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THE 456th FIGHTER INTERCEPTOR SQUADRON |
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THE PROTECTORS OF S. A. C. |
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The Inside Story Of The SR-71 |
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By Col. Rich Graham
Aviation historians, scholars, enthusiasts and aviators judge aircraft of the 20th century by a variety of standards. Some will judge planes by how good they look, or by how well they do their missions, or by their technical advancements, or by their contribution to a particular war effort. Throughout this debate the one plane of the 20th century that always comes to mind is the SR-71 Blackbird. This web site is dedicated to the SR-71 Blackbird family of planes.
Sitting on the ground the SR-71 looks like it's traveling at mach 3 speed, its black color making it look sinister and deadly. Its shapes seems to be part plane, part space ship. Crews in their pressure suits appear part pilot, part astronaut. Cruising routinely at 2,100 mph, at altitudes over 80,000 feet, the SR-71 and its two-man crew fly in the upper limits of the stratosphere. Here the outside air temperature is -65 degrees F., and yet skin friction will cause the leading edges of their plane to reach temperatures of 500-600 degrees F. From heat alone, the plane will "grow" five to six inches in length every time it cruises at mach 3.
Flying highly classified reconnaissance missions all around the world, the SR-71 has been despised by hostile countries. During its 22 years of operational flying, the Blackbird has encountered numerous SAMs and MIGs attempting to shoot it down, but to no avail. The SR-71 Blackbirds were operational from 1968 to 1990, providing six US Presidents, the CIA, NSA, DIA, foreign nations and our own military leadership with the intelligence necessary to make crucial and timely military and political decisions. The SR-71 shaped the future of the world we live in.
This web page was developed to give you a sense of what it was like to fly the SR-71 Blackbird and belong to the small fraternity of highly trained SR-71 crew members. Enjoy !
Col. Rich Graham
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A Short History Of The Blackbird Family Of Planes. |
The SR-71's Roots
It's hard to imagine the fastest jet aircraft in the world today was developed before 1962. The prime architect of the SR-71 was C. L. "Kelly" Johnson, head of Lockheed's Advanced Development Project (ADP), better known as the "Skunk Works". In 1943, Kelly organized the Skunk Works, a small unit of technical and production specialists, to build America's first production jet fighter. The XP-80, the prototype of the F-80 Shooting Star, was completed in less than five months. This effort exemplified Kelly's credo-be quick, be quiet, be on time. For 30 years he headed Lockheed's Skunk Works and played a leading role in the design of more than 40 of the world's most advanced aircraft-among them the SR-71, U-2, F-104 and P-38.
I recall, early in my SR-71 career, Kelly Johnson flying up from Burbank to Beale (as Lockheed ADP personnel routinely did) in their Lockheed Jetstar to attend one of our squadron monthly aircrew meetings. I was highly impressed with his ability to answer our detailed questions about the SR-71, and also by the fact that a Lockheed senior vice president would take the time to attend one of our meetings. Sadly, on 21 December 1990, Kelly Johnson died at the age of 80. He was a giant of his time-revered, admired, honored, and dedicated to excellence in building aircraft. An aviation genius, he achieved what was thought to be impossible.
Designed with slide rules and built in total secrecy, the SR-71 was well ahead of its time. New technologies and frontiers had to be explored to build and aircraft capable of continuous Mach 3 flight, where heat from skin friction alone would build up inside the aircraft to 300 degrees F. The nose of the aircraft would heat up to 800 degrees F, the windshield over 600 degrees F and the exhaust section reached 1,200 degrees F. All these extreme temperatures were developed flying through an air mass with a temperature of -70 degrees F.
Titanium was the only lightweight metal of the time that could sustain the heat and still provide the strength necessary to maintain aircraft integrity. Although difficult to work with as a metal, titanium was chosen to be the primary metal comprising over 90 percent of the SR-71's airframe. Because of the extreme heating and cooling cycles over its lifetime, each aircraft actually became stronger (annealed) every time it flew.
Everything on the airplane had to be specially designed. The hydraulic fluid, lubricating oil, fuel, engines and a variety of other complex systems, all had to be developed to overcome the extreme heat encountered at Mach 3 speeds and the hostile outside pressure and temperature environment above 80,000 feet. Even a special black paint for the aircraft's exterior had to be developed to withstand the extreme heat.
In August of 1959, the CIA awarded a contract to the Lockheed Skunk Works for the development of a Mach 3 aircraft called the A-12. In January of 1960, the contract to build a dozen A-12 aircraft was awarded. The first flight occurred on 26 April 1962 in aircraft 924 and was flown by Lockheed test pilot Lou Schalk from the secret test site at Groom Lake, Nevada. The early test flights barely exceeded Mach 1 because the J-58 engines from Pratt & Whitney were not fully developed and J-75's were used instead. It wasn't until January of 1963 that the first J-58 powered A-12 flew. Soon they were exceeding Mach 3.
Two of the A-12's were modified to carry the D-21 ramjet reconnaissance drone on top of the aft fuselage. The 42 foot titanium D-21 drown was powered by a Marquardt RJ43-MA-11 ramjet and was to be launched from the A-12 at Mach 3. Aircraft 940 and 941 were modified to carry the D-21 drone and included a rear cockpit for a second crew member. Once modified to carry the drone, the A-12 aircraft were called the M-12. The back seat crew member (called the Launch Control Officer) was in charge of safely launching the drone from the M-12. Once launched, the Mach 3.35 drone followed a preplanned flight profile with camera ON/OFF points also controlled by the navigation system. The 11,000 pound D-21 drone had a range of around 3,000 nm and could fly as high as 95,000 feet. Following its mission, the drone flew to a point over friendly territory, and its palletized camera unit was ejected and recovered by a modified C-130 aircraft, equipped with a Midair Recovery System (MARS), where it would be taken for processing. As the D-21 continued its descent, it would soon self-destruct by a barometrically activated explosive device.
After three successful launches, on 31 July 1966, Lockheed pilot Bill Park and launch crew member Ray Torick climbed aboard 941 to launch the D-21 drone. At launch separation the drone hit the tail section of the M-12 causing it to pitch up abruptly. The fuselage forebody separated from the rest of the aircraft with both crew members inside. Both men ejected successfully, however Torick drowned in the ocean before being rescued by the Navy. After the loss, Kelly Johnson canceled the M-12/D-21 program.
B-52's at Beale were then modified to carry the D-21 drones, one under each wing on inboard pylons. The B-52's flew to Guam in darkness and launched the drones into China during daylight. Only a few missions were flown before the project was canceled. Seventeen D-21 drones were stored at Davis-Monthan AFB, Arizona, four of which were delivered to NASA's Dryden Flight Research Center on 2 June 1994, for possible flight research projects. The Museum of Flight in Seattle, Washington, displays the world's only M-12 mated with its D-21 drone.
The Air Force became interested in using the A-12 as a high altitude interceptor to defeat a new generation of Soviet bombers. The next version of the aircraft, an Air Defense long-range interceptor, was proposed by Kelly Johnson in March of 1960 to General Hal Estes II, in Washington, D.C. It was called the YF-12A and had a two man crew. By coincidence, I had the pleasure of working for Brig. Gen. Hal Estes III, 14th Air Division Commander, as my immediate boss at Beale AFB, and meeting his father during a visit. He talked fondly about the start of the YF-12 program as he toured the base.
On 7 August 1963, Jim Eastham flew the first YF-12 (tail number 934). Three YF-12A's were built and tested (934, 935, 936), but finally lost out to funding for the F-111, a favorite of then Secretary of Defense, Robert "Strange" McNamara. Two of the YF-12's and an Air Force SR-71 were given to NASA for high speed research, while the third YF-12 (934) was extensively modified to produce the dual controlled SR-71C trainer (981). The NASA program terminated in October of 1979.
The YF-12 carried the advanced Hughes ASG-18\GAR-9 fire control and missile system (forerunner of today's F-14 Phoenix system), later designated the AIM-47 missile. The radar modification to the nose of the YF-12 degraded directional stability to such an extent that three ventral fins had to be added. Two shorter fins were mounted under each engine nacelle, and a larger, retractable fin was located under the aft fuselage. It retracted to give the necessary ground clearance on takeoff and landing.
Back in January of 1961, Kelly Johnson made a proposal for a dual-role strategic reconnaissance bomber (designated the R-12) to the Secretary of the Air Force and Col. Leo Geary (now Brig. Gen. Ret.), Pentagon project officer for the YF-12. The proposal for the R-12 never got very far. As the Skunk Works continued development on the YF-12, it encountered very strong opposition in the Air Force from those trying to save the B-70 bomber program. While this flurry of activity was going on, the Skunk Works proposed an advanced strategic reconnaissance aircraft for the Air Force, and on 28 December 1962 a contract to build six SR-71 aircraft was issued to Lockheed.
The first SR-71 prototype (950) was driven on two flatbed trucks from Burbank to Palmdale's plant 42 for final assembly on 29 October 1964. Two months later, on 22 December 1964, Lockheed test pilot Bob Gilliland flew the first SR-71 aircraft. The pace of testing the flying envelope and operational characteristics of the SR-71 picked up momentum with the Air Force also testing and evaluating three SR-71's (953,954 and 955).
