Mach 3 mothership: Project Tagboard and the M‑21/D‑21

Following the loss of Powers’ U‑2 and the US Government’s subsequent decision to discontinue manned overflights of China and the Soviet Union, on October 10, 1962 the Skunk Works received authorization to begin studies into the feasibility of producing a Mach 3+ unpiloted platform, or drone, for the CIA. Initial flight tests of the A‑12 had given the design team working on the drone – designated Q‑12 at this early stage – considerable confidence in the aerodynamic precedent set by the chined delta, and this configuration was applied to the vehicle as it took shape. Powered by a high‑speed ramjet, experience about which Lockheed was able to draw upon from their involvement in the X‑7 program, the engine was built by Marquardt and designated the XRJ43‑MA20S‑4. To provide the necessary propulsive power to start the ramjet, the drone would be launched at Mach 3.13 from a modified A‑12. A Launch Control Officer (LCO) was located in what was formally the A‑12’s Q Bay, reconfigured for the purpose. Two A‑12s were modified for these duties: Articles 134 (60‑6940) and 135 (60‑6941). This mother – daughter combination gave rise to their redesignation as M‑21 (Mother) and D‑21 (Daughter‑drone); the numerical designation was also transposed to avoid all confusion with the Oxcart A‑12. The drones were considered “one‑way aircraft,” meaning that they would make one flight only, after which the palletized unit containing the platform’s INS, together with the reconnaissance camera (built by Hycon) and its all‑important film, would be ejected over safe international waters and recovered during the parachute descent by means of a Mid‑Air Recovery System (MARS). The remainder of the drone would then self‑destruct, using an explosive charge, and its remains would fall into a watery grave.

Kelly Johnson highlighted both the cost and dangers of launching the D‑21 from the M‑21 at Mach 3+ and, following a fatal collision between the pair on July 30, 1966, two modified B‑52Hs were used. However, Project Senior Bowl was both expensive and unsuccessful; it was canceled as Project Corona, the US satellite program, became more reliable. (Lockheed Martin)

On August 12, 1964, D‑21 number 501 was sent from Burbank to Area 51, where satisfactory static tests were subsequently concluded. On December 22, 1964, the first D‑21/M‑21 combination flight was successfully completed. Having surmounted a number of technical difficulties, the two‑aircraft combination was flown out to Mach 2.6 in May 1965; however, it wasn’t until October 21 of the same year that the team were finally able to get the M‑21 up to the required launch speed, this being achieved by installing the new 34,000lb‑thrust J58 engines. Delays continued, but finally on March 3, 1966, the first D‑21 launch was accomplished. The drone crashed into the Pacific 120 miles after vehicle separation, but at least the launch technique had been successfully demonstrated. The second flight took place on April 27 and was a brilliant success, the D‑21 achieving a range of 1,200nm – holding course to within half a mile – a speed of Mach 3.3, and an altitude of 90,000ft. The drone finally fell from the sky after a hydraulic pump burned out. Significantly, at this point Johnson proposed substituting the M‑21 mother‑ship for a Boeing B‑52 Stratofortress, and utilizing a rocket to boost the drone up to ramjet speed and altitude.

Having successfully demonstrated the concept, a second order duly arrived on April 29 for 15 D‑21s. Johnson formally proposed that SAC should launch the drone from a B‑52H on the basis of “greater safety, lower cost and greater deployment range” – this proved prophetic.

^{M‑21/D‑21}

^{M‑21 Article 135 (serial 60‑6941) was destroyed during the fourth D‑21 launch, when the drone collided with its mothership during the separation maneuver. Both crewmen ejected safely over the Pacific, but tragically LCO Ray Torick then drowned when his pressure suit filled with water.}

^{When President Eisenhower committed not to undertake further manned reconnaissance overflights of the Soviet Union, use of the M‑21/D‑21 mother/drone combination in Project Tagboard was seen as a possible way to obtain reconnaissance data yet remain true to the President’s pledge. (Lockheed Martin)}

The third launch, on June 16, went well, with the drone clocking up 1,600nm and completing eight programed turns. However, disaster struck on July 30 when, during the course of the fourth flight, D‑21 number 504 collided with M‑21 Article 135 during the separation maneuver. At Mach 3.25 the M‑21 pitched up, the aircraft’s forward forebody broke off and despite both crewmembers successfully ejecting, the LCO, Ray Torick, tragically drowned in the subsequent feet‑wet landing after his pressure suit filled with water.

Following a meeting in Washington, DC on August 15, 1966, it was decided that Project Tagboard would be canceled. During the subsequent D‑21 grounding that lasted a year, a new program codenamed Senior Bowl was initiated. Two B‑52Hs belonging to the 4200th Test Wing at Beale AFB in California were converted to act as launch platforms. The D‑21s (as earlier envisaged by Johnson) utilized a rocket booster like the X‑7’s to blast the drone to speed and altitude before separating and falling into the ocean. However, like its predecessor, Tagboard, results of Senior Bowl were at best questionable and the program was eventually canceled on July 23, 1971, by which time satellites were proving to be far more reliable and cost‑efficient.