Happy 10th Anniversary to the @Boeing X-51A Waverider! This collab. led by @AFResearchLab also included @DARPA & @NASA, producing a scramjet-powered #hypersonic test platform that first flew #OTD 10 yrs ago, flying at Mach 5 for over 2 minutes! That is 1 mile per second! #AvGeek
The X-51 was air-dropped from a B-52 & propelled by a rocket booster to Mach 4.5, then the booster would separate and the scramjet would kick in.
This is the classic scramjet figure you always see. If you’re moving fast enough you can compress with shocks not a turbine!
This is the classic scramjet figure you always see. If you’re moving fast enough you can compress with shocks not a turbine!
The program saw four unmanned test flights, two of which (1 & 4) were successful. The X-51 program concluded on a high note as the 4th flight set a record for the longest air-breathing hypersonic flight of 210 seconds at Mach 5.1! Flight ended when fuel was exhausted.
Another interesting note was that flight 2 failed due to engine unstart—a problem still being researched today. This happens when instabilities cause the shock system in the scramjet to be pushed out of the engine, resulting in a sudden loss of thrust. So not ideal.
We worked on this in @clemens_nt lab @UTAerospace—here’s what unstart looks like at Mach 5 w/ high-speed video. Notice the black blobs moving into the frame from the right, that’s the normal shock system unstarting the isolator and pushing out the supersonic flow.
There are MANY good papers on unstart and unstart control strategies, but here is one from @aiaa Journal using the model seen in the animation above: arc.aiaa.org/doi/abs/10.251…
