Lockheed A-11 / A-12 / YF-12 / SR-71 Blackbird
A-11 / A-12
In response to a programme for the construction of a high-speed, high-altitude, long-range reconnaissance conventional aircraft, funded by and earmarked for service with the Central Intelligence Agency (CIA), a number of US companies submitted proposals for consideration, Lockheed's 'Ox-cart' from the design team led by C. L. 'Kelly' Johnson eventually being adjudged most suitable, and this duly received the go-ahead in the autumn of 1959.
Construction of the prototype (60-5932) single-seat A-12, as the machine was officially known, forged ahead at the 'Skunk Works', the virtually complete prototype being taken by road to the remote Groom Lake flight test facility during January 1962 for final assembly and flight testing. The A-12 got airborne for its first official flight on 26 April 1962, this event being preceded by a totally unexpected 'hop' during the course of high-speed taxi trials two days earlier.
Construction was largely of titanium to maintain structural integrity, as localised skin temperatures of up to about 427°C could be reached through air friction.
In the early days of the flight test the first A-12 relied upon two Pratt & Whitney J75 turbojet engines for power, the same company's J58 turbo-ramjet engine not being installed until much later in the year. Almost inevitably, with such a sophisticated machine, the project suffered from many problems during the early stages of flight testing, these being experienced in virtually every area, but despite this the CIA apparently began to take formal delivery of its initial fleet of 10 aircraft (serial numbers 60-6924/6933) shortly before the end of 1962 and these were later joined by a second batch of five A-12s (60-6937/6941). Of these 15 machines, one (60-6927) was completed as a two-seater for training duties, this differing from its counterparts by virtue of having a second, raised, cockpit and featuring conventional J75 engines which bestowed a maximum speed of about Mach 1.2, well below that of the standard A-12 which was apparently capable of approximately 3860 km/h 2,400 mph) or Mach 3.6 at altitudes in the order of 28040 m (92,000 ft), figures which significant exceeded those records established by the YF-12A at the beginning of May 1965. In addition, the last two production examples of the A-12 were configured to carry the GTD-21B drone and these also featured a second crew station aft of the pilot's cockpit, his housing the Launch Control Officer. As far is is known the GTD-2 1 B/A- 12 pairing was not employed operationally but the drone may have undertaken reconnaissance missions after launch from a specially configured Boeing B-52H Stratofortress.
This A-12 crashed near Wendover, Utah in 1963 after entering an unrecoverable flat spin. Pilot Ken Collins managed to eject safely. He then successfully deterred several locals, who had come to his aid with the canopy of the shadowy A-12 on the back of their pickup, from the crash site by telling them the wreck was that of an F-105 Thunderchief with a nuclear weapon onboard. That same day, the CIA administered sodium pentothal to ensure Collins had divulged every last detail of the incident. When the men in black later carried him home, still heavily under the drug’s influence, Collins’ wife angrily assumed he’d been out drinking all day with his friends. Several decades later, the retired A-12 pilot was finally able to reveal the truth. X-Plane hunters continue to find components of the top secret aircraft wreck at the remote site.
As far as operational employment is concerned, the CIA continues to maintain a tightlipped silence about the A-12 but the type's great speed coupled with its capacity for inflight-refuelling made range considerations virtually irrelevant, the major factor in mission scheduling almost certainly being one of crew fatigue. In view of this and the nonstop 24140km. (15,000-mile) missions accomplished by the later SR-71A it would seem reasonable to assume that intelligence-gathering was accomplished from Groom Lake until at least the summer of 1968, which most sources state as marking the cessation of A-12 activity. In addition, Kadena Air Base on the Pacific island of Okinawa has also been linked with A-12 operations as well as those of the SR-71A, and could well have served for some considerable time as a forward operating location for CIA intelligence gathering activities directed against the People's Republic of China and North Korea. Reliable reports attest that such activity ceased abruptly on 5 June 1968 following the loss of A-12 60-6932, apparently after take-off from Kadena. By then the SR-71A had attained full operational status and the latter type is believed to have assumed responsibility for A-12 missions at about this time. Eight of the 15 A-12s eventually appeared in open storage at Palmdale during October 1977 though where they had spent the intervening nine years remains a mystery.
Lockheed A-12s while in secret storage at Palmdale, CA
In a Presidential announcement of February 1964, Lyndon Johnson formally revealed the existence of the 'A-11 aircraft'.
