XB-70A-2-NA Valkyrie 62-0207 leading a formation of aircraft powered by General Electric engines. Joe Walker’s F-104 is just below the B-70’s right wing tip. (U.S. Air Force)
8 June 1966: During a publicity photo formation flight, a Lockheed F-104N Starfighter, N813NA, flown by NASA Chief Research Test Pilot Joseph A. Walker, was caught in the wingtip vortices of the North American Aviation XB-70A-2 Valkyrie, 62-0207, the second prototype Mach 3+ strategic bomber. The Starfighter rolled up and across the Valkyrie. The two airplanes collided, with the F-104 taking off the Valkyrie’s vertical fins, then exploding.
Lockheed F-104N N813NA collided with North American Aviation XB-70A-2 Valkyrie 62-0207 and exploded, 8 June 1966. (U.S. Air Force)
The Valkyrie continued to fly straight and level for 16 seconds before it began to roll inverted. The B-70’s pilot, Alvin S. White, was able to eject, though he was severely injured. Joe Walker and B-70 co-pilot Major Carl S. Cross, United States Air Force, were killed.
The B-70 is out of control and going down in this photograph. A large section of the left wing is missing. JP-8 fuel is spraying out of damaged tanks. (U.S. Air Force)
Still photographs and motion picture film of the formation were being taken from Clay Lacy’s Gates Lear Jet. The photos were for a General Electric publicity campaign showing U.S. military aircraft that were powered by GE engines. Air Force procedures for requesting and approval of publicity flights were not properly followed and it is likely this flight would not have been approved had they been.
The XB-70A-2 Valkyrie has rolled inverted and pitched nose down. The outer section of the left wing is missing. The trailing edge and tip tank of the Lear Jet photo plane’s right wing are in the foreground. (U.S. Air Force)
Reportedly, just prior to the collision, Walker radioed, “I’m opposing this mission. It is too turbulent and it has no scientific value.”
The wreckage of the North American Aviation XB-70A-2 Valkyrie 62-0207 burns on the desert floor at N. 35° 03′ 47″, W. 117° 01′ 27″, north of Barstow, California, 8 June 1966. (U.S. Air Force)
George S. Welch with North American YF-100A 52-5754. (North American Aviation, Inc.)
25 May 1953: North American Aviation Chief Test Pilot George S. Welch took the YF-100A Super Sabre, U.S. Air Force serial number 52-5754, for its first flight at Edwards Air Force Base. The airplane reached Mach 1.03.
Development of the Super Sabre began with an effort to increase the speed of the F-86D and F-86E Sabre fighters. The wings had more sweep and the airfoil sections were thinner. A much more powerful engine would be needed to achieve supersonic speed in level flight. As design work on the “Sabre 45” proceeded, the airplane evolved to a completely new design. Initially designated XF-100, continued refinements resulted in the first two aircraft being redesignated YF-100A.
North American Aviation Chief Test Pilot George S. Welch in the cockpit of YF-100A 52-5754 at Los Angeles International Airport. (North American Aviation, Inc.)
The two YF-100As, 52-5754 and 52-5755, were 46 feet, 2.4 inches (14.082 meters) long with a wingspan of 36 feet, 9.6 inches (11.217 meters) and height of 14 feet, 4.8 inches (4.389 meters). The Super Sabre had a 49° 2′ sweep to the leading edges of the wings and horizontal stabilizer. The wings were swept to 45° at 25% chord, and had 0° angle of incidence, 0° dihedral, and no twist. The total wing area was 376 square feet (34.932 square meters). The ailerons were placed inboard on the wings to eliminate their twisting effects at high speed. The airplane had no flaps, resulting in a high stall speed in the landing configuration. The horizontal stabilizer was moved to the bottom of the fuselage to keep it out of the turbulence created by the wings at high angles of attack. The pre-production prototypes weighed 18,279 pounds (8,291 kilograms) empty; had a combat weight of 24,789 pounds (11,244 kilograms); and maximum takeoff weight of 28,965 pounds (13,138 kilograms).
