This flight model is specifically designed to operate with Active Sky. Without it, the model will fail. When ANY program sets the temperature of the highest layer, FS will gradually produce warmer temperatures above the highest defined layer.

As AS 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 near or colder than the operating limits. Sometimes much warmer. 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 and speed. I call it "Threading the Amospheric Needle." In the sim, the most important indicators are the Exhaust Gas Temperature (EGT) Air Speed Indicator (ASI) and Fuel Flow (FFI.) To prevent structural damage or stalls, the aircraft has to be flown between a 200 knot speed band (300 - 500 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 following graphic from NASA illustrates the effect of altitude and pressure:

As you fly, FS is constantly comparing the distance to the plane's position to many 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 has the unique ability to create false "virtual" stations in remote areas between real station data. This helps 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 -58 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.) The virtual stations AS creates will help to fill in the gaps between stations, but errors in station data will still cause the FS default conditions to load once in a while. When the aircraft is flying in pressure changes representing hundreds of feet in an instant, the speed and lift of the aircraft can change drastically. Needless to say, this digital weather emulation leaves a lot to be desired compared to the real world. For this reason, the Habu pilot has to be attentive. You can be assured, it is possible to have hundreds of hours of trouble-free flight. I hope I've made you aware though it isn't always that way. Even in the real world, there were some damaged and crashed SR71 planes.

The real plane:

REFUEL: The top left center of the main panel features a gauge with two functional switches (although more are shown)
1) Fuel Transfer Switch (Top Center- shown off in the center position)
2) Rdy/Disc Ready Disconnect Switch (shown enabled.)
The Ready switch must first be activated which opens the fuel door and activates the transfer electronics.
Notice also when the Ready switch is enabled, two rows of numbers also display which were previously hidden.
When the Transfer switch is enabled (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 tank and the tank fills. Because FS2004's ADD_FUEL function always transfers fuel in large chunks, 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 large refuel chunks. After each chunk is transferred, the request number will re-estimate the amount required for the next chunk of fuel, and again when the top number reaches the bottom number the fuel tanks will update.
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 9 1/2 minutes are required to fill from 20K lbs to 80+K lbs. When full capacity is reached, the transfer switch will shut off automatically. 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 show. This 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 display to clear the numbers to zeros.
Constraints: Parameters necessary to operate the switches are very forgiving at this time:
270 - 350 KIAS
24K ft - 36K ft
Both engine fuel valves must be enabled.

High fuel loads at low speeds cause the engines to be near maximum military power during the last portion of the transfer. It's typical for Habu pilots to enable the AB on on engine and use differential engines settings to balance the yaw, thus providing more power headroom.
Note: There is no penalty from leaving the RDY switch engaged although there may be in the future as well as additional refueling constraints. When constrainsts are exceeded, the RDY switch will disable.

CITEGT: The Compressor Inlet Temperature was not permitted to exceeded 427 degrees Centigrade. The CIT temp gauge will display both engines in white text while in normal operation, yellow within 10 degrees of limits, and red within 2 degrees of limit. If the limit is exceeded for 30 seconds or more (428+C) one engine will be commanded to fail. The failed engine will display "FAILED!" in red text. It cannot be restarted and should be a very rare occurrence. Note: The picture on the right is no longer current. There is now a separate analog CIT gauge with dual needles as well as analog fuel flow gauges instead of digital as shown.
The Exhaust Gas Temperature display has a built-in electronic "trimming" system to lean the fuel to air mixture and reduce over-heating. If the EGT reaches 860C or more the de-rich system will engage which shuts off the AT IAS hold function and sets the throttles to 85%. This feature has saved me from an engine failure more than once. There is a yellow "LIMIT" indicator when the EGT reaches 830 C (continuous operating limit) and orange and red "hot" indicators for 845C and 900C. EGT below 400 will indicate "COLD."
The image at the right shows the engine stack at three states of performance: shut down, 28K ft 400 KIAS, and operating near limits above mach 3.5.