Everything about the aircraft turned out to be "unique". At Mach 3 cruise, heating of the entire aircraft length (107 feet) forced it to "grow" several inches in flight. To give you and idea of Mach 3 speed, imagine a 30-06 rifle bullet fired over San Francisco and being able to sustain its muzzle velocity (3,000 feet/sec) all the way to New York City-the SR-71 would arrive first (3,100 feet/sec)! It's hard to imagine an aircraft built in the early 60's, utilizing Radar Absorbing Material (RAM) to produce less than a ten square meter target for enemy radars to find. The mere thought of a stealth aircraft back then was only for dreamers, but Kelly managed the impossible! It was a sad day, on 5 February 1970, when the Skunk Works received word from the Pentagon to destroy all the tooling for the Blackbird so that it would never be built again. A total of twenty nine SR-71A's, two SR-71B's, one SR-71C, fifteen A-12's, and three YF-12's were built by Lockheed.
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The Aircraft |
Cockpit Layout
Front Cockpit
Rear Cockpit
The SR-71's front cockpit was somewhat snug with the pressure suit on, although comfortable. Headroom between the canopy sides was tight, as the canopy narrowed upward. Front cockpit visibility was restricted slightly because of the helmet and the small window panes surrounding the canopy. The rear, RSO's cockpit was considerably roomier. In the back seat he had two small window panes on each side an the ability to also see directly beneath the aircraft through his view sight.
All the cockpit switches and buttons were easily accessible and enlarged where necessary to accommodate the pressure suit gloves. The flight control stick grip was similar to a fighter type but had various buttons located on it to suit the SR-71's needs. There were no flight controls in the rear cockpit. Most people find it amazing that all the SR-71 cockpit instrumentation was the round dial type. The YF-12s had vertical tape displays which seemed to be in vogue for modern cockpits of the time.
A periscope was located directly in front of the pilot's helmet. Pushing it up extended the periscope into the air stream about four inches, giving aft vision to the pilot. Besides using the periscope for rudder alignment, it was very important to check that the aircraft was not producing a contrail when we entered sensitive airspace.
The SR-71 ejection seat was usable from zero speed and altitude to the maximum speed and altitude of the aircraft. The seat was a rocket-propelled, upward-ejecting unit. Most people believe and ejection at 2,200 mph would rip your body apart. However, the air is so thin at 80,000 feet that the actual forces encountered when your body first hits the air stream is a lot less than an ejection from a T-38 at 500 mph at sea level. To eject from the SR-71, you reached between your knees with both hands and gave a sharp, upward tug on the seat's large D-ring. To keep your arms tucked in tight to your body, crews were taught to hold on to the D-ring as the seat fired from the aircraft
After pulling on the D-ring, there was a 0.3 second delay to remove the canopy, and then a catapult gas charge was fired to initiate seat ejection from the cockpit. The gas charge was sufficient to raise the seat above the canopy sills, at which point,a wire lanyard attached to the floor of the cockpit was pulled, igniting the seat's rocket motor. The rocket motor provided sufficient thrust and duration to eject the seat approximately 300 feet above the aircraft.
Navigation
The SR-71's high speed and sensitive missions demanded a navigational system that was highly accurate, reliable, and didn't depend on inputs from other sources subject to electronic jamming. Patterned after navigational systems used on ICBMs, the SR-71's Astro-inertial Navigation System (ANS) filled those requirements.
Simplistically, the ANS was a star tracking navigation system. At least two different stars had to be tracked for optimum navigation performance. With a highly accurate chronometer (to the 100th of a second) supplying Greenwich Mean Time and the Julian date, along with a 61 star catalog stored inside the ANS computer, it was possible to know precisely where the SR-71 was over the ground. Selection of which star to track was made by the ANS computer as a function of latitude, longitude, day of year, time of day, aircraft pitch and roll, and location of the sun. The computer selected the star by going through its star catalog, which was arranged in decreasing star brightness, until it found a star. A telescope like star tracker looked for the stars in an expanding rectangular spiral search pattern. The ANS window was located on top of the fuselage, just forward of the air refueling door. It consisted of a round piece of distortion free quartz glass, 9 inches in diameter, that allowed the star tracker to scan efficiently.
Aerial Refueling
Without air refueling, the range of the SR-71 was limited to around 2,000 nautical miles. Multiple air refuelings extended the range of the aircraft to the limits of crew endurance. Many of our missions have exceeded 12,000 nm. After sighting the lead tanker visually, we maneuvered the SR-71 to what is called the "pre-contact" position, about 50 feet behind and 10 feet low of the tankers fuel nozzle. Adding a small amount of power, the SR-71 slowly moved forward to the contact position. The pilot slowly maneuvered the SR to place the end of the refueling boom about three feet outside his front window. The tanker boom operator completed the hook up. Once the boom nozzle was locked into the receptacle, A Habu's favorite words from the boom operator were, "you're taking gas."
The Engine Inlet Spike
At Mach 3.2 cruise, over 80 percent of the thrust created comes from the inlet, only 20 percent from the engine. The purpose of the inlet spike was to control and position the supersonic air from entering the engine. The sharp pointed movable spike was locked in its full forward position at subsonic speeds. As speed increased, the spikes unlocked above 30,000 feet at 1.6 Mach and moved aft into the throat of the inlet on a programmed schedule, depending on Mach number. The faster you flew, the further aft they traveled, approximately one and five-eighths inch per 0.1 Mach
Each spike was moved by a large hydraulic actuator, to a maximum travel of 26 inches aft into the inlet. The hydraulic spike actuator had to be able to withstand air pressures exceeding 15 tons under certain air flow conditions. To show the pilot the precise position of each spike as it moved aft into the inlet, a spike indicator in the cockpit had needles for each inlet. As each spike slowly moved aft, their conical shape increased the captured air stream area by 112 percent and reduced the throat area by 54 percent.
The Drag Chute
The SR-71 utilized a drag chute system to aid in stopping the aircraft on a landing rollout. The drag chute compartment was located on top of the fuselage, between the rudders. When the pilot pulled the drag chute T-handle on the instrument panel, the drag chute compartment doors sprung open, and a series of chutes went into action. The first chute to be ejected was called the "pilot chute" (42 inch diameter). When it hit the air stream, its job was to pull out a slightly larger chute called the "extraction chute" (10 foot diameter) which produced aerodynamic lift. When the extraction chute hit the air stream, it pulled out the safety pin holding the main chute. With the safety pin removed, the main chute ( 40 feet diameter) was free to deploy and decelerate the 60,000 pound (plus fuel) SR-71.
When the main drag chute deployed, it gave a firm tug on the aircraft. To avoid possible damage to the rudders and main chute, the pilot pushed the drag chute handle in, jettisoning the main chute on the runway before reaching 55 knots on the landing rollout. All three chutes fell onto the runway and had to be retrieved before other aircraft could land. Obviously, if stopping was marginal, we always had the option of retaining the main chute until safely stopped.
The Control Surfaces
The large delta wing of the SR-71 did not lend itself to have separate elevator and aileron control surfaces but instead utilized elevons, a single control surface that combines elevator and aileron inputs. Mechanical pitch and roll inputs from the control stick were blended in a mixer assembly, located in the tail of the aircraft, to actuate the elevons and move the aircraft accordingly.
The two large rudders were fully moveable surfaces, unlike conventional aircraft having a vertical stabilizer with a trailing rudder control. Each rudder assembly was canted inward 15 degrees for increased directional control and to reduce radar returns off the aircraft. At cruise Mach, having the rudders streamlined was important for good imagery results as well as for aircraft performance. To center the rudders, the pilot had to visually align each rudder separately using the periscope.
The Inlet System
The ejector flaps, also known as the "turkey feathers", are the overlapping slats of metal surrounding the exhaust, which opened and closed according to the afterburner's pressure output. They are an integral part of the SR-71's sophisticated inlet and exhaust system.
Each J-58 engine has six, large diameter bypass tubes running along the sides of the engine. At high Mach, a portion of the entering air is bypassed around the compressor and turbine sections through these tubes, giving the engine stall free operation. This bypass feature led to the description of the J-58 as being a turbo-ramjet engine.
Located on the top and bottom of the engine inlet were the forward bypass doors, used to relieve excess air pressure inside the inlet. At supersonic speeds, the louvered doors were controlled by the Air Inlet Computer and modulated from open to closed to relieve excess pressure building up in front of the compressor. The forward inlet doors worked together with the inlet spike to achieve optimum performance efficiency.
Another component of each inlet system are a second set of doors, called the aft bypass doors. Positioning the aft bypass doors was a manual operation by the pilot. The aft and forward bypass doors worked in opposite directions to each other. If you opened the aft bypass doors, the forward doors tightened down and vice versa. The purpose of the aft doors was to help manually keep the forward bypass doors from being too far open. When all of the inlet system components were working together properly, the system would utilize the supersonic airflow to produce massive thrust.
I'll always remember night flying in the SR-71 and looking back at the afterburners through the aircraft's periscope. At high altitude they formed a brilliant blue flame that came to a small point, much like a welding torch. In absolute silence inside the pressure suit, I could advance the throttles to maximum and watch the blue flame grow larger and brighter. I'd think to myself, "such unbelievable power at your fingertips, if only all aviators could live this experience!"