The YF-100A had a fuel capacity of 757 U.S. gallons (2,866 liters) in five fuselage tanks, and could carry two external drop tanks for another 550 gallons (2,082 liters).
The new air superiority fighter was powered by a Pratt & Whitney Turbo Wasp XJ57-P-7 engine. The J57 was a two-spool axial-flow turbojet which had a 16-stage compressor section (9 low- and 7 high-pressure stages) and a 3-stage turbine (2 high- and 1 low-pressure stages). The XJ57-P-7 had a Normal Power rating of 7,250 pounds of thrust (32.250 kilonewtons) at 5,570 r.p.m., N1/9,630 r.p.m, N2; Military Power rating was 8,450 pounds thrust (37.587 kilonewtons) at 5,850 r.p.m./9,630 r.p.m., for 30 minutes; and 13,200 pounds thrust (587.717 kilonewtons) at 5,850 r.p.m./9,630 r.p.m. with afterburner, limited to five minutes. The engine was 20 feet, 3.0 inches (6.172 meters) long, 3 feet, 5.0 inches (1.014 meters) in diameter, and weighed 5,126 pounds (2,325 kilograms). Later production aircraft used a J57-P-39 engine, which had the same ratings.
Cutaway illustration of a North American Aviation F-100A Super Sabre. (Boeing)North American Aviation YF-100 Super Sabre 52-5754, 19 May 1953. (North American Aviation, Inc.)The prototype North American Aviation YF-100A Super Sabre, 52-5754, with the North American F-100 team. Chief Test Pilot George S. Welch is in the center of the front row, seated. (North American Aviation, Inc.)
The YF-100A had a maximum speed of 634 knots (730 miles per hour/1,174 kilometers per hour) at Sea Level, and 573 knots (659 miles per hour/1,061 kilometers per hour) at 43,350 feet (13,213 meters). The service ceiling was 46,000 feet (14,021 meters). The combat radius was 422 nautical miles (486 statute miles/782 kilometers), and maximum ferry range, 1,410 nautical miles (1,623 statute miles/2,611 kilometers).
During testing, 52-5754 reached Mach 1.44 in a dive. On 29 October 1953, Colonel Frank K. Everest set a world speed record of 1,215.298 kilometers per hour (755.151 miles per hour) with 52-5754.¹
In service with the United States Air Force, the Super Sabre’s mission changed from air superiority fighter to fighter bomber. It was used extensively during the Vietnam War. North American Aviation, Inc., built 2,294 single and tandem-seat Super Sabres between 1954 and 1959.
The F-100 pushed the State of the Art in the 1950s. There was a very steep learning curve back then. They remained in service with the USAF until 1979, and with the Republic of China Air Force until 1988. They also flew for France and Turkey.
In USAF service, 889 were destroyed in accidents, resulting in the death of 324 pilots. During the Vietnam War, the F-100s flew more combat sorties that all of the 15,000+ P-51 Mustangs during World War II. 186 Super Sabres were shot down by antiaircraft fire, but none were lost to enemy fighters.
North American Aviation YF-100A Super Sabre 52-5754 over Edwards Air Force Base, California, 25 May 1953. (North American Aviation, Inc.)North American Aviation YF-100A Super Sabre 52-5754 lands on the dry lake at Edwards Air Force Base, California. (North American Aviation, Inc.)
George Welch was born George Lewis Schwartz, in Wilmington, Delaware, 10 May 1918. His parents changed his surname to Welch, his mother’s maiden name, so that he would not be effected by the anti-German prejudice that was widespread in America following World War I. He studied mechanical engineering at Purdue, and enlisted in the Army Air Corps in 1939.