Annunciator:
System state and failure warning system. Many of the warnings mimic actual plane warning lights although for space and practical purposes many are left off. The systems and warnings are as follows:

Warning		Description
Oil Psi		Psi drops below 25
OIL TEMP		Below 15C or above 177C
FUEL PRESS		Below 7 Psi
OIL LEVEL		Below 15%
HYD PRESS		Below 2000psi or above 3500psi
HYD LEVEL		Below 25%
BUS VOLTS		Below 22 Volts
GEN OFF		Generator Switch Off
Fail		Engine Failed
GEAR GEAR TR or GEAR LIMIT! or GEAR DAMAGED!	Pitot H	GEAR will display when throttle is low and aircraft below 3000ft. GEAR TR when the gear is in transit. Pitot H indicates PH switch is off
SPEED HI and STALL Warnings	Fuel Low	SPEED HI and STALL WARN in yellow and red to indicate various levels. Fuel Low indicates tank2 is below 5400 lbs AND tank4 is below 4050 lbs
COG Warnings	Emer Bat	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. Emer Bat indicates battery is being drained.
TRIM	Canope	Pitch Trim is too nose down (> -1.5) caused by too fast, too low or Aft COG. Canope Open Warning.
LIMITER	Future Reserved	Surface Limiter (Yaw Damper Off). Future Reserved.

Drag Chute:
The drag chute gauge has three states: not deployed, auto-armed (shift-/) and deployed (/.) Full chute deploy takes apprx 5 seconds. The drag chute can not be deployed while in the air. 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 and 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.
Note: When retracting or "jettesoning" the chute, it takes 5 seconds for the lever to return to is normal position. The image at the right displays these three states. Notice the "normal" un-deployed state has a black center. The armed for auto deployment state shows an orange-ish center but otherwise looks like the un-deployed state. The deployed state has a bright green center and is extended toward the pilot on an red-ish shaft. The gauge cannot be activated by mouse at this time.

TEB: Below the engine throttles are two TEB chemical 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, 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. The TEB count is only lowered if the engine start is successful or the throttle position is 70% or more for engaging afterburners. An engine which is fully functioning will remain working if the counter reaches zero until another failure occurs.

Spike: The Spike position gauge is a critical key to the ability of the J-58 to obtain Mach 2 and 3+. Together with front and rear bypass doors, they prevent super sonic air from entering the compressor and stalling the engine. At this time, the door operation is not yet implemented. 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 out and away from the engine intake) to +26 inches (AFT) or fully retracted into the engine.
A small text readout also shows the percentage of spike travel currently used. You can move the spike manually while on the ground to confirm its operation, but having it retracted in other than the zero position while in flight and below mach 1.6 will cause a failure.
Beginning at Mach 1.6 and faster, various kinds of failures related to high AOA, too-low descent speeds, and high bank angles can cause compressor stalls and unstarts. Please consult the specifications section related to turn, descent, and AOA limits in order to avoid these problems. Unstarts were a well known problem on the SR-71 and happened most frequently during descents. In this simluation, you need to be more attentive to descents than other flight profiles. Habu pilots refer to various modes of flight where specific procedures or airfcraft systems settings and operation are required as "schedules."
The "Unstart" term comes from the idea that close to Mach 1.6 and above, supersonic flow inside part of the inlet has "started" and a shock wave builds behind the spike lowering the intake pressure. 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. Loss of the shock wave position control allows the shock to enter the engine and causes similar symptoms as a compressor stall.
When the engine unstarts 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 AT tries to recover speed with full RPM on the remaining engine. The computer will move the spike position forward to re-capture the shock wave for restarting the engine. At this time, both spikes ALWAYS move together. The computer will keep the spike forward until the failed engine condition is corrected. When the engine RPM drops to 22% or less, the failed engine will restart itself as long as all dynamic conditions which caused the failure have been corrected. If you wait too long, 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 a hit of TEB. Restarts are normally performed at Full Military throttle to prevent another compressor stall.
An unstart will still require the loss of two TEB hits to ignite the engine and restart the AB. 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 a failed engine (as well as all the engine gauges indicating low.)
Note: It is very important to have the special gauge "SelectCorrect.xml" installed. This gauge corrects the FS2004 timing error on some panels when performing multi-select operations. Without this gauge (which is invisible) attempts to select only one engine using the key sequence e1, or e2 or e12 will fail and only the #1 engine will be selected. When this happens, attempts to move the throttle or operate the AB will affect only one engine and normal two engine operation cannot be re-established.
The normal procedure for re-igniting one AB when it fails is to select the failed engine with the key sequence e1 or e2. Re-engage the AB with shift-F4, then re-select BOTH engines for normal operation by pressing the key sequence: e12 BACKSPACE. It's important to tap BACKSPACE at the end of ANY operation in Flight Simulator where a number key has been pressed. Failure to observe this rule may result in FS "remembering" you had started a mutli-key operation and you might have it complete at an unexpected or critical moment. ALWAYS tap BACKSPACE after every multi-key sequence or you have returned to 1:1 sim rate after using other sim rates. Be aware I have corrected a fault with this utility which used too many resources. If you have trouble operating the canopy with the EXIT doors feature (shift, 1) then you should request a replacement from me. At this time, I believe I have sent this too all my testers.
Note2: The SelectCorrect gauge has a critical timing which the pilot needs to cooperate with. I have found it's best to wait about 1 second after pressing the engine select sequence for engine 2 before activating the AB or engine restart switches and key presses. Otherwise, you may not get the engine selection you expected.
Note3: An engine failure or unstart may cause the spike to move at a very small portion of its normal rate during electrical/hydraulic system failures or both engines are failed.
Note4: Compressor stalls are now simulated. If the pitch is too high for the flight profile, or the mach descent is not maintained above 350 KAES 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 (-4500 FPM or more). The failed engine will ignite once speed is restored above 350 KEAS. Sometimes a manual restart is necessary.

