Tag Archives: Pratt & Whitney JT11D-20

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).

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

During the 59-minute test flight, Schalk kept the airspeed to just 340 knots (391 miles per hour, 630 kilometers per hour), but climbed to 30,000 feet (9.144 meters) while he tested systems and handling characteristics. He described the airplane as very stable and extremely responsive.

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

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22 December 1964

The first Lockheed SR-71A, 61-7950, takes of fo rthe first time at Air Force Plant 42, Palmdale, California. (Lockheed)
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 via habu.org)

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

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