North American Aviation YF-100A Super Sabre 52-5754 banks away from a chase plane during a flight test. (U.S. Air Force)
George S. Welch is best remembered as one of the heroes of Pearl Harbor. He was one of only two fighter pilots to get airborne during the Japanese surprise attack on Hawaii, 7 December 1941. Flying a Curtiss P-40B Warhawk, he shot down three Aichi D3A “Val” dive bombers and one Mitsubishi A6M2 Zero fighter. For this action, Lieutenant General H.H. “Hap” Arnold recommended the Medal of Honor, but because Lieutenant Welch had taken off without orders, an officer in his chain of command refused to endorse the nomination. He received the Distinguished Service Cross. During the War, Welch flew the Bell P-39 Airacobra and Lockheed P-38 Lightning on 348 combat missions. He had 16 confirmed aerial victories over Japanese airplanes and rose to the rank of Major.
Suffering from malaria, George Welch was out of combat, and when North American Aviation approached him to test the new P-51H Mustang, General Arnold authorized his resignation. Welch test flew the P-51, FJ-1 Fury, F-86 Sabre and F-100 Super Sabre. He was killed 12 October 1954 when his F-100A Super Sabre came apart in a 7 G pull up from a Mach 1.5 dive.
North American Aviation pre-production prototype YF-100A Super Sabre 52-5754 with drag chute deployed on landing at Edwards Air Force Base, California. The extended pitot boom is used to calibrate instruments early in the flight test program. (U.S. Air Force)North American Aviation YF-100 Super Sabre 52-5754 with external fuel tanks, parked on the dry lake at Edwards Air Force Base, California. (U.S. Air Force)
The first Lockheed F-104A Starfighter, 55-2956, is towed out of its hangar at Air Force Plant 42, Palmdale, California, 17 April 1956. (Lockheed Martin)
17 April 1956: Lockheed Aircraft Corporation rolled out the very first production F-104A Starfighter, 55-2956, at Air Force Plant 42, Palmdale, California. This airplane, one of the original seventeen pre-production YF-104As, incorporated many improvements over the XF-104 prototype, the most visible being a longer fuselage.
Once the configuration was finalized, 55-2956 was the first YF-104A converted to the F-104A production standard. In this photograph, the F-104’s secret engine intakes are covered by false fairings.
Lockheed F-104A Starfighter 55-2956 rollout at Palmdale, 17 April 1956. (Lockheed Martin)
The Lockheed F-104A Starfighter was a single-place, single-engine supersonic interceptor. It was designed by a team lead by the legendary Clarence L. “Kelly” Johnson. The F-104A was 54 feet, 8 inches (16.662 meters) long with a wingspan of 21 feet, 9 inches (6.629 meters) and overall height of 13 feet, 5 inches (4.089 meters). It had an empty weight of 13,184 pounds (5,980.2 kilograms), combat weight of 17,988 pounds (8,159.2 kilograms), gross weight of 22,614 pounds (10,257.5 kilograms) and a maximum takeoff weight of 25,840 pounds (11,720.8 kilograms). Internal fuel capacity was 897 gallons (3,395.5 liters).
The F-104A was powered by a single General Electric J79-GE-3A engine, a single-spool axial-flow afterburning turbojet, which used a 17-stage compressor and 3-stage turbine. The J79-GE-3A is rated at 9,600 pounds of thrust (42.70 kilonewtons), and 15,000 pounds (66.72 kilonewtons) with afterburner. The engine is 17 feet, 3.5 inches (5.271 meters) long, 3 feet, 2.3 inches (0.973 meters) in diameter, and weighs 3,325 pounds (1,508 kilograms).
The F-104A had a maximum speed of 1,037 miles per hour (1,669 kilometers per hour) at 50,000 feet (15,240 meters). Its stall speed was 198 miles per hour (319 kilometers per hour). The Starfighter’s initial rate of climb was 60,395 feet per minute (306.8 meters per second) and its service ceiling was 64,795 feet (19,750 meters).
Lockheed F-104A-5-LO Starfighter 56-737 launches two AIM-9B Sidewinder infrared-homing air-to-air missiles. (U.S. Air Force)
Armament was one General Electric M61 Vulcan six-barreled revolving cannon with 725 rounds of 20 mm ammunition. An AIM-9B Sidewinder heat-seeking air-to-air missile could be carried on each wing tip, or a jettisonable fuel tank with a capacity of 141.5 gallons (535.6 liters).