The J58 Engine
Engine Characteristics
Length Maximum Diameter Sea Level Air Flow Compressor Ratio Total Pressure Ratio
The basic Pratt and Whitney J-58 engine had its early beginnings in late 1956. When Lockheed and Pratt and Whitney got together to identify the engine and airframe parameters for the SR-71, the enormous advances in technology that had to be developed became apparent. The engine inlet had to be capable of sustaining temperatures in excess of 800 degrees F under certain conditions; the fuel inlet temperatures would reach 350 degrees F at times; fuel temperature would reach 600 to 700 degrees F; lubricating temperatures would vary from 700 to 1,000 degrees F in some localized parts of the engine.
The J-58 engine was every bit as innovative as the aircraft. It was the first dual cycle engine put into service. At subsonic and transonic speeds it was a standard, single-spool turbojet engine, and it essentially transitioned to a ramjet engine around Mach 2. In fact, at cruise, the rotor of the engine actually has a small negative thrust load on the engine. Other significant features of the J-58 engine include: first and only engine rated for continuous afterburning; engine oil can withstand 550 degrees F without degradation; first use of fuel as hydraulic fluid; extensive use of high temperature nickel and cobalt alloys; and use of metals seals on plumbing joints. In full afterburner, each J-58 engine produced more horsepower than the ocean liner, the Queen Mary produced.
Fuel Tanks
The SR-71 burned JP-7 fuel. A one-of-a-kind fuel that used an additive to raise its flash point so the fuel would not break down at extreme temperatures. All 80,285 pounds of JP-7 were carried in six main fuselage tanks numbered 1 through six, moving forward to aft. Located in each cockpit was a large fuel quantity gauge, with a selector switch beneath it, to read each tank quantity individually or total fuel on board. The fuel was actually used to cool the aircraft itself and as a cooling medium for other components throughout the aircraft.
The fuel tanks formed the exterior skin of the aircraft and, consequently, always leaked when the SR-71 was cool. Shallow drip pans were placed under the aircraft after refueling to capture the dripping JP-7. Over the years, many sealants have been tried to permanently stop the leaks between the six main fuel tanks, but were never successful. The extreme heating and cooling cycles, as well as the large pressure changes of the fuel tanks, created a situation where all maintenance could do was minimize the amount of leakage. As the aircraft and fuel warmed up with increasing speed, the sealant did its job, and the tanks were tight.
Chine
The SR-71 had no high-lift devices of any sort, other than the lift created by the aerodynamic body of the fuselage, called the "chine". The chines were the flared portions of the fuselage extending outward, starting at the pitot tube on the tip of the nose and extended aft to the point where they blended into both wings. The chines improved directional stability with increasing angle of attack at all airspeeds. However, their primary purpose was to provide a substantial portion of the total lift at high supersonic speeds and eliminate the need for canard surfaces or special nose-up lifting devices. Besides being aerodynamically functional, the chine contained various compartments, called "bays", to house electronics and sensors.
Nose Section
The primary imaging sensor for the SR-71 was located in the nose of the aircraft. It was either a photographic camera or a radar imaging camera. The photographic camera, a high- resolution Optical Bar Camera (OBC), was used for taking panoramic photographs. The side looking radar system, known as the CAPRE (Capability Reconnaissance, pronounced "caper"), provided all-weather, day/night imagery. In 1986, this radar system was replaced by the Advanced Synthetic Aperture Radar System (ASARS), which provided imagery of extreme clarity. The entire nose section of the SR-7 contained either sensor and was removed and replaced after each operational mission.
Pitot Mast
The pitot boom mast is where outside air enters for the pitot/static instruments to use. Pitot and static instruments are flow measuring devices that measure velocity. They are usually located on a section of the aircraft where the air flow has not yet been affected by the body of the plane. Pitot tubes are open, L-shaped tubes that have one end open to the drive wind and the other connected to a pressure measuring device. Perpendicular to the main tube, is the static tube. This tube measures static pressure. This is the pressure that is exerted radically in all directions, like inside a balloon. The pitot tube measures the total pressure in the tube. This pressure is comprised of the velocity pressure (pressure due to the momentum of the drive wind) and the static pressure. On the left hand side of the pitot boom mast is another probe that is used to measure our Alpha (Angle of Attack) and Beta (Sideslip or Yaw) while flying.
Mission Bays
All the sensors and other mission equipment were located in "bays"- separate compartments extending from the nose of the aircraft back to the wing roots. Each bay had an alphabet-letter prefix for ease of discussion and location. The right side of the chine had five large bays (D, L, N, Q and T), and the left side four bays (K, M, P and S) for housing mission equipment. A-Bay was the removable nose section, J-Bay the nose wheel well, and G-Bay the rear cockpit. Directly behind the rear cockpit was C-Bay to house a camera, R-Bay holding all of the radio equipment, E-Bay containing all of the electronic equipment, and H-Bay with air conditioning equipment.
To keep high temperatures out of the bays, they were air conditioned and insulated with layers of silicone impregnated fiberglass cloth, pre-compressed fiberglass slab, and aluminum foil. All of the intelligence sensors inside the bays were of the "remove and replace" type - none permanently stayed aboard the aircraft. These included Panoramic, long-range and infrared cameras, electronic intelligence sensors and side-looking radar. They were truly one of a kind, making them very expensive and required extensive maintenance preparation between each mission.
Landing Gear
The aircraft's main gear consisted of three wheels on each side, any one of which could support the SR-71 at normal landing weights and were rated for a maximum speed of 239 knots. Each main gear was equipped with anti-skid protection for slippery runway conditions. The front cockpit had an emergency gear release T-handle, permitting the gear to be released and free fall by gravity to the down and locked position when pulled out by the pilot.
The nose gear consisted of two smaller tires used to steer the aircraft . By pressing the "Nose Wheel Steering" button on the stick grip, the pilot engaged a holding relay that allowed hands free steering of the aircraft through his rudder pedals. Nose wheel steering was limited to 45 degrees left and right.
The 32-ply tires were silver coated to reflect heat and filled with high-pressure nitrogen for inserting. Depending on how well pilots landed, each tire was good for about 15-20 landings (full stop or touch-and-go).
Tail Cone
The tail cone, the far aft center section of the plane, is the location of the dump mast. In emergency situations, a fuel dump switch could be opened by the pilot, dumping fuel overboard at a nominal rate of 2,500 pounds per minute. We used the fuel dump to reduce our gross weight quickly for optimum landing conditions.
The Equipment Bay
"Operational" missions were those that flew through what was called a "sensitive area". The majority of our operational sorties were flown repeatedly with only minor changes to the track or sensor operations. Most of these "routine" missions were flown to gather what was called "Indications and Warnings" (I & W) intelligence on other countries using sophisticated intelligence sensors.
All of the intelligence sensors were of the "remove and replace" type - none permanently stayed aboard the aircraft. They were truly one of a kind, making them very expensive and required extensive maintenance preparation between each mission
The primary imaging sensor was located in the removable nose of the aircraft, while others were located in the various equipment bays. With this equipment, the SR-71 could provide continuous sensor coverage over the ground from 80,000 feet. With all sensors operating, the SR-71 could gather intelligence over 150,000 miles every hour.
Optical Bar Camera / OBC
The OBC was a high-resolution camera, used for taking panoramic photography. It utilized a continuous moving roll of film. Camera operations were automatic, but the RSO manually controlled its operating modes: vertical exposure or stereo photography. In operation, the camera took photographs while scanning from left to right across the SR-71's flight path. The OBC's terrain coverage was 2 nm along the ground track and extended 36 NM to each side of the aircraft (further if banked). Sufficient film was onboard to cover approximately 2,952 NM, or 1,476 NM in stereo mode.
Advanced Synthetic Aperture Radar System / ASARS
ASARS replaced the older CAPRE (Capability Reconnaissance) system in 1986. ASARS was a state-of-the-art, high resolution radar imaging system, which provided the intelligence community with all-weather, day/night imagery. ASARS viewed terrain by means of radar to the left and right of the ground track, at selected ranges. It had the capability for search, acquisition (navigation update), and two high-resolution spotlight modes. In search and spotlight modes, the imaged area was perpendicular to the ground track, or it could be "squinted" forward or aft up to 30 degrees. In the acquisition mode, the imaged area for a navigation fix point was 37 degrees forward of perpendicular.
In the search mode of operation, the terrain coverage was a 10 NM swath, positioned 20 to 100 NM to the left or right of the ground track. In the large spotlight mode, the terrain coverage was approximately one NM square. In the small spotlight mode, a rectangle approximately one NM by 1/3 NM Both spotlight modes could be positioned 20 to 85 NM to the sides of the ground track. The ASARS sensor required the nose section to be slightly modified in the shape of a "duck's bill", with obvious dimples on each side of the nose chine. All operations were controlled automatically by the ASR (Astro-inertial Navigation System) and/or manually controlled. Ground based processing equipment produced high-resolution radar imagery from airborne-collected digital data. The data link system had the ability to downlink ASARS data when the flight path permitted.
