SR71

The Blackbird

The Lockheed A-12 and YF-12A aircraft were the basis for the long-range, Mach 3+ strategic reconnaissance aircraft known as the SR-71, or “Blackbird,” as it was unofficially called.

The 4200th (later 9th) Strategic Reconnaissance Wing at Beale Air Force Base, California, received the first SR-71 to begin service in January 1966. The first SR-71 flight occurred on December 22, 1964.

Everything that had come before the Blackbird was not comparable. “Everything had to be invented. Everything,” renowned aircraft designer Kelly Johnson of Skunk Works remembered in an interesting post that appeared on the Lockheed Martin website.

The SR-71 flew at over 2,000 miles per hour. Theoretically, other aircraft of that era could reach that speed, but only in brief bursts powered by afterburners. The Blackbird maintained a record-setting speed for hours at a time. Friction with the atmosphere at such a speed produces temperatures that would melt a traditional airframe.

Two Buick Nailhead V8 engines to start the SR-71 Mach 3+ plane

When Kelly Johnson was designing the A-12/YF-12 /M-21 and SR-71 he didn’t want the weight to be added for a starter on the airplane. According to him, the more it weighs, the more fuel it will need. It was decided that the job could be accomplished by two Buick Nailhead V8 engines.

As you can hear in the video below, starting the fastest aircraft in the world, the Blackbird, was amazing, but it also sounded like the Indianapolis 500 was getting ready the SR-71 for takeoff with its two V8 engines.

Autoevolution claims that two of the aforementioned Nailhead V8 engines were fused together for this specific usage only, using a common drive shaft and transmission. The combined engines were then housed in a metal container with four wheels and a trailer hitch, which was given the name AG330 “start cart.” The two engines of the Blackbird were directly connected to the resultant Chimera. The two V8s spun the turbines until they could sustain compression on their own by using the combined drive shaft. SR-71 and its cousins, the A-12 Archangel and the YF-12 fighter, used nailhead V8s as impromptu starter motors until at least 1970, when most of them were swapped out for Chevy 454 V8s.

Phased out

When a new, quieter pneumatic system was put in place to perform the same function as the start cart at the majority of US airbases where the Blackbird and company were stationed, these were also phased out. A few continued to serve longer at auxiliary bases abroad, some of them with the original Buick Nailheads, until the Blackbird and all of its variants were retired in 1999.

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Photo by John Freedman and User:Jaydec via Wikipedia

The SR-71 Blackbird

The Lockheed A-12 and YF-12A aircraft were the basis for developing the SR-71, also called the “Blackbird” or long-range, advanced strategic reconnaissance aircraft. The 4200th (later 9th) Strategic Reconnaissance Wing at Beale Air Force Base, California, received the first SR-71 to begin service in January 1966. The first SR-71 flight occurred on December 22, 1964. On January 26, 1990, the US Air Force retired its entire fleet of SR-71s.

For almost 24 years, the SR-71 held the record for being the fastest and highest-flying operational aircraft in the world. It could cover 100,000 square miles of the Earth’s surface per hour from 80,000 feet. Two world records for its class were set on July 28, 1976, by an SR-71: an absolute speed record of 2,193.167 mph and an absolute altitude record of 85,068.997 feet.

The fifth SR-71 crewmember to reach the 900-flying hour plateau

Six of the nine years that Colonel (Ret) James H. Shelton Jr. spent at Beale Air Force Base (AFB) passed by piloting the SR-71. He was the fifth member of the SR-71 crew to achieve the 900 flight hour plateau. Though few Habus have reached that milestone, most commercial airline pilots would consider that a paltry amount of flying time.

According to Richard H. Graham’s book SR-71 Blackbird Stories, Tales and Legends, Shelton recalls a special operational Blackbird mission that took place during his initial overseas deployment to Kadena AB in May 1969 with Major Tom Schmittou (RSO):

“The operational tasking from SAC headquarters always had maintenance personnel generating a primary and secondary aircraft. On 13 June 1969, we were in primary aircraft #979 for an operational mission over North Vietnam. It was a typical four-hour flight, consisting of a single east-to-west pass across Hanoi, air refuel over Thailand, then a west-to-east pass just south of Hanoi, returning to Kadena AB.

