54mm Launch Tower - Mountain Bike Style

So I had this idea a few weeks back and I am not sure if I was subliminally inspired by someone or if it is truly an original Dan Patell idea. Over the past 5-6 years, my dad has had an ever growing love (obsession) of mountain biking. He rides when it's sunny, when it rains, and even when it snows thanks to his two "fat tire" bikes (no, not THAT Fat Tire).

He has a TON of extra parts laying around. He treats his bikes like a lot of people treat cars, motorcycles, or rockets...he's constantly modifying them, upgrading them, and tweaking them to his liking. He loves it the hobby, and why discourage him?

Did I mention he has tons of parts laying around? Those include tires upon tires, rims upon rims...which brings me to my idea. Why not use a bike rim as a tower disc? The rim itself is robust as it is made out of aluminum and is designed to be a resilient part. The best part is that there are a series of 36 holes drilled equidistant (enough) around the perimeter for the spokes!

I am using a base plate made out of two 1/4" ply triangles clamped and glued together with Titebond and will soon receive a layer of fiberglass for some flame resistance (I understand it won't be too effective, but this is a semi-single use plate). The guides are 1" tubular aluminum from Lowes. I had to turn caps that slip into the tubes and have a 1/4-20 tapped hole in the center to engage the plate. These caps were epoxied in with RocketPoxy, should be more than sufficient.

At the top is the bike rim with 1/4-20 allthread going to the aluminum tubes. There's a Nylok nut inside (what a PAIN to get that to start threading, we're talking 1/32 rotations until it was completely engaged), and various nuts and washers to space it. I am awaiting a McMaster shipment that includes a few 8-32 bent wire eyebolts that will be located in the holes next to the allthread and will hold the guy wires that will go to the ground. It also includes a 3/4-16 bolt to affix the ply base plate to the pad shown. A 1" shaft collar will be used as a standoff.

So...what do you guys think? Am I on to something? STEAL THIS IDEA IF YOU THINK IT WILL WORK!

I think it is an awesome Idea. I love to re-purpose stuff.

Nice tower design Dan! I am still waiting to build a 54 MD rocket to use mine. Wayco has built a nice tower and I am sure he could provide you with a couple of tips.

Awesome idea...it's like repurposing parts that are begging to be a tower launcher, but nobody else ever (?) thought of it before.

How long does the Lowe's tubular aluminum go? Maybe using rails could get it even taller, for those huge rockets.

Looks great Dan!

One suggestion that I would have to give is that you possibly add some guide wires. It would be as simple as bolting some eye bolts onto the rim. If you want to do this, I would absolutely say that you should not use ratchet straps and that you use 1/16" steel cable instead. I have found that with a set-up such as this ratchet straps are impossible to get really tight, where as steel cable with a turn-buckle and a good stake in the ground will give you an extra sturdy set-up.

Here is a picture of my 3 fin, 54mm tower with one of the cables and stake.



Here is picture of my 4 fin, 75mm version after an M2245 flight at Black Rock.




Manny

mannyskid said:

Looks great Dan!

One suggestion that I would have to give is that you possibly add some guide wires. It would be as simple as bolting some eye bolts onto the rim. If you want to do this, I would absolutely say that you should not use ratchet straps and that you use 1/16" steel cable instead. I have found that with a set-up such as this ratchet straps are impossible to get really tight, where as steel cable with a turn-buckle and a good stake in the ground will give you an extra sturdy set-up.

Here is a picture of my 3 fin, 54mm tower with one of the cables and stake.

View attachment 255335

Here is picture of my 4 fin, 75mm version after an M2245 flight at Black Rock.

View attachment 255336


Manny

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Yea Manny, my eye bolts are on the way in that McMaster Carr order I mentioned. I'll likely use some ratcheting tie downs to provide the ability to adjust it.

The 1" tubular aluminum is 8' long. My guides are ~46" long.

jus_rockets said:

Nice tower design Dan! I am still waiting to build a 54 MD rocket to use mine. Wayco has built a nice tower and I am sure he could provide you with a couple of tips.

Click to expand...

Do you have any more pictures of this tower?

Here's the tower installed on the base. The base is something my dad made years ago. 5" diameter aluminum disc with a central 3/4 hole that is tapped. The legs all spin and collect together for ease of transport.

The tower attaches with this central 3/4" bolt. There's a few washers under it so that the tower plate contacts the base via the three 1/4-20 bolts and the central washers for a very study mount.




I also installed the eyebolts for the guy wires.



This thing is ready for some exhaust! I will be testing this with a MUCH lesser rocket made out of LOC paper tube.

This is essentially the tower I have made. The main difference is that he is using a second tire rim as the base vs. my fixed base. I had contemplated a second wheel as he has done, however I didn't want to sit the assembly on the ground. My design has a more robust mount (in my opinion), however both should be sufficient!

My main concern is whether or not the legs can take the force of an L right at start. I highly doubt that the 1/4-20 bolts will fail in tension.

Sorry Dan, that garage/workshop is way too clean. Nice design and easy to replicate or modify.