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Well-Known Member
Jan 9, 2004
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Hey All,

I'm looking for about 6" of PML 7.51 Airframe to make a ring fin for a rocket. Anyone who has any to sell if you could contact me I'd appreciate it.

ed, did you ever find your ring material?

if not, go check out your pantry
you can get a pretty good length of large-diam 'tubing' by cutting out the middle of a plastic gallon jar (pickles, mustard, etc)
or you can often find pretzels in large plastic containers (Sams club?) where you can also cut out the middle

last but not least, don't forget that for about 49 cents you can buy a sheet of posterboard (about 2 x 3 ft, the light cardboard stuff that kids use for school projects) in just about any color you want-----cut a strip of this and roll/glue it to whatever size you need
if you don't mind using a little fiberglass, you could use anything (of the right diameter) as a mold, cover it with release agent, and wrap it with fiberglass.

for a rigid, very round, and cheap idea for a possible mold, go to a construction site and look for a scrap length of 8 or 10 inch PVC sewer pipe----those guys are always throwing away the odd lengths of cut-off stubs
after you wipe off the mud, it's very round, usually quite smooth, very sturdy-----we used some of that stuff for a different school project and it was way solid (and a pretty green color too)
I actually am starting building a new house on Tuesday, so there should be stuff left over from the drainage, etc. I was looking for PML tube just because it fit the size. The design is a 2.5" rocket with a 54mm motor mount with 5 fins supporting the ring fin. I'll look around...maybe even wander to Home Depot and check out their concrete forms.

If you are looking for some large PVC in the range of 8 to 10 inch diam, you will probably have to look around for some major construction projects in your area (commercial buildings, apartment complexes, etc). Usually residential constr only requires PVC up to 4 or 5 inch. But congrats on the new house. Be sure to wire it for everything (cable, phone, alarm, internet to every room?) while you have the chance to do it cheap and clean!

PVC is pretty heavy stuff to use directly for fin rings. I hope I was clear that you might use it for a lay-up tool for making some rings out of another material. In the 8 to 10 inch sizes, PVC wall thickness is 1/4 inch or more and that stuff is HEAVY.
That actually might be better to use it to make a fiberglass ring fin :) That would be light and strong, and pretty easy to make :) Great idea! And yes, on the house the owner has requested two internet connections per room, one cable and one phone. Also, every room will have surround sound (even bedrooms) and a PA system in every room so that you can talk back and forth. Probaby by far the most 'techo' house I've done. I'm looking forward to building it. It will also have a communications room - where all the A/V, stereo for the house is. You can also play different radio stations in each room by way of the little control box/PA on the wall. :) I should be done with it Mid August :) It also has radiant floor heating (I'm jealous)