Lockheed built 153 of the F-104A Starfighter initial production version. A total of 2,578 F-104s of all variants were produced by Lockheed and its licensees, Canadair, Fiat, Fokker, MBB, Messerschmitt, Mitsubishi and SABCA. By 1969, the F-104A had been retired from service. The last Starfighter, an Aeritalia-built F-104S ASA/M of the Aeronautica Militare Italiana, was retired in October 2004.
Lockheed JF-104A Starfighter 55-2956 at NOTS China Lake. (U.S. Navy)
This Starfighter, 55-2956, was converted to a JF-104A with specialized instrumentation. It was transferred to the U.S. Navy to test AIM-9 Sidewinder missiles at Naval Ordnance Test Station (NOTS) China Lake, approximately 55 miles (88 kilometers) north-northeast of Edwards Air Force Base in the high desert of Southern California. 55-2956 was damaged beyond repair when it lost power on takeoff and ran off the runway at Armitage Field, 15 June 1959.
While on loan to the U.S. Navy for testing the AIM-9 Sidewinder missile, Lockheed JF-104A Starfighter 55-2956, with Commander Herk Camp in the cockpit, crashed on takeoff at Armitage Field, NOTS China Lake. (U.S. Navy)
Lockheed XF-104 prototype, 53-7786, photographed 5 March 1954. (Lockheed Martin)
4 March 1954: Lockheed test pilot Anthony W. LeVier takes the prototype XF-104 Starfighter, 53-7786, for its first flight at Edwards Air Force Base in the high desert of southern California. The airplane’s landing gear remained extended throughout the flight, which lasted about twenty minutes.
Lockheed XF-104 53-7786 rolling out on Rogers Dry Lake, Edwards Air Force Base, California. This photograph shows how short the XF-104 was in comparison to the production F-104A. Because of the underpowered J65-B-3 engine, there are no shock cones in the engine inlets. (U.S. Air Force via Jet Pilot Overseas)
Designed by the legendary Kelly Johnson, the XF-104 was a prototype Mach 2+ interceptor and was known in the news media of the time as “the missile with a man in it.”
Tony LeVier was a friend of my mother’s family and a frequent visitor to their home in Whittier, California.
Legendary aircraft designer Clarence L. “Kelly” Johnson shakes hands with test pilot Tony LeVier after the first flight of the XF-104 at Edwards Air Force Base. (Lockheed via Mühlböck collection)
There were two Lockheed XF-104 prototypes. Initial flight testing was performed with 083-1001 (USAF serial number 53-7786). The second prototype, 083-1002 (53-7787) was the armament test aircraft. Both were single-seat, single-engine supersonic interceptor prototypes.
The wing of the Lockheed XF-104 was very thin, with leading and trailing edge flaps and ailerons. (San Diego Air & Space Museum)
The XF-104 was 49 feet, 2 inches (14.986 meters) long with a wingspan of 21 feet, 11 inches (6.680 meters) and overall height of 13 feet, 6 inches (4.115 meters). The wings had 10° anhedral. The prototypes had an empty weight of 11,500 pounds (5,216 kilograms) and maximum takeoff weight of 15,700 pounds (7,121 kilograms).
Lockheed XF-104 53-7786 (San Diego Air & Space Museum)
The production aircraft was planned for a General Electric J79 afterburning turbojet but that engine would not be ready soon enough, so both prototypes were designed to use a Buick-built J65-B-3, a licensed version of the British Armstrong Siddeley Sapphire turbojet engine. The J65-B-3 was a single-shaft axial-flow turbojet with a 13-stage compressor section and 2-stage turbine. It produced 7,200 pounds of thrust (32.03 kilonewtons) at 8,200 r.p.m. The J65-B-3 was 9 feet, 7.0 inches (2.921 meters) long, 3 feet, 1.5 inches (0.953 meters) in diameter, and weighed 2,696 pounds (1,223 kilograms).
On 15 March 1955, XF-104 53-7786 reached a maximum speed of Mach 1.79 (1,181 miles per hour, 1,900 kilometers per hour), at 60,000 feet (18,288 meters).