Technical Objective Camera / TEOC
We always flew with TEOCs (pronounced techs) onboard for specific target areas. These high-resolution cameras were installed in the left and right hand mission bays and could be pointed from 0 to 45 degrees to the side of the aircraft. The ASR controlled the TEOC cameras automatically. At 0 pointing angle, the TEOCs covered a 2.4 NM square area, and at a 45 degree pointing angle, covered a 5 by 6 NM diamond shaped area, 14 NM from the side of the aircraft. Each TEOC had approximately enough film for 1,428 NM of coverage. I've seen excellent photos from the TEOCs showing MiGs falling out of the sky, from attempted intercepts on the Blackbird, as they ran out of airspeed and ideas!
Electronics Intelligence / ELINT
ELINT is the recording of electronic signals covering a broad range of frequencies of the electromagnetic frequency spectrum. ELINT included collecting signals from the Electronic Order of Battle at the low end of the spectrum (like radar acquisition, tracking and guidance signals) to the very high frequencies of the Soviet SA-10 missile. The SR-71 was excellent for "stimulating" the enemy's electronic environment. Every time Habus flew in a sensitive area, all kinds of radars and other electronic wizardry were turned on to see what was flying so quickly through their airspace.
To receive and record signals we first used the Electromagnetic Reconnaissance (EMR) system. Due to the fact that it had no discretion on what signals it received, it was later replaced with the EMR Improvement Program (EIP). The EIP was a highly sophisticated and programmable scanning system capable of receiving only specific signals. It had the logic to key off specific signals it found, then move on to look for other associated radar frequencies. The EIP continuously recorded signals from horizon to horizon along our flight path, a distance of around 1,200 NM If the system recorded a specific frequency for a short period of time, computer could plot the precise position of the transmitter on the ground within approximately one half mile, at a distance of 300 miles from the Blackbird.
Flying over the same sensitive areas on a regular basis allowed intelligence analysts to determine such things as troop movements, changes to the EOB, and the aircraft deployments-all good indications and warnings that something was about to happen. If the intelligence indicated a high level of activity, we could then focus our intelligence gathering in greater detail on a particular geographic area
Survival Systems
As a physical environment, space begins at about 125 miles above the earth, but as a physiological environment, it begins at about 63,000 feet. At this altitude the atmospheric pressure becomes so low that fluids boil off at body temperature. The main function of the pressure suit was to save your life at the extreme altitudes, temperatures and speeds the SR-71 flew. Above 45,000 feet a crew member's Effective Performance Time (EPT) is between nine to twelve seconds without oxygen. Frost bite to the skin would occur rapidly at the SR-71's operational altitude, where the outside air is -56 degrees C. Without a suit on at 80,000 feet, and the loss of all cabin pressure or an ejection scenario, you would not survive.
The Suit
Most people are amazed that the SR-71 didn't have sealed cockpits upon ejection, but individual ejection seats. There have been ejections from the SR-71 at high Mach and high altitude, as well as low airspeed on the runway. The pressure suit and ejection seat combination have served Habus well, with only one known fatality during ejection. The pressure suit became our capsule and protector.
Although not considered a military uniform, the David Clark Co. model 1030 pressure suit was the most prized uniform for aspiring Habus. The suits, costing $120,000.00 each, were made up of six layers. Three of the layers were significant.
The exterior layer was made of a fire retarding material called Nomex. It contained various pockets , a Velcro patch for your checklist, and parachute harness connections. It also gave access to two important valves, each located around the bottom of your ribcage. The adjustable valve on the left side was connected to a cooling air supply and controlled the amount of air coming into the suit. The valve on the right side was the critical pressure controller. In the event of a loss of cabin pressure, the suit controller sensed the loss and immediately inflated the suit.
The inner layer, called the bladder, was made up of a rubber compound and became inflated, much like a balloon, when air pressure was added. The rubber layer was irritating to bare skin, thus the need for a comfort liner made from lightweight Dacron material. Because it was called a "pressure suit" most people thought we flew with the suit inflated at all times. Nothing could be further from the truth. It only inflated when necessary to save your life. Also located inside the bladder was a network of tubes to direct cooling air to the extremities.
Between the outer layer and the bladder of the suit was a tightly woven mesh netting designed to provide rigidity and keep the bladder from inflating too much. The netting was woven in such a manner that it utilized the same principle as a familiar child's toy. Remember the Chinese finger pull? When you put your two fingers in and then tried to pull them apart, what happened? You discovered the harder you pulled, the harder it was to get your fingers out. The same principle applied to the suit - the more pressure exerted by the bladder against the webbing, the more rigid it became.
To accommodate our feet, the pressure suit utilized a single layer of heavy material, make it look as if we had "booties" on our feet. Over the booties we wore thick, leather boots. Stirrups were attached the heals of each boot by strong Velcro straps. The stirrups attached to retractable cables located on the bottom of the ejection seat. The cables automatically retracted and locked your feet into the correct position when ejecting.
The gloves were one item that had to be perfectly tailored to fit each individual. Nothing was more irritating than flying the SR-71 with a pressure glove that didn't fit properly. Each glove had a locking metal ring, mating it to the sleeve of the pressure suit. Cooling air supply tubes ran down the inside of your arms and had to be placed inside the gloves during the suit up. Habus routinely demonstrated how they could pick up a thin dime with a fully inflated pressure suit.
After donning the suit, it had to be checked out thoroughly before a mission. Sitting in a large overstuffed reclining chair, the suit was connected to a pressure testing unit and fully inflated to make sure it held pressure satisfactorily on both systems, and the communications and face heat worked properly.
The Helmet
The helmet was adjustable only in terms of the face seal - a latex rubber liner (later changed to foam rubber) surrounding the front of your face. The face seal was designed to trap and contain the 100 percent oxygen in front of the crew member's face for breathing. An external adjustment knob on the side of the helmet allowed the crew member to tighten or loosen the face seal to suit his comfort.
The helmet mated to the pressure suit's metal neck ring and was locked into place by a lift- and- pull locking device. Located at the bottom of the helmet was a small hole that allowed us to drink fluids and eat "tube food" in the pressure suit. A microphone was located inside the helmet, positioned directly in front of your lips. An adjustable dial on the outside of the helmet allowed you to move the mike closer or further away from your lips.
The clear helmet face plate was the final locking mechanism that made your pressure suit a sealed unit. The glass face plate was connected to a metal ring on the bottom called the "Bailer Bar". By lifting up on the Bailer Bar, the entire face plate rotated up on top of the helmet for storage. Rotating the Bailer Bar down, and locking it to the bottom of the helmet, sealed the face plate. When the Bailer Bar was locked, a flow of 100 percent oxygen was initiated inside the helmet. A dark tinted sun visor also rotated up and down to block out the brilliant sunlight.
Early face plates were made of very expensive Pittsburgh Plate Glass, which later changed to a high quality plastic material. Imbedded in the face plate was a grid work of extremely thin electrical wire, providing us with face heat. The wires were heated to prevent condensation from forming on the inside of the face plate as we breathed. Once connected to the aircraft systems, a rheostat in the cockpit allowed crews to individually select whatever face heat temperature they required. With the rubber face seal trapping the face heat and 100 percent oxygen around your face, it was easy to dry your eyes out after a four hour mission. Often you were desperate for tears to form just to moisten your dry eyes.
The UCD exit tube was connected to a small rubber hose inside the pressure suit and continued down the left leg and entered an open/close valve. The valve was located in a zipper pocket near the left knee and was the only thing accessible from outside of the pressure suit. Another tube exited the valve and continued down the left leg to a lower zipper pocket. Inside the pocket was a plastic container with a highly absorbent sponge to collect and hold the urine. As you can well imagine, there were plenty of pranks played on each other with the UCDs!
Just in case your wondering, there weren't any provisions in the pressure suit for passing solid waste.
What's involved in a top-secret SR-71 mission?
Most aircrews arrived for SR-71 training with an Air Force Top Secret (TS) security clearance. However, the SR-71 program was compartmentalized and demanded a Special Access Required (SAR) security clearance, a rare classification, reserved only for highly sensitive military programs. The unclassified SAR name for the SR-71 program was called "Senior Crown". The Senior Crown security clearance was issued at Beale for all personnel who had a "need to know" about the SR-71 program .
Once you were briefed into the Senior Crown access program, aircrews signed for, and were issued flying manuals at the squadron. To control all classified documents issued to Habus, an entire wall of the squadron administration room was lined with security safes. This was a Habu's first introduction to an increasing maze of combination locks, cipher codes and secrets he would have to memorize in order to fly a mission.
DETS
Beale Air Force Base
Det 1 - Kadena AFB, Okinawa
Dets stands for Detachments. Dets were SAC/ACC deployment bases for U-2 and SR-71 reconnaissance aircraft. Dets were established at various bases throughout the world, enabling quick response for any intelligence mission. Listed below are the Det numbers, locations, units, and aircraft based there. Notice that some Dets only served as bases for the U-2. SR-71's, fewer in numbers and able to cover larger areas because of speed, could effectively be based at fewer locations and achieve the same coverage. Beale AFB, in Marysville California, was the SR-71 and U-2 home base. Both aircraft were part of the 4200th (later, 9th) Strategic Reconnaissance Wing which was headquartered at Beale.
Det 1 - Kadena AB, Okinawa, Japan, 1129th SAS, A-12, and 9th SRW, U-2, SR-71.