ABThrottle: 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. Current Implementation: While on the ground the throttle will not permit movement past 70% (full military power.) To increase beyond 70% you have to engage the AB (shift-F4) which simulates lifting the throttle over the stop. Once the AB is engaged, the throttle can be moved at will. If you reduce the throttle below 70%, the AB will disengage automatically. In flight, the AB will also disengage below 70% but you can use the throttle at ANY setting without the AB, even 100%. The gauge also provides a 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. I decided to make it permanent. Note: The real plane has throttle/engine performance which differs from FS in an important way:
The real plane operates at near max RPM through climb and cruise. What changes primarily is the fuel sent to the afterburner. In FS, engine power from the AB is not independant of RPM changes. For that reason exact PRM for modes of flight is not strictly simulated. This is also why the throttle movement allowing for normal military power in the top portion of the throttle is allowed, to account for restrictions in the panel movmement

This gauge also provides AB off/on and TO/GA indication. AB ON is indicated by changing the throttle precent number from green for "normal" military power to white for After Burner. The image on the right shows these two states with full military power on the left and 85% with AB engaged on the right. Also shown are the two TEB counters at the bottom. Take Off/Go Round power can be activated by Shift-Control-G or clicking on the Throttle percent numbers. When activated, the throttle selection numbers will change from green to orange.
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. 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.
Reducing throttle below idle will shut off the engine (into the red or negative numbers on the throttle position display.) Restart requires moving throttle lever back to idle position (green) or above (F1.)

TRIM:Three gauges show the degrees of Pitch, Yaw, and Roll trim movement of the aircraft components. Use these before flight 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. See specifications section for Pitch/COG limitations.

The DERICH switch permits operation of the derich feature which reduces engine power when the EGT exceeds 860C (which is unlikely at high altitude mach cruise. When the switch is in the default down position, the derich feature is disabled. It's usually a good idea to have this enabled to further protect the engines from over-heat faults during hot take-offs.

A-SKID Anti-Skid switch limits the breaking strength by pulsing the breaks while the ground speed is above 65 knots during landing rollout. The parking break is also disabled. When below 65 knots, all breaking returns to normal. Steady "toe break" pressure is required to activate the function when the switch is on. Leave the switch off if maximum effort is need to stop in time.

As you all well know, faults of any kind are not a normal part of FS simulations. The built-in random failure system is so unlikely and unrealistic no one wants to use it. Alternatively, the faults built into these 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 faults are not random. The pilot has to fail to react to out-of-limit flight parameters for them to happen. In a normal flight, you will not have any faults.

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

Min Operating temperature = -75 deg C

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

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

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

Active Sky Weather Simulation:
Design Mach Speed = 3.2 (above 35Kft)
Note: Mach speed over 3.2 and under 75K ft may cause unexpected-instant overspeed with weather changes. Overspeed should now be very rare when Normal operating speeds are used with Auto-Throttle.
Maximum Operational Mach = 3.35
Overspeed Mach = 3.45
Maximum Indicated Air Speed = 505 KIAS, 450 KEAS subsonic, 400 KEAS supersonic.
Note: Aactive Sky has to be operated in "Force Constant Route Pressure" mode for high speed mach in remote areas like Northern Canada and North Atlantic.

