Obtaining a Giant Ring Fin

[jcsalem]

I'd like to make a large ring-finned rocket. The ring fin should be somewhere between 6" to 10" in diameter

For an example, check out the OOP Fat Cats' Ringleader which features a ring ~6" in diameter.

The ring must be fairly sturdy to deal with the high stresses. The Ringleader used a plastic (PVC?) ring which was both thin and sturdy. It also whistles in flight!

Fiberglass would be an awesome material. I think cardboard may be too weak for this use.

Any suggestions where I could find such a ring? I don't want to pay for an entire airframe tube when I'll only need a couple inches. The hardware stores only sell 4" dia PVC. Anyone want to sell me a couple inches cut off from their 10" fiberglass airframe?

-- Jim

 

[brianc]

Concrete form tube from Home Depot or Lowe's. Take your tape measure, as these
are 'nominal' sizes and will vary widely. About $6-8 for a tube.

If it's too thick, peal some off (from the inside). If you want to glass it, but it should
be OK as is.

Good luck!

 

[bobkrech]

Jim

I second the concrete form sonotube.

It's cheap and very strong: it will withstand a high load as a 16' concrete column isn't light. You can get it in 6" diameter in some locations, but 8" and 10" is easier to find.

Bob

 

[TeenRocketNerd]

if you could find a large enought dia. mandrel, you could easily roll your own from thinish poster board too.

 

[Nate]

or just write to hawk mountain and ask if they've got an extra 1 foot scrap of a 10" (or whatever diam you're looking for) tube you could buy.

should only be about $30, and it'll certainly be strong.

 

[mike_bar]

Originally posted by jcsalem
I'd like to make a large ring-finned rocket. The ring fin should be somewhere between 6" to 10" in diameter [Snip]
Fiberglass would be an awesome material. I think cardboard may be too weak for this use.

Ditto on the sonotube. Or, if you want to lay-up your own fiberglass ring, then you could use the sonotube as a mandrel. Just a thought…

Originally posted by jcsalem
Any suggestions where I could find such a ring? I don't want to pay for an entire airframe tube when I'll only need a couple inches. The hardware stores only sell 4" dia PVC. Anyone want to sell me a couple inches cut off from their 10" fiberglass airframe? [Snip]

Why not ask a plumber about the larger PVC tube? I think you know one!

PS- the Ringleader looks pretty slick!

 

[jcsalem]

Sonotube is a little heavier than I'd like but it's certainly cheap and strong. Perhaps, I could use it as a mandrel, though I think poster board would be too weak unless I glassed it.

Originally posted by Mike_BAR
Why not ask a plumber about the larger PVC tube? I think you know one!
[/B]

Oh, ya...

Thanks for the suggestions!

If anyone has a couple inches of extra fiberglass airframe left over from their 10" dia. build, let me know!

-- Jim