One of the most interesting aircraft types to be stored at AMARC is the pilotless Lockheed D-21 Reconnainassance Drone.
The D-21 is a stand-off high speed, high altitude reconnainassance drone that was the result of a 'Black' project, codenamed 'Tagboard',
carried out by the famous Lockheed Skunk Works at Palmdale, CA.
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The D-21 was powered by a Marquardt XRJ 43-MA20S-4 Ramjet engine, a modified version of the XRJ 43-MA20 engine which powered the Bomarc surface-to-air missile.
The modifications were neccessary to ensure the engine would operate efficiently at the much lower pressures and higher temperatures that
would be experienced while operating at speeds in excess of Mach 3 and altitudes of over 90,000 feet. The ramjet, by it's design, can only start delivering thrust at a very high airspeed
and as a result the D-21 required a delivery platform which would accelerate the aircraft to it's operational velocity.
Lockheed converted two of their Mach 3+ capable A-12 Blackbird aircraft, serial numbers 60-6940 and 60-6941, to become D-21 motherships, these modified aircraft were designated M-21. The modifications
allowed the D-21s to be carried 'piggyback' on top of the M-21 rear fuselage, after reaching a supersonic release speed the combination would seperate with the use of ballistic charges and the D-21 would continue it's mission
powered by it's ramjet engine.
On completion of it's mission over a designated landmass and it's return to 'friendly' airspace the drone's camera and exposed
film would be jetisonned and recovered in mid-air by a Lockheed C-130 Hercules transport aircraft. Having no landing gear or other means of recovery, the D-21 would self destruct at low level
after completing it's mission.
The first flight of a D-21 took place during December 1964, the first actual launch of a D-21 took place on March 5, 1966, followed by two others on April 27, 1966 and June 16, 1966.
The fourth launch which took place on July 30, 1966 ended in disaster when D-21B #504 lost control after seperation and struck M-12 Blackbird 60-6941
resulting in both aircraft being destroyed. The two M-21 crewmen successfully ejected but unfortunately Launch Control Officer (LCO) Ray Torrick died while in the water
of the Pacific Ocean awaiting rescue. This incident prompted the cancellation of the entire M-21/D-21 program.
An alternative launch method was found by utilising Boeing B-52H Stratofortresses as motherships and the programme name was changed to 'Senior Bowl'.
A 60 foot long, solid-propellant rocket booster was manufactured by Lockheed which would be used to propell the D-21 to ramjet ignition speed after being dropped from the B-52. All remaining D-21s were modified to support this new configuration and were re-designated D-21Bs.
Two B-52H's (61-0021 and 60-0036) were modified to carry the D-21Bs by adding pylons under each wing, electrical launch control systems and high-speed
cameras to record the drone releases.
In total four operational missions were carried out using D-21Bs over China to collect data from the Lop Nor nuclear test area, 2,000 miles from the China/Mongolia border.
Due to various technical problems not a single mission resulted in the film being recovered, however three of the D-21s did complete their missions and return successfully only
for the film to be lost due to parachute and recovery issues.
In 1971 diplomatic relations with China were improving and the Senior Bowl programme was cancelled by President Nixon
Between July 1976 and January 1977 a total of 17 of the type arrived for long term storage at AMARC. Since then many have left
for display at various museums across the USA, however, two were transferred to NASA and are currently being stored at one of their facilities at Barstow, CA. It has been reported
that NASA were considering using the D-21 for reusable launch vehicle (RLV) propulsion tests using a revolutionary air-breathing propulsion system, if anyone knows more of this we would like to hear from you.
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