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

Max Rated Altitude = 92K ft (can go higher when weather 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.

Min IAS above Mach 1 = 310 KIAS (real world) 290 KIAS (simulated)
Note: Descend rapidly if the weather system causes a sudden drop in IAS 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.

Refueling:
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

EGT:
Idle: ~430C @ sea level (typical)
Max start temp (idle) = 565 C
Normal Cruise Range: 780 - 820C
Continuous Limit: 830C
Emergency Zone = 805 - 845 C up to 15 minutes
Red Zone: 900 C up to 2 minutes
950 C up to 15 seconds

COG:
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 = 24.3% 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

Electrical:
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 under auto-pilot control will conform to the following flight trim settings:

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

This general overview of technique for flying this aircraft in FS2004 is not real-world but based on manipulating the sim to obtain consistent results. Active Sky weather is assumed. FS and SB3 weather should not be used as the data doesn't support altitudes over 45K ft.

o PRE START PREPARATION:
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:

	CLIMB	CRUISE	DESCENT
SPEED	900	1790	700
FUEL RATE	22500	40000	16500
VERTICAL RATE	1750(ave)		1800(ave)
ALT		81000

Note: The SR71 is capable of fuel balancing automatically and manually. The tank attrition schedule built into the model simulates the auto transfer system AS LONG AS you load the amounts below and always keep the fuel transfer switch in the STOP position. DO NOT USE "AUTO."

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%

FS Fuel Dialog:

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

Fuel distribution is as follows (rough):

< NOSE to TAIL(111ft)					>
	1,1a	2	3LR	4,6a	5,6b
<  pilot	LRtip	Cntr	LRmain	Cntr2	LRaux >
		|	<wing	<engCTR>	wing>
		o		o

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's built-in default tank attrition schedule which chooses the order in which tanks deplete until empty. Habu pilots considered 60+K 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 deault loads of 45K, 55.6K or 66K lbs (depending on when you can intercept the tanker) and plan on an air refuel.
END FUEL PREP.

The SR71 is sensitive to pressure more than wind speed and temperature because of the high altitude. Near the flight limits large pressure changes can throw the flight model well beyond its operational limits. If forecast pressure areas over the course of your flight have the potential to be below 29.45 you should use the Active Sky Enhanced Version feature "Force Constant Pressure" while preloading Flight Plan or descend to a safe altitude near the problem area. Pressures over 30.10 are problematic because they force you to fly very high (which can be fun, but increasingly risky.) You can expect to fly 92K ft or higher to barely maintain M 3.20 safely with a pressure of 30.35.

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. I 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.

81,000ft should be used for flights East and 80,000 for west. Although the model supports flights up to 92K ft (normal limit is 85K ft) unstable weather over coastal transition boundaries (300 - 500 miles from land crossing over large bodies of water) may cause highly unstable flight. AS does not support temperature layers above 82,000ft. As you climb above this, temps actually INCREASE rather than decrease. This can cause failures of the type where sudden weather changes produce extreme engine efficiency changes with consequential overspeed or stall. Engine power is reduced by periods of extreme off axis air flow.

Note: 170 miles suppression, 5 min update interval settings.
The default setting of 100/10 does not work at all because the SR will fly 320 miles or more in 10 minutes at cruise.
Using a 5 min interval (although it has the potential of keeping the SRs flight distance updated) has the problem that FSUIPC cannot load all the dense area stations in 5 minutes. Even 6 minutes is not enough time sometimes. At 7 minutes, the station loading sequence completes, but errors in the station data and FSUIPC station count limits still cause "blanking." Blanking is where there is no valid local data. This can be caused by no local stations close enough to the aircraft location, or the station ID being sent to the weather simulator cannot be found (bad location description) in which cases FS creates a default weather condition which is "Clear and Calm" in the weather dialog presets. The "blank" or "Clear and Calm" condition is unsuitable for flying the SR at high altitudes. In AS build 479 and later I have had acceptable results using 170/5 but blanking persists in parts of the world where station data contains errors (Many parts of Canada cause blanking.) On my 2.2 GHz AMD, turning off update throttling greatly assists the speed up update writing so the stations will all write before even 5 minute updates. The cost is a few more studders during updates.

