Tag Archives: Pratt & Whitney JT11D-20

5 June 1968

Lockheed A-12 60-6932 (Article 129). (Central Intelligence Agency)

5 June 1968: Lockheed A-12 60-6932 (Article 129) was lost during a functional check flight following the change of its right engine. The Mach 3 reconaissance aircraft had taken off from Kadena Air Base, Okinawa. Central Intelligence Agency Pilot Jack Warren Weeks, call sign “Dutch 29,” was killed.

Weeks’ mission started off with a top-off refueling, then the test hop route dictated by weather conditions. The climb-out and start of the turn back North apparently went as planned. Then the on-board telemetry system (Birdwatcher) started sending downlinks indicating the right engine was overtemping, followed by low fuel flow signals and finally that the altitude was below 70,000? approximately. Then all signals from Article 129 ceased and it was presumed that the airplane was down. Intensive searches failed to show any sign of the airplane or its pilot. The ensuing accident board concluded that the most likely cause of the loss of the airplane was catastrophic failure of the right engine.” —Roadrunners Internationale

The remaining eight A-12s were retired in favor of the new U.S. Air Force Lockheed SR-71A. Thirteen A-12s had been built by Lockheed. Four had previously been lost. The final flight of a Lockheed A-12 took place 21 June 1968, when it flew from Area 51 in Nevada, to Palmdale, California.

Jack Warren Weeks was born 23 February 1933 at Birmingham, Alabama. He was the first of two children of Nathan Malcolm Weeks, a dry cleaning salesman, and Abbie Ellen Kearney Weeks.

Weeks attended the University of Alabama at Tuscaloosa from 1951 to 1955, where he majored in physics. He was a member of the Reserve Officers Training Program (ROTC), the Delta Chi (ΔΧ) and Sigma Pic Sigma (ΣΠΣ) fraternities.

Jack W. Weeks (1952 Corolla)
Mrs. Jack Warren Weeks (The Birmingham News)

Jack Weeks married Miss Sharlene Thera Fenn, 5 September 1953, at the West End Baptist Church, in Birmingham, Alabama. The ceremony was presided over by Rev. James H. Butler. They would have four children.

Weeks graduated in May 1955 with a bachelor of science degree. He was commissioned as a second lieutenant, United States Air Force Reserve (USAFR).

Lieutenant Weeks served with the 22 Fighter Day Squadron at Bitburg Air Base, Germany, from April 1957 to April 1960. (On 15 May 1958 the squadron was redesignated 22nd Tactical fighter Squadron.) The unit flew North American F-100 Super Sabres. On 3 August 1958, Weeks was promoted to first lieutenant.

North American Aviation F-100C-20-NA Super Sabre 54-1941, 22nd Fighter Day Squadron, at Bitburg Air Base, Germany. (U.S. Air Force)

From April 1960 to February 1963, 1st Lieutenant Weeks was assigned to the  4520th Combat Crew Training Wing at Nellis Air Force Base, Las Vegas, Nevada.

Jack Weeks was recruited by the Central Intelligence Agency (CIA), and from 1963 to1968 he worked as an experimental test pilot on the Lockheed A-12. He and his family lived in resided in Canoga Park, California.

Weeks also flew the A-12 on flew reconnaissance missions over Southeast Asia during the Vietnam War (Operation Black Shield), and over the Democratic people’s Republic Korea (North Korea), during the Pueblo Incident. (Weeks’ obituary said that he was a consultant for Hughes Aircraft, and that he was performing equipment calibrations at Okinawa.)

The Central Intelligence Agency posthumously awarded Jack Warren Weeks its Intelligence Star for Courageous Action, 17 May 1968. The award was presented to Mrs. Weeks.

Central Intelligence Agency A-12 pilot Jack Warren Weeks, circa 1963. (CIA)

The Lockheed A-12 was a top secret reconnaissance airplane built for the Central Intelligence Agency under the code name “Oxcart.” It was the replacement for the Agency’s high-flying but subsonic U-2 spy plane which had become vulnerable to radar-guided surface-to-air missiles. It was a single-place, twin-engine hypersonic reconnaisance aircraft. The A-12 could fly faster than Mach 3 and higher than 80,000 feet—so fast and so high that no missile could reach it. By the time missile site radar locked on to an A-12 and a missile was prepared to fire, the Oxcart had already flown beyond the missile’s range. It was 101.6 feet (30.97 meters) long, with a wingspan of 55.62 feet (16.95 meters) and overall height of 18.45 feet (5.62 meters). It had an empty weight of 54,600 pounds (24,766 kilograms) and maximum gross weight of 124,600 pounds (57,878 kilograms).

