Flameout ?

[Warzouz]

Nearly all engines (especially non air-breathing ones) have this data (10% flame-out).

This concept is not explained (as many things on KSP...). I suppose it would mean if we reduce throttle below 10% the engine provide no thrust.

BUT it's not the case for any engine.

Is the flameout data a remnant of an ex-future feature ??

Edited April 6, 2017 by Warzouz

[bewing]

No, it's just a bug that it's listed for the non-airbreathing engines. Only airbreathers can flameout.

 

[AeroGav]

1 hour ago, bewing said:

No, it's just a bug that it's listed for the non-airbreathing engines. Only airbreathers can flameout.

 

The question is, 10% of what?   I take it they mean that when the thrust multiplier , after taking account of the effects of both speed and altitude, drops to 0.1 x the Static thrust , the engine stops?   So for the RAPIER, with a static thrust of 105kn, flameout occurs when max thrust falls to 10.5kn?

[Streetwind]

2 hours ago, AeroGav said:

The question is, 10% of what?   I take it they mean that when the thrust multiplier , after taking account of the effects of both speed and altitude, drops to 0.1 x the Static thrust , the engine stops?   So for the RAPIER, with a static thrust of 105kn, flameout occurs when max thrust falls to 10.5kn?

No, I believe it's "10% of propellant requirement met"

So if there's an engine that takes in 10 kg per second of a resource, and that feed speed drops below 1 kg/sec, it flames out.

However, in KSP, all engines except airbreathing ones are always fed at 100% speed, until no more fuel is available. So as @bewing said, the stat is pointless for rocket engines.

[AeroGav]

Just now, Streetwind said:

No, I believe it's "10% of propellant requirement met"

So if there's an engine that takes in 10 kg per second of a resource, and that feed speed drops below 1 kg/sec, it flames out.

However, in KSP, all engines except airbreathing ones are always fed at 100% speed, until no more fuel is available. So as @bewing said, the stat is pointless for rocket engines.

OK this sort of makes sense if you spin around a few times and stand on your head.

As you know, intake hogging no longer works, so it does not flame out when intake air drops below 10% of requirement. You can spam as many intakes as you like, but so long as intake air > requirement the engine runs, if not it splutters and surges asymmetrically causing loss of control.

However the thrust is modified by the atmospheric pressure/thrust curve  and by the mach number/thrust curve 

However, ISP is constant so the available thrust is governed by modifiying the engine's fuel flow rate.  There was a mod where you could upgrade engines in career mode,  you could spend science points on any engine to either increase ISP, reduce weight , or increase fuel flow (ie. increase thrust)

So, when the sum of the engine output modifiers are such that fuel flow (max thrust) is less than 10% of the static (base) thrust rating, the engine quits.

For example, between mach 3 and 4, you have an 8x fuel flow modifier from the velocity curve.   The atmosphere modifier would need to be less than 0.0125  to flame out, because  8 x 0.0125 is 0.1 

At higher or lower speeds, the velocity multiplier is less so the engine hits flameout threshold at a lower altitude.   Scott Manley made a rocket car (with cheats enabled) that flamed out at sea level, because even with an atmosphere multiplier of 1, at some point close to mach 6 the velocity multiplier drops low enough to flame you out all on its own.

[Spricigo]

I think you mean Scott Manley made a jet car.