OKTO pod impossible to use?

[YonansUmo]

When I use the mk1 command pod I have no problems with the same setup, but I can not stop the OKTO pod from flipping shortly after takeoff and it's driving me crazy.

Even using just the pod, a single fuel tank, and a non-gimbal engine it flips. I have tried adding fins, as well as rotating the pod but it still flips in the same direction so it's not a balance issue. The pod has reaction wheels and is connected for control, and the yaw shifts to try and correct the orientation but to no avail. I tried adding drag/weight to the otherside but I can't get it to balance. I know I could use a gimbal engine but that would defeat the purpose as I'm trying to build a stable satellite before I add more stages.

I would really appreciate any help on this, I don't even know what else to try.

Edited February 12, 2017 by YonansUmo

[DD_bwest]

if you can post a picture it would be much easier to see whats going on

[bewing]

Flipping in general is caused by having too much drag at the front, and not enough at the back -- and too little weight at the front, and too much at the back. The reaction wheels on the OKTO are also very tiny compared to the MK1 command pod.

So, you can add extra (bigger) reaction wheels. Instead of fins, you can put aerodynamic control surfaces behind the CoM (or sometimes even ahead of it). You can put drag-reducing parts on the front end, and drag-increasing parts at the back (such as fins). And/or you can rearrange your ship to move the CoM forward.

Edited February 12, 2017 by bewing

[Foxster]

It's not mounted upside down is it?

[George van Doorn]

If you wish a quick solution to your issue and implement what @bewing pointed out, you can add an FL-a adapter between the probe and your (very likely) 1.25m parts below and add a nose cone above the probe (of the same size as the probe). You'll see how chillax it can become.

[YonansUmo]

Okay I think what @bewing said is my problem, I didn't notice that the reaction wheels on the OKTO are so much weaker than the mk1.

When would it be a good idea to put drag inducing parts ahead of the CoM though? That is something else that I've been having trouble with, everything I read says to put fins at the bottom of the rocket which makes sense logically, but my other rockets become unstable when I do that and are much more stable when the aerodynamic center is slightly above the CoM. The only thing I could think of is that maybe the aerodynamic center is too close to the center of lift but I don't know why that would matter.

[George van Doorn]

@YonansUmo, look at this for example:

 

You can have stupid drag and still make it to orbit just fine if you "fly safe".

Still, you might want to think of the bullet shape and make your rocket resemble that. Why do you think the bullet has the shape that it has? It's very important to add adapters to your parts, don't just put 1.25m parts above 2.5m without adapters. Also reaction wheels, engines with gimbal like the Swivel and some control surfaces, like the AV-R8 winglets at the bottom of your rocket can compensate for a lot of drag and instability.

Edited February 13, 2017 by George van Doorn
more clarifications

[bewing]

1 hour ago, YonansUmo said:

When would it be a good idea to put drag inducing parts ahead of the CoM though?

When your design demands it and you can get it into space, then it's a good idea. (ie. there are no rules.)

@George van Doorn: Hehe -- that's silly! I like it!