Warping fins

I have a 4" Madcow Super Batray.
It has 1/4 inch plywood fins.
It hasn't flown yet, and I finished building it a few months ago.
Not too long ago, I noticed the fins are warping.

This creates lots of concern for me.

Will it shred?
Will it spin a lot on the way up?


Can I "un-warp" the fins?




Thanks,

What are the fins made of?

MaxQ said:

What are the fins made of?

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Plywood.




Thanks,

Are they painted?

timbucktoo said:

Are they painted?

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Yes.



Thanks,

Don't think it will shred, possibly spin. Don't think there is much you can do since they are painted. Pretty odd though for 1/4" ply fins to warp unless they were wet or stored in moist environment!

Can you use steam to re-bend then? Might muck up the paint. IDK.

Andrew, which way are they warping?

And, surprising, once painted, that they are warping. Usually wood will warp when humid / moist, and when untreated..

You 'can' try to unwarp them, but I feel you'll have a hard time, lots of energy spent, for little gain.

If you look down from the nose do you see the side(s) of the curved fin(s)? Or do you just see the leading edge like the fins are curling around the body tube, but not twisting into the airstream? If you only see the leading edge the rocket won't spin as their is no force from the air passing over the fin to cause it to rotate.

Curious... Did you paint both sides of the fins at the same time?

Many times plywood will warp if only one side is painted and allowed to dry... then the other side is painted.

Zeus-cat said:

If you look down from the nose do you see the side(s) of the curved fin(s)? Or do you just see the leading edge like the fins are curling around the body tube, but not twisting into the airstream? If you only see the leading edge the rocket won't spin as their is no force from the air passing over the fin to cause it to rotate.

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I highlight the sentence. That's what the fins are doing. It's difficult to get pictures of it, because the BT is so long.

lakeroadster said:

Curious... Did you paint both sides of the fins at the same time?

Many times plywood will warp if only one side is painted and allowed to dry... then the other side is painted.

Click to expand...

Painted it all at the same time.



Thanks,