D-21 Tagboard

Refer to the disambiguation page for other articles titled "Tagboard".

The Lockheed D-21 Tagboard was a Mach 3+ reconnaissance drone that began development in October 1962. Originally known by the Lockheed designation Q-12, it was intended to be launched off the back of the Lockheed A-12 for extra-long range flights and/or missions that were too dangerous for a manned vehicle. With a single Hycon high-resolution photographic camera, it was designed to fly over a pre-programmed location, and then drop the hatch containing the camera into the ocean, where it could be retrieved. The D-21 itself would then self-destruct.

Contents

1 Design 2 Testing 3 Operational Use 4 References

Design

The Q-12 design was finalized in October 1963. An air-launched vehicle, it was powered by a single Marquardt RJ43-MA-11 ramjet, and used key technology from the A-12 project, including titanium construction. Its double-delta wing was similar to the A-12's outer wing design.

In late 1963, the project was named Tagboard and the Q-12 was re-designated D-21 while the A-12 became M-21 (D- for "daughter" and M- for "mother") to prevent confusion between Tagboard and the Blackbird family, which spawned from the A-12 design.

Testing

The M-21/D-21 combination began captive flight-testing in December 1964, continuing through 1965. Aerodynamic covers that were in place over the intake and exhaust were removed after the first few tests, as it was unable to drop them at Mach 3 without damaging the M-21 and/or D-21. Increased drag caused by the removal was overcome by using the D-21's ramjet as a third engine.

The first launch of the D-21 from the back of the M-21 occurred successfully on March 5, 1966, followed by two others on April 27 and June 16 of that year. The fourth and final launch occurred a month later on July 30. The D-21 impacted with the M-21's tail immediately after separation, leading to the crash of both aircraft and the death of one of the two M-21 crewmembers. Due to this accident, the M-21/D-21 combination program was terminated.

An alternate method of launch had already been proposed before the ill-fated flight, as the M-21/D-21 launch procedure was known to be risky. A modified D-21 would be launched from an under-wing pylon on a B-52H. The Tagboard drone had to use a large solid-propellant rocket booster to accelerate to the target speed before igniting the ramjet, as the B-52 had a much slower speed.

The modified drone was designated D-21B - although there was no -21A version - and all D-21s on order in mid-1966 were completed as D-21Bs. Two B-52Hs were modified to carry two drones each and could communicate with the D-21Bs, which had improved remote control links that remained active up to 10 minutes into the mission.

Initial testing began in September 1967 and went on until July 1969, and was not very successful for some time. The first flight ended with the drone falling off the wing of the B-52 before even reaching the launching area. Not until the last two flights, having recovered the camera hatch after the drone had covered more than 5370 km (2900 nm), did the B-52H/D-21B system get declared ready for operational missions.

Operational Use

Four operational missions took place under the name SENIOR BOWL, from November 9, 1969 to March 20, 1971, all over the People's Republic of China to spy on the Lop Nor nuclear test site. Only two drones completed the flight, and system malfunctions prevented the recovery of the reconnaissance camera. Due to the poor level of success and the introduction of a new generation of photoreconnaissance satellites, the Tagboard project was cancelled in July 1971.

In the end, 38 D-21/D-21B drones were built. Twenty-one were expended in tests and missions, and the remaining 17 vehicles were placed in permanent storage and redesignated as GTD-21B. Since the mid-1990s, they have been released to museums for display.

References

• Directory of U.S. Military Rockets and Missiles (http://www.designation-systems.net/dusrm/app4/d-21.html)
• Weapons of Precise Destruction (http://muller.lbl.gov/TRessays/04_Weapons_Precise_Destru.htm)
• The Museum of Flight in Seattle (http://www.museumofflight.org/collections/craftdisplay.html?ID=68)

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