I was just listening to C2C, and Noory has some character on who claims to know something about "Aurora" or whatever the purported hypersonic plane is. Says the thing has a dual propulsion system. One slow speed system for take-off and landing, and the hypersonic engine for high speed.
The guy claimed on a test flight coming back in to Groom Lake or Edwards or wherever, they had a problem transitioning back down to the low speed engines, and feared they would loose the aircraft so they directed the pilot to take back out over the ocean so they wouldn't have a crash of an aircraft that didn't exist to clean up.
He said they were able to fix it and it took 15 minutes. By that time, he was over Hawaii.
Now, I ask you, is this kind of speed actually feasible, even liberally extrapolating the limits of current technology that the secret black-projects outfits might have?