RAPIER vs Turbojet and Rocket engines?

[SpaceToad]

Hey all,

I'm working on making a spaceplane with around 200m/s dV remaining in space for maneuvering. I am curious how much weight a RAPIER can handle efficiently, and if the RAPIER's are even worth it.

Thanks.

Edited May 28, 2015 by SpaceToad

[Starhawk]

The Rapiers in air-breathing mode have the highest velocity, thrust, and operational ceiling of any air-breathers. For many spaceplane builders they have become the go-to engine in 1.0.2.

On the other hand, there are some examples of Turbojet based spaceplanes in this thread.

Happy landings!

edit: One Rapier can handle at least 13-15 tonnes. I've seen people push that to 18 even, but I've never gone that far.

Edited May 27, 2015 by Starhawk

[KarateF22]

When it comes to SSTOs, Turbojets have kinda fallen by the wayside. Their best use is helping break the sound barrier, as RAPIERs sometimes have difficulty doing that. Once you're supersonic though, RAPIERs are far superior.

[Murph]

Turbojet + Aerospike combinations seem to work mostly as pre-1.0 if, like me, you never believed in "air hogging" (due to it being a blatant and obvious cheat). Personally, I quite like them. Historically, I found they were often superior to the RAPIER (it was never clearly better than them pre-1.0, and I always felt it was a bit mediocre, falling quite short of what it should be). 1.0 has changed the ascent profile needed, and altered the fuel usage a bit, but they are quite usable for a spaceplane. N.B. I'm talking about larger spaceplanes, which can deliver useful payload, there was an edge case for micro spaceplanes (with basically zero payload) pre-1.0 which the RAPIER seemed to win.

Because I was always unimpressed with the RAPIER historically, I've yet to really properly evaluate it in 1.0, so not sure just how it measures up now. I just know that with a little adjustment to designs, I can produce reasonably viable low orbit spaceplanes using traditional non-air-hog turbojet + Aerospike. If anything, the turbojet is now superior to the old one (with no air hogging), due to the big burst of power before it falls off due to lack of air.

The pre-1.0 RAPIER always felt to me like I'd been promised a Ferrari, but a Fiat painted Ferrari Flame Red was delivered, and the salesman thought that was ok.

Edited May 28, 2015 by Murph

[GoSlash27]

I agree with Starhawk (I almost always do).

The turbojet+OMS rockets was unbeatable pre- 1.0, but now the RAPIER is superior.

Each engine will handle 15 tonnes of spaceplane comfortably and I've pushed some of mine beyond 18 tonnes. For spaceplanes, this will translates to roughly 3 1/2 tonnes payload per engine.

Best,

-Slashy

[Wanderfound]

FAR rather than stock, but just for a point of comparison:

Turbojet + Thuds:

RAPIER:

Clear win to the RAPIER.

[Mikki]

Hey all,

I'm working on making a spaceplane with around 200m/s dV remaining in space for maneuvering. I am curious how much weight a RAPIER can handle efficiently, and if the RAPIER's are even worth it.

Thanks.

Hi SpaceToad

Me i dont like the Rapiers, they lack of thrust in 10000- 15000m somehow.

Try these shapes:

Make some delta configs with stable CoM, and the CoL very close to it behind:

Problem in KSP is the limitation of the Enginesize of the airbreathers...

I tried anything with Rapiers but i had no success... Turbojets are best in my Opinion still .

Greetings

[KerikBalm]

When 1.0-1.02 first came out, I spammed rapiers and only rapiers for my spaceplanes.

Since then, I've found their lackluster thrust below mach 3 is not so nice.

By the time you are ascending at >1,000 m/s at 15-20 degrees, your thrust is quite low, and the rate of climb is quite high... rapiers don't get you all that much more airbreathing power.

I've made many very capable turbojet+ lv-T45 designs in career, that didn't seem to improve much when I converted to pure rapier designs (part of it may have been I was ascending too steeply, even if the rapier had less static thrust, the greater number from replacing the rocket engines with rapiers compensated).

Now I just use about half and half on my designs.

Rapiers can burn a lot of fuel trying just to break mach 1, so some turbojets can definitely help there, and they are still pushing pretty hard as your craft passes 1,100 m/s