Metal parts and other delights

  It's pretty well known that the NAR Safety Code does not permit metal parts composing a model rocket.


However, there are a few notable exceptions.

First, is the metal spring clip.  This is almost essential for most rockets, and it tends to be something that is permitted, or overlooked.

Second, is the screw-eye.  In the days of balsa wood nosecones, this was essential to securing the shock cord and/or parachute to the nosecone.

Third, is the fishing lure swivel, which is very commonly added at the gathering point of the shroud lines of a chute to prevent tangling. Though this device can be quite heavy and strong in higher power levels, they are relatively minor for low power.  The only drawback that I have heard, is that most cheap versions contain a sharp point on the clasp, which can poke or rip a plastic chute.

So, with this background of metal parts in mind, I was a bit surprised to see an old-school plan for a model rocket that specifically calls for a metal strip, 1"x5" long.

This is described as the "rib" and acts as the spine of a rocket assisted glider.  The majority of the model is balsa wood fins, wings, stabilizer or rudder. But this plan specified the rib.

I know of no source to order such a part or device.  If I'm going to make this kit, I can order a BNC-20A and an BT-20 body tube from a parts supplier. The balsa wood fins can also be cut from a balsa plank from Hobby Lobby or eRockets.   But when it comes to the rib, I am stumped.

A rocketry Elmer has suggested metal foil (perhaps a sheet of foil with adhesive on one side), to act as a hinge or spine, and add a slight amount of weight.  But it seems to me that one could also make something similar out of a small portion of aluminum foil and epoxy to created this spine.  

As above, the amount of metal is relatively slight, but the need for it is clear in this design.  I'm considering shopping Lowes or Menards for a small strip of metal, like the tin supporting strap from a metal downspout... cutting the 1"x5" strip and then epoxy it to the wings.  But I am concerned that this will amount to a flying javelin when launched, and may be too much weight.


What do you think?

What metal parts should be allowed?

The Thrifty Rocketeer wants to know.

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