Need help with rapier

[SpacedCowboy]

I've just opened up Rapiers on the tech tree. I'm confused as to how to operate them. In the assembly at SPH or VAB and you right click on a rapier, it gives you the various options; Automatic or Manual switching, Toggle mode, on or off, ETC. Do you leave it on Automatic or what? I'd like to be able to control them via action groups. Also, what arrangement of fuel tanks are needed, jet fuel vrs. rocket? Is there a specific tutorial somewhere for this? I would appreciate any help. thanks, One Spaced Cowboy

Edited January 19, 2014 by SpacedCowboy

[thereaverofdarkness]

Just leave it on automatic. It makes it really easy to fly with one. How much liquid fuel you need vs oxidizer depends on how you fly it. If you take a steep ascent path straight to space and don't bother speeding up much under the engines before they switch to rocket mode, you might only end up using around 30-40 liquid fuel per engine, but if you pack on several air intakes and spend a while building speed in air breathing mode at 25-30km, then you'll use a lot more, like maybe 100 or more per engine. Once it switches to closed cycle, it burns just like a rocket, and liquid fuel and oxidizer run down at the same rate (with the 9:11 ratio).

They start out weak on takeoff, and you might need more of them than you would of other jet engines to get off the ground, but once you get past around 10km, their thrust starts picking up, and they are rather powerful in the uppermost parts of the atmosphere at very high speeds. They can run on a bit less air than the turbojet engines, but rather than fit less air intake, you should fit the same amount and use it to go faster before switching to rocket mode. Once in closed cycle/rocket mode, they are less efficient than most rockets but rather powerful, so you should have no trouble getting to orbit after that if you brought enough fuel.

I find the RAPIER engines make jet/rocket/wing SSTOs so much easier.

[bsalis]

As thereaverofdarkness explained, RAPIERs are a hybrid engine that operate as a Jet engine or a Rocket engine.

Automatic or Manual switching

If set to Automatic the game will automatically switch between Jet and Rocket mode, based upon availability of IntakeAir (ie. if starved of air, they switch to rocket mode). Use auto for convenience, or use manual with action group to switch in order to squeeze the most out of Jet mode.

Toggle mode, on or off

Sets if you want craft to spawn with the engines in Jet mode (AirBreathing) or Rocket mode (ClosedCycle).

Gimbals

Like other engines, controls if you want the engines to use directional thrust. Typically you always leave this on.

jet fuel vrs. rocket?

I find about 100 units per jet engine to be a good guide. If you run with more you can always burn it up in flight before switching to rocket ascent.

[SpacedCowboy]

Ahh, yes, okay ! It was that "starved for air" thing that I wasn't getting! thank you for the clarification! The "Closed Cycle" thing was also throwing me off; thought it meant total shutdown. Thanks again !

[thereaverofdarkness]

Glad to hear you got your answer! Please edit your post to reflect that it has been answered! = )

Be sure to click [ Go Advanced ] when editing your post so that the option to change the thread prefix will show up.

Edited January 19, 2014 by thereaverofdarkness

[baberbot]

i have tried these in combination comparison to others in combinations, the best combination that I found was turbo jet, rapier, nuclear. use jet for accent once running out off air toggle rapier on when jet is flaming out jet will then stop flaming out, turn of rapier get to 35,000 m this way use rapier to get out of atmo then use nuclear to circularise and other in space stuff land with jet engine.

[Claw]

Also know that RAPIERs have the same ISP as a TurboJet as you climb out in air breather mode, so they have the same fuel economy as a TurboJet. However, because of the slightly lower thrust than TurboJet, the RAPIERs do all those things that thereaverofdarkness and bsalis said (such as being a little more sluggish on takeoff, and requiring less air at altitude).

Unfortunately, they also weight a little more than their TurboJet/Rocket alternative.

[Anton P. Nym]

For what it's worth, my most successful RAPIER design had two of them, plus a Turbojet to help get it off the ground as RAPIERS are really low thrust at low altitude. Still had some of the problems with non-RAPIER SSTOs, though, that I have to remember to shut down the jet before it starves out and (of course) it's lugging into orbit an engine that's just dead weight in space... but not as badly as my earlier designs.

-- Steve

[SpacedCowboy]

Sorry about that. I fixed it, due to your quick tute on editing posts and such. (I'm a bit of a neandrethal when it comes to that stuff) Yeah my spelling kind of sucks too. Anyways, thanks again for your informative response!

[SpacedCowboy]

OK, I think I'm going to try that combo. Thanks to you and others informative answers and suggestions, I just might be able to get up there and do some of that "and other in space stuff"!