Det 2 - Osan AB, South Korea, 9th SRW, redesignated 6th RS, 9th RW, redesignated 5th RS, 9th RW, U-2.
Det 3 - Ramey AFB, Puerto Rico, U-2, moved to: - RAF Akrotiri, Cyprus, 9th SRW, redesignated 5th RS, 9th RW, U-2.
Det 4 - Plattsburgh AFB, New York, U-2, (HASP-deployment),
moved to:- Ezeiza AB, Argentina, U-2, (HASP-deployment 9/11/58 to 8/1959 and 5/1960 to 6/1960),
moved to:- RAF Mildenhall, UK, 99th SRS, 9th SRW, established 3/31/1979, U-2 and SR-71A, (the U-2s moved 1980 to RAF Alconbury, UK, becoming the 95th TRS, 17th RW, 1991 to OL-UK, which moved 03/15/1996 to RAF Fairford, UK) 1980 - 1991 only SR-71.
Det 5 - Patrick AFB, Florida, 9th SRW, U-2.
Det 51 - Palmdale, California, Air Force Plant 42, Lockheed Plant 10, 2762th Logistics Squadron, AFLC, U-2 and SR-71, (before 12/31/1970, operations were part of AFSC), reorganization 09/1977 to:
Det 6 - Palmdale, California, Air Force Plant 42, Lockheed Plant 10, 2762th Logistics Squadron (parts supplier), AFLC, (formerly Det 51), U-2 and SR-71, (Headquarters at Norton AFB, California)
Mission Prep.
Once it was your turn on the "ladder" to fly, mission planning began in earnest the day before the flight. The primary and backup crew met in Operations to go over details with our mission planners. The pilot and RSO discussed the air refueling tracks, fuel offloads, bank angles, Mach numbers, fuel minimums, threat areas, SAM missile sites, the Closest Point of Approach (CPA) to unfriendly airspace, abort scenarios, alternate bases, and weather forecasts.
2100 - Sleep (if you could)
0500 - Wake up (the hard part), shower, dress
0530 - Eat high protein/low residual meal
0615 - Formal mission briefing start
0645 - Physical exam and suit up
0715 - Arrive at aircraft
0730 - Start engines (depending on taxi distance)
0800 - TakeoffFor a routine sortie, mission planning took about 30 minutes for an experienced crew and about one and a half to two hours for a new crew. New and more complicated sorties could take several days to plan effectively.
After mission planning was finished to everyone's satisfaction, crews stored their classified materials back in the safe and were free to do as they pleased until crew rest time came around - the standard Air Force 8 hours of uninterrupted sleep. However, since our wake-up time was usually about 3 hours before takeoff, Habus had to get to bed much earlier. We typically followed the schedule to the right for a 0800 takeoff.
Flying The Mission
Go on an SR-71 Operational Mission
Engine Start
A few minutes before the crew was ready to start the engines, they went through their STARTING ENGINES checklist. One minute before starting engines, the crew lowered and locked their Bailer Bars to start the flow of 100 percent oxygen to begin the denitrification of their bodies. As the pilot turned on the retractable anti-collision lights, the bright red lights swirled around the hanger walls, signaling everyone the start of engines in one minute. Like a dragster revving up at the starting line, you could hear the souped-up "Buicks" idling rough as their exhaust echoed throughout the hanger.
When the pilot was ready for engine start he queried the crew chief over the interphone, "Intakes and exhaust clear, fire guard posted, chocks installed?" After the crew chief replied the pilot called out, "I'll take rotation." At that point the crew chief signaled back under the wing to his assistants to open full throttle on the "Buicks." Their exhaust noise was deafening, but to a Habu, it was sweet music. At the first sign of engine rotation on the RPM gauge, the pilot brought the throttle out of cutoff to idle position. As the J-58 rotated faster and faster, the TEB ignited the fuel and the engine was started. The pilot then called out "disconnect rotation", when he saw 3200 RPM on the gauge
Starting the engines was accomplished by a direct mechanical drive to initiate engine rotation. The large starting cart used to turn the engine over was called a "Buick" because it originally had two large Buick V-8 engines, mounted beside each other, providing over 600 horsepower to rotate the J-58 engine. When Buick engine parts became scarce, maintenance converted over to using large block Chevrolet V-8 engines. The "Buick" engines didn't have mufflers, just 16 straight pipes coming off of the exhaust manifold. Through a series of gears, the two "Buicks" drove a vertical shaft, extending upward and connecting directly to the bottom of the J-58 engine.
After waiting two minutes for the hydraulic fluid to thoroughly circulate throughout the aircraft, a flight control check was made by the pilot and verified by the crewchief, watching for the rudders and elevons to move appropriately. After the single hydraulic system checked satisfactorily, the second engine was started in the same manner.
Before Taxing
The BEFORE TAXI checklist was next. The Stability Augmentation System (SAS) was engaged, and the pitch and roll switches of the autopilot were turned on. The Digital Automatic Flight and Inlet Control System (DAFICS) was thoroughly tested, taking about one minute. Navigation systems and radios were checked thoroughly. Pitch, roll and yaw trim switches were checked and confirmed for proper movement, as well as checking the Right Hand Rudder Synchronizer moving the right rudder correctly. Next, the pilot tested the fuel derich system, which cut back the fuel richness in an over-temperature situation.
While the derich check was being accomplished, the crew chief walked up the stairs and into position to check that the air refueling system were working satisfactory and that the drag chute doors were closed. All the time these checks were being completed the RSO was busy checking out the ANS for navigational accuracy. After the crew chief did his checks, the PSD technicians reached in each cockpit and armed the ejection system. As the PSD techs started down the stairs, the crew chief lowered both canopies.
The Digital Automatic Flight and Inlet Control System, was designed to control inlet positioning automatically and position flight control surfaces to insure optimum flight performance and to help control unstarts. The heart of the system consisted of three triple-redundant computers that constantly compared inputs and voted among themselves. DAFICS replaced the analog AFCS system in 1983.
The crew chief walked down the stairs, and with the help of his assistants, rolled both ladders to the sides of the hanger. The pilot then engaged the air refrigeration system, and the crew chief asked permission to disconnect the ground cooling air supply hose. After checking the periscope and the nosewheel steering, and a final check with the crew chief that all panels an gear pins were "secured and removed," the crew chief was cleared by the pilot to disconnect his interphone. Most Habus gave their crew chief a few words of "thanks" before disconnecting.
Taxing
The crew chief walked smartly about 150 feet out in front of the aircraft and stood at "parade rest" waiting for a flash of the taxi light. During these final minutes the mobile crew had been watching tower for the flashing green "cleared to taxi" light signal. When it was received, the mobile car started onto the taxiway to lead the SR-71 out. A quick flash of the taxi light signaled the crew chief for his assistants to remove the chocks. With "taxi" hand signals from the crew chief, the pilot added a small amount of power and gracefully taxied out of the hanger.
During taxi the only check was to test the brakes on the individual hydraulic systems. Sometime during taxi, the RSO switched the ANS into the "ASTRO INERTIAL " mode, enabling it to achieve star tracking whiled taxiing out. At the departure end of the runway, the crew chief jumped out of his van and walked into position on the taxiway to help line the aircraft up for the BEFORE TAKEOFF checks. He then gave the signal for "chocks installed". The pilot and RSO then coordinated the navigation system for departure and ran the engine run. During the engine run at full military power, engine gauges were checked for their proper values and all engine systems were checked. After the engine run, the crew rechecked the flight controls, oxygen system and that Baylor bars were down and locked.
The Astro-Intertial Navigation System (ANS) was a star tracking navigation system. ANS was highly accurate, reliable and didn't depend on inputs from other sources subject to electronic jamming. ANS would track two different stars to determine precisely where the SR-71 was over ground. By comparing the position to the stars to their known location, and with the exact time of day, the ANS could compute the aircraft's exact position. Things may change here on earth from century to century, but the same stars guided both Christopher Columbus and Habus.
After the crew chiefs assistants removed the chocks, the pilot gave the final "thumbs up". The crew chief responded back with a salute and walked back to the maintenance truck to wait for takeoff. As soon as the Tower Officer saw through his binoculars that the crew was ready and the runway was free, he asked tower personnel to give the steady green "cleared for takeoff" light. Mobile led the aircraft onto the runway and continued down the full length looking for anything that could possibly damage the tires or engines.
Takingoff
Lined up on the runway, the TAKEOFF checks began. They consisted of turning on the IFF (Identification Friend or Foe) transponder, engaging all SAS channels, insuring all warning and caution lights were out, circuit breakers checked in, compass headings checked, nosewheel steering engaged, and tank-4 boost pumps turned on. After the mobile crew was clear of the runway, tower gave the crew another "cleared for takeoff" light signal with about a minute to go. Habus took pride on releasing the brakes at the precise takeoff time, using the RSO's ANS clock for an accurate countdown.
As the throttles were slowly advanced, the pilot released the brakes when the IGV (Inlet Guide Vane) shift light illuminated. After pausing briefly at full military power, the pilot lifted both throttles up and moved them forward into the mid-AB range for ignition, then smoothly advanced them to max afterburner once the lit. The takeoff acceleration was rapid, and the pilot had to be ready to bring the nose off the ground at 180 knots (207 mph). Slowly, but steadily pulling back on the stick, the nose traveled upward to about 10 degrees pitch allowing the aircraft to break ground around 210 knots (242 mph.)