The A-12 was powered by two Pratt & Whitney JT11D-20 (J58-P-4) turbo-ramjet engines, rated at 25,000 pounds of thrust (111.21 kilonewtons) and 34,000 pounds of thrust (151.24 kilonewtons) with afterburner. The exhaust gas temperature is approximately 3,400 °F. (1,870 °C.). The J58 is a single-spool, axial-flow engine which uses a 9-stage compressor section and 2

-stage turbine. The J58 is 17 feet, 10 inches (7.436 meters) long and 4 feet, 9 inches (1.448 meters) in diameter. It weighs approximately 6,000 pounds (2,722 kilograms).

The A-12’s speed was Mach 3.2 (2,125 miles per hour/3,118 kilometers per hour) at 75,000 feet(22,860 meters). Its cruise altitude was 84,500–97,600 feet (25,756–29,748 meters). The range was 4,210 nautical miles (4,845 miles/7,797 kilometers)

The A-12 was equipped with a Perkin-Elmer Type I stereo camera. With its 5,000-foot (1,524 meters) film supply, produced pairs of photographs covering a 71-mile (114 kilometers) swath with ground resolution of 12 inches (30.48 centimeters). Kodak Type II stereo camera, 8,400 foot (2,560 meters) film supply, 60-mile (97 kilometers) swath, 17-inch (43 centimeters) resolution. Hycon Type IV, 12,000-foot (3,658 meters)  film supply, 41-mile (66 kilometers) swath with resolution of 8 inches (20 centimeters).

Article 129 was the ninth of thirteen A-12s built by Lockheed’s “Skunk Works.” They were operational from 1964 to 1968, when they were phased out in favor of the U.S. Air Force two-man Lockheed SR-71A “Blackbird.”

Lockheed A-12 Oxcarts and YF-12As at Groom Lake, Nevada. (Central Intelligence Agency)

© 2024, Bryan R. Swopes

30 April 1962

"Article 121" takes off on its first flight at Groom Lake, Nevada, 30 April 1962. (Lockheed Martin)
“Article 121” takes off on its first flight at Groom Lake, Nevada, 30 April 1962. (Lockheed Martin)

30 April 1962: Though it had been airborne briefly just a few days earlier, “Article 121”, the first Lockheed A-12, serial number 60-6924, took off from a Top Secret facility at Groom Lake, Nevada, on its “official” first flight. Lockheed test pilot Louis Wellington (“Lou”) Schalk, Jr. was in the cockpit.

The 72,000-pound (32,659 kilogram) airplane lifted off the 8,000-foot (2,438 meters) runway at 170 knots (196 miles per hour, 315 kilometers per hour).

A Central Intelligence Agency report on the A-12 project states:

“. . . rolled out for its first official flight on 30 April, just under one year later than originally planned. A number of senior Air Force officers and CIA executives, including Deputy Director for Research Herbert Scoville and former project chief Bissell (who left the Agency in February 1962), witnessed the long-awaited event. Schalk again was the pilot. He took the aircraft up for 59 minutes and reached 30,000 feet and just under 400 mph; most of the flight was made at under 300 mph. He reported that the A-12 responded well and was extremely stable. Johnson said this was the smoothest official first flight of any aircraft he had designed or tested.”

ARCHANGEL: CIA’s Supersonic A-12 Reconnaissance Aircraft, by David Robarge, Center for the Study of Intelligence, Central Intelligence Agency, 2012

Lockheed test pilot Louis W. Schalk, Jr. (Lockheed Martin)
Lockheed test pilot Louis W. Schalk, Jr. (Lockheed Martin)

The A-12 was a top secret reconnaissance airplane built for the Central Intelligence Agency under the code name “Oxcart.” It was the replacement for the Agency’s high-flying but subsonic U-2 spy plane which had become vulnerable to radar-guided surface-to-air missiles. (A U-2 piloted by Francis Gary Powers had been shot down with an SA-2 Guideline missile while over Russia exactly one year before.)

The A-12 could fly faster than Mach 3 and higher than 80,000 feet—so fast and so high that no missile could reach it. By the time missile site radar locked on to an A-12 and a missile was prepared to fire, the Oxcart had already flown beyond the missile’s range.

Lockheed A-12 60-6924 (Lockheed Martin)
Lockheed A-12 60-6924 (Lockheed Martin)

The Lockheed A-12 was a single-place, twin-engine hypersonic reconnaisance aircraft. It was 101.6 feet (30.97 meters) long, with a wingspan of 55.62 feet (16.95 meters) and overall height of 18.45 feet (5.62 meters). It had an empty weight of 54,600 pounds (24,766 kilograms) and maximum gross weight of 124,600 pounds (57,878 kilograms).

The A-12 was powered by two Pratt & Whitney JT11D-20 (J58-P-4) turbo-ramjet engines, rated at 25,000 pounds of thrust (111.21 kilonewtons) and 34,000 pounds of thrust (151.24 kilonewtons) with afterburner. The exhaust gas temperature is approximately 3,400 °F. (1,870 °C.). The J58 is a single-spool, axial-flow engine which uses a 9-stage compressor section and 2-stage turbine. The J58 is 17 feet, 10 inches (7.436 meters) long and 4 feet, 9 inches (1.448 meters) in diameter. It weighs approximately 6,000 pounds (2,722 kilograms).

