Cause of launch spiral?

[Rktman]

Hoping the glider pros here can diagnose why my scratch-built slide pod did a 360° spiral on the way up? It wasn't a tight spiral, but more like a quick loop before settling into a normal glide at ejection.
Confirmed that nothing is misaligned (although I purposely made one wing 1/8" lower to get the glider to circle) and there was no rod-whip, it only did the loop about midway up.

[ghrocketman]

If it does not do it regularly on subsequent flights, I would bet on a wind gust at that altitude.

[Rktman]

Any chance it's because there's not enough dihedral?

[ghrocketman]

Possibly. Dihedral tends to dampen the roll axis.

[Rktman]

Possibly. Dihedral tends to dampen the roll axis.

Oh, didn't know that. I thought it only functioned that way in horizontal flight, didn't realize it affected vertical trajectory as well.
Easily fixed though, it's already a polyhedral wing with enough space to put in another canted panel if need be.

[Rktman]

I think I may finally I have discovered the reason for the spiraling at launch: too much play in the motor pod slide box. I had the same problem with my Apogee Cirrus Breeze, only it was a slide wing and therefore a much more severe situation because the slide box was even looser, causing it to get into a death spiral once it transitioned to glide mode.

Apparently having the pod's slide box loose enough to rock a few degrees on the way up is enough to cause a bit of spiralling (in itself not a bad thing) but it's definitely not something you'd want once it transitions to glide. I've since managed to tighten things up, but due to the pandemic thing, won't be able to test fly it till later.

[BigRIJoe]

"Go home and get your slide box."