Jet Engines Spool Down

[selfish_meme]

I had a look and could not find anyone else complaining, and I am not really either, I just thought the behaviour was funny. When you throttle to zero on a jet engine, it takes ages to respond, just like in real life, however if you disconnect the fuel source, instant cessation of thrust.

[Geschosskopf]

Hmmm.   Well, I suppose that's a function of how engines work in the game.  Each tick of the internal clock, engines need to have some minimum amount of whatever resources they consume available or they just quit.  So yeah, I can see that if you turn off or jettison the fuel tank the jet is drawing from, instant kill, same as a rocket running out of LF or O.

[Temstar]

If you shut intakes the engines also more or less come to a crash stop immediately.

[Murdox]

Haha never thought this before and really interesting point of view actually! I just wonder if there should be delay after you disconnect fuel source, because its different than shutting off engine completely. Am i lost?

So does it count as cheating if someone fiddle instant power responses to jet engines after this public information

[selfish_meme]

5 minutes ago, Temstar said:

If you shut intakes the engines also more or less come to a crash stop immediately.

That sort of makes sense as the flow of heated air is what needs to spool down, cut off the air and it should stop pretty quickly, but stopping the fuel does not stop the compressor as it shows when you throttle to 0

[Temstar]

This is actually a legit issue in real life too - gas turbine engines, which is basically a jet engine minus the high bypass fan is rubbish when used to drive a car because turbines just don't respond to sudden throttle changes very well unlike piston engines.

Planes both in real life and in KSP just don't care - they run their engine on one throttle setting for most of the trip. Where it does matter in KSP is when you want to use the jet engine for VTOL and you want to have precise control over the hovering. For this I use panthers as my hovering engine and set it so that on dry mode the panther engines give about 0.9 TWR, so if i stay on dry mode the VTOL will slowly start falling.

Panther can switch between dry and wet mode instantly, so by rapidly toggling between 0.9 TWR dry mode and some TWR higher than 1 in wet mode you can fairly precisely control vertical ascent and descent.

[selfish_meme]

19 minutes ago, Murdox said:

Haha never thought this before and really interesting point of view actually! I just wonder if there should be delay after you disconnect fuel source, because its different than shutting off engine completely. Am i lost?

So does it count as cheating if someone fiddle instant power responses to jet engines after this public information

You could turn fuel crossfeed on and off on a connecting piece

Edited January 6, 2016 by selfish_meme

[numerobis]

This has been the case as long as I've been playing.

I used to build "rockets" with a jet first stage that staged the intakes separately from the engines specifically so that the jets would abruptly stop when I hit the space bar -- otherwise I'd have that first stage fly through my upper stage.