Your flight setup procedure should include use of the "New Route" button at the main screen. When clicked, set the cruise speed to 1750 and "Import" an FS flight plan of your flight route. This will cause AS to pre-scan all the weather along your route and create some optimizations including "Virtual" stations between large gaps in real world stations. With "Constant Pressure" selected both real world and virtual station data will be modified slightly to reduce the severity of pressure changes.
I have experimented with "Constant Temperature" a bit and although it has the potential of smoothing out large temperature changes, it can also cause them. If the temperature profile the program selects to simulate is unfriendly, you are stuck with this profile for the whole flight. With this feature unselected, you at least have a chance a bad profile could improve.

Sometimes even with a flight plan pre-loaded and pressure smoothing, the conditions can still be totally unfavorable to flying the SR. The options are to change your flight to another part of the world, or not pre-loading a flight plan and letting the AS program create a more dynamic "load as you go" environment (which is AS's default condition.) Virtual stations will still be created (based on the suppression and update intervals you entered.) This dynamic environment may cause more disruptions in your flight, but you have an equal potential of getting an acceptable high altitude condition at any given time as a bad one. Instead of a bad condition the whole flight, you may get periods of acceptable conditions. Another way to get through a large are of rapidly changing weather is to set a reasonal alititude and lock in 400 KIAS on the AT, then live with whatever speed and fuel rate this provides. This is the lowest maintenance method at the cost of fuel and speed efficiency.

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 X 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. Take a look at the temperatures above 50K ft and the current pressure. If you pre-loaded a flight plan with force constant pressure, the current pressure shown will only deviate slightly through the flight (most of the time.)

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. The altimeter in the provided panel "Triple" gauge is non-compensated. It will display the same altitude as if the altimeter was not reset to 29.92. You can use this to compare the compensated display in the main altimeter to the non-compensated in the triple display to tell if you are flying in higher or lower than normal pressure. As you get more experienced, you will come to expect certain IAS readings at certain altitudes. Higher or lower than normal air speeds at Mach 3.2 are an indication you are flying in unusually low or high pressure.

The following settings in the WINDS section of FSUIPC are necessary to smooth the wind for Mach speed flight. If you are using the free version, you cannot set this resulting in less than satisfying weather conditions in all aircraft:
CHECK "Smooth Changes"
Knots or degrees/second = 0
OR for this many seconds for each 1 degree = 2
After weather clear delay smoothing by seconds = 0
CHECK "smooth only when airborne."

NOTE on PRESSURE: In practice using AS weather, pressures during M3+ flight OVER 1024.4 (30.25mb) or UNDER 997.3 (29.45mb) are problematic. You can expect to have to climb very high (90K+) to obtain M3 or descend very low (72K) to avoid stall near these pressures. Avoid IAS over 460 or under 380 at cruise. I cannot stress enough that the most maintenance-free flights will have cruise speeds near 400KIAS (the middle of the model's stability range.)
END WEATHER PREP. PRE START PREPARATION CONTINUES...

PRESET THE AUTOPILOT to have AutoThrottle ENABLED, set initial altitude (usually 10,000 AGL to 28,000) 255 knots IAS (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 420 KIAS. This will hold close to 400 IAS (350 KEAS.)

Switch NavGPS switch to GPS (note: GPS mode disables ILS approach so you need to turn the switch back to ILS during automated approach.)
END PRE-START PREP

o Start-up:
If necessary activate the fuel pumps with control-shift-F4 or the fuel pump valves in the fuel panel. on the left of the main panel, click and HOLD 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 (starts at 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. 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.

o Position and Run-Up:
-Position on the runway into the wind, set the breaks and bring up the autopilot.
-Inspect all gauges and switches for correct position for take off. -Place the DERICH switch in the up (enabled) position.
-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 controls and observer they all move to maximum positions 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 (70% 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 poper 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:
KIAS vs KAES:
Equivalent Air Speed is used for high speed flight. You will see KIAS (Indicated Airpseed) or KAES 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 KAES) 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 70% (full military.)
-Release the breaks and engage the Afterburner (shift-F4.) Throttle position numbers will change from green to white and the TEB counter will drop another number to ignite the ABs.
-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 orage.) Using this feature will help prevent over speed on the engines.
-Passing 156 knots (speed check) you should be over half way through your rol 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 in 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, non-restricted stay in TOGA mode.
-At full weight 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. It will break above 300 KAES/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 space.
-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 KIAS as possible transitioning to IAS speed hold of 420 KIAS when the speed nears 400 KIAS (350KEAS.)