“The engine start, takeoff, air refueling, and acceleration to Mach 2.8 at an altitude of 77,000 feet went as planned. At the navigation checkpoint, Tom informed me that the navigation system was drifting and the mission should be aborted. Tom made the abort call, and I turned the aircraft back to Okinawa. The descent from altitude and approach for landing was normal. Moderate rain was falling, so I applied the rain remover fluid to the front windscreen, allowing me to see the runway about 2 to 3 miles out.

Cockpit fogging and drag chute deploying

“The touchdown on the runway went smoothly. However, as I retarded the throttles to idle, the cockpit began to fill up with fog (water vapor). I had forgotten to increase the cockpit temperature to 85 degrees or higher, to prevent the formation of cockpit fogging; I remembered one pilot had previously blown the canopy off on landing just to see the runway and I really didn’t want to do that! I quickly flipped the cockpit temperature switch from automatic to manual hot. This eliminated the fog in the cockpit, but did nothing to slow the aircraft down. Being so engrossed with holding the temperature switch in the full hot position (spring-loaded), thereby fixing one problem, I inadvertently created another: I forgot to deploy the drag ‘chute.

“The drag ‘chute must be deployed to slow the aircraft on landing, especially on a wet runway. In my mind, and in actuality, the aircraft was slowing enough. I applied the brakes and the antiskid started cycling like crazy, so I turned it off, but to no avail. I then shut down one engine as I saw the end of the runway coming up very, very quickly (at about 120 miles hour). Fortunately, the runway at Kadena had a cable barrier installed about 1,000 feet from the end, specifically for the SR-71.”

As Graham explains “the BAK 11/12 barrier was installed at two of our operating locations – on runway 16 at Beale and on runway 05R on Kadena. The barrier was designed to stop the plane at a maximum speed of 180 knots. Arming and disarming the barrier was controlled in the tower. At both Kadena and RAF Mildenhall, we had a crewmember in the tower during all takeoffs and landings to make sure everything went smoothly.

Only two successful SR-71 Blackbird Barrier Engagements

“When armed, the barrier was activated by the aircraft nosewheel and main gear as they rolled over pressure-sensitive switchmats located in the runway before the arresting cable. The switches energized a timing computer that caused the arresting cable to be thrown up to engage the main gear struts. On engagement, the arresting cable was pulled out with a relatively constant restraining force to stop the aircraft within 2,000 feet. This was all theoretical. In actual practice, the number of unsuccessful SR-71 engagements far outnumbered the successful ones. Besides Jim successful engagement, I know of only one other.”

Shelton continues. “The barrier is designed to pop up in front of the two main landing gear and stop the aircraft in 400 to 500 feet. The barrier unit uses the B-52 aircraft brake system to slow the aircraft and bring it to a stop (hopefully!). Boy, was I relieved that the barrier worked as advertised! There was one unsuccessful barrier engagement on 10 October 1968 at Beale, where the SR-71 (#977) was destroyed. There were only two barrier engagements recorded at the time, and fortunately, ours was the successful one.

Allowed to continue flying after one of only two successful SR-71 Barrier Engagements

“Well, I just knew my SR-71 flying days were over as I climbed out of the aircraft. This incident terminated my flying at Kadena AB for this tour. The maintenance personnel worked the rest of the day and all through the night replacing the gear doors, hydraulic lines, and electrical wires on the main landing gear damaged by the barrier cable. I owe a big thanks to those maintenance personnel, because the aircraft was ready to fly the next day. They sure saved my six o’clock position (butt).

“Since this was the second fogging incident, Lockheed designed a lever that the RSO moved to stop air from entering the cockpit before landing, eliminating any chance of fogging the cockpit as the throttles were retarded. I call that handle the “Shelton lever.” Needless to say, I was allowed to continue flying, thanks to the thorough flying evaluation the standardization crews administered to me on my return to Beale AFB.”

