SR71

The SR-71 Blackbird

The SR-71, the most sophisticated spy plane in the Blackbird family, which also included the A-12 and YF-12, was created by a team of Lockheed personnel under the direction of Clarence “Kelly” Johnson, who was vice president of Lockheed’s Advanced Development Company Projects at the time. Known as the “Skunk Works,” this group is now a division of Lockheed Martin. The Blackbird completed its first flight on Dec. 22, 1964.

The SR-71 was built to reach altitudes of up to 85,000 feet and cruise at “Mach 3+,” or more than three times the speed of sound, or over 2,200 miles per hour.

SR-71 Blackbird flying with just one engine in full afterburner

The amazing pictures in this post, taken on Nov. 1, 1981, by US Air Force (USAF) Scene Camera Operator Ken Hackman, show an SR-71 Blackbird employing only one rudder and one engine running at full afterburner.

Why is that?

‘That is what we called a “single-engine go around,”’ says Stormy Boudreaux, SR-71 Blackbird pilot. ‘It was a practiced emergency procedure. It simulated what you had to do if you were making a single-engine approach to land and for a variety of reasons something made the runway or the landing impossible so you “went around” on only one engine. The tremendous thrust with one engine in full afterburner and the other in idle was eye-opening! To counter the yaw from that engine required full rudder as well as banking the aircraft into the good engine in order to maintain your flight direction down the runway.

‘Most twin-engine aircraft have to do something similar but it’s darn right frightening the first time you try it in the SR-71. That one engine in AB is really pushing the nose around trying to turn the jet away from that engine and the amount of bank angle when at low speed makes you glad you are strapped tightly in the seat. It’s almost a knife-edge pass!’

Single engine go around

Boudreaux is echoed by David Peters, another SR-71 pilot.

‘As Stormy said the picture[s] indicate a single engine go around. Thrust was never an issue. What became imperative was the ability to point the airplane. Under most conditions full opposite rudder and a slight bank into the operating engine was enough. By under certain conditions other factors came into play. Minimum control speed being most important.

‘We had a couple of missions out of Mildenhall that went hot to the tankers. That required a heavy takeoff using a 65,000-pound yo-yo fuel load. In the winter time with freezing temperatures in England min control speed was a huge factor. Once the burners lit if you lost an engine on takeoff once the burners were lit your only option was to eject. Why you ask.

Blackbird aircrews’ most dangerous operation

‘Well the runway there is only 8,000 feet. There was so much thrust developed in the cold, heavy air climate that your speed combined with gross weight would not allow you to abort since you couldn’t stop the airplane. There was plenty of thrust available to fly on one engine but there was so much thrust you could not control it below min control speed which in those cases was generally around 260 knots. So, the only thing you could do was pull both engines to idle pop the chute and eject.

‘I always felt that was perhaps our most dangerous operation.’

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Photo by Scene Camera Operator Ken Hackman / U.S. Air Force

RAF Greenham Common Women’s Peace Camp

Angered by the UK’s decision to station cruise missiles, (guided nuclear missiles), a group of women planned a protest march in 1981 that started in Cardiff, Wales, and ended at RAF Greenham Common, which is located near Newbury in Berkshire. This is where they established the Greenham Common Women’s Peace Camp.

The Imperial War Museum claims that the demonstrators tried to hinder the construction work at the base in 1981 and 1983. They blocked the base and cut sections of the fence, among other things. At the “Embrace the Base” event held in December 1982 at Greenham, almost thirty thousand women came together to form a human circle around the base.

SR-71 Blackbird at 1983 IAT at RAF Greenham Common

RAF Greenham Common hosted the 1983 International Air Tattoo (IAT) as well. A video of a Blackbird being flown by SR-71 pilot BC Thomas, with John G. Morgan serving as RSO, arriving at Greenham Common for the 1983 International Air Tattoo was posted on his YouTube channel.

Thomas recalls in the video description;

‘I was the pilot in this video, but did not fly the SR-71 out of RAF Greehnam Common. I was the “mobile control” officer when the aircraft departed and the pilot was Maj Jim Jiggens, a USAF Thunderbird pilot and formally a US Army helicopter combat pilot in Vietnam.

Protest women throw paint on SR-71 Blackbird

‘On the evening of the air show featured in this video, women, who were protesting President Reagan’s decision to station intermediate nuclear missiles in England, broke into the security cordon around the air show aircraft and threw paint on several, including this SR-71.

‘Owing to the unique metals associated with the SR-71, the removal of the paint required special maintenance procedures to assure that no “hot spot” would develop on subsequent flights. It was quite a hassle and we were not amused over this incident. Jim and I planned a farewell departure for the protesters who were encamped in a squalor of tents just outside the main gate.

