[RESOLVED] Engine Shutdown and Flame Out

[lennycutler]

First let me say that I am very pleased with this module...it is a challange, but also a pleasure to learn this bird.

 

I am trying to understand why the engine shutsdown or flames out so often.

 

I put it into After Burner, climb to 25,000 ft, then dive, then level off and climb...and the engine shutsdown or flames out.

 

No inverted flight here.

 

I apply the Emergency Restart and I think I have that mastered.

 

I know that the manual cautions about exceeding 95% RPM...but of course you exceed that with After Burner.

 

So....is this a documented bug, that shutdown occurs when it shouldn't...or is the manual not explicit eneough about how to avoid flame out, shut down....

 

I don't think a dive from altitude should cause this/

 

See my attached track.

Flame out example and restart.trk

Edited March 12, 2015 by Cobra847

[golani79]

After your 2nd climb you get negative G - even if it doesn´t look like that much I think this is the cause why your engine flames out.

 

The 21 really doesn´t like -G.

[Buzzles]

Just watched your track, there's no bug. It's all you :)

 

After you pulled up from your dives, you leveled back out by nosing down, causing a sustained period (5+ seconds) of flight at 0g.

 

See page 35:

 

21. Flight with g-loads approximating zero (±0.2 g) should not last for longer than 1 -2 s.

You can even see the red light come on for the dispenser tank just before the engine cuts out.

 

As noted above, the 21 doesn't like negative g but it can cope for 3-5-10 (2nd ab, 1st ab, no ab), however it really hates 0g, and can only do a couple of seconds. If you'd have been more aggressive in nosing down to level out, you'll find the engine doesn't stop as it still gets fuel.

Edited January 17, 2015 by Buzzles

[lennycutler]

Just watched your track, there's no bug. It's all you :)

 

After you pulled up from your dives, you leveled back out by nosing down, causing a sustained period (5+ seconds) of flight at 0g.

 

See page 35:

 

You can even see the red light come on for the dispenser tank just before the engine cuts out.

 

As noted above, the 21 doesn't like negative g but it can cope for 3-5-10 (2nd ab, 1st ab, no ab), however it really hates 0g, and can only do a couple of seconds. If you'd have been more aggressive in nosing down to level out, you'll find the engine doesn't stop as it still gets fuel.

Thanks for the input...I will focus in on trying to eliminate as much as I can the zero g situation.

[Stealth_HR]

The best way to eliminate the problem is to figure out when you want to level out, flip yourself inverted, then level out and flip back from inverted. That way you keep a constant positive G load and the engine won't flame out.

 

The same principle is used when you want to dive for a ground attack. Invert, pull until you're at 30-50° attitude, then flip back from inverted.