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.
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 its 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 its 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 to designated launch points. Before launching the D-21 engine would be started to help accelerate the paired aircraft to the Mach 3 launch speed. After reaching the launch speed the D-21 fuel tanks would be topped off, the combination would seperate with the use of ballistic charges and the D-21 would continue its mission powered by its ramjet engine. On completion of its mission over a designated landmass and its return to 'friendly' airspace the D-21 would enter an unpowered descent. At 60,000 ft a hatch assembly was ejected and the drone's camera and exposed film would be jetisoned 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 52,000 ft after completing its 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-52Hs (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 seventeen of the thirty eight D-21s built 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.
In the late 1990s a proposal was drafted to utilise three D-21s in NASA's possession as vechicles to test and develop a revolutionary DRACO (Demonstration of Rocket and Air-Breathing Combined-cycle Operation) engine. The plan was to use a B-52 as a launch platform, although a ground launch set-up was not ruled out and to develop a recovery system which would allow the D-21s to be re-used. Due to its original mission no low speed flight characteristic data availeble for the D-21 so any idea of multiple landing techniques would need to be proven before incorporated into the final design. When the three NASA D-21s were visually examined they were found to be in relatively good shape with the inlet and engine areas appearing to be clean and well preserved, although the composite leading edge elements had degraded from exposure. No details of the internal condition of the aircraft were noted and it was assumed that they may have been stripped of some parts.
It appears that the NASA proposal was not successful and that the three NASA D-21s are still in storage.
|Construction||Titanium Alloy Beta-120 (Titanium - 13% Vanadium - 11% Chromium - 3% Aluminum) monococque airframe with some composite plastics|
|Powerplant||One Marquardt XRJ 43-MA20S-4 Ramjet engine, 1,500 lbs thrust.|
|Length||42 ft 10 in|
|Wingspan||19 ft 9 in|
|Height||7 ft 1/4 in|
|Max. takeoff weight||11,000 lbs|
|Maximum speed||Mach 4 (2,500+mph) at 80,000 to 95,000 ft|
|Service ceiling||95,000 ft|