The second major 'Blackbird' variant to appear was the YF-12A, and it was this model which formed the basis of the Presidential announcement of February 1964 when Lyndon Johnson formally revealed the existence of the 'A-11 aircraft', adding that it was then under test as a long-range interceptor'. Three aircraft (606934/6936) of this type were built, the first example making its maiden flight from Groom Lake on 7 August 1963. Eventually to become the most publicly visible of all the 'Blackbirds', the three aircraft all featured significantly different nose contours, the forward fuselage chine having had to be redesigned to permit the installation of the Hughes AN/ASG- 18 long range radar required in the interceptor role. Armament was intended to be the Hughes AIM-47A air-to-air missile, four of which would have been housed internally, occupying space which was presumably given over to reconnaissance sensors and systems on the A-12. The type is based on advanced aerodynamics using a blended fuselage/wing design built largely of titanium alloys and covered in a special heat-radiating paint that led to the type’s nickname. The powerplant comprised a pair of 32,500-lb (14740-kg) afterburning thrust Pratt &Whitney J58 (JT11D-20B) bypass turbojets (or turbo-ramjets) which at high speeds produced their power not only as direct thrust from the exhaust nozzle but also as suction at the inlet.
The fighter derivative of the basic model was the experimental YF-l2A, of which at least four were produced with the A-11’s original short fuselage, a Hughes pulse-Doppler fire-control system and, in the fuselage chine bays originally used for the carriage of reconnaissance equipment, four AJM-47A air-to-air missiles. The YF-12A never served operationally, but was important in several evaluation programmes.
The YF-12A programme, seen as important in its own right, distracted attention from the more sinister A-12, the model which mounted an assault on several world records at the beginning of May 1965, capturing the headlines and setting new marks for sustained altitudes and speed with what appeared to be consummate ease. That the A- 12 was able to exceed these figures handsomely was not brought to anyone's attention.
Subsequently, the YF-12As and a single YF-12C (itself simply the demilitarized second production SR-71A with the bogus serial number (06937) spent most of their flying careers at Edwards AFB, California, eventually being used until 1999 by NASA in a major research effort into high-speed flight. This came to an end during 1979, the sole surviving YF-12A (60-6935) being turned over to the USAF Museum at Wright-Patterson AFB, Ohio, in November while the YF-12C was apparently placed in storage at Palmdale. Of the other two YF-12As, 60-6934 fell victim to a landing accident at Edwards at a fairly early stage, most of the rear fuselage later being used as a basis for he sole SR-71C, while 60-6936 was destroyed Arhen it crashed on approach to Edwards during June 1971.
Crewed by a pilot and flight test engineer, these aircraft flew under NASA for 10 years.
On 1 May 1965, A YF-12A established records including 2062 mph and 80,000 ft sustained horizontal flight.
The YF-12As were capable of speeds in excess of Mach 3 and of sustained supersonic flight at heights of up to 24,385m.
The YF-12A paved the way for the SR-71A ‘Blackbird’ strategic reconnaissance platform that was retired from first-line USAF service in 1989, but even so the whole programme is still shrouded in secrecy and uncertainties.
On Dec. 28, 1962, Lockheed got the contract to build the first group of SR-71s, which were to become the largest and best known branch of the Blackbird family. Bob Gilliland made the first flight on Dec. 23, 1964.
One year after the YF-12, the first SR-71 arrived at Beale Air Force Base, California, operational home of the Blackbird. First flown on 22 December 1964, the SR-71 is an unarmed strategic reconnaissance aircraft. The SR-71B and SR-71C are training variants.
Developed from the A-12 and flown for the first time during December 1964, the Lockheed SR-71A was the world's fastest operational aircraft, approximately 12 examples being active with the 9th Strategic Reconnaissance Wing at any given time. Possessing the ability to survey 260000 sq.km (100,000 sq miles) of the Earth's surface in just one hour, the SR-71A routinely cruises at Mach 3 at altitudes in excess of 24385 m (80, 000 ft) during the course of its duties, and is able to gather a variety of data by virtue of highly classified but interchangeable photographic and electronic sensors which are installed to meet specific mission objectives.
Deliveries to Strategic Air Command began in January 1966, and it is believed that a total of 32 aircraft was built, this figure including two examples of the two-seat SR-71B plus a single SR-71C, the latter model also being a two-seater for pilot training, built of components taken from crashed aircraft and a structural test specimen.
Unlike the A-12, the SR-71 is a two-seat aircraft with additional accommodation for a Reconnaissance Systems Officer (RSO). Externaly, this model also differed from its predecessors in that it has a fully extended chine which is much broader around the nose while the rear fuselage boat-tail was extended by some 1.83 m (6 ft) aft of the trailing edge to improve overall fineness ratio and provide additional fuel capacity. JP-7, the fuel used by the SR-71, is so special due to its properties for operations at the high temperatures caused by Mach 3 cruise that the aircraft has its own fleet of tankers, designated KC-135Q.