The AB (afterburner) engine noise was so loud that its sound waves caused your entire body to shake. During an engine test, standing 20 feet to the side of the engine, you could try holding your teeth tightly together, but they still rattled! In max AB at sea level, the AB section reached temperatures of 3,200 degrees F and at the distance of a football field behind the engine, exhaust temperatures were still 311 degrees F at a velocity of 150 knots. Every visitor who saw a J-58 night engine run went away overwhelmed by the sheer power and beauty of the spectacle.
Once airborne, the pilot had to relax back pressure on the stick to stop the nose up pitch rate. The first priority for the pilot after getting airborne was to get the gear up and then quickly scan the engine instruments. We climbed out at 400 KEAS (Knot Equivalent Air Speed) until reaching 0.9 Mach, then held the Mach constant until reaching our subsonic cruise altitude.
"Cold" Refueling
Most all of our operational sorties started off with refueling right after takeoff. We took off without a full load of fuel. Take off with a full load of JP-7 was possible, but not practical. Fuel leakage, tire and break heating, abort criteria and single engine performance were stacked all stacked against you the closer you were to a full 80,000 pound fuel load. With no weather radar on the SR-71, most crews were anxious to establish secure radio contact with the tankers. All our tankers were required to be established in the air refueling track 30 minutes before our time of arrival, to evaluate the weather and determine if the track needed to be moved.
Soon after takoff, the RSO began to establish ranging and bearing on the tanker with the ARC-50 radio. The rendezvous was basically left up to the lead tanker crew to accomplish - we merely flew on course, straight towards the ARCP (Air Refueling Control Point) at 0.9 Mach, and monitored his progress during the final stages of rendezvous. After visual sighting the lead tanker, we maneuvered the SR-71 to place the end of the air refueling boom about three feet outside the front window. It was up to the refueling boom operator to make the hookup. While you were in the final stages of refueling with the lead tanker, the second tanker was slowly maneuvering into position. After release from the lead tanker, the hookup process was repeated with the second tanker.
The climbout and departures were radio silent - we spoke to no one! The monitoring radar control facility identified the SR-71 by our IFF ( Identification Friend or Foe) code appearing on their radar screen. Air traffic controllers cleared the airspace around us so there was no need for radio transmissions. If they had to call us or give emergency instructions, we acknowledged by pushing the identification feature of the IFF rather than making a UHF call.
Even though the tanker crews were briefed previously , we reminded them before disconnecting which direction the accel started out and told them on which side the SR-71 would clear them after refueling. Once clear of the tankers, the pilot selected roll autopilot and "AUTO NAV" to start the aircraft heading on course to begin the accel.
The Acceleration
The trans-sonic acceleration called for a climb-and-descent maneuver we called the "Dipsey Doodle." The maneuver accelerated the SR-71 to supersonic speeds as rapidly as possible to minimize the time spent between Mach 1.05 an 1.15, an area of excessive drag on the aircraft. The "Dipsey Doodle" started out by lighting both ABs to their minimum setting and climbing at 0.9 Mach.
As you passed through 30,000 feet, the throttles were advanced to max AB, continuing the climb to 33,000 feet and slowly increasing the airspeed to 0.95 Mach. Approaching 33,000 feet, Habus nosed the aircraft over gently an began a descent of 2,500 - 3,000 feet/min. For optimum acceleration, it was important to exceed Mach 1.05 early in the descent and to avoid turning until the climb was established. Going through Mach 1 in the SR-71 behaved no different than any other aircraft. Approaching 420 -430 KEAS (Knot Equivalent Air Speed), the pilot started to bring the nose up slowly, so as to capture and hold 450 KEAS while climbing. Stabilized at 450 KEAS, he engaged the pitch autopilot and the "KEAS HOLD" function. For the remainder of the accel the autopilot held 450 KEAS until the KEAS bleed schedule was reached at Mach 2.6. Pilots watched for the forward bypass doors to begin opening up at around Mach 1.4. During the accel, there was considerable pilot technique and finesse involved in managing the inlets.
KEAS stood for Knots Equivalent Air Speed and is calibrated airspeed corrected for compressibility effects of altitude and airspeed. Once the aircraft was supersonic, the only speed (other than Mach) we talked about was KEAS. During the accel, we engaged the KEAS HOLD at 450 KEAS to keep the speed constant until reaching what was called the KEAS bleed schedule. This began at Mach 2.6 and automatically decreased the KEAS 10 knots for each tenth of Mach speed increase. The bleed schedule kept the aircraft from exceeding its maximum KEAS.
Around Mach 2.95, the pilot disengaged the KEAS HOLD function of the autopilot and began to control pitch by rotating the pitch wheel forward to achieve a smooth level off. He slowly lowered the nose of the aircraft until the pitch steering bar on the ADI (Attitude Direction Indicator) barely touched the miniature aircraft while retarding the throttles from full AB to the approximate fuel flow readings for Mach 3 cruise.
High Mach Cruise
Above 60,000 feet, the airspace was all ours! Since there was no other aircraft to concern ourselves with above 60,000 feet, we flew the SR-71 in what was called a cruise/climb maneuver for maximum efficiency. Because of the tremendous rate of fuel consumption in afterburner cruise (around 44,000 lbs./hour), we flew continuously at the optimum cruise altitude for the aircraft as our gross weight decreased. That worked out to about 100-150 feet/minute rate of climb for the aircraft.
With a full load of fuel, Habus typically started off a mission with an initial level-off altitude of around 71,000 feet. By the time they were ready to descend, they were cruising up around 78,000 feet. We generally flew the Mach programmed on the flight plan as long as "temp devs" were not a factor. Often, because of warmer temperatures, we flew slightly faster to keep the forward bypass doors running tighter. The SR-71's cruise performance was not like other jet aircraft. In other jets, if you wanted to fly considerably faster, it cost you more fuel. The Blackbird was just the opposite; the faster you flew, the more fuel you saved.
Above 80,000 feet the horizon-to-horizon view of the ground beneath was tremendous, providing a pronounced view of the curvature of the earth. Colors in the sky were deeper and more vivid, and the sun was so brilliant that it washed out cockpit instrumentation as it moved across the panel in turns. During the day the horizon was a deep blue color, slowly changing to the black of night as you looked higher and higher above the horizon. Peering upward into the dark sky, you could see the stars in the daytime.
The design Mach of the SR-71 was Mach 3.2. However, when authorized by the Commander, speeds up to Mach 3.3 could be flown. The maximum altitude was 85,000 feet unless specifically authorized higher. After the SR-71 cruised for about 15-20 minutes, the entire aircraft had heated up to cruise temperatures. This ranged from around 500-699 degrees F on all leading edges to 1,100 degrees F at the exhaust nozzle area. At our cruising altitudes, there is very little sensation of traveling at 2,200 mph. I always had a greater sensation of speed over the ground flying a T-38 on one of our low level navigation routes at 415 mph at 1,000 feet. The only sense of speed at high altitude was watching the DME (Distance Measuring Equipment) click off at 33 miles per minute. More than a speed sensation, Habus gained a greater appreciation of time and distance relationships. To be able to fly from California to England in only four hours, or Japan in five hours, was a remarkable feat for any aircraft.
The Deceleration
The SR-71's decel was a maneuver that left little room for error. Unlike most jet aircraft, Habus didn't have the latitude to change throttle settings at random or add and subtract drag devices to modify their rate of descent. Once the throttles were brought out of AB at 78,000 feet, the bottom-out point of our decel was basically set. The SR-71's engines and inlets had to be managed during the decel in precise configuration to preclude unstarts, compressor stalls, and engine flameouts.
Prior to starting down, the RSO established ranging with the tanker to make sure he was there waiting for us. When the aircraft arrived at the computed start-descent point, the pilot slowly retarded both throttles to min AB, paused momentarily, and pulled them back further to drop into full military position. As the KEAS began to decrease, the pilot slowly rolled the pitch wheel forward, and intercepted a speed between 350-365 KEAS to reduce the probability of an "unstart," engine stall, or flameouts. As the airspeed approached 365 KEAS, the "KEAS HOLD" function was engaged. At Mach 2.5 the throttles were pulled back slowly and set to 6900 rpm. Below Mach 1.3, the inlet controls were checked in their proper positions, the spike full forward, and the bypass doors closed. After Mach 1.3, the throttles could be placed anywhere to adjust the descent profile as necessary.
Anytime the inlet pressure became unacceptable to the AIC (Air Inlet Computer), a phenomenon know as and Aerodynamic Disturbance, or "unstart" took place. An inlet unstart can only occur when the aircraft is supersonic and after and inlet has been "started"; that is, supersonic flow is established inside the inlet. As supersonic speed increases, the supersonic air flow inside the inlet slowly moves aft, to an exhaust port called the "shock trap bleed". An unstart occurs when the Compressor Inlet Pressure becomes too great and has no place to go inside the inlet, causing a shockwave expulsion to relieve the excess pressure build up. An unstart usually caused a very unpredictable and violent maneuver of the aircraft.
