Rocket Engines Shutting Down on Reentry

[Brigadier]

KSP 1.0.5 32-bit, Win7 64-bit

I have a vessel that I've used before to rescue Kerbals from LKO.  Traditionally, I've been able to use the upper stages (stock engines) to decelerate and stage them just before touchdown/splashdown.  In fact, I've been able to use the uppermost stage all the way to splashdown and recovered the parts.

All of a sudden, during the reentry burn, the engine stops (i.e. thrust goes to zero).  I stage to get to a new engine and it doesn't work either.  I have sufficient EC and fuel, although despite the engine running and generating EC, the first engine EC store goes from 0.12 to 0.  The engines are not overheating.

This has worked many times before and has stopped only just recently.  What am I doing wrong?  This has implications if I want to use an engine to soften a landing on another body.  If I can't rely on the strategy to work on Kerbin, I can't use it on any other planet or moon.

[kiwi1960]

are you using mods, if so, which ones... you probably have an incompatible mod...

 

[Fury1SOG]

7 hours ago, Brigadier said:

KSP 1.0.5 32-bit, Win7 64-bit

I have a vessel that I've used before to rescue Kerbals from LKO.  Traditionally, I've been able to use the upper stages (stock engines) to decelerate and stage them just before touchdown/splashdown.  In fact, I've been able to use the uppermost stage all the way to splashdown and recovered the parts.

All of a sudden, during the reentry burn, the engine stops (i.e. thrust goes to zero).  I stage to get to a new engine and it doesn't work either.  I have sufficient EC and fuel, although despite the engine running and generating EC, the first engine EC store goes from 0.12 to 0.  The engines are not overheating.

This has worked many times before and has stopped only just recently.  What am I doing wrong?  This has implications if I want to use an engine to soften a landing on another body.  If I can't rely on the strategy to work on Kerbin, I can't use it on any other planet or moon.

Are you using MechJeb, and the Limit Q option in particular?

You need to turn the option off during landing.

[Brigadier]

On 3/20/2016 at 9:38 PM, kiwi1960 said:

are you using mods, if so, which ones... you probably have an incompatible mod...

Yes, 57 of them but I haven't changed that mix in a while.  Updates, yes, but nothing new.

On 3/20/2016 at 4:30 AM, Fury1SOG said:

Are you using MechJeb, and the Limit Q option in particular?

You need to turn the option off during landing.

This seems very likely.  Yes, I use MechJeb and recently unlocked the landing guidance tool and utilities window in the tech tree.  I will check this out.

[kiwi1960]

I used to have a similar problem a very long time ago while launching, I forget now what it was, but either mechjeb being out dated or a conflict between mechjeb and another mod...

and yes, now a days, that Q gets around, at least he isn't picking on Captain Picard any more.... make sure its turned off.

BUT..... you play career mode, I shall remain silent as I hardly ever play that way, it may be something I know nothing about ... as you said when you stated it was a thing you recently unlocked....

Good luck.

 

[Brigadier]

On 3/20/2016 at 4:30 AM, Fury1SOG said:

Are you using MechJeb, and the Limit Q option in particular?

You need to turn the option off during landing.

That was the problem...give the man a cigar!

Many thanks @kiwi1960 and @Fury1SOG

[Padishar]

It is a bit unfortunate that MJ's Q limiter simply disables the engine when above max-Q as you are actually trying to burn the engine to reduce the Q.  I wonder if @sarbian would be interested in fixing this...

[sarbian]

hum, indeed having it lower the thrust when using the engine to brake is not a good idea. I ll see what I can do about it (most likely ignore Q on landing)