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Xavven

How do you get your inflatable heatshield out of the way when jettisoned?

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I'm designing a rover for Eve, and I need help with getting my inflatable heatshield out of the way when I jettison it. It's aerodynamically stable during reentry and descent, and then I pop my chutes and jettison the heatshield, but the darn heatshield is so light and has so much drag that it doesn't fall away, but rather sticks to the bottom of my rover and starts causing disturbances, like out of control spinning.

What have you all done to solve this type of problem? Weigh down the heatshield with a full tank of rocket fuel? Ballast hurts my dV so I want to avoid that. Add a bunch of drogue chutes to my rover? Push it away with sepratrons?

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Posted (edited)

Sepratrons!  This is the sort of problem they're intended to solve.  Aim them to pull the thing away and slightly off to the side so you don't land on it.  And only stage it off once you're already slow, well after the fires go out.

Alternatively, attach a TAC Self-Destruct to it set on the same stage as the heat shield's decoupler.  Then the heatshield will explode when staged and won't be a problem.  Plus you get fireworks!

Edited by Geschosskopf

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If it's still contributing more drag than mass to your craft, you don't need to drop it yet.

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Are you waiting until after your chutes open up, or are you doing it right when they deploy?

You don't want to dump it until the chutes actually open.

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I ran into the same problem on an Eve lander.  I found the simplest way to solve it was to turn on one of my lander's off-center engines (I had 6 in a ring) just a smidge.  The off-center thrust was enough to get the heat shield tumbling, and it took maybe a unit of LFO, if that.

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Just a suggestion: mount the heat shield on top, come in top-first, then flip right-side-up when you're ready to discard the shield. 

But as others suggested, you can just ride it as additional aerodynamic deceleration until the chutes open and it should fall away on its own. 

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Posted (edited)

Are you opposed to modding it?  I have no reason to believe this won't still work.

Edit: Just tested it, it works in 1.7.2.

Edited by Geonovast

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Posted (edited)

I set my SAS to Normal in Surface mode once I no longer need the heatshield. This almost always causes the craft to start to oscillate wildly. During an oscillation, when it is in an orientation with the heatshield above the craft, I decouple the heatshield. It then flies away upward and I never see it again. Then I can open my parachutes.

 

Edited by bewing

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56 minutes ago, Geschosskopf said:

Sepratrons!  This is the sort of problem they're intended to solve.  Aim them to pull the thing away and slightly off to the side so you don't land on it.  And only stage it off once you're already slow, well after the fires go out.

Alternatively, attach a TAC Self-Destruct to it set on the same stage as the heat shield's decoupler.  Then the heatshield will explode when staged and won't be a problem.  Plus you get fireworks!

Sepratrons did the trick. I put a pair of them mirrored pointing to one direction to the side and just a few degrees down. It blows the heatshield well clear. Thanks!

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I also used sepratrons, when I needed to decouple a glider from a heat-shield and needed help separating cleanly,  but now...

With version 1.7.2, the 'Deploy Limit' of the inflatable heat-shield is controllable through an axis group,
so we can deflate it in flight, if we go to the trouble to bind it to an axis group when building.

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I've found with my heavy (100+ ton) Eve rover that I release the trailing shield after a bit of tumbling won't kill me, and drogue chutes will help keep the rover aligned.   That shield will fly away behind you so that it doesn't cause a problem.  I usually wait to release the other shield after my main chutes have opened up, and the craft is slow enough the shield will fall away from me.  The odd aero of the shield should cause it to drift a bit to the side as it falls, so I shouldn't land on it. 

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just wait that chutes are fully deployed, than detach it. it will fall down faster than lander.

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