Photo by U.S. Air Force

SR-71, KC-135Q and JP-7

If not for air refueling, the SR-71 Blackbird’s range would be relatively limited to about 2,000 NM. The aircraft’s range was increased by several air refuelings, reaching the crew’s endurance limit. A few missions have gone above 12,000 NM. The SR-71 and KC-135Q tankers’ forward basing allowed for increased overall efficiency, shorter range, shorter length missions, and faster response.

There were various ways in which KC-135Q crews and their aircraft were different from other Air Force crews. Their boom operators were the only ones qualified to refuel the SR-71, and their aircrews were the only ones qualified for Blackbird’s specific radio-silent rendezvous procedures. The Q-model tankers could transfer JP-4 and JP-7 fuel between different tanks because of the special plumbing between the fuel tanks. They may use JP-4 or JP-7 fuel in their engine. If the SR-71 landed in an area without JP-7 fuel, the Q-model tankers would fly in with the fuel and refill the aircraft using ground-based transfer hoses.

How to get better gas mileage in an SR-71 Blackbird flying at Mach 3

David Peters, former SR-71 pilot, describes how to get better gas mileage in a Blackbird flying at Mach 3.

‘We had some gimmicks we used to make fuel. Each plane was different, but the techniques were very close. As soon as we started the climb away from the tanker, I would select tank two manually and even sometimes go to manual aft transfer to get the CG aft as soon as possible. After leveling off at Mach 3, I would get the CG situated where the trim was at zero for a slight cruise climb thus eliminating induced drag. Next, I would have the aft doors in A position and manipulate the speed to close the forward doors as much as possible without creating an unstart. This might be anywhere from 3.0 to maybe as high as 3.04 or 5.

‘Much of this was dependent on the outside temperature. If it was colder than standard, you could do even better. Hotter than standard not so good but always better than the plan. Using these techniques and a few more I would often see fuel flows below 3600 lbs/hr/per engine at Mach 3. Ed and I rarely came back from a mission with less than 5,000 lbs more fuel than the flight plan called for. There are a lot of those things involved. Flying the SR required a great deal of stick and rudder abilities under some circumstances but I always told people it was primarily a cerebral machine. You had to have a very deep understanding of how it worked to get the job done.’

Skill and knowledge

Peters concludes;

‘I have said many times before, much to the contrary of the engineers, that DAFICS [digital automatic flight and inlet control system] really screwed up what the airplane was capable of just like everything we seem to do anymore, it took the skill and knowledge of the operator pretty much out of the equation. But that is another discussion.’

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Photo by David Peters and TSgt. Michael Haggerty / U.S. Air Force

The Blackbird

Developed from the Lockheed A-12 and YF-12A aircraft, the SR-71, sometimes known unofficially as the “Blackbird,” is a long-range, advanced, strategic reconnaissance aircraft. The 4200th (later 9th) Strategic Reconnaissance Wing at Beale Air Force Base, California, received the first SR-71 to begin service in January 1966. The first SR-71 flight occurred on December 22, 1964. On January 26, 1990, the US Air Force (USAF) retired its fleet of SR-71 aircraft.

For almost 24 years, the SR-71 held the record for being the fastest and highest-flying operational aircraft in the world. It could cover 100,000 square miles of the Earth’s surface per hour from 80,000 feet. The Blackbird’s extraordinary capabilities allowed it to gather intelligence in some of the most hostile environments.

SR-71 Blackbird Mission on the day of the Chernobyl Disaster

Former SR-71 RSO, Lt. Col. Doug Soifer, recalls in Richard H. Graham’s book SR-71 Revealed The Inside Story;

‘Mike Smith and I were TDY for our first time to Mildenhall for our normal six-week rotation. We went to the Det one morning to fly a routine six-hour sortie—the Barents and the Baltic. During the preflight briefings, the intelligence officer said a nuclear power site (Chernobyl) in the Soviet Union had an accident a few hours earlier. They had no other information on it yet. The weather briefing officer gave his normal briefing but also mentioned they double-checked with the weather service at Offutt AFB that we would not fly through any of the fall-out from Chernobyl. With the briefings done and no one concerned about our route of flight, we went to the jet and flew a normal mission.

