Low cost LPR/MPR launch pad tilt head

I posted plans for this launcher head in another thread, but I have been waiting until it was actually tested before posting in a thread of it's own. The attached plans are the latest version.

"Mr. Martensite" and I have been working on a LPR/MPR tilting launch pad head to be used with a PVC base.

The tilt head was designed trying to avoid the necessity of welding or a machine shop. So using "normal" rocket construction tools such as a band saw and drill press, we came up with this.

All of the wood and hardware was purchased at our ACE Hardware store. We did have to resort to having a friend w/ a home machine shop make the rod holder, but after we got the parts, this thread popped up so you could use the adapter instead (although they say 3/16" rod max). The parts list (or bill of material) is listed in the "MPR Launcher BOM" file.

EDIT: The eyebolt callout in the original BOM file is wrong...see new post #12

View attachment MPR_LauncherHead.PDF

The head is designed to allow 30 degree maximum tilt angle, then it hits a positive stop. This will require playing with the location of the hinge. I attached the hinge to the tilting block, then used a triangle and square to determine the position on the fixed post.

We found when the tilting block was pulled up to "zero", it actually went past due to the offset of the hinge assembly. Adding a stop block and sanding it to the thickness of the hinge assembly makes the block stop at true vertical.

Pre-drilling all the screw holes really helped to prevent splitting. We used drywall screws to assemble as they seemed easier to work with than standard wood screws. I used a spade bit to create the counter bore for the rod holder bolt.

Our club was finally able to launch yesterday after burn bans, windy weather, and hay baling . The pad got a pretty good work out and performed nicely. Being able to cinch down on the angle adjustment nuts provided a very stable platform, even with wind gusts on fairly large models. Pictured is a TLP Hawk 23B launching on an E18W-4.

Another friend who has a home sheet metal shop produced the blast deflectors for us. If anybody is interested in obtaining some from him, PM me and I will pass on your contact information. He sells stuff via ebay.

I must say these turned out great! Very stable with larger rockets on the pad even in Oklahoma wind (it really does go sweeping down the plains:cry. This pad performed great at the club launch. Here's a shot of the one I put together. Thanks Rocketguy101!

Mr. Martensite said:

Very stable with larger rockets on the pad even in Oklahoma wind (it really does go sweeping down the plains:cry:

Click to expand...

I lived in Oklahoma City for two years. Fantastic kite flying and sailing- but I can't imagine trying to launch rockets!

I remember a High Frontier(Pawhuska Ok.) launch a few years ago, the rockets flew both vertically and laterally after coming of the rods. A very strange sight.

I have once seen a small (sub-A) low power rocket fly in a dead-straight vertical orientation but follow a perfect parabola in the ground's reference frame, up and down, landing before the ejection charge went off. The wind was at the very limit of what you're allowed to fly in.

My previous posting could indicate an arc, or otherwise bad flight. It should have read " Moving laterally while flying vertically etc. and so forth". Two more posts till I hit 100! (Hears crickets chirping)

Yeah, that's what I got from it, since I was trying to describe the exact same thing. It was moving laterally faster than it ever moved vertically, though...

Unfortunately, you've described a few launches we've had! Yes, rockets launched in southern Oklahoma do have parabolic trajectories! We've canceled many a launch due to wind and burn bans...but, I keep telling myself "If you build it, the Rocket Gods will come"! November's launch was good, winds pushed 12 mph out of the southeast....just have to wait for a lull.

thats where the monte python countdown is handy...5,21 launch .
rex

I started building some more of these for our club launchers, and discovered an error in my bill of material (BOM) posted in post #1. We had substituted 1/4" eyebolts for the 3/8" called out when we built the original heads. They fit better on the 1/2" all-thread with less slop than a 3/8" eye bolt. That was no biggie. But I bought 1/4" x 3" eyebolts at ACE, and when I got home discovered they were too short (the big wing nut hits the upright block). Puzzled, I started measuring things, and evidently the 3" is the overall length from the top of the eye to the end of the bolt.

So...I had to go back to store and buy 1/4" x 4" eyebolts...they work much better, and I guess that is what we bought before. I was thinking the length referred to the thread length. So here is an updated BOM with 1/4" eyebolts, nuts, and washers. The figure did not change.

View attachment MPR Launcher BOM_RevA.pdf

Pretty darn good looking launcher with an interesting tilt adjustment.

I bought an Openbeam 15mm rail after reading about the mini buttons in this thread. I wanted to come up with a simple launcher with this rail, and came up with the following modification to this tilt head. Here are some CAD images and a drawing to replace the vertical support. A similar setup will work for the 10mm Makerbeam rails.

BTW our club has adopted this tilt head for our saw horse launcher for LPR rockets...it is very sturdy in our Oklahoma winds. I think these mini rails will be an even better improvement!!!