Trouble with Asparagus Staging

[StevieC]

I have built an asparagus-staged vehicle based on the Kerbal-X, with asparagus staging, and have been trying to use MechJeb-dev v512's ascent guidance to automate ascent to orbit with autostaging.

The issue I have is that when auto-stage sends the command to jettison an emptied pair of boosters, the two decouplers do NOT fire simultaneously, and that causes the rocket to wobble, resulting in a collision with one of the jettisoned boosters, triggering an explosion that destroys at least one of the six tail-fins, and often destroying the central Mainsail engine as well. I use AutoAsparagus, and have tried virtually everything I can think of to remedy the problem. Everything I've tried has proved useless.

Please help!

[Dfthu]

You can uses sepatrons to fire them away from you ship. I would also suggest not using autoasparagus and just do it manually, its not that hard. Maybe the stages are firing wrong and mechjeb is just carrying out the wrong stages. Pics would also be good too.

[tbarcello]

No pictures - solve yourself.

I mean really, is it really that hard to take a screenshot and post it?

From what we know so far, your staging seems wrong, you should put both decouplers on the same stage. Mechjeb follows your programmed staging.

Don't use 4way simmetry if only detaching 2 boosters on each stage.

Don't mix up the decouplers on staging. Double check.

Use retro separatrons.

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You can uses sepatrons to fire them away from you ship. I would also suggest not using autoasparagus and just do it manually, its not that hard. Maybe the stages are firing wrong and mechjeb is just carrying out the wrong stages. Pics would also be good too.

Agree completely

[Michael R]

I would guess that Mechjeb isn't auto-decoupling, it's just auto-hitting-the-space-bar. So auto or manual, you've probably got a different problem. At least, I've never seen anything like out of time decoupling of parts in the same stage.

My guess would be that you're ejecting your boosters into different air flows due to the rocket's attitude, so they seem to be coming off differently. A booster that's under a heeled over ship might get lift when ejected and fly right back into the rocket.

Or so I've been told.

[Eddiedigits]

I have had this problem with Asparagus (no auto anything). I solved the problem by moving decoupler to be closer to the centre of mass for the outside rocket and moving the outside rockets further down.

My guess would be that you're ejecting your boosters into different air flows due to the rocket's attitude, so they seem to be coming off differently. A booster that's under a heeled over ship might get lift when ejected and fly right back into the rocket.

Or so I've been told.

I agree.

[Sharpy]

A solution somewhat neater than separatrons is "separating fins". Place four of the cheapest fins on each staged rocket, angled slightly away from the central one.

Make sure your staging includes both per stage, otherwise the delay will be inevitable.

Nevertheless, if you don't work with excessive TWR, if you stage while deep in gravity turn, the booster on top (above) the main rocket will simply fall down onto the main rocket. Or the side pair of boosters will fall down onto the fins of the main rocket.

One more method of rapid separation of the stages below 550m/s is to attach drogue chutes to them (just above the engines/exhausts,on the outside) and have them in the same stage as their decouplers.

But in the end, that really sounds like you aren't staging them in pairs but separately, one booster per stage.

[Friend Bear]

I have built an asparagus-staged vehicle based on the Kerbal-X, with asparagus staging, and have been trying to use MechJeb-dev v512's ascent guidance to automate ascent to orbit with autostaging.

The issue I have is that when auto-stage sends the command to jettison an emptied pair of boosters, the two decouplers do NOT fire simultaneously, and that causes the rocket to wobble, resulting in a collision with one of the jettisoned boosters, triggering an explosion that destroys at least one of the six tail-fins, and often destroying the central Mainsail engine as well. I use AutoAsparagus, and have tried virtually everything I can think of to remedy the problem. Everything I've tried has proved useless.

Please help!

I have heard of issue with mechjeb and asparagus, but that was a long time ago. I would just fly without it (more fun anyways). Sorry that is not incredibly helpful.

However, I support the notion sepratrons are a good idea.

Also, look at Space Y mod. It has sweet decoupler/sepratron parts to keep partcount down and staging simpler. I presume that helps with programming it into mechjeb.

No pictures - solve yourself.

I mean really, is it really that hard to take a screenshot and post it?

No need for the attitude. Pictures play very little role here and you have given a sufficient explanation even without pictures; identifying staging is the issue.

Edited September 18, 2015 by Friend Bear