SR-71 Blackbird noise on the protesters at RAF Greenham Common

‘Jim obtained clearance for a “closed pattern” and turned to a downwind leg, descended to about 50 feet above the ground, and flew directly over the protestors’ encampment. It was early and probably most were asleep, but not for long. Jim was flying about 250 knots and selected afterburner in both engines as he was approaching the tents. As the SR-71 accelerated to 350-400 knots, he pulled up and focused the plume (and noise) directly on the protesters. It was a magnificent sight.’

Thomas concludes;

‘As we were leaving the base immediately after Jim’s departure, the gate guard (British) said to me: “I say, that was a jolly good show, but next time, please warn me before you do it.” I also had the honor to prefer charges against the women, but the British government later declined to prosecute.’

Greenham Common today

In 1987 US President Ronald Reagan and Soviet President Mikhail Gorbachev signed the Intermediate-range Nuclear Forces (INF) Treaty, which paved the way for the removal of cruise missiles from Greenham.

Today Greenham no longer belongs to the military. Part of it is a business park and the rest is common land.

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Photo by Mike Freer – Touchdown-aviation via Wikipedia

The SR-71 Blackbird

One of the most sophisticated Blackbirds, the SR-71 (along with the A-12 and YF-12) was created by a group of Lockheed personnel under the direction of Clarence “Kelly” Johnson, who was vice president of Lockheed’s Advanced Development Company Projects at the time. Known as the “Skunk Works,” this unit is now called Lockheed Martin.

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+,” which is more than three times the speed of sound, or more than 2,200 miles per hour.

The SR-71 Blackbird’s slowest speed

‘How high and how fast does it really fly?’ is arguably the most commonly asked question regarding the “Blackbird family”.

What about the slowest speed a Blackbird has ever been known to fly at? The following anecdote from SR-71 pilot Brian Shul’s book Sled Driver may help to clarify this question.

‘I was flying the SR-71 out of RAF Mildenhall, England, with my back-seater, Walt Watson; we were returning from a mission over Europe and the Iron Curtain when we received a radio transmission from home base. As we scooted across Denmark in three minutes, we learned that a small RAF base in the English countryside had requested an SR-71 fly-past. The air cadet commander there was a former Blackbird pilot, and thought it would be a motivating moment for the young lads to see the mighty SR-71 perform a low approach. No problem, we were happy to do it. After a quick aerial refueling over the North Sea, we proceeded to find the small airfield.

Uncomfortable speed

‘Walter had a myriad of sophisticated navigation equipment in the back seat and began to vector me toward the field. Descending to subsonic speeds, we found ourselves over a densely wooded area in a slight haze. Like most former WWII British airfields, the one we were looking for had a small tower and little surrounding infrastructure. Walter told me we were close and that I should be able to see the field, but I saw nothing. Nothing but trees, as far as I could see in the haze. We got a little lower, and I pulled the throttles back from 325 knots we were at. With the gear up, anything under 275 was just uncomfortable. Walt said we were practically over the field-yet; there was nothing in my windscreen. I banked the jet and started a gentle circling maneuver in hopes of picking up anything that looked like a field.’

Airspeed indicator sliding below 160 knots

Shul continues;

‘Meanwhile, below, the cadet commander had taken the cadets up on the catwalk of the tower in order to get a prime view of the fly-past. It was a quiet, still day with no wind and partial gray overcast. Walter continued to give me indications that the field should be below us but in the overcast and haze, I couldn’t see it. The longer we continued to peer out the window and circle, the slower we got. With our power back, the awaiting cadets heard nothing. I must have had good instructors in my flying career, as something told me I better cross-check the gauges. As I noticed the airspeed indicator slide below 160 knots, my heart stopped and my adrenalin-filled left hand pushed two throttles full forward.

‘At this point, we weren’t really flying but were falling in a slight bank. Just at the moment that both afterburners lit with a thunderous roar of flame (and what a joyous feeling that was) the aircraft fell into full view of the shocked observers on the tower. Shattering the still quiet of that morning, they now had 107 feet of fire-breathing titanium in their face as the plane leveled and accelerated, in full burner, on the tower side of the infield, closer than expected, maintaining what could only be described as some sort of ultimate knife-edge pass.

