APE - 24mm-75mm and 24mm-98mm Adjustable Launch Towers

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ChrisAttebery

Well-Known Member
Joined
Feb 15, 2014
Messages
2,454
Reaction score
90
I've been working on this design for a couple months and I'm finally ready to preview it.

Key features:
The tower will be EASILY and infinitely adjustable from 24mm OD up to 4.5" OD.
75mm tower up to 11.5" fin span.
98mm tower up to 14.5" fin span.
Handles 3 or 4 fins.
Only one tool needed to assemble/adjust.
All metal.

There will be 3x .187" steel rings. Each ring will have holes for 3 or 4 sets of rail guides. Each ring will also have 1/2" holes for stakes or tie downs All of the hardware necessary for assembly will be included. The vertical guide rails will be 1" EMT tubing available at your local HW store for less than $10 each. The purchaser will have to drill 3 holes into each tube for mounting.

Tower set up for 4.5"
98mm tower.JPG

Tower set up for 29mm
29mm tower.JPG


The 75mm tower will be priced at $400. The 98mm tower will be priced at $450.
 
Last edited:
I'm almost done machining the EMT to adjuster brackets. I just need to cross drill the ends.

ImageUploadedByRocketry Forum1433473066.754590.jpg

ImageUploadedByRocketry Forum1433473078.856817.jpg
 

Attachments

  • ImageUploadedByRocketry Forum1433472919.134870.jpg
    ImageUploadedByRocketry Forum1433472919.134870.jpg
    52.8 KB · Views: 202
  • ImageUploadedByRocketry Forum1433472932.691413.jpg
    ImageUploadedByRocketry Forum1433472932.691413.jpg
    34.4 KB · Views: 195
Wow. This is really interesting. The ability to transport this disassembled makes it very attractive.
I'll keep my eye on this.

I had a Giant Leap tower. That is a long story that's not relevant to this thread. The GLR tower was fine but transporting it 12 hours each way was not. Let me be clear, the GLR tower is very good and I didn't mean to detract from it. I have use of it but donated it to someone who keeps it local to a launch site far from me.

Short version is that I would like to have another tower. Lots of non rocketry stuff is keeping me occupied right now.
This is the best tower design I've seen. Another APE win!
 
Last edited:
Len,

Thanks for the kind words. I really try to build something that nobody else can offer into every product that I produce. I'm really looking forward to completing the prototype so I have something physical to show everyone.

On that note, I should have a tower completed by the end of the month.


Chris



This is the best tower design I've seen. Another APE win!
 
Very nice Chris! I have a 8' tower that is made out of 1-5/8" chain link fence post. It was free and more rigid than EMT. One thing that you might consider on on the brackets that mate to the EMT is instead of using a perfectly fitting curved profile is to switch to a shallow V-notch. This way you still have two points of contact to center the EMT, but you don't have to worry as much about out of specification EMT mucking things up.
 
Thanks ptrocketry. I thought about that on the brackets, but I don't think it will be that big of an issue. We'll see soon enough. All of the parts should be done by next weekend. I'll try to get pictures posed ASAP.
 
I got the 1" rounds of aluminum that go inside the tubes drilled and tapped this morning. Then I drilled a piece of EMT and got three of the brackets and their adjustment rails mounted. This only took a few minutes and is the only part of the tower that will not be prefabricated. Honestly if you can drill three 5/16" holes in a reasonably straight manner you can handle this.

IMG_2971.jpg


IMG_2972.jpg
 
It's a long story, but at this point I'm waiting on the rings. I should have them soon.
 
I machined a rail stop last night. It can be adjusted to have anywhere from .25" to 1.06" of lip to support the rocket.

ImageUploadedByRocketry Forum1436209316.583099.jpg
 
Thanks. I have been following this thread and notice no post for a few weeks.
 
At this point I'm just waiting on the rings all of the other pieces have been machined. I decided to make the rings big enough to handle 75 or 98mm rockets so now they are too big to cut on my machine. I had to send them to a water jet shop. The shop is backed up now and I'm low priority, so I just have to be patient. I might have to have another vendor cut them, but I'm not ready to do that yet.
 
I got some good news yesterday. I found a shop to cut the rings for what I feel is a reasonable price. This was the biggest stumbling block to production.

If you have your heart set on buying one let me know.
 
Nice tower Chris. I REALLY like the eccentric stop idea. The tower setup is kinda similar to my 6' comp-to-MPR tower that I just rebuilt for NARAM except I used 1" aluminum tube which is accurately round (though more expensive) so I can set it all the way down to BT-5 size, and I just use plywood rings to hold down the weight. It will handle up to at least a 54mm MD rocket and I can get 8' tubes if I want more length. I used a similar scheme with machined plugs for the tube ends but drilled/tapped for 5/16" allthread which passes through machined runner blocks with Delrin bushings that are bolted to the rings. 1010 rail slides are a great idea for heavier rockets.

FWIW I think field reconfiguration from 3 to 4 fins is time consuming; usually for 4-finners I'll just slap on rail guides or buttons.
 
Hi Dave,

Thanks for your input. I'm hoping that it will be fairly easy to swap over. If you have a power screwdriver it should only take a few minutes. Setting the rail spacing should also be fairly simple and quick. I'll post a video once I get all of the parts in house. Honestly I think the most time consuming part is going to be putting the rocket into the tower and then erecting it. I have some ideas on how to make quick, but we'll see how ti works out in reality.


Chris
 
I picked up the rings and mounting plates on my break lunch today and they look great. It's too bad I'll have to paint them. I'll try to get one completed this weekend and post some pictures.
 
I tapped 2 holes each in 24 of the adaptor plates tonight. The holes were within .001" of what was specified. I did a test fit of the plates on a ring. Again, the holes were right on the money.

I'm running them in my vibratory deburring machine tonight. I'll paint all of the steel parts tomorrow.

ImageUploadedByRocketry Forum1437191777.693857.jpg
 
I painted the steel parts, drilled three more rails and assembled the tower. Everything went together smoothly.

ImageUploadedByRocketry Forum1437320809.941878.jpg
 
I got the 1" rounds of aluminum that go inside the tubes drilled and tapped this morning. Then I drilled a piece of EMT and got three of the brackets and their adjustment rails mounted. This only took a few minutes and is the only part of the tower that will not be prefabricated. Honestly if you can drill three 5/16" holes in a reasonably straight manner you can handle this.

Chris, do you mean there is a plug that goes inside EMT? If so, how will you get the center one to line up to thread the bracket in?
 
I marked a piece of scrap wood (1/2"x3/4") at 59 1/4" and used it to slide the slug into the tube. Then I used a scribe to turn it until the threads were lined up.

Chris, do you mean there is a plug that goes inside EMT? If so, how will you get the center one to line up to thread the bracket in?
 
Honest feedback, here. As someone who struggled to design/build a tower with basic home shop tools and no metalworking experience, I really like this concept. Chris designs and makes the rings and supports, and I add the EMT. However, the $400-$450 price gives me pause, considering I still need to buy, drill, and assemble additional materials before the tower is functional. The craftmanship looks top notch, and I admit that I don't know the cost/value of good metalwork. So, this may be a good buy for a club, but maybe not for an individual. :2:
 
Back
Top