Can anyone find a solution for uncontrollable spinning?

[MSByrne]

I've been experimenting with asparagus style rockets and I've come up with an interesting(ish) design which has the command pod launched upside down. The rocket looks cool enough and I've hooked up the fuel lines well and there seems to be no apparent asymmetry to the design - it's also loaded up with SAS and ASAS. However, when I launch the rocket it just immediately starts spinning extremely fast and no amount of button mashing will stop my ship from spinning and eventually exploding spectacularly! I've attached a link to the design and I would greatly appreciate if anyone could tell me where I've gone wrong or if this problem is repairable!

Link: http://www./?ih22tsossn4p3pi

Thanks in advance.

[EpsilonSigma]

It's difficult to tell exactly because the rocket is in the way, but it would appear (using the buttons provided in the constructor) that the centre of mass, weight and lift are all slightly offset from the central column. There is no apparent reason why this is doing this though :|

Okay, it's not that. It was hard to tell and I failed completely to look at it properly.

Maybe it something to do with the fact that you have two sets of 4 engines on either side in sort of U shapes, with nothing perpendicular to them. Not sure how to describe that.

EDIT:

Okay, so I removed all the winglets and added extra structural cables to connect both sides of the rocket.

This prevented it from spinning at launch, but as soon as it de-stages it begins to spin, runs out of fuel and is near impossible to flip over in order to continue accelerating on the inverted engines by the time gravity has taken hold and you're just falling again.

Edited October 9, 2012 by EpsilonSigma
Correcting

[EndlessWaves]

Your fuel is burning unevenly. I quickly tried redoing the lines but the same thing happened so you may have run into a bug - doing the lines individually without symmetry may help.

[antbin]

which has the command pod launched upside down.

Does anyone know if ASAS can cope with the navball being inverted with an upside-down pod?

[Vanamonde]

I don't know why, but sometimes having both SAS and ASAS together seems to cause problems. Maybe try doing without one or the other? (As a matter of fact, I find one ASAS and no SAS is enough to control all but the very largest rockets.) Have you tried adding more fins/canards/fins with control surfaces? They are the best control devices to stop spin in atmosphere.

[Moach]

i believe the stock SAS unit was botched on .17... it causes the ship to start spinning like mad...

you're better off without those - use a single ASAS (no point in adding more of those) and enough RCS packs for your vehicle to be controllable... it should be less mad then

i hope....

[TheHengeProphet]

I had a very similar problem HERE. Avoid using SAS until you've jettisoned what appears to be your orbiting stage. That will help some.

I've noticed your rockets are dying out unevenly, meaning that one side of a given "stage" dies out before the other. This is not causing anything significant, other than wasting fuel.

I only encountered a spin problem once your asparagus staging was completely gone. I don't know why that would be, but it also wanted to spin during its interplanetary stage. All spinning was counter-clockwise (relative to the pod) for me, consistantly, which tells me that something on your upper section is off-balance or improperly supported. This was the case for my rocket, in the above link (though that problem stemmed from an imbalance in the design of the rockomax adapters).

Glad to see I'm not the only crazy out there trying to fly backwards! Good luck!

[MaverickSawyer]

If the empty stages are even slightly off-center on the decouplers, the force of ejecting them does cause a snap roll.

To mitigate this, I use MechJeb's Ascent Autopilot. Combined with a single SAS from the Nova Punch pack, and winglets on the lower stage, I have no further issues with the uncommanded rolls.

[Khiro]

As I mentioned in the thread that TheHengeProphet linked, I believe the issue is caused by there being a discrepancy between the three-axis orientation of the SAS module, and the SAS in your command pod. Whichever axis they are not aligned in (due, usually, to command pod rotation during construction), the stronger SAS goes to full-force trying to compensate for the erroneous feedback loop of the weaker SAS.

Since it's essentially impossible to see the axial orientation of your SAS, it is difficult to re-align it with an unusually-placed command pod, but do give it a try and see if you can find an SAS orientation that doesn't cause your rocket to flip out.

[TheHengeProphet]

As I mentioned in the thread that TheHengeProphet linked, I believe the issue is caused by there being a discrepancy between the three-axis orientation of the SAS module, and the SAS in your command pod. Whichever axis they are not aligned in (due, usually, to command pod rotation during construction), the stronger SAS goes to full-force trying to compensate for the erroneous feedback loop of the weaker SAS.

Since it's essentially impossible to see the axial orientation of your SAS, it is difficult to re-align it with an unusually-placed command pod, but do give it a try and see if you can find an SAS orientation that doesn't cause your rocket to flip out.

Correct orientation of your SAS might be easily done by attatching it directly to your pod before rotating it to its desired end direction. I'll have to agree that you want your SAS to be oriented properly, in respect to your pod, but even so, if your pod is inverted, don't count on an SAS to do you any good while there is a large mass "above" your pod.

I'm going to agree with Moach here in thinking that ASAS was botched in general, in 0.17. I can hardly fly a plane with an aeronautics package, anymore, much less rely on it to keep a rocket straight (omitting the habitual destruction they have always caused).

[Grand Lander]

Try the sas parts

[TheHengeProphet]

Try the sas parts

Did... you read anything before you posted?