XF-104 53-7786 was destroyed 11 July 1957 when the vertical fin was ripped off by uncontrollable flutter. The pilot, William C. Park, safely ejected.
Lockheed XF-104 53-7786 with wingtip fuel tanks. (Lockheed Martin)
Lockheed XF-104 53-7786 with wingtip fuel tanks. Compare these finned tanks to those in the image above. (Lockheed Martin)
Lockheed Martin has an excellent color video of the XF-104 first flight on their web site at:
Lockheed YF-12A 60-6934, the first of three prototype Mach 3+ interceptors. (U.S. Air Force)
29 February 1964: President Lyndon B. Johnson publicly revealed the existence of the Top Secret Lockheed YF-12A, a Mach 3+ interceptor designed and built by Clarence L. “Kelly” Johnson’s “Skunk Works.” President Johnson referred to the interceptor as the “A-11.”
The following day, the Los Angeles Times ran two lengthy articles on its front page:
Johnson Discloses New Jet Secretly Developed by U.S.
Manned Aircraft Flies at 3 Times Speed of Sound; Military Potential Great
By ROBERT C. TOTH
Times National Science Correspondent
WASHINGTON—President Johnson disclosed Saturday the secret five-year development of an experimental jet aircraft whose performance “far exceeds that of any other aircraft in the world today.”
Several of the craft, designated A-11, have been “tested in sustained flight” at speeds greater than 2,000 m.p.h. and at heights over 70,000 ft., he said.
The craft has been made possible “by major advances in aircraft technology of great significance to both military and commercial application,” Mr. Johnson told a press conference.
Tests are under way at Edwards AFB, Cal., to determine the capability of the airplanes as long-range interceptors of enemy bombers. The plane was developed by Lockheed Aircraft Corp. of Burbank as a special project.
“Appropriate members of the Senate and the House have been kept fully informed on the program since its day of inception” in 1959, Mr. Johnson said.
Costs of the A-11 were not revealed, and the President said detailed performance information on the aircraft “will remain strictly classified.” Personnel working on the project have been told to keep quiet, he added.
Why the project has been wrapped in secrecy was not immediately clear. All that a White House spokesman would say, in answer to a question, was the A-11 represents “a new plateau in aircraft potential”—of such great potential that the military wanted to “explore it in secrecy.”
The A-11’s development also will aid in building a supersonic transport for commercial airlines, Mr. Johnson said. Like A-11, the transport would fly about Mach 3, or three times the speed of sound.
One of the most important technological achievements of the A-11 project, the President said, has been the mastery of the problem of using titanium metal on aircraft.
Great Heats
The aluminum used in today’s airplanes wears out in sustained flight at speeds greater than about Mach 2.2. This is due to the great heats generated by friction as air rushes over the surfaces of the aircraft, particularly the leading edges of the wings.
“The existence of this (A-11) program is being disclosed today to permit the orderly exploitation of this advanced technology in our military and commercial planes,” Mr. Johnson said.
High performance aircraft like the controversial TFX multi-service airplane and the Navy’s Phantom fighter will have speeds up to about Mach 2.5—about 1,600 m.p.h. These high speeds are possible for relatively short duration, however.
Funds for the A-11 were presumably buried in other appropriations, conceivably in part in Air Force appropriations for the B-70.
Dimensions of the A-11 were not revealed although an in-flight picture of the side view of the plane was distributed. It suggests the A-11 is more than 100 ft. long, based on the size of the pilot’s head in the cockpit.
The front half of the A-11 looks very similar to that of the X-15 rocket plane which has flown at speeds over 4,000 m.p.h. The characteristic tail surfaces of the X-15, extending both above and below the fuselage, also were obvious.
The A-11’s engine, a J-58 from Pratt & Whitney, occupies the rear third of the vehicle.
The experimental fire control and air-to-air missile system was developed by the Hughes Aircraft Co. The “A” in the aircraft’s designation suggests an “attack” function.