Once the aircraft was subsonic, we maintained 0.9 Mach, disengaged KEAS HOLD, and leveled off with either the pitch wheel or the control stick. The descent was fairly steep by now and required about a 2,000 foot lead point to level off at the air refueling altitude.
"Hot" Refueling
We leveled off from the decel 40 nm from the ARCP (Air Refueling Control Point) and 2,000 feet below the air refueling altitude, continuing to close at 0.9 Mach. Once the lead tanker was ranging on us, they began timing and controlling the length of their racetrack orbit legs, planning to end up at a precise point when the SR was about 15 miles out from the ARCP. The tanker navigator used timing charts, based on the distance between the two aircraft, to help him compute when to make the final turn to join up.
When the time was right, the lead tanker navigator had his pilot being their final left-hand turn, planning to roll out about three to four miles in front of us. With ARC-50 giving us range and bearing we were allowed by "the book" to rendezvous down to one mile in the weather before we had to visually sight the tankers. To get their gas, many Habus joined up on the tankers with visibilities well below one mile.
The SR-71 was the first aircraft to use its own fuel for hydraulic fluid-called the Fuel-Hydraulic system. An engine driven pump provided 1800psi of recalculated fuel to actuate various engine components and then returned it back to the aircraft's fuel system to be burned.
If everything proceeded normally during the rendezvous, the tanker cell initiated their "descend and accelerate" maneuver when the SR-71 was one mile behind them and closing fast. The maneuver called for the tanker cell to add power, descend 1,000 feet, and accelerate to 310 knots. We remained at our altitude until sighting the tankers visually, then slowly closed in, and up to the pre-contact position. Normal refueling altitudes were anywhere between 25,000 and 28,000 feet. Once the rejoin was accomplished there is no difference between a "hot" rendezvous and the "cold" rendezvous previously described.
Subsonic Recovery
The final decel began as close to the Dets as possible. On the final return leg we stopped using radio-silent procedures and made normal radio calls to Air Traffic Control agencies as we descended through 60,000 feet. Generally, we received radar vectors to a precision final approach. With power back to idle, the SR-71's subsonic descent rate was over 6,000 feet/min. After going through the DESCENT checklist and the BEFORE LANDING checklist we were ready for the final approach.
We entered the VFR traffic pattern at 300 KIAS and 1,500 feet above the ground. Flying directly over the runway, we "pitched out" by rolling into a 60 degree bank. After turning a 180 degrees, the airspeed was reduced sufficiently to lower the gear at 250 KIAS on the downwind leg. Before turning base leg the pilot quickly scanned the landing gear lights, hydraulic pressure gauges, and the annunciator panel for proper indications. Coming off the downwind leg, the base turn was a gradual 180 degree descending turn, slowing to 230 KIAS with the power close to idle. Rolling out on the final approach, about one mile from the end of the runway and 500 feet, the power remained near idle as the pilot slowed the aircraft to its computed final approach speed.
One technique to minimize the landing distance was to pull the drag chute handle while the SR was just a few feet above the runway and ready to touchdown. Time just right, the main drag chute blossomed right at touchdown. Obviously, if your timing was off it could ruin your day by slamming the aircraft onto the runway. Since any drag chute is most effective at higher speeds, it made a significant difference in your overall stopping distance to deploy it as soon as possible.
The final approach pitch altitude was relatively steep, somewhere around 10 degrees nose up. Forward visibility during landing was good although the long nose and chines blocked out runway references beneath and to the sides of the aircraft. The large delta wing and chine area created a large amount of "ground effect" allowing the SR-71 to float, and cushioned the landing for a smooth touchdown.
After the main gear touched down, your first action was to reach forward with your left hand and pull the drag chute handle out, deploying all three chutes. As the main chute blossomed, the pilot slowly lowered the nose wheel onto the runway by releasing back pressure on the stick. After the nose wheel was on the runway, the steering was engaged, and the brakes where checked for normal operation before jettisoning the drag chute. As the aircraft passed mobile, they floored the car onto the runway, chasing after the SR-71. If anything was abnormal during the landing rollout, the mobile crew advised the fliers over the radio. The mobile car caught up with the aircraft just about the time the drag chute jettisoned, then passed along side the SR-71 to lead him back to the hangar.
After Landing
For all operational sorties, we taxied directly into the hangar so maintenance could download the sensors expeditiously. We followed the crew chief's hand signals, guiding us safely into the tight confines of the hangar until signaled to stop. After he geve the "chocks installed" signal, the pilot released the brakes, disengaged the nosewheel steering, and transferred fuel forward to a CG of 17 percent to facilitate downloading of sensor equipment. The crew chief's assistants were busy placing the brake cooling fans around each main landing gear.
After all our loose items in the cockpit were secured, we opened the canopies and locked them up. By this time the crew chief already had the ladder in place. The remainder of the SHUTDOWN checklist had us verifying the electrical and hydraulic back-up systems. The crew chief had been on the intercom headset as soon as the chocks were installed and cleared the pilot to shut down the engines.
The main landing gear wheel wells didn't dissipate heat well and consequently, the main gear remained quite hot after landing. The main landing gear assembly was generally too hot to touch after parking the aircraft in the hangar. Every time Habus came to their final stop for engine shutdown, cooling fans were immediately placed in front or behind each main gear to cool down the brakes.
The first person to greet you during the engine shutdown was PSD (Physiological Support Division). They reached in the cockpits and inserted the ejection seat and canopy safety pins. After the seats were pinned, we unlocked our pressure suit helmets and handed them to PSD, followed by gloves, checklist, and other mission materials. Once you disconnected the parachute harness, lap belt, survival kit straps, the stirrups, both oxygen hoses, the manual parachute D-ring, communications cord, and cooling air supply hose, you were free to exit the cockpit. Most Habus waited for each other at the top of the ladder before stepping down to the hangar floor.
Debriefing
As soon as the last engine was shut down maintenance personnel immediately swarmed all over the aircraft, like bees on honey, each with a specific job to do. It was a sight to behold, watching everyone working on the aircraft in perfect orchestration. Highest priority was to download the sensors from the chine bays as quickly as possible and rush them to our Mobile Processing Center for film development, computer processing, and analysis. After our photo interpreters first looked over the film, they immediately put out the Initial Photo Interpretation Report, letting everyone know the success or failure of the intelligence we were sent to gather.
At the foot of the ladder, waiting for the crew to descend, was the Det Commander, the maintenance supervisor, mobile crew, and the aircraft's crew chief. Everyone was interested to hear what the pilot and RSO had to say about how everything rand. It was a quick debriefing, lasting about five minutes or so, depending on how many maintenance problems the crew had with the aircraft. Often, by the time we debriefed at the aircraft, the sensors were already downloaded and well on their way to being processed.
For ease of maintenance, the aircraft was equipped with a Mission Recorder System (MRS), that recorded every three seconds on magnetic tape, various parameters of the aircraft and its associated systems. After flight, maintenance removed the MRS tape and through a computer process converted the electrical inputs into meaningful information. The MRS tape was distributed to experts to look over and see if anything was going wrong with their particular system.
Soon after, we changed back into our flight suits, gathered up all our classified materials and were off to debrief the mission. Crews attended the operations debriefing session first. The Det Commander, Operations Officer, fliers, mobile crew, weather personnel and mission planners attended the debriefing to as a series of routine questions. At the end of each debriefing, the Det Commander usually had a few words of prais if everything went smoothly. If it didn't, we discussed our problems and came up with ways to improve the operation next time. When the Commander stood up to leave, everyone came to "ATTENTION!", and we departed for the maintenance debriefing session. The maintenance debriefing session covered all major aircraft systems, allowing maintenance personnel to trouble-shoot and correct any discrepencies quite accurately. Everyone else went back to their office and began filling in classified reports that had to be sent to various agencies.
Aircraft Support
The SR-71 didn't complete its missions alone. Various support aircraft, air crews, ground crews, Lockheed personnel, and other technical representatives all played their part. They too became part of our "Habu" family.
The T-38
At Beale, crews typically flew the SR-71 only about 3 or 4 times a month. The T-38 "Talon" was considered the low-cost alternative to maintaining our flying proficiency. Subsonic, it flew and handled similar to the SR-71. The T-38 is a twin-engine, high-altitude, supersonic jet trainer used throughout the USAF in a variety of roles because of its design, economy of operations, ease of maintenance, high performance and exceptional safety record.
Habus used T-38s to practice aerobatics, stalls, basic instrument flying, and formation practice between 11,000 and 23,000 feet. The T-38s were also used as a chase aircraft for the SR-71 whenever it got into trouble and needed to be looked over externally. Flying the T-38 in formation with the SR-71 was called "pace chase." Every time the SR-71 was flying at Beale, a T-38 had to be up flying or "cocked" on the ground, ready for immediate response with a qualified "pace chase" crew member
T-38 Specifications
Primary Function: Advanced jet pilot trainer
Length: 46 feet, 4.5 inches Height: 12 feet, 10.5 inches Wingspan: 25 feet, 3 inches Speed: 812 mph (Mach 1.08 at sea level) Ceiling: Above 55,000 feet Date Deployed: March 1961
The KC-135Q
The KC-135Q model tankers were "unique" within the Air Force and thus, earned the "Q" model designation. The aircrews of the "Q" model tankers were the only ones certified in our "unique" radio silent rendezvous procedures, and their boom operators were the only ones qualified to refuel the SR-71.
