Pratt & Whitney
Aerospike Engines
Lots of hours on them.
Probably lots of variants now.
Probably way more efficient per unit of thrust.
Fuels that they were fucking around with were LOX and I believe some super cooled methane.
That is one way if it is an actual craft.
Even if it is unmanned, you can refuel. We have special KC135's for the fastmovers. But these are typically airframes that you want back. It gets interesting when you are talking about an airframe that is part of the weapon and you are not getting it back. In that scenario, hypersonics is less effective than are current ICBMs because they travel slower. However, the speed reduces the enemies ability to shoot the missile down. That is why the CCP Sizzler missile is such a threat to carrier battle groups. But that is not a long range weapon platform.
P&W has been refining engine design for a lot of years and have tested some absolutely mind-boggling stuff in the Santa Susana mountains.
At one point, Lockheed got a contract for the VentureStar, I think it was the X34 or something. It was to be a replacement for the shuttle. All of a sudden, the program got cancelled but miraculously, there was a lot more activity in the black world, almost as though the program was a front so that they could spend some white money to make a breakthrough on something they were building on the black budget side of the house.
https://newatlas.com/military/aerojet-rocketdyne-hypersonic-scramjet-engine-thrust-record/
white rook take black pawn
We've spent a shit ton of time and money on it so you would think we have it right by now but they are still screwing around with an "SR-72" We were doing hypersonics by 1990 but maybe not doing it well. I think the whole idea of a manned suborbital recon bird is just a romantic's pipe dream. We really don't need it anymore. However, 6th gen fighters are supposed to be hypersonic so mebbe SR-72 is a front to test propulsion for 6th gen without having to have a budget item. They are sneaky bastards.
>Oh we are taking contracts agian?
We were informed not to sign any new contracts or even new change orders. Everything goes to legal.