SR-71 Blackbird – Speed and Stealth Like No Other
Two aircraft inspired me to get my private pilot’s license when I was 20, the Concorde and the SR-71 Blackbird, the fastest aircraft ever built, which certainly did not look anything like what most people would expect in an aircraft. In fact, many of the so-called “UFO” sightings may have been an SR-71! I saw one on display in Los Angeles, one on display in New-York (on the USS Intrepid) and one on display at the National Air and Space Museum in Washington. Even on the ground, a frontal view looks like some kind of extraterrestrial space ship set between parts of two Earth type aircraft. It has been seen in many movies, such as X-MEN, Transformers, and Space Cowboys.
Just what is the SR-71? Called the “Sled” by its highly skilled pilots, it was the world’s fastest air-breathing aircraft over its 35 year US military career. Built by Lockheed Martin, a total of 32 of these spectacular spy-planes were built and flown from 1964 to 1999. Designed to be capable of cruising at Mach 3.2 at 85,000 feet, the SR-71 had a top speed of 3,540 km/h (2200 mph). To date, no jet has flown faster (the X15 was a rocket powered plane that reached speeds over 4000 mph).
The order for the plane that became the SR-71 came as the cold war heated up, when the CIA approached Lockheed Martin in 1957 to build an “undetectable” spy plane that could fly higher and faster than the then-used U-2. When the Soviet Union shot down Francis Gary Power’s U-2 in 1960 with surface to air missiles, it became a priority to get the new plane built. It needed to fly higher than the U-2, be virtually invisible to radar, and it had to be able to outrun missiles.
While conventional military jets, from fighters to bombers and spy planes, were designed to fly at high speeds for short, evasive periods, the new planes were required to fly at “insane” speeds full time. This was previously impossible, due to the problem created when any object moves too quickly through the atmosphere: heat.
This led to Lockheed choosing titanium, known for its ability to withstand high temperatures, as the material to use for 85% of its structure. This presented some very difficult and sometimes frustrating new challenges for the engineers, as titanium does not behave the same as aluminum or steel, and its use presented some real challenges for their engineers, including special washing requirements for exposed titanium and all new tooling.
An interesting note is the fact that, due to the requirement for such a large amount of titanium, the CIA created phony companies all over the world to buy the metal from the Soviet Union, the world’s largest supply, and also an enemy of the USA at the time!
One of the interesting (and hotly debated, at first) engineering choices for the skin was to make the surface corrugated, rather than smooth, which presented some further aerodynamic challenges, but allowed the skin to expand vertically and horizontally at high speed, rather than peeling off, as it would have if it was smooth and therefore stiff.
Heat was a major issue. The titanium skin and skin design solved a major part of the structural issues, and it was finished off with a quartz outer windscreen that was ultrasonically fused to the frame. Because of the crazy amount of expansion due to heat at the high speeds flown by the Blackbirds, the panels were loosely fitted, including the fuel tank panels, which means they leaded fuel when they were on the ground. This required them to be refueled almost immediately once they were airborne. Once the skin warmed up, the panels all sealed up. Imagine being the engineers who had to calculate the expansion accurately enough, or how thankful they must have been that the US Air Force had decided only a few years before to develop the CNC system capable of accurately cutting out the panels!
While black might at first glance seem like a crazy choice for a plane whose surface would reach 600 degrees fahrenheit, the flat black finally chosen for the SR-71 (hence the name “Blackbird”) is able to both quickly absorb and quickly give off heat, reducing the temperature of the plane by up to 86 degrees fahrenheit.
The tires were impregnated with aluminum powder to help dissipate the heat, making them appear silver. Tires may seem a small detail, but to the pilots coming back down to earth, they are absolutely indispensable!
Due to the very high temperatures and extreme conditions that come from flying at more than 80,000 feet, the pilots required very special flight suits, similar in design and look to what astronauts wear.
The 107′ 5″ long Blackbird’s twin specialized Pratt & Whitney turbojet engines were powerful enough to power an ocean liner, producing an incredible 34,000 pounds of thrust, each, and burning 5,000 gallons of fuel per hour at its cruising speed of Mach 3.2. The fuel actually helps to cool the plane by being circulated in the chines. The engines operated as normal jets at subsonic speed and above 80,000 feet, becoming ramjets above 2000 mph.
A Blackbird, after takeoff, would fly for approximately seven minutes before rendezvousing with an special air-tanker to refuel. It could then fly 2,900 nautical miles (5,400km) before needing to refuel. At more than 2000 mph, that went by very quickly!
The design of the Lockheed SR-71 Blackbird was modified several times during its development to reduce its radar imprint. In the end, with its special design and paint, even with the finest modern radar developed by the Soviet Union, it would appear no larger than a bird if spotted at all. Furthermore, with its specialized early warning detection system, it would warn the crew the moment a missile was fired at them, and it was too fast and maneuverable for any missile in existence during its career. In fact, more than 4,000 missiles were fired at the Blackbird, but it was never hit.
Remember R2-D2 from the Star Wars series? It was a nod to the SR-71 navigation system, which was called “R2-D2” and had a sensor powerful enough to detect more than 60 stars in broad daylight while it was still sitting on the ground. The camera used on this spy plane was so advance, it could pick up the license plate on a car traveling on the ground from 80,000 feet!
The Blackbird set several speed records that have never been beaten. Its United States coast to coast (2,086 miles) record was 1 hour, 7 minutes, 53.69 seconds, cruising at an average of 2,124.5 mph. In March, 1990, an SR-71 flown by Ed Yielding and Joseph Vida made the trip from
Los Angeles, CA, to Washington, DC, a distance of 1,998 miles, in one hour, four minutes and 19.89 seconds, cruising at an average speed of 2,144.83 mph. On September 1, 1974, an SR-71 flown by USAF pilot James V. Sullivan and Noel F. Widdifield, RSO, flew from New York, USA, to London, England, a distance of 3,461.53 miles, in 1 hour, 54 minutes, 56.4 seconds, at an average speed of 1,806.964 mph. Nothing else has come close to breaking these records.
There is a story from one flight crew flying over the USA at 80,000 feet. As they crossed Arizona with Los Angeles coming quickly into view, they heard a Cessna pilot call the LA flight center for a ground speed check. The center very professionally told him he was showing 90 knots to the ground. Then a Twin Beech, asked for his ground speed. The flight center calmly replied that he was at 125 knots of ground speed. Suddenly an F-18 pilot, just to let everyone know, asked for a ground speed check and was calmly informed his speed to ground was 620. That’s when the RSO, seated behind the pilot of the SR-71 could no longer contain himself, and, very calmly and professionally, he asked for a ground speed check from Los Angeles Center. The calm reply was, “Aspen 20, I show you at 1842 knots across the ground.”
Sadly, satellites, modern cameras and modern computers have now taken the place of the mighty SR-71 Blackbird, and they have been retired in various locations around the world. The US military, NASA and the powers-that-be in Washington have decided that they are too expensive to continue using and obsolete. Yet there are still other who disagree, and the debate continues. Perhaps they will fly again. Perhaps they will build something even more exciting. Maybe they already have… Perhaps that would explain the latest UFO sightings!
Enjoy this video tribute to the “most epic aircraft ever.” Tribue to the Lockheed Martin SR-71 Blackbird HD . See many additional pictures, docs, and videos in my personal folder…
Please leave a comment below and perhaps, if you have one, a photo or two.
Jean-Christophe Huc (Jay)