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. Sustainable climb using 7000 ft/min is possible up to 24K ft in cold 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 5+ degrees.
Marginal military power at high pitch can be compensated by enabling AB on one engine and using differential engine control to compensate for yaw.

Dipsy Doodle (modified for FS9):
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.
Between 30K-32K ft increase ATspeed bug to Mach 0.95. Passing M0.95 and 33K ft set AT bug initially for 524 (for 450 KAES climb) or 464 (for 400 KAES climb) and start a -1500 to -2500 descent through Mach 1.15. Passing 320 to 340 KAES (on the triple gauge) slowly increase climb to +2000 fpm or more. Continue climb adjusting Autothrottle IAS bug by 2 knots at a time to hold 400 or 450KAES on the climb until reaching M3.0 at 70K ft.
The "Dipsy Doodle" is designed to transition through high pitch drag around M1.05 - M1.15 as quickly as possible after refueling to a "heavy" jet.

o Mach Climb:
There are two common climb speeds used:
450 KAES which is the typical high performance climb into a high risk area after tanking. Fuel burn rates are fairly high reaching 40-44K lbs/hr at Mach 3. This profile gets you over the target area at high speed, but low altitude soon after 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 KAES 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 to the 400 KEAS schedule.

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, advance the AB and set the AT bug to 460 (to obtain 400 KAES) or 520 (to obtain 450 KAES) and ease into the desired climb rate starting shallow passing 380 KAES or 420 respectively. As in the Dipsy Doodle climb, the initial climb target is 70K feet at Mach 3.0.

MACH MODE:
NOTE: FS9 does not show the whole digit mach number when the speed is over Mach 1.
At Mach 3.0 it will indicate 00.
At apprx Mach 2.80 to Mach 2.85 switch autopilot to MACH. Observe these two things:
1) The speed hold bug in the airspeed gauge should be near the actual speed indication on the gauge.
2) The mach bug indication in the AP should read between .00 and .30 while the air speed gauge indicates near Mach 3 or more.

AP/AT Mach adjust Procedure:
Switch back and forth between IAS and Mach mode and increase-decrease IAS bug numbers until the mach indication reads .00+ (typically while crossing Mach 2.85 on the IAS gauge. This will hold Mach 3.0+. Use the same procedure to change Mach speed. Switch back and forth between IAS and MACH and change the bug while in IAS mode, switching to Mach mode to test your result.
Note1: It is POSSIBLE to switch to mach mode too long after transitioning to mach 3 so when switching the indication hold is actually mach 4 or 5. If the difference between the speed hold bug on the airspeed gauge and the actual indicated airspeed is large, this might indicate you have accidentally advanced to the next mach range on the AT Mach bug. This will cause an over-speed condition eventually. Lower the IAS bug until you jump to the proper mach range. This can be challenging during radical weather pressure changes.
Note2: I find it easiest to keep the mouse over the autopilot speed numbers and use cntrl-R and cntrl-M to switch back and forth between IAS and Mach modes while refining the setting using the mouse.

At high fuel loads and 450 KAES climb speed, climb rate is slowly decreased as follows:
Note: These are guides. Actual operation may vary depending on weight and weather conditions.
60K ft = 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 100ft/min above 60K ft. You should cross 70K ft at Mach 3.0. The 400 KAES climb profile can use more aggressive climb rates than the 450 KAES profile.

Note: FS9 setting for max climb in Auto-Throttle is to set 525 IAS, then manage the climb rate to keep the Triple gauge as close to 450 KEAS as possible.

COG:
At take-off the plane is tail heavy which assists rotation. Too high COG at take off makes it possible to have a tail strike from rapid rotation. During flight the aft fuel burns off 1st- slowly moving the COG forward for mach cruise. During approach and landing, normal fuel attrition will result in COG which is in the typical range for landing (unless the pilot has used unusual fuel loading.)

As speed increase stops or begins to drop, advance IAS bug to hold 450+ KEAS. When using Max Climb, keep the 450 KEAS bug setting until Mach hold is engaged. The goal is to hold as close to 450 in the speed gauge as practical to avoid too-high pitch, yet avoid potential overspeed in high pressure and cold temps.
As you approach Mach 3.0 at 70K ft, engage Mach hold to M 3.0. Continue shallow climb and watch fuel flow. As it drops below 20K lbs/engine, slowly advance Mach hold to stay under 20K lbs/hr until desired speed is reached.