‘The normal routine after an operational mission is to land and continue to taxi off the runway and directly into the hangar so they could download the mission take. But as we landed and turned off the runway, we were told to stop way before the hangar. We both thought this was very strange and couldn’t understand why we were stopping here. Then one person, and only one, dressed in very funny-looking gear, came walking up to the plane.’

Soifer continues;

‘As he got closer, we could see he was in full chemical gear and had a Geiger counter. After they had guaranteed Mike and I that we were in no danger of through radiation from Chernobyl, they were checking the plane before any of THEM would get close to us! Once he walked about the plane with the Geiger counter, we were allowed to continue to taxi into the hangar.’

Photo by NASA and Unknown

The SR-71 Blackbird

A group of Lockheed members led by Clarence “Kelly” Johnson—then vice president of Lockheed’s Advanced Development Company Projects, also referred to as the “Skunk Works” and currently a part of Lockheed Martin—designed the SR-71, the most sophisticated Blackbird—including the A-12 and YF-12.

Beginning in the late 1950s, the A-12 reconnaissance aircraft—which made its first flight in April 1962 and remained classified until 1976—served as the model for the Blackbird. The YF-12A interceptor variant was first made public by President Lyndon Johnson on February 29, 1964, which was more than six months after it made its first flight. On December 22, 1964, the SR-71’s maiden flight was completed.

The Blackbird was built to reach altitudes of up to 85,000 feet and cruise at “Mach 3+,” faster than three times the speed of sound, or more than 2,200 miles per hour.

Checking out in the Blackbird like a cowboy

Col. David P. Dempster, Blackbird Reconnaissance Systems Officer (RSO) who was also part of the first US Air Force (USAF) contingent to fly operational SR-71 reconnaissance sorties from Okinawa into “denied areas” (the term “denied area” was referred to a specific area over or around a foreign country where you could encounter anything and everything… from MiGs to SAMs), recalls in Richard H. Graham’s book SR-71 Blackbird Stories, Tales and Legends:

“Jim Watkins was a great pilot to be crewed within the Blackbird. A Texas cow-boy who raised horses in his off time, Jim loved, breathed, and lived for flying.

“But, like his horses, he ‘felt’ and handled them with cowboy common sense. Imagine checking out in the Blackbird, a World War II B-24 pilot who flew fighters, transports, KC-97 tankers, and KC-135 tankers at Beale. In tanker, Jim was on the initial OXCART team and provided the air refueling support for the A-12s flying from the Ranch. Jim checked out in the SR-71 like a cowboy putting on an old familiar leather glove!

“We were honored to be among the four SR-71 crews selected to deploy for the first time to Okinawa in March 1968. On 21 March, the first operational sortie flew and the crew encountered a double-engine flameout during descent to their tanker as they exited the target area. After refueling, they returned to Okinawa. A week later the second operational sortie flew, and again, with a different crew and different Blackbird, they encountered the same double-engine flameout at the start of their descent. They landed in Thailand due to the left generator not working. What was happening? Both planes checked out good on the ground after landing and we had lots of jaw-boning among ourselves and with Lockheed tech reps, with no conclusions.

KC-135Q saving an SR-71 over Laos

“Then, on 19 April 1968, Jim and I launched on the third operational sortie (the first for us and Crew Chief Technical Sergeant Bud Martin’s #974). We zipped through the target area with no problems and began the start descent checklist. As Jim pulled the throttle back to the rpm setting called for in our procedures, we had a double-engine flameout. Excitement, adrenaline pumping, and we dropped like a rock into Northern Laos! Jim got both engines started around 30,000 feet, and we headed south. 