The KC-135 provided the basis for Boeing's Model 707 civil airliner and Model 717 (C-135) tanker/transport families, and also set the design philosophy which extended throughout Boeing's hugely successful airliner dynasty.
The Q model tankers had special plumbing between their fuel tanks, allowing them to move JP-4 and the JP-7 fuel used exclusively by the SR-71, between various tanks. This design gave the KC-135Q the distinction of being the only airplane capable of refueling the fastest airplane in the world. Also, if the SR-71 landed somewhere JP-7 fuel was not available, we used the "Qs" to ferry our fuel.
A special bond developed between our tanker and SR-71 crews that didn't exist throughout the Air Force. They took considerable pride in their work because of the exclusive SR-71 refueling. They knew, and so did we, that the SR-71's mission success was directly related to our ability to get refueled in the air. They were always there, somewhere in the murk and dark of night, with a full load of JP-7 waiting for us.
Specifications
Primary Function: Aerial refueling
Length: 136 feet, 3 inches Height: 41 feet, 8 inches Wingspan: 130 feet, 10 inches Speed: 530 miles per hour at 30,000 feet Ceiling: 50,000 feet Date Deployed: August 1965
The KC-10
In the early 80s, crews occasionally refueled from KC-10 "Extender" tankers. They were able to fly at higher airspeeds than the KC-135Qs, making refueling easier for SR-71 pilots. The high angle-of-attack (AOA) associated with a slow airspeed make the SR-71 more difficult to fly locked on to the boom of a KC-135Q. Based on the McDonnell Douglas DC-10 Series, the KC-10 can carry more than 356,000 pounds (160,200 kilograms) of fuel -- almost twice as much as the KC-135Q Stratotanker.
The KC-10's boom operator controls refueling operations through a digital fly-by-wire system. Sitting in the rear of the aircraft, the operator can see the receiver aircraft through a wide window. During boom refueling operations, fuel is transferred to the receiver at a maximum rate of 1,100 gallons per minute.
Specifications
Primary Function: Aerial refueling
Length: 181 feet, 7 inches Height: 58 feet, 1 inch Wingspan: 165 feet, 4.5 inches Speed: 619 mph Ceiling: 42,000 feet Date Deployed: March 1981
Ground Support
SR-71 crews formed a close bond with the people they relied on to make their missions a success. This bond was unique in the Air Force, closer than any of us had ever experienced in our careers. The longer Habus remained in the SR-71 program, the closer they got to this extended Habu "Family." The personal relationships that developed between the SR-71 aircrews, ground support personnel, refueling crews, Lockheed personnel, and other technical representatives made our program very "unique."
Our Habu family extended from the likes of Kelly Johnson and Ben Rich, to the Lockheed mechanic turning the wrenches out on the flight line. Our eternal gratitude goes out to all who played a part in the SR-71 story, without them we couldn't have done what we did.
Mobile duty consisted of assisting the fliers in their preflight routines, a very responsible position that could determine the success or failure of each mission. The mobile crew was generally a formed crew, but didn't necessarily have to be for training sorties. For operational missions, the mobile crew also performed as the backup crew, ready to fly the mission in case the primary fliers couldn't for one reason or another.
The organization that maintained our pressure suits was the "PSD". The facility was located close to the flight line and was the Air Force's entire repository for all pressure suit operations, and consequently, had a high level of experienced personnel working there. They had the technical expertise and capability to do anything and everything with our pressure suits.
The crew's transportation to and from the aircraft - the white PSD van. The mobile crew and their car are waiting for engine start. The car was equipped with two UHF radios for communication with the SR-71, the command post, tower, weather personnel, and other air traffic control agencies handling the aircraft. They also had a portable military VHF radio, nicknamed the "brick," for worldwide communications.
Tech Reps
"Tech Reps" was short for Technical Representatives, who were employed by their specific companies (Pratt & Whitney, Northrop, Itek, Goodyear, Honeywell, etc.), each having highly sophisticated equipment on the SR-71. As civilians, they played an important role in maintaining our aircraft and lived wherever the SR-71 was deployed - Okinawa, England and Beale. "Tech Reps" were the experts in their specific fields.
RTS The RTS personnel (Reconnaissance Technical Squadron) were the highly trained people who processed, analyzed, and disseminated the SR-71's inteligence take. They manned our Mobile Processing Center (MPC), which consisted of around fifteen large portable vans, interconnected to each other.
Members of the 9th Reconnaissance Technical Squadron (9th RTS), Beale AFB, California, analyze the SR-71's intelligence. Through the use of portable vans, the 9th RTS developed, processed, and analyzed our intelligence on a worldwide basis.
By Richard H. Graham, Col., USAF (Ret.)
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Richard H. Graham, Col., USAF (Ret.) |
A Biography
Colonel (ret) Richard Graham was born August 19, 1942 in New Castle, Pa. He graduated from the University of Akron, Akron, Ohio, in 1964 and received a master's degree in sociology in 1977 and in Public Administration in 1979 from Pepperdine University, Los Angeles, California. He graduated from Air War College in residence in 1982.
After receiving his commission from AFROTC he entered pilot training at Craig AFB, Alabama. In 1965 he graduated from pilot training and remained at Craig AFB as a T-37 instructor pilot and flight examiner. In August 1970 he was assigned to Davis-Monthan AFB, Arizona, to begin F-4 training. Upon completion of his training he was assigned to the 555th Tactical Fighter Squadron ("Triple Nickel") at Udorn RTAFB, Thailand from March 1971 to March 1972. During that time he flew 145 combat missions over North Vietnam and Laos in the F-4C/D aircraft. In April 1972 he was assigned to the 44th Tactical Fighter Squadron at Kadena AFB, Okinawa, Japan, flying F-4D aircraft. Four months later he volunteered for, and joined, the 67th Tactical Fighter Squadron as an F-4C "Wild Weasel" pilot. In September 1972, until February 1973, Colonel Graham was deployed with his squadron to Korat RTAFB, Thailand, to augment F-105 "Wild Weasel" aircraft. At Korat he flew 60 combat missions, suppressing enemy surface-to-air missile sites in North Vietnam. During Christmas 1972 he participated in six Linebacker II sorties over Hanoi. In March 1973 his squadron joined the 17th Tactical Fighter Wing deployed to CCK Air Base, Taiwan. He departed Kadena as the F-4 Standardization/Evaluation Branch Chief.
Colonel Graham was selected to enter the SR-71 strategic reconnaissance program in 1974 at Beale AFB, California. After several years as a crew member, he was further selected to become an instructor pilot, and in 1978 was selected as the Chief, Standardization / Evaluation Division, which included the SR-71, U-2 and T-38 aircraft. In January 1980 he was selected to be the SR-71 Squadron Commander, 1st Strategic Reconnaissance Squadron, where he served until his assignment to Air War College, Maxwell AFB, Alabama in 1981.
Following Air War College in June of 1982, he was assigned to the Headquarters USAF (Pentagon) to work in Programs and Resources as a strategic force programmer. In April 1984, he was selected to work in the Office of the Assistant Secretary of the Air Force for Manpower, Reserve Affairs and Installations. As the Director of Program Integration, he worked Air Force budgetary matters closely with the Office of the Secretary of Defense, the Joint Chiefs of Staff and the Air Staff.
In June of 1986 Colonel Graham was selected to be the Vice Wing Commander, 9th Strategic Reconnaissance Wing (SRW), Beale AFB, California. In that capacity, he was able to fly all of the wing's aircraft: the U-2, T-38, KC-135Q, and SR-71. In June of 1987 he was selected to become the Wing Commander of the 9th SRW, where he remained until November 1988. As the Wing Commander, he was responsible for 10,000 personnel and their dependents on base, over 85 Air Force aircraft deployed around the globe, and a base of 22,000 acres in northern California. He was assigned to the 14th Air Division, Beale AFB, until he retired on 30 September 1989.
Colonel Graham was a command pilot with more than 4,600 military flying hours. His military decorations and awards include the Legion of Merit, Distinguished Flying Cross with three oak leaf clusters, Air Medal with 18 oak leaf clusters, Air Force Commendation Medal, Air Force Outstanding Unit Award wtih "V" device and one oak leaf cluster, Air Force Organizational Excellence Award, Combat Readiness Medal with one oak leaf cluster, National Defense Service Medal, Armed Forces Expeditionary Medal, Vietnam Service Medal with four service stars, Republic of Vietnam Gallantry Cross with palm, and the Republic of Vietnam Campaign Medal. Upon retirement he joined American Airlines in Dallas, Texas, where he retired as a Captain on the MD-80 aircraft and with over 6,000 flying hours. His wife's name is Pat and they have five children and three grandchildren. His books, "SR-71 Revealed: The Inside Story" and "SR-71 Blackbird: Stories, Tales, and Legends" allow you to experience the SR-71 and the world of Habus as never before. A veteran of 15 years of assignments within the SR-71 community, he is uniquely qualified to tell their story. Col. Graham frequently speaks about the SR-71 program at aviation events across the United States.
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