The greatest SR-71 Blackbird fly-past

‘Quickly reaching the field boundary, we proceeded back to Mildenhall without incident. We didn’t say a word for those next 14 minutes. After landing, our commander greeted us, and we were both certain he was reaching for our wings. Instead, he heartily shook our hands and said the commander had told him it was the greatest SR-71 fly-past he had ever seen, especially how we had surprised them with such a precise maneuver that could only be described as breathtaking. He said that some of the cadet’s hats were blown off and the sight of the plan form of the plane in full afterburner dropping right in front of them was unbelievable. Walt and I both understood the concept of “breathtaking” very well that morning and sheepishly replied that they were just excited to see our low approach.

‘As we retired to the equipment room to change from space suits to flight suits, we just sat there-we hadn’t spoken a word since “the pass.” Finally, Walter looked at me and said, “One hundred fifty-six knots. What did you see?” Trying to find my voice, I stammered, “One hundred fifty-two.” We sat in silence for a moment. Then Walt said, “Don’t ever do that to me again!” And I never did.

Just a routine low approach

Shul concludes;

‘A year later, Walter and I were having lunch in the Mildenhall Officer’s club and overheard an officer talking to some cadets about an SR-71 fly-past that he had seen one day. Of course, by now the story included kids falling off the tower and screaming as the heat of the jet singed their eyebrows. Noticing our HABU patches, as we stood there with lunch trays in our hands, he asked us to verify to the cadets that such a thing had occurred. Walt just shook his head and said, “It was probably just a routine low approach; they’re pretty impressive in that plane.”’

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Top image: courtesy of Robin Harbour

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 of 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 80,000 square miles of Earth’s surface per hour while flying above 80,000 feet. Furthermore, on the off chance, an enemy tried to shoot it down with a missile, all the Blackbird had to do was speed up and outrun it.

JP-7

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

In fact, standard jet fuel could not be employed in the Blackbird because of its Mach 3.2 cruise speed, which caused it to get extremely hot. According to former SR-71 pilot Richard H. Graham’s story in his book SR-71 Revealed: The Inside Story, Shell created a unique fuel blend known as JP-7. This fuel used an additive that raised its flash point, preventing the fuel from breaking down at extremely high temperatures.

SR-71 Blackbird needed TEB (Triethylborane) to light its engines and afterburners

Graham explains;

‘The high flashpoint brings up another problem. Most jet engines use igniter plugs—nothing more than a very hot spark plug if you will. Using these igniter plugs they used with the JP-7 and just drowns it out, it won’t ignite. Kelly [Johnson] put his engineers to work, and he said, ‘OK, gentlemen, how are we going to start this?’ They came up with a very unique way. Triethylborane (TEB for short).

‘Each engine has a one-and-a-quarter pint. If I had it in a squirt gun and I squirted it into the atmosphere, it would go Kaboom!—it explodes with contact with the atmosphere. And that’s how we started the engines. As the engines rotate, at the right time, it sprays this amount of TEB into the turbine section, which goes kaboom, which in turn lights the engine. When you take the throttles up into the afterburner, it puts this metered amount of TEB in that lights up the JP-7. You get 16 shots for each engine.’

TEB was the most dangerous material after fissionable nuclear material

A sealed tank that had been inerted with nitrogen gas and filled with 600cc of TEB by maintenance before each flight was mounted on each engine.

Former SR-71 Blackbird pilot David Peters adds: ‘An interesting note to this is the transport of it. If we landed away, servicing had to be hauled to our location. The NTSB lists TEB as the following most dangerous material, one step below fissionable nuclear material. The folks that handled this stuff were highly trained and good.’

How to light SR-71 Blackbird afterburners without Triethylborane

If TEB wasn’t available, one may now wonder if there was a way to light the Blackbird’s afterburners. Although Peters claims that during the 24 years the SR 71 was in flight, its TEB never ran out—there was a backup plan, just in case. John Olp, an SR-71 mechanic at Beale AFB from 1975 to 1985, explains;

‘The J58 engine had a unique way of lighting the afterburners if TEB wasn’t available for whatever reason.

‘Inserted into three rings of the flame holders were six catalytic ignitors. If TEB wasn’t available, the engines could be manually over-trimmed to increase the exhaust temperature and superheat the ignitors. When the throttles were advanced into afterburner, the glowing catalytic ignitors would light off the fuel, albeit somewhat harshly!

‘The catalytic ignitors were in place as a backup if TEB wasn’t available. There was a manual up-trim switch in the cockpit to control engine EGT. It was a hard light off if used, but was an option!’

Olp concludes;

‘Overtemping the engine would only be momentary to allow the afterburner light, probably not enough to cause any damage to the engines. That’s why the manual up-trim switches were available.’

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Photo by TSgt. Jose Lopez / U.S. Air Force