“Our [KC-135Q Stratotanker] tanker, the real hero of this story, saw our rate of closure on him stop. He knew what had happened and headed north immediately, unprotected, into enemy territory and rendezvoused with us. Refueling with him, we headed back into Thailand and proceeded to our preplanned end refueling point.

“What to do now? We were scheduled to go back to the target area for another ‘hot loop.’ Over the intercom, I heard this commonsense cowboy say, ‘Dave, I think if when we start our descent, we hold a higher-than-normal rpm we can avoid the flameouts. Want to give it a try?’ ‘Sure,’ I answered. We accelerated back to Mach 3-plus and on course into the target area. We eyeballed adding about 30 miles to the start descent range and when the time came Jim’s theory worked perfectly. No flameouts and a smooth descent.

‘Ichiban,’ the ‘number one’ Habu

“What was the secret and why did this work? The answer turned out to be the way the engine’s fuel controls were programmed. They used standard adiabatic lapse rates, which engineers all over the world assumed depicted the height of the tropopause and outside air temperatures at varying altitudes. WRONG! What we discovered was that in Southeast Asia, the tropopause (and magnificent thunderstorms we would look down on) could go as high as 65,000 feet, rather than the textbook 55,000 feet. Moreover, the air was much colder. Lockheed and Pratt & Whitney Co. eventually reprogrammed the fuel controls correctly and the problem went away. In the interim however, all of the crews adopted the cowboy’s technique and the flameout problems disappeared.

“The day after this flight Jim, Technical Sergean. Bud Martin, and I proudly stenciled the first Habu on the side of #974, which went on to be so successful that it was dubbed ‘Ichiban,’ the ‘number one’ Habu in the 1968 period on Okinawa.”

Photo by U.S. Air Force

The SR-71 Blackbird

The US Air Force (USAF) created the SR-71 Blackbird in the 1960s. It was a plane that could move at a speed that was more than three times the sound made by its own engines.

The SR-71 spy plane held the record for being the fastest and highest-flying operational aircraft in the world for about 24 years. At a speed of Mach 3+, it could cover 100,000 square miles of Earth’s surface per hour while flying at 80,000 feet. Additionally, the Blackbird only needed to accelerate and outrun any missiles in the unlikely event that an enemy attempted to shoot it down.

The SR-71’s engineering was so advanced that new tools had to be created in order to build it.

What it’s like to fly the world’s fastest plane

Spencer Hall spoke with former SR-71 Blackbird pilot Rick McCrary for SBNation to find out what it’s like to pilot the fastest plane in the world.

McCrary explained;

‘You waddle out there in your spacesuit, carrying your little cooler, because it gets quite hot in that spacesuit. You go out to a van with some La-Z-Boys in it, these big recliners, and they drive you out to the airplane. It’s sitting there with all the cables hooked up to it, just like a space launch. It’s outgassing stuff, people are checking it, and then people start unhooking it and leaving and then it’s just you and the crew chief. You get into the seat, close the hatch, and you’re in your cocoon.

‘Startup was also a unique thing. It had this special fuel, because the temperatures during flight got up to over 600 degrees Fahrenheit when you’re at speed. The worry is that with normal fuel, which you want to explode quickly during flight and have a low flashpoint, well… you wanted the exact opposite with the Blackbird. You’re carrying so much fuel that the last thing you want to worry about is self-igniting.

‘You’d burn 80,000 pounds of fuel in about an hour and twenty minutes. That’s a lot of gas. You’re on the boom a lot, and that was why in-flight refueling experience was such a critical part of the screening process. You didn’t have a lot of time to do it, and you had to get it right the first time. Three refuelings were common, but on longer missions, you’d refuel six or eight times. Those were long days.

Last flight on the SR-71 Blackbird

‘You’d light up the afterburner right after that first refueling, and take it to full power for the next hour. That’s pretty amazing, because no other plane can fly in full afterburner continuously. All other planes have either a three-minute limit, or five minute limit on that, but you’d be going at full afterburner for an hour, hour and a half.’

