Launch Tower Plan and Parts - Completed

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Cl(VII)

Chris Bender, Lab Rat
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Although I am not planning my first minimum diameter build until the spring my Dad is retiring, so I am about to lose the chance to have some very sweet launch tower parts made by a serious metal worker. Therefore, I slapped together the best plans I could and turned creative license over to him. Below you see his handy work. With these parts all I have to do is acquire the rails, cut and tap them, and assemble. Deburring and some edge softening may also be in order...sharp buggers as my right pointer finger can attest.

The plan (pdf attached) is not really all that original, just borrowed/copied/modified ideas and feature many many tower designs posted about into a Frankentower. The idea was to have a single tower from 38 mm through I am never going to fly that. I like to make things one time, that's it, so I tried to make this thing expandable and super robust. Which is why it is way overkill for 38 mm MD, but that's where I'm starting. The outer rails will be the 8020 aluminum extrusion 10 series we are all familiar with. The inner will be a curved variant thereof. See the attached pdf for the catalog spec sheets on each.

tower_scheme.jpg

The only real deviation from the plans is that 1/4-20 threading was used for everything, and that the ground spike is removable.

View attachment tower_plans_revised.pdf
 
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A 25 lb package was delivered today, and it contained exactly what I have been waiting for. 12" Ruler included inside ring for perspective.

tower_all.jpg

The base plate is made from 1/4 SS, and is damn sexy rocket swag if I do say so. The SS ground spike/launch pad attachment (1/2" diameter, 12" long) screws into the base plate boss. To complete the customization the plate is personalized "C F Bender & Sons" for me and my launch crew.

tower_base1.jpg tower_base2.jpg tower_base3.jpg

In order to deal with the TX clay, and not have to hammer on the base plate, a pilot spike and spanner (to aid in removal there of) to help were included. He helped me dig some footers for my shed, and the dirt made an indelible impression upon him. If you don't know about the soil here consider yourself lucky.

tower_spike.jpg

The rings that make up part of the outer skeleton and supply ample tied down points are cut from 1/8" aluminum. The holes match up perfectly with those of the base plate.

tower_ring1.jpg tower_ring2.jpg

The sections of skeletal rail will be held together with all thread pieces. Dad made the suggestion of leaving an unthreaded portion of no thicker than 1/8" in the middle so they would remain relatively centered. I like.

tower_pins.jpg

The tops of the rails will be held by brackets that allow them to be held firmly while being readily adjusted. The length of these allows them to be used as the top tie downs points.

tower_tops.jpg

Some nice 1/4-20 rods were also included for support of the inner rails. These attach to the rails using the below brackets. The pdf lays out how this works.

tower_brackets.jpg
 
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I could have never made this stuff, and I can't imagine what it would have cost to have it custom made. Sounds like Dad liked it too...

An excerpt from his included note: "Making parts like this is what I've done for the past 40 years and was my rocket dream job come true."

It will be a few months before I get this thing finished, but I'll be sure to post some pics when I do.

I know he won't read this as he is not particularly fond of the internet, but let me say in front of the crew here, Thanks Dad!
 
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Beautiful job and you can see the love he has for you in his craftsmanship.
 
Since the pics won't display correctly I'll try posting them again. I think I got the original post working...sorry for redundant pics, but I'm afraid to change anything now.

base plate:

tower_all.jpg tower_base1.jpg tower_base2.jpg tower_base3.jpg
 
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top bracket.

View attachment 249071
- I can't get this one to work, just have to click it I guess. -


I apologize for that messy series of posts, but the images keep displaying as attachments. It's a real mess tonight.
 
Might I suggest using a photo hosting site, such as Flickr? The you can just copy and paste the bbcode they provide and your pictures will work perfect.
 
Your dad does fine work! I'll bet he could make you one heck of a Guillotine Fin Jig out of aluminum and/or stainless steel and I know exactly where you can get a set of plans for him. :wink:
 
Beautiful job and you can see the love he has for you in his craftsmanship.

He definitely put some care into this project. We had a pretty good design refinement cycle going before anything got cut too.

Might I suggest using a photo hosting site, such as Flickr? The you can just copy and paste the bbcode they provide and your pictures will work perfect.

I'm trying to avoid one more login to keep track of, but it may come to that.

Your dad does fine work! I'll bet he could make you one heck of a Guillotine Fin Jig out of aluminum and/or stainless steel and I know exactly where you can get a set of plans for him. :wink:

That would be a good idea...if he weren't retiring in 2 days. I will probably be purchasing a set of those plans sooner or later. Besides, dad will be searching for some projects, just the super cool, super heavy machinery won't be at hand anymore.
 
I ordered all the rail, and other hardware today. Hopefully I can steal some time over the holidays to work on it.
 
I ordered all the rail, and other hardware today. Hopefully I can steal some time over the holidays to work on it.

Am I to believe this will be a DARS launches? If so I might just have a couple designs that would benefit from this! ;)
 
Impressive. Didn't realize how big it is.

