Posted on Aug 5, 2017
Saw a 3-engine variant of the SR-71 in Seattle museum. Does anyone know how many of these were built and why they needed the extra engine?
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If I remember right, that isn't a 3rd engine, it is a reconnaissance drone attached to the aircraft....and I just doubled checked, it is a drone...called the D-21 and the SR-71 was used as its infil platform for a brief period of time.
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Capt Seid Waddell
@SFC (Anonymous), You are right. This is a better view of the drone than I could see walking around it...
http://www.museumofflight.org/aircraft/lockheed-d-21b-drone
http://www.museumofflight.org/aircraft/lockheed-d-21b-drone
Lockheed D-21B Drone | The Museum of Flight
The D-21 drone was an unpiloted aircraft originally designed for CIA and Air Force surveillance missions over particularly hostile territories. Launched from airborne carrier aircraft, the D-21's Marquardt RJ43-MA-11 ramjet engine propelled it at speeds over 2,000 mph. (3,200 km/h). The two Lockheed M-21 Blackbird "mother ships" were designated M/D-21s when the D-21 "daughter" drone was mounted on top.
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Interesting, there's an SR-71 at the Pima Air & Space Museum that I've seen but I believe it only had two engines.
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Capt Seid Waddell
SPC (Join to see), there is - I've seen that one and it does just have two engines. It turns out that the third engine on the SR-71 in the Seattle Museum of Flight had a D-21 drone on top that I took to be a third engine.
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