What are you wanting to do? 1/8 G10 is *very* thick. I used it once and then haven't since. I generally use 1/16" or 3/32" thick. Both I've had success in beveling. I've used 1/4" plywood but didn't like that I couldn't get the finish as nice and was filling it and the pores in the wood.

Edward

Higher speeds. Mach 1+. I already have the oversized extended loc magnum. I was looking at possibly getting the big nuke 3e which has the options of either 1/4" plywood or 1/8" G10 fins. More of a kit to learn dual deploy with but having the option of the higher speeds.

It is going to take a lot to push a Big Nuke (5.5" diameter) to mach plus. I'm thinking very high thrust 54mm motors or 75mm motors. I'd get the rocksim file and see what motors it takes to make it go mach before you make your purchase.

Edward

This one will be with the 75mm mount. CTI has some big L's in the 6xl case that will do it. I am leaning more toward the wood fins and just glassing them.

Shrink it to 4" and you'll be sure to break mach 🙂

Edward

Plywood at Mach? Splinters. Use G10 on everything with light (& different) layers of composite material. Did you see JW's record altitude rocket? See the Mach burn on the fins? Plywood will not take it. If you're serious, use serious materials. Seriously.

Another consideration is do you have the parachute space for the 75mm motors weight.

Edward

It should have the space. It comes with the 75mm mount along with a 18" drogue and 60" main. I am starting to think at this point to just build it with the plywood and just not worry about speed at this point and do a scratch build later for speed and altitude.

Plywood at Mach? Splinters. Use G10 on everything with light (& different) layers of composite material. Did you see JW's record altitude rocket? See the Mach burn on the fins? Plywood will not take it. If you're serious, use serious materials. Seriously.

That entirely depends on the fin shape and exactly how high you take it. Mach 1.3 with fairly thick, well designed plywood fins is completely doable. Even mach 2 should be doable without any composites. Of course, you have to be quite careful about it, but there's nothing about mach that requires composites. It certainly is easier to use them though. One good method that would work fine would be to use plywood with a layer of tip to tip glass. This would avoid much of the expense sometimes associated with composites, while adding significant strength to the rocket.

Sometime, I should make a high speed rocket with no composites at all, just to see how fast I can get it to go. It could be fun 🙂

Food for thought. My 14X Swift was a 'slow motion' of fin flutter.
1/2" plywood fins.

In was not even close to mach but the extra large fins fluttered
badly and tore the lower part of the rocket apart. If it had been
going any faster, there would be nothing left.

I know the Swift was an exteme example of fin size. Most do not
thing anything would have helped.

Mach fin flutter is scarrry. Most have seen this video but here
it is again.

http://www.youtube.com/watch?v=u-b_VDFWFDg

No rocket I have built is ready for this. Much to learn.

Definitely listen the the Guys that have been there.

I'd recommend the G10, but shy away from the thinner stuff like 1/16, unless you're very light or have a large chute.

The last flight of Excess in Moderation was perfect, other than when it touched down. One of the 1/16" G10 fins (with 3 layers tip-to-tip) tore along the root edge, pulling it outside of the fillet. Definitely too much flex, but that was with a 5lb rocket (unloaded), with 4 38mm motor casings loading down it's fat rear. Still need to rebuild.

Any recommendations on repair without making it a ton heavier still? This is 4" LOC paper tube, 1/16" G10 fins, 3 layers glass (heavy and light) tip to tip, and foamed fin can. Definitely messy to tear apart.

Thanks,
Ken

I generally use 1/16" G10 and a big parachute. My Bunny Thumper rocket was 5.5", 15lbs loaded and I used a chute that gave me a descent rate of 7 fps. I even cart wheeled it a couple times and didn't do any damage. No tip to tip. Instead of epoxy I used PL Premium polyurethane glue (from Lowes) to secure the fins. When the rocket finally met it's demise in a flat spin, the PL was still bonded to the G10, but it peeled back the MMT.

Edward

I've a PML Kit with the same thickness 1/16 inch (0.0625) G-10 fins. It's 46 Oz empty. I have torn fins on rough landing though I have significantly increased the chute size.

A five pound bird will be tough on these, especially if there's a cross wind upon landing.

My fix is to grind out the whole fin down to the motor tube with a dremel fixed with a tungsten grinding tool taking care not to ding up the motor tube. It takes less time than you'd think, if your tool is sharp. Since I foam my fin cans, all that's left is a slot. Then puddle epoxy in the slot and slide in a brand new fin taking care to align it well. I usually leave the slot slightly unfilled with the fin in place. After it sets I replace the fillet filling the remaining slot volume at the same time.

I've seen people try to epoxy a torn fin with bad results. 2 fin rockets have stability issues 😉

I use GLR G-10 3/32 (0.09375), which meanders from .095 to .102 in thickness, on a 7 pound rocket (empty) with good results.

I too am still playing with fin thickness/weight issues. The video from Mike above was impressive. I shy away from wood on anything flying over H sized engines. I may be too paranoid...

I appreciate all the good info. I think I will stick with what I have now and go with slow speeds and lower altitudes until I get the dual deployment down and continue learning.