The A-12’s speed was Mach 3.2 (2,125 miles per hour/3,118 kilometers per hour) at 75,000 feet(22,860 meters). Its cruise altitude was 84,500–97,600 feet (25,756–29,748 meters). The range was 4,210 nautical miles (4,845 miles/7,797 kilometers)

Article 121 was the first of thirteen A-12s built by Lockheed’s “Skunk Works.” They were operational from 1964–1968, when they were phased out in favor of the U.S. Air Force two-man SR-71A “Blackbird.”

Today, the first Lockheed A-12 is on display at Blackbird Airpark, an annex of the Air Force Flight Test Museum, Edwards Air Force Base, California. It has made 322 flight and accumulated a total of 418.2 flight hours.

Lockheed A-12 60-6924 lands at Groom Lake, Nevada, after its first flight, 30 April 1962. (Lockheed Martin)

© 2018, Bryan R. Swopes

22 December 1964

The first Lockheed SR-71A, 61-7950, takes off for the first time at Air Force Plant 42, Palmdale, California. An F-104 Starfighter follows as chase. (Lockheed Martin)

22 December 1964: Lockheed test pilot Robert J. “Bob” Gilliland made a solo first flight of the first SR-71A, 61-7950, at Air Force Plant 42, Palmdale, California. The “Blackbird” flew higher than 45,000 feet (13,716 meters) and more than 1,000 miles per hour (1,609 kilometers per hour) before landing at Edwards Air Force Base, 22 miles (35 kilometers) northeast, to begin the flight test program.

Bob Gilliland made the first flight of many of the Lockheed SR-71s. It is reported that he has logged more flight time in excess of Mach 3 than any other pilot.

Robert J. Gillilan (Lockheed)
Blackbird test pilot Robert J. Gilliland, with a Lockheed SR-71A. Gilliland is wearing an S901J full-pressure suit made by “Northeast Manufacturing” (the David Clark Co.) (Lockheed Martin)

The SR-71A Blackbird is a Mach 3+ strategic reconnaissance aircraft designed and built by Lockheed’s famous (but Top Secret) “Skunk Works” for the United States Air Force. It was developed from the Central Intelligence Agency’s A-12 Oxcart program.

The SR-71A is a two-place aircraft, operated by a Pilot and a Reconnaissance Systems Officer (“RSO”). It uses electronic and optical sensors. The fuselage has a somewhat flattened aspect with chines leading forward from the wings to the nose. The wings are a modified delta, with integral engine nacelles. Two vertical stabilizers are mounted at the aft end of the engine nacelles and cant inward toward the aircraft centerline.

The SR-71A is 107 feet, 5 inches (32.741 meters) long with a wingspan of 55 feet, 7 inches (16.942 meters), and overall height of 18 feet, 6 inches (5.639 meters). Its empty weight is 67,500 pounds (30,620 kilograms) and maximum takeoff weight is 172,000 pounds (78,020 kilograms).

Lockheed SR-71A 61-7950 in flight. (U.S. Air Force)
Lockheed SR-71A 61-7950 in flight. (U.S. Air Force)

The Blackbird is powered by two Pratt & Whitney JT11D-20 (J58-P-4) turbo-ramjet engines, rated at 25,000 pounds of thrust (111.21 kilonewtons) and 34,000 pounds of thrust (151.24 kilonewtons) with afterburner. The exhaust gas temperature is approximately 3,400 °F. (1,870 °C.). The J58 is a single-spool, axial-flow engine which uses a 9-stage compressor section and 2-stage turbine. The J58 is 17 feet, 10 inches (7.436 meters) long and 4 feet, 9 inches (1.448 meters) in diameter. It weighs approximately 6,000 pounds (2,722 kilograms).

The SR-71A has a maximum speed of Mach 3.3 at 80,000 feet (24,384 meters)—2,199 miles per hour (3,539 kilometers per hour). Its maximum rate of climb is 11,810 feet per minute (60 meters per second), and the service ceiling is 85,000 feet (25,908 meters). The Blackbird’s maximum unrefueled range is 3,680 miles (5,925 kilometers).

Lockheed built 32 SR-71As. They entered service with the 4200th Strategic Reconnaissance Wing (later redesignated the 9th SRW) in 1966 and were initially retired in 1989. Several were reactivated in 1995, but finally retired in 1999.

Lockheed SR-71A-LO 61-7950 was lost to fire during a brake system test at Edwards AFB, 10 January 1967.
Lockheed SR-71A-LO 61-7950 was lost to fire during a brake system test at Edwards AFB, 10 January 1967. (Lockheed Martin via habu.org)

© 2016, Bryan R. Swopes