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 have to change altitude in small increments once reaching target altitude to optimize the flight for weather conditions. Crossing Mach 3.0 fuel rate will typically reach 40K - 44K lbs/hr. As you reach M 3.2, rates may drop to 36K-38K lbs/hr or less. Above M3.2 fuel rate will increase again. Occasional extreme errors in weather server data may cause extremely high or low fuel rates. It is suggested you use the Active Sky option: "Force Constant Route Pressure" and pre-load your flight plan into AS to provide smoother pressure changes during flight. Force Constant Temperature will add a bit more weather predictability with the trade-off of having less dramatic weather changes between wide spaced regions of the world.

!!!! PITCH WARNING !!!!
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 @ 510 KIAS.
-75 C 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 350 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.

AERODYNAMIC STALL PROCEDURE:
- Reduce climb rate, level off, or descend as conditions require. 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. 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.

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 KAES) during descent rates greater than 1500 ft/min. Increase descent until faster than 350 KAES.
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.

UNSTARTS:
- Caused by improper spike position. Place spike in proper position. Continue to monitor for correct position during rapid deceleration. Reduce climb, level out, or descend. Wait for auto-restart sequence. If auto-start fails, use fuel panel to enable fuel and hold start button on mail 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 1.6.

!!!! ENGINE POWER WARNING !!!!
High pitches due to excessive climb rate, severe weather changes, or inattentiveness to power profile may result in loss of power at max throttle. Max throttle is typically @94% RPM at -68C static Air Temperature.
Too-high pitches will cause power loss.
Temperatures warmer than -55 degrees C or colder than -75 degrees C will cause power loss.
POWER LOSS PROCEDURE:
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 engine RPM is between 83 and 87%.

!!!! Engine Overheat Warning !!!!
If the CIT temps are permitted to hold or exceed 428C continuously for 30 seconds or more, one engine will be commanded to fail. Each engine has a 50% chance of failure. A failed engine cannot be restarted. The non-failed engine will continue to operate. The rapid reduction in speed 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 it no longer requires 100% power on the remaining engine to sustain 300+ knots you can look for the nearest runway with 7000 ft or more to land. This should occur between 65K to 70K ft. Depending on your fuel load, you should be able to find a runway up to 250 miles away.

!!!! OVERSPEED WARNING !!!!
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 speed is to set the Mach to provide as close to 400 knots as is practical.
OVER-SPEED PROCEDURE:
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. 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:
Airspeed
Attitude
Altimeter
Vertical Speed
Radar Altimeter

Engine Spike:
21 inches of total movement normally auto-controlled starting at mach 1.7.
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.
Subsonic to Mach 1.7 = retracted-spike fully extended (F5)
Mach 1.7 to Mach 2.2 = position 1 (1 tap F7) (25%)
Mach 2.2 to Mach 2.7 = position 2 (1 tap F7) (50%)
Mach 2.7 to Mach 3.2 = position 3 (1 tap F7) (75%)
Mach 3.2 = position 4 (1 tap F7 full engine retraction-flaps deploy) (100%)
NOTE: At speeds of Mach 1.6 or above, 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. The functionality is as follows:
Below M1.6 and spike position is out for 15 seconds or more, the AB will be disabled if it is on. Restarting the AB will lower the TEB count by one for the engine that failed (each engine has a 50% change of failing.) There will be no engine shut-down below M 1.6. Once the TEB count reaches zero, another engine start or AB start is not possible, but the AB and engine will continue normally until shut down.
Above Mach 1.6, the spike out of config for 15 seconds will cause AB shut-down. If left out of config for 30 seconds, the associated engine which had the AB shut down will shut down causing loss of power. If the spike is corrected before the RPM reaches 22%, the engine fuel value will re-arm and the engine will attempt to restart itself. If an auto restart fails, the engine must be started manually.

o Cruise:
After switching the AP AT bug to Mach Hold at Mach 3.0, monitor the engine fuel rate. As the rate drops below 20K lbs/engine, slowly advance the mach hold 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 500 KIAS max or slower than 300 KIAS and/or 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 turn rates to obtain maximum range between re-fueling assets and turn rates to prevent border or threat area incursions. The few times pilots got to test the limits 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 flown above this limit. The limits set in this model provide a generous margin when operated in typical real-world flight profiles.
Ideal Cruise Summary:

• As close to 400 KIAS/350 KAES as possible
• CIT below 427C
• EGT below 830C
• Fuel rates as close to 18K lbs/engine as possible
• Pitch below + 6

o Descent:
Note: At high mach speeds procedures use KEAS (available in your "Triple" gauge.)
Following information is simplified excerpt from Pilot Manual.

