SR-71 Blackbird in flight
SR-71 Blackbird from the front
Without doubt one of the most spectacular and distinctive military aircraft in history the SR-71 Blackbird played a vital roll in US Reconnaissance.
It was for many years and may still be the worlds fastest and highest flying air breathing machine and despite over two decades of top secret missions over such hostile countries as Cuba, North Korea and China has never been shot down. Flights over the former USSR were technically banned after the Soviets shot down the US U-2 spy plane in 1960.
By 1960 three mach 3 aircraft were under development, the A-12, YF-12 and SR-71, the A-12 flew in 1962, the YF-12 in 1963 and the first SR-71 on 23rd December 1964. The programme was kept secret until February 1964 when President Johnson made a television announcement. The A-12 was designed as a replacement for the U-2, it was a smaller lighter forerunner of the SR-71 and was operated by the CIA until the Blackbird became operational in 1968 under the US Air Force. The YF-12 was a long range interceptor that never went into production, its Hughes radar and AIM-47 missiles were later to be developed into the AWG-9 Phoenix weapon system on the US Navy’s Grumman F-14 Tomcat.
A mini Blackbird drone was also developed, the D-21. Ramjet powered and unmanned this project was designed to be launched from an A-12 mothership to fly at even higher speed over areas of interest. The project was abandoned after a fatal accident. It continued until 1971 with about 20 test launches from under wing pylons on B-52s. Formal Blackbird operations started in January 1966 when the first aircraft arrived at custom built facilities at Beale AFB California. During their history they also operated out of Mildenhall AFB in the UK (where the photos at the end of this article were taken) and out of Kadena AFB in Japan. During the Vietnam War they also operated out of Thailand and South Korea.
About 32 Blackbirds were made with only about 10 in service in any one time due to the massive demands made on the airframe; it is believed that 11 have been written off in accidents. The aircraft is two seat and pilots for it are some of the best in the USAF, before requesting to fly the aircraft they must have 1,500 of jet flying time be recon qualified and be well-experienced military navigators. They must then be checked out on the Northrop T-38, which has similar handling characteristics at sub sonic speeds and complete 100 hours simulator time before progressing to the SR-71B trainer. Full data on the Blackbirds performance was classified but released figures for the world speed and altitude records gained on 28th July 1976 are a speed of 3529.56km/h (2,193.17 mph) and a sustained height of 85,069ft (25929 m).
To deliver this performance the delta wing design is powered by two huge and incredibly noisy Pratt and Whitney J58 engines. These are rated at 32,500 lb of thrust at sea level in afterburner. A complex inlet, nacelle and ejector design modifies the airflow to the extent that at mach 3.2 the engines are only generating one tenth of the thrust, a Honeywell onboard computer controls this system. The outside airframe is subjected to temperatures as high as 500 Celsius or 932 Fahrenheit so had to be made of titanium alloys. To allow expansion the airframe has gaps and actually leaks fuel until heat expands and seals the gaps in flight. The synthetic hydraulic fluid almost goes solid below 30 Celsius.
So in the days of hi tech satellite imaging what use was and is a dedicated recon aircraft? Well Satellites have some limitations firstly their track is fixed so time is taken to move them over an area of interest and these moves can be seen by an enemy. They have a limited life in space and are expensive to launch and finally they can be attacked and destroyed by ground and air launched missiles and other satellites. Even if a recon aircraft cannot over fly a hostile country for military or political reasons, its high altitude can allow it to over look a wide area. It is believed the sensor systems on the Blackbird can survey 259000 km or 100,000 square miles an hour and probably include infra red and airborne side looking radar.
Preparation for a mission takes most of a day with the sensors taking the most prep, some sensors are modular with a whole bay being fairly easy to replace to swap say photo recon sensors for a radar package. Actual route and mission details are normally left to the last minuet for security reasons. The aircraft itself takes 2 ½ hours to prep for flight mainly due to warming the engine oil to 86 F. The crew under go a full medical before each flight and for high altitude nitrogen is purged from the body to prevent the bends by breathing gaseous oxygen for an hour before take off. Crew may also be given anti fatigue drugs and a special diet helps reduce bowel movement. The crew then put on their s-1010B full pressure suits similar to those used in space. 3 hours before the Blackbird takes off 3 KC-135 tankers will have taken off to head for prearranged refueling locations. The last tanker will take off just before the Blackbird and wait for it to top it up at 25,000 ft near to the airbase.
After take off and the top up the Blackbird will perform a manoeuvre called the Dipsy Doodle, here it passes mach 1 by a climb to 33,000ft followed by a sharp dive to allow the aircraft to traverse high drag transonic range without using a lot of fuel. The aircraft will then climb to at least 60,000 ft. From Mildenhall the Blackbirds would overfly East Germany, the Baltic and the Kola Peninsula.
The unrefuelled range of the SR-71 seems likely to be over 4825km (3,000 miles) and most missions last about 5 hours with several refuels at 25,000 ft, longer flights of 10 hours covering 15,000 miles have been undertaken. At high attitude and with various stealth technologies it is very hard to spot and may be able to reach 100,000 ft ceiling height. Very few aircraft could keep contact with the SR-71 except possibly the MIG-25 Foxbat and very few SAM could reach that altitude. Once the mission is completed the SR-71 is drained of oil while still hot and the crew undergo another medical check, they would then not be required to fly again for 48 hours.
The SR-71 was probably the most famous aircraft to come out of Lockheed’s famous Skunk Works, its amazing performance, futuristic looks and cloak of secrecy made it a very popular plane among enthusiasts. It was very much a product of the cold war but a vital intelligence asset that has served in many areas around the world. Its possible replacement the Aurora project is cloaked in secrecy and with the changing nature of warfare in the 21st century may be a very different aircraft.