Rail guides

It depends on the rocket. How about some particulars?

Size, weight, expected speed, describe airframe thickness and composition etc. Phil

______________________________________________________________

Well, right now I'm building two:

1. 5 lbs, 7 ozs, 0.125" fiberglass, 54mm MMT, about six feet in length.

1. 3 lbs, 14 ozs, 0.125" phenolic (non-fiberglassed), 38mm MMT, about 4.5 feet in length.

Weights without motors, not sure about expected speeds at this point.

________________________________________________________________

Oh, and both are 4" in diameter.

Use delrin (or some other plastic) buttons that are attached in such a way that they are easy to replace. It is much simpler to replace worn buttons than it is to repair or replace munged launch rails.

I like to screw them into a centering ring if one is handy. If it isn't, I cobble up a backing plate from plywood sanded to match the tube profile and a t-nut in the plate. This way I can easily replace the buttons if they become worn. But I haven't had to replace any yet.

The aluminum rail guides that I have seen look like they were designed to damage launch rails. The part of the guide that rubs against the launch rail has a sharp 90 degree edge which will dig into any imperfection on the rail. Why they don't at least break those edges is beyond me.

I use nylon buttons from

and a self-clinching nut on the inside of the airframe and tack with 5 minute epoxy. If the button is in the path of the recovery system I "cover" the nut with epoxy clay. This adds very little weight and makes the buttons easy to change similar to David's method described below.