Tag Archives: Lockheed SR-71A-LO

6 March 1998

Into the sunset....
Into the sunset….

6 March 1998: Secretary of Defense William S. Cohen approved the permanent retirement of the Lockheed SR-71A “Blackbird” Mach 3+ strategic reconnaissance aircraft.

With that decision, the U.S. Air Force would retire two SR-71A models (returned to active duty in 1995), an SR- 71A and the SR-71B trainer model on loan to NASA, and two from returnable storage.

© 2015, 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

18 December 1969

Lockheed SR-71A 69-7953. (U.S. Air Force)
Lockheed SR-71A 61-7953. (U.S. Air Force)
Colonel Joseph W. Rogers with a Lockheed SR-71A. (U.S. Air Force)
Colonel Joseph W. Rogers with a Lockheed “Blackbird.” (U.S. Air Force)

18 December 1969: Colonel Joseph William Rogers and Major Gary Heidelbaugh were flying  Lockheed SR-71A 61-7953 to test a new system installation followed by a training mission. The functional test had gone well and the Blackbird rendezvoused with a KC-135 tanker before proceeding with the mission.

After coming off the tanker, Colonel Rogers (call sign “Dutch 68”) radioed the regional air traffic control center for permission to climb through all flight levels to 60,000 feet (18,288 meters), or Flight Level Six Zero Zero.

A short transcript of the radio and intercom transmissions follows:

(Pilot, Colonel Joseph W. Rogers; RSO, Major Gary Heidelbaugh; L.A. Center: Los Angeles Center, the Federal Aviation Administration Air Traffic Control Center at Palmdale, California. Times listed are UTC.)

Pilot’s station of a Lockheed SR-71A. (NASM)

Pilot: “Los Angeles Center, Dutch 68.” [2106:45]

L.A. Center: “Dutch 68, rog, loud and clear. How me?”

Pilot: “Roger, you’re loud and clear. I’m in a left turn flight level two six zero, requesting climb above six zero zero Route Aqua.”

L.A. Center: “Rog, your routing is approved. Climb and maintain above 600 and squawk 4400.”

Pilot: “Four four squawking.” [2107:13]

L.A. Center: “Dutch 68, Rog. Have you radar contact. Report 310 climbing.” [2107:27]

Pilot: “Roger.”

Pilot: “Okay, I’m going to light them off, Gary.” [est 2107:30]

RSO: “Rog.”

RSO: “That’s our heading.”

Pilot: “Roger.”

RSO: “What caused all that?” [est 2108:00]

Pilot: “I don’t know.”

RSO: “. . . Climbing.”

Pilot: “Let’s go.” [est 2108:15] CREW EJECTS

L.A. Center: “Dutch 68. Say your altitude.” [2110:30]

L.A. Center: “Dutch 68. Say your altitude.” [2110:50]

L.A. Center: “Dutch 68, Dutch 68, Los Angeles.” [2111:12]

L.A. Center: “Dutch 68, Dutch 68, Los Angeles.” [2111:28]

When Colonel Rogers advanced the SR-71’s throttles to go into afterburner for the climb, the compressor sections of both engines stalled. (Compressor stall is a condition that occurs when airflow through the engine intake is disrupted. Normal flow ceases, the engine stops producing thrust, and there can be violent oscillations and uncontained failure of the compressor section.) The SR-71A slowed abruptly and then violently pitched upward. Rogers said, “Let’s go,” and both men ejected from the out-of-control airplane.

Rogers and Heidelbaugh safely parachuted to the ground. 61-7953 crashed near Shoshone, California, and was totally destroyed by the crash and fire that followed.

The accident investigation determined that a small roll of 2″-wide (5.08 centimeters) duct tape was lodged inside one of the tubes of the airplane’s pitot-static system. When the new system had been installed, it required that the pitot-static tubing be modified and rerouted. A technician apparently placed the rolled duct tape inside an open section of tubing to prevent entry of dirt or foreign objects. When the tubing was reassembled, this makeshift plug was not removed. Post crash testing showed that the plug did not totally close off airflow, but that it decreased it, causing the altimeter to read too high and the airspeed indicator too fast. The normal test of the pitot-static system following the modification did not reveal the problem.

A Lockheed SR-71 Pratt & Whitney J58 turbo ramjet engine running on a test stand, in full afterburner.

When Joe Rogers advanced the throttles, he was at approximately 27,000 feet (8,230 meters) rather than the indicated 25,000 feet (7,620 meters). He was also about 30 miles per hour (48 kilometers per hour) slower than indicated.  The sudden demand for increased airflow as the throttles advanced could not be met by the thinner, slower air, and the compressors stalled.

Joe Rogers was a fighter pilot in World War II, the Korean War and the Vietnam War. He was a highly experienced test pilot with considerable experience in Mach 2+, high-altitude aircraft. He had been the commanding officer of the F-12/SR-71 Test Force at Edwards Air Force Base. Ten years and three days before this accident, he had set a World Speed Record while flying a Convair F-106A Delta Dart. (See TDiA post for 15 December 1959)

The wreck of Lockheed SR-71A 61-7953 burning near Shoshone, California, 18 December 1969.
The wreck of Lockheed SR-71A 61-7953 burning near Shoshone, California, 18 December 1969. (Check-Six.com)

© 2016, Bryan R. Swopes

9 October 1999

9 October 1999: At a Saturday air show at Edwards Air Force Base, California, NASA Research Pilot Rogers E. Smith and Flight Test Engineer Robert R. Meyer, Jr., flew Lockheed SR-71A-LO 61-7980, NASA 844, on what would be the very last flight of a Blackbird. Although it was scheduled to fly again for the Sunday air show, a serious fuel leak prevented that flight.

61-7980 (Lockheed serial number 2031) was the final SR-71A to be built.

NASA 844 was retired after the final flight and placed in flyable storage, but in 2002, it was placed on static display at the Dryden Flight Research Center,¹ Edwards Air Force Base, California.EC92-02273 

¹ In 2014, DFRC was renamed the NASA Neil A. Armstrong Flight Research Center (AFRC).

© 2017, Bryan R. Swopes