When Hall asked McCrary if he remembered when his last SR-71 Blackbird flight took place, he answered;

‘The answer is kind of an interesting yes and no. There came the time to move on, and we had a good deal. We got to take it to the National Air Show in Washington, DC, and put it on display there. That was going to be our last flight.

Setting 13 acres of Maryland on fire during last flight on the SR-71 Blackbird

‘As we took off from there and came back around for a pass, the right engine exploded. We had to dump gas and set about thirteen acres of Maryland on fire as we did that. That was kind of interesting, just spewing flaming fuel and titanium pieces around.’

McCrary explained that this wasn’t rural Maryland;

‘Actually, we were pointed at the White House out of Andrews Air Force Base. It was funny listening back to the voice tape because I start by saying “Well, we’ll go out over the bay here and dump this fuel.” About thirty seconds later, I say “Screw it” and just dump it. We defoliated southern Maryland, but we got it back on the ground, which was great. After all that happened, I absolutely remember shutting it down. My legs started shaking uncontrollably with the adrenaline from it all when I knew it was over with. My co-pilot never flew again, either.’

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Photo by Lockheed Martin and U.S. Air Force

The SR-71 Blackbird

The US Air Force (USAF) created the SR-71 Blackbird in the 1960s; it was a plane that could fly at a speed greater than three times the sound made by its own engines.

The SR-71 spy plane held the record for being the fastest and highest-flying operational aircraft in the world for about 24 years. At a speed of Mach 3+, it could cover 100,000 square miles of Earth’s surface per hour while flying at 80,000 feet. In the unlikely event that an enemy attempted to bring it down with a missile, the Blackbird just needed to accelerate and outpace it.

The SR-71’s engineering was so advanced that new tools had to be designed to build it.

Dents on the SR-71 Blackbird Nose

Former SR-71 RSO Richard “Butch” Sheffield (Butch was his nickname because of his haircut that he had back in the 60s) used to point to the nose of the SR-71 Blackbird. He would point to the dimples and say, “This is really important, but I can’t talk about it.”

He would smile.

In the SR-71, he and Bob Spencer executed one of the most crucial missions when they intercepted an SA-5 missile that was flying just inches from the Russian border. Receiving that signal was important to the SR-71’s defense. An SR-71 was never shot down; none ever got close. It was impossible due to defense and speed.

According to former Blackbird pilot Col. Richard H. Graham’s book SR-71 The Complete Illustrated History of THE BLACKBIRD The World’s Highest, Fastest Plane, the nose section allowed the SR-71 to have radar-imaging capability with the advanced synthetic aperture radar system (ASARS), photographic imagery with the optical bar camera (OBC), or a ballast installed. The nose section was held on by faun-massive fasteners.

The Dents that prevented Surface-to-air Missiles from Scoring any Hit on the SR-71 Blackbird

What are those two little dents on the nose of the SR-71 Blackbird?

‘I’m assuming you’re talking about the two “dents” in the chines at the front part of the nose, one on each side? Those aren’t dents, those were put there on purpose for the more advanced ECM systems the Blackbird got in the ’70s and ‘80s,’ says Kelly Pedron, an aviation expert, on Quora.

‘There weren’t any good places to put the ECM receivers in the front of the aircraft, so those “dents” were put in the chine to allow the installation of ECM receivers there. If you’ll notice, the flat part of the “dent” is facing about 60 degrees forward, in order to cover that quadrant of the airspace around the aircraft. Earlier models of the SR, including the A-12, were more concerned with attack radar signals from the rear, so front-mounted ECM receivers weren’t as necessary at the time. With the advent of more advanced Soviet SAM systems, like the S-200 and S-300, a forward warning receiver and jammer were required, hence the development of the so-called ECM “dents” in the nose.’

Pedron concludes;

‘So, yes, those were put there on purpose; nobody accidentally taxied an SR-71 into a solid object.’

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Photo by Linda Sheffield Miller and U.S. Air Force