How is intake air distributed between engines?

[THX1138]

I was wondering whether intake air limits how much thrust the engines can produce and (on a plane with two RAPIERS and two jet engines) whether it might make sense to switch the RAPIER engines to closed loop in order to give more air to the jet engines.

Do the engines only produce maximum thrust when the intake air meter is full or do they produce maximum thrust at all times as long as there is air in the meter?

[Red Iron Crown]

I wrote a simplified version of how intake air is handled, you can read it here. When an engine attempts to draw intake air from the pool and not enough is there it will automatically throttle back to compensate. The problem arises when one engine is receiving more air than another, the engine with less air will be throttling back while the other isn't.

Assuming your intakes/engines are laid out "properly", you can gain some time on air-breathing mode if you switch the RAPIERs to closed cycle, but IME it is hardly worth it as the thrust produced by the jets will be minimal compared to the rockets (and at that point you should probably be climbing and raising apoapsis anyway).

[THX1138]

Okay, thanks. Does the air-meter need to be full in order for all engines to produce maximum thrust? If the intake air is limiting, I might as well have only the turbojet engines and a couple of dedicated rocket engines.

[Red Iron Crown]

The intake air meter is borderline useless, it only displays how much intake air is in the pool at the end of each frame. As an experiment, try mounting a fuel tank to a launch clamp. Place intake, then jet engine, and ignite the engine, observe the meter reading. Then do the same but place the engine first, then the intake, and repeat, you'll see a very different reading.

[capi3101]

Do you mean to say that the Intake Air bug is still in the game? To my knowledge, the guy who was maintaining Intake Build Aid didn't update that mod for 1.0.x because it was supposed to have gone away...

Anybody know if Intake Build Aid still works in 1.0.x?

[Red Iron Crown]

Intake air is still handled the same way as before, not sure I'd call it a "bug" as it works as implemented (but is definitely suboptimal). Intake Build Aid still works, there's a recompiled .dll in the last few pages of the thread for 1.0.x compatibility.

[cybersol]

Anybody know if Intake Build Aid still works in 1.0.x?

Intake build aid has now been updated for 1.0 by LordFjord, since it was discovered you can still have asymmetric flameout without it.

EDIT: Note to self, read post after question before posting

[capi3101]

Gotcha; thanks y'all. My bad for not checking this again myself recently.