Descent Profile: If cruise speed is below 365 KEAS, hold current mach in decent until passing 365 KEAS, then hold 365 KEAS. Mach 0.90 is the standard cruise speed below Mach 1. Descent angle is typically between 1 degree at the start to near 7 degrees around Mach1. Expect to drop out of AB soon after descent starts, followed by two rapid spike movements. The chart graphic above is converted into more FS friendly table below:

At 14k ft AGL, slow to 300 KIAS by setting AIS bug to 290. At 12K ft AGL, slow to 250 KIAS by setting IAS bug to 240. Within 40 miles of landing slow to 220 KIAS minimum turn speed.

o Terminal maneuvers and approach:


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."

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 key sequence to lower the view to see the runway (typically two steps down from normal.)
shift-backspace to pitch up or SPACE key to recenter view to default.
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 10 degrees.
- 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 center changing from black to orange. If there is significant crosswind, operate the chute manually after the front wheels touch down.
- 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 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 when the nose begins to drop to 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.
- Around 30 knots jettison drag chute (/) or increase engine speed slightly for a few moments. Increaseing speed resets the auto-spoiler logic.
Taxi to parking not exceeding 20 knots ground speed. Shut down engines using contrl-shift-F1, reducing throttle(s) below zero two notches or fuel panel switches.
Note: The high RPM of the 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. It's a trade off.

Real world tanker descent (assumes M3.2 80Kft):
If slower than 422 KIAS, use Mach hold on initial descent. Otherwise use 422 KIAS.
-Start descent 325 miles from runway. Tanker is expected 100 miles this side of runway.
-Set descent alt (target) in AP for 29K ft.
-Gradually set initial dec rate to 4500.
-Crossing -2500 ft/min on VSI disengage AB.
-As air speed in mach hold approaches 425,
set 375 in the AT bug and adjust as needed to hold 420 - 425 until 40K ft. Use SPEED Warning gauge to help you keep it in check. -Observe dec calc and adjust dec rate so calc and target runway distance match crossing 70K ft.
-At 70K ft set AP alt for 7000ft. Keep watch on the speed and adjust dec rate to keep the calc reading near or just over the distance to runway. Try to cross 50K ft with 180 miles to go.
-At 50K ft set target alt on the AP for 4,000ft. Adjust dec rate to cross 30K ft 150 miles from runway. Target crossing 40K at 163 miles. You should be -6000 to -7000 ft./min by now.
-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 KIAS minimum maneuvering speed.

PROCEDURE SECTION COMPLETE

Some interesting facts:
The SR is composed of Titanium and Composite (plastic) 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.

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 and $1 million/mission to launch.

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!

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.

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.

In 1981 Kelly Johnson announced that the SR-71 had over 1,000 missile launches against it, but none successful.

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

The SR71 nickname Habu is the name of a Cobra snake in Okinawa, Japan. Apparently it's not normally aggressive to humans but has a nasty bite.
Because of the sleek "hooded" appearance of the Blackbird caused by the chine, the Okinawans claimed it looked like a Habu snake. Thus the nickname.
Additionally, SR-71 Crew members are called "Habus."

The SR-71 flew for 17 straight years (1972-1989) without a loss of plane or crew. Of the 50 variants produced, 19 crashed with no loss of US Air Force crew.
One crew was lost launching a drone in an A12. The recon officer drowned in his chute. I have heard another accident related to unbalanced engines at cruise causing a breakup and loss of the recon officer in a CIA crew.
The Seattle Museum of Flight in addition to the drone-mounted A12 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.

478 total people have flown the Blackbirds. More people have climbed to the top of Mount Everest. Last flight of a military SR71 into Beale AFB for display: 1997 http://www.wvi.com/%7Esr71webmaster/sract%7E1.htm NASA used one of its two SR aircraft for research on the LASRE aerospike engine project as late as 1998:
http://www.nasa.gov/centers/dryden/history/pastprojects/SR71/Lasre/index.html NASA/DRYDEN documents the last flight of the SR71 as 1999: http://www.nasa.gov/centers/dryden/news/FactSheets/FS-030-DFRC.html

Program Info:(as of Jan 1990) Source: http://www.blackbirds.net/

* 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