Number of Questions
Announcement of the project raises a number of questions, some of which Presidential Press Secretary Pierre Salinger answered at a subsequent briefing.
For example, why did the Pentagon object to the Boeing Aircraft Co.’s proposal to use titanium in the TFX if the A-11 had proved that the metal can be used?
“The technical knowledge obtained in the A-11 program made it possible to evaluate Boeing’s proposal,” Mr. Salinger said, and the Pentagon concluded that the titanium in the TFX represented a “High development risk.”
Technical Justification
This seemed to be further technical justification for the choice of General Dynamics over Boeing for the TFX, a choice which raised a political furor in Congress.
The economic meaning of the A-11 was another question put to Mr. Salinger. While the project makes a major contribution to Mach 3 flight, he replied, “It cannot be converted into a transport. A major independent development program is still necessary to produce a supersonic transport.”
—Los Angeles Times, Vol. LXXXIII, Sunday, 1 March 1964, Page 1, Columns 7–8, and Page 6, Columns 3–4
The second Times article identifies the designer as Clarence L. (“Kelly”) Johnson:
NEW PLANE GREAT FEAT OF SECURITY
BY MARVIN MILES
Times Aerospace Editor
President Johnson’s announcement of a new triple-sonic interceptor Saturday disclosed on of the best kept secrets in military annals, a security feat comparable in many ways to that achieved with the atomic bomb.
Apparently even the House Armed Services Committee didn’t know of the project for it recommended $40 million for an improved manned interceptor, a fund approved by the full House just 10 days ago.
The Senate, however, must have had more information, for it made no provision for the new interceptor studies in approving aircraft funding last Thursday, including $52 million for an advanced bomber.
The secret of Lockheed’s new A-11 interceptor was kept far better than that of the same company’s U-2 reconnaissance plane that was eventually shot down on a sky-spy flight over Russia.
Dozens of reports on the mysterious U-2 from various sections of the world had filtered into the news before the international incident over Russia.
The Times learned the new A-11 was spurred by the same aircraft genius who headed development of the U-2 and Lockheed’s famed F-104 Starfighter interceptor, Clarence (Kelly) Johnson, vice president for advanced development projects.
Johnson and his crew work in a carefully-guarded area at the Lockheed Burbank factory known as the “Skunk Works.”
Pierre Salinger, White House press officer, told newsmen the A-11 was funded and managed by the Air Force in the normal manner for a classified project.
Inasmuch as the new plane was started in 1959, this gave rise to speculation as to why a similar plane, the F-108, was canceled in that year.
The F-108 was a North American Aviation project in the same time era that the company’s triple-sonic B-70 bomber was started.
Like the A-11, it was to have had a speed of Mach 3 (about 2,000 m.p.h.) with a range of about 2,000 miles, plus combat time.
Reason for canceling the F-108 was largely budgetary, according to reports in 1959, with the Defense Department declaring that of the two North American projects, the B-70 bomber was a more urgent program than the F-108.
Some estimates of the A-11 can be drawn from the F-108. The North American plane was to have been powered by two engines, and one considered was the Pratt & Whitney J-58, the engine that will power the A-11.
This indicates the new Lockheed interceptor will have two engines also. The J-58 has never been used, either militarily or commercially, as far as The Times could determine. It has a thrust of about 30,000 lb.
Another indication from the F-108 relates to the armament of the A-11. The canceled North American interceptor was to have been armed with Hughes GAR-9 nuclear-tipped rockets.
The A-11 has a Hughes fire control system and its armament could well be the same guided, air-to-air rocket or an advancement of it.
The new interceptor will answer fears expressed by many military experts that Russia’s bomber fleet poses a greater threat to North America than her intercontinental missiles.
The A-11 will have the speed to intercept high speed bombers and shoot them down at ranges that would precluded their launching air-to-ground missiles against U.S. targets.
In appearance, the A-11 looks something like the X-15 rocket plane, a long, slim craft with sharp pointed nose section similar to that of the F-104 Starfighter.
It has both ventral and dorsal fins and appears to be about 90 ft. long over-all.
