Lockheed M-12 and D-21

On November 9, 1969 one of the first D-21B send spying Lop Nur, China, never returned. The damn thing kept going ahead until it had no fuel left and actually crashed in Kazakhstan. In 1986 Ben Rich was send a fragment of it by a Soviet engineer.

Now, I think it is a very interesting bit of history.

In his memoir, when arguing with Johnson about early stealth in 1975, Ben Rich make clear the D-21B was the most stealth flying machine - before "true" stealth come in the shape of "Hopeless Diamond", HAVE BLUE and F-117.
Johnson bet with Ben Rich they could never do more stealth than the D-21, and lost his bet when the two shapes were tested on the same range.

Now back to that November 9, 1969 incident.

What I would really - but really - like to know is whether the Soviets were caught by surprise and the thing was found randomly on the coutryside the next day; or their air defenses were alerted and they tracked it down.

At the time the Chinese only had SA-2s but the Soviets of course had much thicker and lethal air defenses, notably in Kazkhastan - because Semipalatisnk, Baikonur and Sary Shagan, for a start.

It was kind of a "acid test" for both D-21 and its stealth shape: which had been designed to survive over China but not over USSR AFAIK.
 
Story goes that both China and Russia never detected any of the overflight attempts.
 
M21 D-21B.jpg

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From Lockheed website

sr-71-blackbird-1920.jpg

The D-21 was initially designed to be launched from the A-12 (a variant of the Blackbird), with the purpose of traveling at Mach 3.0+ speeds to capture crucial intelligence. The experience gathered through the development of this system – to include uncrewed navigation and scramjet / solid rocket booster engine technology – has enabled the Skunk Works team to consistently progress in these key technology areas.
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scramjet ?!
 
Scramjet refers to the propulsion system. You can have a Scramjet flying at subsonic flight on theory ;)
 
D-21 had a Marquardt RJ43-MA20S-4. A ramjet, not a scramjet where combustion occurs in supersonic airflow - INSIDE the engine.
Lockheed's SR-71 'Blackbird' Family by James Goodall and Jay Miller, Aerofax 2002, has some notes on the RJ43-MA20S-4's development, p.46-47.
 
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Arjen said:
D-21 had a Marquardt RJ43-MA20S-4. A ramjet, not a scramjet where combustion occurs in supersonic airflow - INSIDE the engine.
Lockheed's SR-71 'Blackbird' Family by James Goodall and Jay Miller, Aerofax 2002, has some notes on the RJ43-MA20S-4's development, p.46-47.
Click to expand...
Quite! I had highlighted it as the text was direct from Lockheed themselves. A typo?
 
I did an OCR-scan of Goodall/Miller p.46-47:
The Marquardt and Lockheed teams determined that the unmanned drone would most suitably be powered by a modified Marquardt RJ43-MA-11 ramjet engine similar to that used on Boeing lM-99 Bomarc surface-to-air-missile during cruising flight.

Using Marquardt's propulsion system experience, it was not difficult for the Lockheed team to execute a functional reconnaissance platform in a relatively short period of time. Concurrently, the technology base that had been generated by initial flight trials of the A-12 had given the engineering team (under Johnson) considerable confidence in the aerodynamic and low-observables precedent (i.e., reduced RCS) set by the chined delta. This configuration was a given by the time initial design options were studied for the D-21.

The new project was assigned to Art Bradley under the supervision of Dick Boehme. A small team was assembled to handle engineering and a section of the Skunk Works shop at Burbank was walled off specifically to accommodate the new drone activity.

The D-21 engine was properly identified as an XRJ43-MA20S-4 and was developed from the earlier RJ43 series of ramjets optimized for use on the Boeing IM-99 Bomarc series of surface-to-air anti-aircraft missiles. The RJ43 had the ability to function as an independent external power plant on any vehicle that could reach sufficient speed to allow efficient inlet operation. lt was developed in supersonic wind tunnels at Marquardt's Van Nuys, California, test facility, flight tested on the Lockheed X-7A-3 at Holloman AFB, New Mexico, and, in its MA11 version, was deployed operationally on the Bomarc B.

The MA20S-4 engine employed in the D-21 used many MA-11 components but was modified to operate at lower pressures and higher temperatures. The S-4 was mounted internally in the D-21 and had no inlet structures of its own. Instead, it utilized the D-21's inlet system. The engine's center body and main structure were retained to house the fuel control, fuel pump, fuel injector nozzles and flame-holder assemblies. The latter was redesigned to allow for stable combustion at extreme high-altitude, high-temperature and low-pressure situations. lgnition was by a pyrophoric fluid known as triethyl borane (TEB) to allow for re-ignition in the event of flameout. The combustion chamber/exit nozzle was redesigned to provide for the much greater expansion ratio required for high-altitude cruising.The design also incorporated an ejector system for engine structure cooling.
lt is noteworthy that until the advent of the D-21, no ramjet had ever powered any craft for longer than fitteen minutes; the D-21's XRJ43-MA20S-4 routinely operated on missions lasting 1½ hours or longer.

[...]
Propulsion system work began to accelerate at this time as well. A Marquardt RJ43-MA-3 engine was tunnel-tested at simulated "Q-12" operating conditions. Per Johnson: "We were all amazed, including Marquardt, that the engine could be shut off as long as 45 seconds and still restart, due to hot engine parts."
Click to expand...
Quotes truncated to just cover engine development.
I can recommend the book.
 
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There is subsonic combustion, and there is supersonic combustion. Subsonic - ramjet - was done in the 1940's, but supersonic - scramjet - had to wait the 2000's (at least).
So yes, D-21 had a ramjet...
 

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