Currently up on eBay is a Lockheed summary of data on the Yak-21. However… it’s not even close to accurate. The actual Yak 21 was a trainer version of the early Yak 15 jet fighter, which was very much a WWII-tech-level design, being similar to a number of wartime German aircraft projects. But the Yak-21 as described in the Lockheed document is… well, it’s also clearly a wartime German technology development, but quite a different one. Instead of a single-engine jet fighter with the engine tucked under the nose, this time the Yak-21 was a straight-winged rocket powered interceptor. Again, numerous wartime German projects showed much the same thing. It’s unclear how Lockheed came to believe that that’s what the Yak-21 was.
The data visible in the photos indicates a maximum speed of Mach 1.3 and an endurance of 3 minutes, and a combat altitude of up to 66,000 feet. How such a small vehicle with such limited endurance could get there is anyones guess.
