Craft flipping on duna reentry.

[Cloakedwand72]

How do I stop my duna craft from flipping during  duna reentry?

Edited December 5, 2021 by Cloakedwand72

[linuxgurugamer]

Moar drag at the top, or more weight at the bottom

[Cloakedwand72]

18 minutes ago, linuxgurugamer said:

Moar drag at the top, or more weight at the bottom

Would  small fins also help. Placed on top?

[linuxgurugamer]

10 minutes ago, Cloakedwand72 said:

Would  small fins also help. Placed on top?

Yes, but that can cause other issues, during launch, etc

[Cloakedwand72]

3 minutes ago, linuxgurugamer said:

Yes, but that can cause other issues, during launch, etc

Then I can always add fins at the bottom of the launch vehicle then.

[GuessingEveryDay]

Will you be covering all that with a bigger fairing, or is that what it'll look like on top of the booster?

You'll have to use fairings if you attach fins at the top, or add airbrakes just above the tapering of the fairing below, that should help with the flipping.

[king of nowhere]

I don't understand that craft, though.

it has a parachute, for landing. and a stage, for ascent.

and it has landing legs in the second stage. what are those landing legs for? they can't be used

[Wizard Kerbal]

Make the fairing more like a raindrop/capsule, it’ll provide extra stability.

Edited December 13, 2021 by Wizard Kerbal

[Cloakedwand72]

On 12/5/2021 at 6:48 PM, king of nowhere said:

I don't understand that craft, though.

it has a parachute, for landing. and a stage, for ascent.

and it has landing legs in the second stage. what are those landing legs for? they can't be used

The both stages decouple the rover will parachute down as well as the ascent/crew vehicle will soft land. Plus I could add in inflatable modules to the rover! Hence I find this to be the way to go to duna in the short term in campaign.

[magnemoe]

Assumed it was an rover inside the fairing who would separate in air  
Two easy thing you can do, add 2-4 airbrakes on the capsule as other recommended, another tricks is an 1.25 meter service bay on top of capsule. Opening this give lots of drag, its also nice for storing stuff like batteries and probe cores. 

[Snark]

On 12/5/2021 at 3:21 PM, Cloakedwand72 said:

How do I stop my duna craft from flipping during  duna reentry?

I'm guessing that you have your CoM up near the top of the vessel.  If that's the case, it's going to be very hard to keep it from flipping.

We could talk about that, sure, but... out of curiosity, why do you you need to care about flipping?  As long as you have a pretty good transfer window and don't come screaming in at many thousands of meters per second, Duna reentry is pretty gentle (just a bit over 1500 m/s).  I usually don't even bother with heat shields; I just make sure not to have anything extra-melty (i.e. science instruments) exposed to the blast, and even that's not a problem if I just apply a bit of retro-thrust before hitting atmosphere.

So, why not just let it hit atmosphere in whatever orientation it likes?  (And save the mass of the big heat shield, in the bargain.)

[Kryxal]

For that matter, if you flip, just start using body lift to add extra drag.  If you're going to be on the low side, pitch up, and if you're high, pitch down. 

[Sivako Aerospace]

On 12/5/2021 at 12:21 PM, Cloakedwand72 said:

How do I stop my duna craft from flipping during  duna reentry?

The best thing I’ve found is to use air brakes with the pitch and yaw activated. These should be placed near the top of the craft so it gives you the most drag stability during reentry. Also, when using air brakes they can be folded away during launch so you don’t have to deal with aerodynamic instability. 

Edited December 23, 2021 by Sivako Aerospace