My plane wants to keep doing backflips

[guitarxe]

What is wrong with this plane?

 

 

The lift is a bit above the COM for roll stability, and a little bit behind the COM, just like in Scott Manley's guide. But when I try to take off it keeps doing backflips all the time.

[steuben]

try moving the center of lift backwards or your mass forwards.

or you're being to aggressive in your manouvers.

Edited April 9, 2016 by steuben

[Snark]

Can you show a top-down picture?  It's kind of hard to see where your control surfaces are.

Bear in mind that the effectiveness of a control surface (i.e. the amount of control authority it has) will be proportional to its lever arm, i.e. how far it is from the CoM along the relevant axis.

Thus, for example, if your horizontal control surfaces are all located really close to your CoM on the longitudinal axis (i.e. they're not far in front or far behind the CoM), then they'll have little ability to control the plane.  A top-down view, with both the control surfaces and the CoM displayed, would make it easier to diagnose.

[Plusck]

Rotate your root part to give a significant angle of attack, and look where CoM and CoL are located. I'd wager CoL will move ahead of CoM.

[guitarxe]

You were right, it was a combination of being too close to COM and too hard on the pitch (although seeing as how in KSP you can't exactly control that very well other than flying by trim, I had to just limit the pitch control surface). Worked very well after that. Thanks

But now I have another weird thing

This one I downloaded a different Procedural Wings mod (Procedural Dynamics), and for some reason the plane constantly rolls to the right all the time. Even after being inverted it continues to roll.

Any idea what might be the matter here?

 

[nater662]

I spent 3 hours trying to make a working Jet with only the first science Aerodynamics unlock.  With small planes this is difficult. 

Make sure your COT is in line; it looks like it is slightly lower than the COM. That will make you do back flips.

You have to zoom in but this is the best help I have seen. 

 

Also, try tilting your wings back. When looking at the plan from the side have a 20-degree pitch moving down toward the back of the plan.

Edited April 11, 2016 by nater662

[Nich]

Make sure all surfaces were put on using mirror symmetry and not radial symmetry.  Been bitten by that one before.

 

Also if you want stability and balance.