Message posted by Sundog on October 01, 2006 at 21:16:13 PST:

Back when I was studying Aerospace Engineering in the late 80's, a hypersonic aircraft was considered feasible back then. The problem most people have is what speed range of the hypersonic envelope you're talking about.

The A-12, the original Blackbird, was designed for M=4.0 at 120,000 ft. How close it came to that is still classified, but it has been reported that the A-12 was the fastest of the Blackbird family. Now, consider that the SR-71 used the same wings and propulsion system as the A-12, but was longer and heavier. It's top speed was reportedly M=3.55 to M=3.6 based on atmospheric conditions and you have to consider that's a 45 year old design.

I would find it hard to believe that the USAF isn't flying a M=6 aircraft. When I was in school it was pretty much a given that our current axial flow engine technology with standard hydocarbon fuels would be good out to M=4 to M=6, but once you get up around M-6 you need to switch over to other fuel types.

Also, there was a report back then done at the behest of the USAF on hypersonic interceptors (the Mach six region) and in the sizing study the aircraft were between 70ft and 100ft long. This seems about right based on the reported sightings. Also, I don't think this aircraft people are seeing is code named Aurora, I think it's ASTRA (Advanced Strike and Tactical Recon Aircraft).

As for aircraft like the X-43, they aren't hypersonic testbeds as much as they are Scramjet testbeds which make more sense for the upper regions of the hypersonic flight envelope.

In Reply to: Re: Aurora: Back In Black? posted by Mick on September 13, 2006 at 9:55:36 PST:

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