You know, I didn't either. It is one thing to draw it out, but it is quite another to see it in reality. The scary thing is there is another 2' extension that can be put on the bottom in about 10 min. Doubt it will get much, if any, use.

I'm hoping to have it done by this months launch, so I can bring it out and see how it functions in one of the high power pivoting bases. Won;t have a rocket for it until spring/summer sometime though. Maybe some other folks will get some use out of it too.
 
You know, I didn't either. It is one thing to draw it out, but it is quite another to see it in reality. The scary thing is there is another 2' extension that can be put on the bottom in about 10 min. Doubt it will get much, if any, use.

I'm hoping to have it done by this months launch, so I can bring it out and see how it functions in one of the high power pivoting bases. Won;t have a rocket for it until spring/summer sometime though. Maybe some other folks will get some use out of it too.

Are you planning for guy wires to stake out the tower as well?
 
There is an outer set of holes in each ring. Those are for guy wires if the thing isn't rigid enough for a given launch.

My guess is that your tower will need the wires. I had similar plans to just stake my tower in the ground or put in a HPR pad like a 1/2" launch rod. However, it was a bit top heavy and wobbly, and guy lines were needed.
 
I don't quite understand the reason for having a cage?
Doesn't that limit the fin size you can put in it?

The rings do limit the size rocket that can be flown, but the rings have an ID of 13". The tabs that stick in don't reduce the usable area as they are in line with the rails and therefor not available for collision with the fins. Therefore, you can fly a 75 mm MD with slightly larger than 1.5 caliber semi-span fins. You could even fit a 98 mm MD rocket with 1.1 caliber semi-span fins in this tower, but then I'd be getting worried about the structure itself. In any event I can't see ever building a 75 mm MD, much less a 98 mm. So while it is by definition a limiting factor, it never will be to me.

Also, as Chuck said the rings impart a great deal of rigidity. As well as providing attachment points for guy wires. They also serve to make this design modular. I can add or remove a section relatively quickly.
 
Can you launch off the backside of the rail, opposite the cage?
I never did high power or seen one, so I'm not trying to be stupid, but learn.
Someday I might just get to move to where I can appreciate the big boys.

I think I know what you are asking, but if I don't answer your question sorry. The rail sections are cut and the ends tapped for 1/4-20. There is a piece of all thread that goes through the ring and the two rail sections are tightened down like two nuts would be around the ring. You end up with a ring sandwich that creates a stop inside the rail channel, so none of the 4 sides of the rail would be useable for launch buttons. The buttons would be stopped by the first ring they came to.

Also, I don't mind answering questions as best I can. Keep in mind though I have never used, or seen a High Power launch tower used. There people far more experienced than I with such things that are welcome to chime in with their two cents also.
 
Mini build thread.

Doing the cutting a 10" Diablo 80 tooth carbide blade in my cheap saw. Seriously the blade cost 50% of what the saw cost, and worth every penny. Goes through aluminum extrusion and bar like butter. I've read this is a good one for composites too. This setup made short work of the aluminum extrusion. The square stuff was cut into 4x18" pieces and one 23 7/8" piece. The pieces were tapped together with the ends flush, and each matching set numbered, so any slight variances wouldn't matter as each set would make up one level of the stack. The center rails were cut to 72 5/8" and 1x24". The odd measurements on some of the cuts account for the extra length in the stacks brought on by the 1/8" rings.

1-blade.jpg 2-rails.jpg 3-cutup.jpg

To hold the outer cage stacks together a piece of 1/4-20 all thread goes through each ring and the two extrusions thread onto the all thread making a ring sandwich. Therefore, the ends of the extrusion were tapped using a little WD40 to smooth things along. Not shown is the 6 year old son clamp I used to help hold the rails in place while threading.

4-tap.jpg 5-threaded.jpg

To ensure that the joints stayed together nicely braces that would span the ring were cut from 1/4" aluminum bar stock and drilled for fastening to the outer cage.

6-braces.jpg
 
Jumping ahead because I didn't take pictures...Finished!

7-complete.jpg 8-top.jpg

9-railsupport.jpg
Central Rail supports, fully adjustable with the two wingnuts.

10-braces.jpg
Braces installed...no twisting here.

11-bottom_withspike.jpg
Take that ground!

14-29mm_side.jpg 15-29mm_front.jpg
Yes young Hagen, it takes 29 mm. The washers on the bottom screws had to be removed to get to minimum spacing, but they really weren't necessary anyway.
 
Standing tall in 6' configuration. I did a test run, and the bottom can be extended 2' in about 10 minutes with only a screw driver, and an hex key for the not pictured central rail braces (much like the braces for the outer rails, but made from aluminum angle so the hold alignment from both available surfaces.

13-upright.jpg

A few pieces of hardware were changed from what is pictured when I did the extension test. Was able to make things more field friendly. Goes to show always ground test, even the launch equipment.
 
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