—Los Angeles Times, Vol. LXXXIII, Sunday, 1 March 1964, Page 1, Columns 7–8 and Page 6, Column 5–6
The YF-12A first flew 7 August 1963.
Clarence L. (“Kelly”) Johnson, Director of Lockheed’s Advanced Development Projects (“the Skunk Works”) with the first YF-12A interceptor, 60-6934. (Lockheed Martin)
Intended as a replacement for Convair’s F-106 Delta Dart, three pre-production YF-12As were built for testing. On 1 May 1965, a YF-12A set a speed record of 2,070.103 miles per hour (3,331.507 kilometers per hour) and reached an altitude of 80,259 ft (24,463 meters).
The reason for President Johnson’s announcement of the existence of the YF-12A prototypes was to conceal the existence of the Central Intelligence Agency’s fleet of Lockheed A-12 Oxcart reconnaissance aircraft based at Groom Lake, Nevada. Any sightings of these aircraft could be attributed to test flights of the YF-12As based at Edwards Air Force Base, 160 miles (258 kilometers) to the southwest.
Lockheed A-12 Oxcarts and YF-12As at Groom Lake, Nevada. (Central Intelligence Agency)
The YF-12A interceptor is very similar to its A-12 Oxcart and SR-71A Blackbird stablemates. It is a large twin-engine delta wing aircraft, flown by a pilot and weapons system operator. Because of the altitudes that the F-12 operates, the crew wears S901F full-pressure suits produced by the David Clark Company. The A-12 is 101.6 feet (30.97 meters) long with a wingspan of 55.62 feet (16.953 meters) and overall height of 18.45 feet (5.624 meters). It has a zero fuel weight of 54,600 pounds (24,766 kilograms) and a maximum ramp weight of 124,600 pounds (56,518 kilograms). ¹
Lockheed YF-12A three-view illustration. (NASA)
The YF-12A is powered by two Pratt & Whitney J58 (JT11D-20A) engines. These are single rotor bleed-bypass turbojets with a 9-stage compressor section and 2-stage turbine. They have a static thrust rating of 31,500 pounds (140.118 kilonewtons), each, at Sea Level with afterburning. The J58s use a unique JP-7 fuel.
The YF-12A has a maximum speed of Mach 3.35 (2,232 miles per hour/3,342 kilometers per hour) at 80,000 feet (24,384 meters). The A-12 has a normal operating cruise speed of Mach 3.1. Its maximum operating altitude is 85,000 feet (25,908 meters) and it has a range of 3,000 miles (4,828 kilometers). Unlike most fighters, the A-12 has a maximum load factor of 2.5 gs. Its maximum bank angle when above Mach 2.5 is 30°.
The United States Air Force ordered 93 production F-12B aircraft, which would have been armed with three Hughes AIM-47A Falcon air-to-air missiles in enclosed bays in the bottom of the fuselage. However, Secretary of Defense Robert S. McNamara refused to release the funds for the purchase for three consecutive years and eventually the project was cancelled.
Hughes AIM-47A guided missile ready for loading into the weapons bay of a Lockheed YF-12A. (U.S. Air Force)
The first YF-12A, 60-6934, seen in the top photograph, was extensively damaged by a brake system fire on landing at Edwards AFB, 14 August 1966. It was salvaged and rebuilt as SR-71C 61-7981. The third YF-12A, shown in the photograph below, was lost due to an inflight fire 24 June 1971. The crew safely ejected.
The only existing YF-12A, 60-6935, is in the collection of the National Museum of the United States Air Force at Wright-Patterson Air Force Base, Ohio.
Lockheed YF-12A 60-6936, holder of three World Absolute Speed Records and the World Absolute Altitude Record, at Edwards Air Force Base, California. (U.S. Air Force)
¹ The Lockheed SR-71A has a length of 107.4 feet (32.74 meters). Wingspan and height are the same. Its zero fuel weight varied from 56,500–60,000+ pounds (25,628–27,216+ kilograms) and the gross weight had a range of approximately 135,000–140,000+ pounds (61,235–63,503+ kilograms).
