Mega Der Red Max Warped fins

Just got a Mega Der Red Max and the plywood cores are warped. My thought was that if I glue the balsa skins on and clamp the fins flat while they dry that the warp would go away. Does anyone have experience doing this and have any thoughts on whether or not that will work? Thanks for your help.

Jason

I had a slight warp on mine - I just used a large pile of books (with a layer of saran wrap on each side of the fins to protect the books from the glue) - came out fine and flat.

Zebedee said:

I had a slight warp on mine - I just used a large pile of books (with a layer of saran wrap on each side of the fins to protect the books from the glue) - came out fine and flat.

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Agreed. Good luck!

This sounds similar to how mine arrived.
I sprayed then down with a little warm water, then put then between a couple of weights to dry in the sun. They came out ok.

Thanks for the input. I'll probably wet the cores and clamp them flat while they dry before gluing.

To your original question, the balsa will not likely pull out the warp from the plywood during layup. Try the advice of other responders to flatten that core first.

There are several threads about MDRM fin challenges. I personally had a call with Estes during my build. One thing they mentioned was to use epoxy for laminating the fin layers. Once you go to the effort of truing the cores, you will risk them re-warping if you use wood glue. Expoxy creates significantly less risk of warping during the balsa layup step. My second attempt with epoxy and a lot of weight came out dead flat.

Good luck!

Salvage-1 said:

This sounds similar to how mine arrived.
I sprayed then down with a little warm water, then put then between a couple of weights to dry in the sun. They came out ok.

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Every one of my PSII kits have had this issue. I did the same. A little water spray, wrapped in a paper towel and weight added while it dried. They didn't get perfectly flat, but you can't see it with the naked eye.

My MDRM fin parts had some minor warping, but all disappeared when I laminated them with Titebond and allowed them to dry while weighted down for about a week. They are warp free months later. Fins have not yet been mounted.

Epoxy is probably the best solution, but minor warping can be effectively removed with wood glue and a long cure time under pressure.

This is one of the reasons I decided to abandon balsa, ply and cardboard and only fly fiberglass/carbon kits.

Hmm, no warping on mine at all, but these sound like some great methods should my next one have this problem. I'm not sure how much longer mine will hold up, it gets flown a lot, usually on the H210, H265, and I200. The month it spent lost in the field was rough on it too, though the fins are still solid and straight.

-Paul

the mower wasn't kind to it either . though to be fair it didn't shred it into a myriad of pieces.
Rex

My first partizon had warped fins. I wet em a bit put them under weight for a dew days and they were still warped. I fixed one with a squirt bottle and clothes iron. The other two were worse off. I ended up using bungee cords, a dowel and a hair dryer. I used the bungess to hold tension on the fin with the dowel under the fin. Squirt with water and hit it with the hair dryer. Finally got em. Maybe yours aren't that bad, mine were pretty bad.

Mike

Light plywood almost always is warped, even if you do get it straight it most likely won't stay that way. In the case of the Der Red Max, the balsa sheeting they provide for the fins is both thick and hard enough that it will straighten out the center core. Use can use a thin coat of epoxy on the core and the balsa sheeting and weigh it down until completely dry. I never use wood glue because it causes everything to warp, and drying time is much longer.