The configuration of this aircraft results from extensive wind-tunnel testing to evolve a minimum-drag fuselage providing maximum speed while keeping kinetic heating to the minimum; and to maintain the best possible handling characteristics at supersonic, take-off (about 370km/h) and landing (about 278km/h) speeds.
Power plant comprises two 144.6kN Pratt & Whitney turbojets. The 36,287kg of special fuel for these engines - which is contained within upper-fuselage and inner-wing tanks - acts as a heat sink for the entire aircraft, fuel temperature being raised to 320°C before being injected into the engines. Highly complex air intakes with computer-controlled fail-safe systems are essential to ensure that smooth airflow to the engines is maintained over the enormous forward speed range of 0-3,200km/h, at the upper limit of which the engines are virtually operating as turbo-ramjets.
An initial batch of six aircraft formed the subject of the first contract which was placed in December 1962, and the first example took to the air for its maiden flight from Palmdale on 22 December 1964.
Deliveries to the designated operating agency (Strategic Air Command) began on 7 January 1966, the first example assigned actually being the second SR-71B to be produced. SR-71As began to follow during June of the same year to the 9th Strategic Reconnaissance Wing.
Attaining operational status in mid-1967, over 16 years later virtually everything about the SR-71's usage and mission-related sensor equipment was still the subject of a stringent security blanket, although the USAF has revealed that it can survey 100,000 square miles of the Earth's surface in one hour'. It seems certain that the intelligence-gathering effort entails unauthorized overflights of potentially hostile territory every now and then. However, since much valuable data can be obtained without recourse to actual overflight, it seems probable that many missions are of a peripheral nature, the SR-71A operating in international air space at extreme altitude whilst going about its duties.
Operations were routinely conducted from two forward operating locations by aircraft detached from the wing's headquarters at Beale AFB, California. Kadena in Okinawa, normally had three aircraft attached at any time, while Mildenhall in the United Kingdom was the location of the second SR-71 detachment which usually controled the activities of two aircraft. In addition, 9th SRW's headquarters at Beale served as the centre for crew training. The two-crew members, comprising a pilot and a reconnaissance systems operator, both wear full pressure suits similar to those of astronauts.
Regardless of the equipment fitted, it is apparent that the 'Blackbird' was highly regarded as an intelligence-gathering tool, clear evidence of this being provided by the massive expense incurred in supporting just a handful of aircraft. There is the large fleet of Boeing KC- 135Q Stratotankers (specially modified to carry the SR-71A's unique JP-7 fuel. In addition, the unique aspects of high-altitude flight require the services of a large physiological support division, further 9th SRW infrastructure including a reconnaissance technical squadron with the task of processing data, and an extensive training element which uses several Northrop T-38A Talons as well as a surviving SR-71B.
A total of 31 new-build SR-71 Blackbird aircraft were constructed in addition to the SR-71C. Of the total production, 29 examples (64-17950/17955 and 64-7958/17980) are SR-71As, the two remaining (64-17956/17957) being completed SR-71Bs with a second, raised, cockpit for pilot training duties. 64-17956, was originally built as an SR-71A, but was later converted to an SR-71B trainer by the addition of a second cockpit. Two aircraft were converted.
They have the capability to survey an area of 155,400sq.km within an hour and in 1976 established a closed-circuit speed record of 3,367.221km/h; a world absolute speed record of 3,529.56km/h; and a sustained-altitude record of 25,929.031m.
Including all three members of the 'Blackbird' family, production of new airframes totalled just 49, a fiftieth hybrid machine being completed with parts from a wrecked YF-12A and an engineering mockup.
The SR-71 left US Air Force service in January 1990. On a flight from the West Coast to the East Coast, where the aircraft was to retire to permanent static display at the Smithsonian, the Blackbird set a new transcontinental speed record, flying from Los Angeles to Washington D.C. in 1 hour, 4 minutes, and 20 seconds, averaging a speed of 2,124 mph.
Engines: two Pratt & Whitney J58 turbo-ramjet engines, 14742-kg (32,500-1b) afterburning thrust.
Wing span 16.94 m (55 ft 7 in)
Wing area: 167.2 sq.m / 1799.72 sq ft
Length 32.74 m (107 ft 5 in)
Height 5.64 m (18 ft 6 in)
Wing area 166.76sq.m (1,795 sq ft).
Empty weights: 27216 kg (60,000 lb)
Maximum take-off 78019 kg (172,000 lb)
Fuel capacity 13,000+ USG
Maximum speed at 24385 m (80,000 ft) 3661 km/h (2,275 mph) or Mach 3.35
Operational ceiling 26060 m (85,500 ft)
Maximum unrefuelled range at Mach 3: 5230 km (3,250 miles).
Lockheed SR-71 Blackbird