With the Cosmo rocket pretty much done, it was apparent my 6' launch rod wasn't going to do the trick, as the rocket is nearly 9' tall. I needed a something new, and a rail system is much more ridged than a rod. I also wanted it big enough to handle future larger rockets.
I decided to go with what is commonly called uni-strut, I think that's a brand name as the product I bought is called B-line. It's is basically a steel "U" beam, 12 gauge thick and 10 feet long, with a couple of inward bent "U" shaped lips on the inside of the "U" beam. Take a look at the picture below to get the idea.
Here is the rocket resting on the rail.
This rail is plenty big for a 3.25" diameter rocket, but I like things simple and strong. I think it should be both.
Above is a picture of the rocket body with guides installed. I can't really call these buttons because they are a little big to be called buttons.
While the guides look awfully large, they don't have any more surface area exposed to the air flow than the 1/2" cpvc pipe I have used in the past for guides. I am going to allow the rocket body to ride on the rail itself, and the round guides go into the rail. It's really a nice fit, and the rocket slides up and down easily with little resistance but is very secure.
Here's a rather crude drawing of how I will put it together. The upright of the base will be 2" square tubing, it will have four 12" long legs welded to the bottom, then I will use slightly larger tubing to extend the legs for extra stability at the launch site. The rail itself will pivot to a horizontal position, and be held there by a welded stop. That will allow easy loading of the rocket on the rail.
Here is the completed launch rail. I need to buy some more 1" EMT for the leg extensions, as I only had enough for two 3' legs. The launcher is sitting in the horizontal position, ready for a rocket to be loaded.
Here is a close up of the base pivot point. The base is 2"x2" square tube 36" long, with a 1/4" thick 3"x9" plate welded to the top of the base. Two pieces of angle iron were drilled out to .75" and welded to the plate to form half of the hinge. The block of wood is the rest when the rail is lowered for loading.
Here is the other half of the hinge. It is a 3" length of pipe welded to the rail. The bolt and nut are 3/4".
Here is the rail in the upright position.
Here is the rail broken down for transport. The 10' rail is a bit long, but it will fit in my full size van with no problem.