Skipjack wrote: SpaceX is planning on doing just that with the BFR which will be powered by their new Raptor Methane/LOX engines. That will be very interesting.
I need to look back and see if that is not a repackaging of Black Horse. I'm pretty sure I encountered that description back in the 90's.
That's not a criticism, but a nice illustration of how these ideas get knocked around for a decade or two and somebody finally figures out a business plan and makes it work.
We honor Goddard, but he didn't get rich off of liquid fueled rockets. And before we honored him, we had to get past the business plan Germany had for his inventions.
Whether you use a rocket or scramjet you need to get the propellent to the engine's frame of motion before you can use it. (ok, you can fudge that a little with the scramjet, but not a lot in terms of kinetic energy). Since a scramjet uses a chemically less energetic propellent mix than common rockets it must make up the difference from the kinetic energy of the incoming air. Efficient ram inlets at higher Mach numbers are very difficult.
The Sabre engine is interesting in how it uses temperature difference between the incoming air and liquid hydrogen fuel to power the pumps, and cool the air in the process making the pumps more efficient. But they can't cool the air as much as they want at higher Mach numbers without using a horrible excess of hydrogen.
The daylight is uncomfortably bright for eyes so long in the dark.
hanelyp wrote:
The Sabre engine is interesting in how it uses temperature difference between the incoming air and liquid hydrogen fuel to power the pumps, and cool the air in the process making the pumps more efficient. But they can't cool the air as much as they want at higher Mach numbers without using a horrible excess of hydrogen.
I thought they were using liquid helium for the precoolers?
Such a tower is essentially useless. For MUCH less cost you could put up a Hypersonic Skyhook or a HASTOL, or a Kite-Launcher and get much better bang for your buck.