I couldn't even wait for the RAPIER engines

[The Destroyer]

First 0.23 RAPIER SSTO, small, lots of fuel, decent.

[Hodo]

Curious about RAPIER vs. B9 SABRE vs. Jets+LV-909s/Aerospikes vs. Jets+LV-Ts vs. Jets+LV-Ns vs. Jets+48-7s (mainsails and skippers are worthless other than for lowering part count, they have less Isp and TWR). Obviously, FAR would make a pretty substantial difference in which one works best, but I'm still interested either way.

Ironically, all are far INFERIOR to real SABRE engines in thrust and Isp.

A real SABRE has 3000 kN of thrust and an Isp of 3500 air, 460 vacuum. B9 SABRE has 390 Isp in space. A RAPIER has 360 in space. Sure, the LV-N has 800, but it has 1/50th the thrust of the SABRE.

I find the use of mainsails and skippers to be situational. I would never put them on a 12ton craft, but they work great as VTOL engines on my larger 100-250ton SSTOs. And your ISP doesn't amount to a hill of beans if you have 400 smaller engines doing the same job one large engine will do at half power.

[Pds314]

I find the use of mainsails and skippers to be situational. I would never put them on a 12ton craft, but they work great as VTOL engines on my larger 100-250ton SSTOs. And your ISP doesn't amount to a hill of beans if you have 400 smaller engines doing the same job one large engine will do at half power.

Well, maybe not 400, 25, sure, but not 400.

But consider this. 50 48-7s engines weighs 5 tonnes, a mainsail weighs 6 AND has a lower Isp. Lag-prevention notwithstanding, there is little reason to use a mainsail.

[AppleDavidJeans]

Ah R.A.P.I.E.R. (How appropriate of a name...) engines. Guess that makes the B9's SABRE engines redundant now, don't it?

[lazarus1024]

SABRE engines use a turbocompressor to compress incoming air and feed it in to the combustion chamber burning hydrogen fuel. At roughly Mach 5/28km altitude it switches over to pure rocket propulsion pumping oxidizer in to the combustion chamber.

RAPIER engines are just what a real life SABRE engine is called in KSP.

There are also other concepts (probably has a name, can't recall it) that use a ramjet/scramjet and rocket combined cycle engine. Effectively it is a ramjet at lower speeds and altitudes, as velocity and altitude increase it transfers over to scramjet operation (supersonic flow through the entire engine) and then rocket operation (oxidizer pumped in to the engine). Basically it is a variable position inlet spike and can be pushed all the way forward sealing the combustion chamber when in rocket mode. A concept I have seen allows it to function as a rocket at take off until sufficient velocity is built up to open the inlet spike and operate in ramjet mode, then scramjet and later close it up again once high engine to resume rocket operation.