NEW 7075 Aluminum U-Bolts - beta testers wanted

Landru

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I have never really liked the use of eye-bolts in rocketry as most off the shelf hardware is extremely bulky with no concern for weight.

These are designed to remedy a lot of those issues.

Machined from 7075 Aluminum, they have a tensile strength comparable to steel, but at a fraction of the weight. (Only 2.33g!) They are also only 0.25" tall.

I've run these through FEA, and they look to have a max load of around 700lbs before deforming. A welded eye-bolt is 800lb for reference.

The main through hole is sized for 1/4-20 rod/nut, and the secondary mount point is for a #6-32 screw/bolt.

Since these are not a closed loop like an eye-bolt, they can be attached directly to a sewn Kevlar loop and also eliminate a quick link.

I have an initial run I would like to send out to volunteers for test flights. Shoot me a PM if you are interested.

Please keep in mind this is beta hardware, and while I have done preliminary analysis to ensure their performance, you should take additional precautions and an extra dose of common sense with their implementation.


Any other comments/questions/suggestions are welcome.




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JohnCoker

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Very clever idea. I've used SS webbing guides as something of an equivalent, but they're a bit long and thus limited to larger diameters.

Your idea is great and I hope to see it turn into a product.
 

kyle

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I'm curious as to why the two different sized mounting holes. And am willing to give it a go if you still need testers. After not launching anything for years after moving from the middle of nowhere to the middle of everywhere I've overcome my stage fright and am setting myself up for my level 1 and 2 flights in the next couple of months, hopefully.
 

Lloyd Leichentritt

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I just went with two Eye-bolts over the U-Bolts for my LOC BBX. I added a 5/8″ Tubular Nylon Y-harness from LOC Precision to the Eye-Bolts. It's hard to tell from the photo is the loops will fit.
 

Landru

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I'm curious as to why the two different sized mounting holes. And am willing to give it a go if you still need testers. After not launching anything for years after moving from the middle of nowhere to the middle of everywhere I've overcome my stage fright and am setting myself up for my level 1 and 2 flights in the next couple of months, hopefully.

Didn't seem to need a 2nd 1/4-20 for strength, and it made things bulkier. Mostly needed to 'complete the loop' and prevent the U-bolt from unscrewing. I may change my mind if testing indicates I need a beefier 2nd.

I just went with two Eye-bolts over the U-Bolts for my LOC BBX. I added a 5/8″ Tubular Nylon Y-harness from LOC Precision to the Eye-Bolts. It's hard to tell from the photo is the loops will fit.

These won't fit. This is for ~1/4" Kevlar and smaller. This is for ~3" and lighter 4" rockets. If these go well I will offer bigger versions.
 
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manixFan

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I also would love a couple to test out. I fly a lot of MD rockets and have been doing something similar with fender washers, but your solution is much more elegant and I'm sure much more robust. I'll send you a PM as well. I use kevlar with fingertrap loops so these would be perfect.

Thank you,


Tony
 

Hybrid33

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Finally completed my first beta test
54mm min Diameter carbon airframe Max Q fin can propelled by Loki M1378 to 35,242 ft using your parts on the nose cone coupler and AV bay lid, in other words on both ends of recovery gear !!!Thank you for great strength and low weight !!!
 

Hybrid33

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First and foremost Thank You Thank You for this product !!! After flying the pair you so kindly shipped to me at your expense at Airfest, main at apogee, not planned that way !!!When will these be available for purchase ?
 

Landru

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I'll push to get them up in the next week.

What did you all end up using for bolts? The ones I sent, or something else? Pictures please!
 

Hybrid33

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OK here they are
I used 8-32 X 1" SHCS because I the 1/4" thick AV bay lid and nose cone coupler lid required
a longer bolt to engage the nylon in the nylock nut .
If you need more pics let me know
 

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manixFan

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Any updates on availability on these? It's a great solution for my needs.


Tony
 

David_Stack

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Good Evening Andrew;

Photos are of my 'chute shelf' that I installed in an Estes Pro Series Nike Smoke. I wanted a way to be able to remove/replace the kevlar harness (I can reach the cap screws with the appropriate hex bits on an extension). Only thing I changed from what you were kind enough to ship me was that I swapped out the hardware for aluminum cap screws and nylon lock nuts in an effort to save a few grams.

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Admittedly in this MPR your U-bolt will not be stressed to any degree, but regardless it is a very elegant solution to what I wanted to accomplish.

I have every confidence that it will work admirably once flown.

r/
Dave
 

cautery

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Genuinely provocative engineering. Wonderful stab in a direction likely to lead to great benefit to what we cyclists call "weight weenies".
I would think the altitude junkies would really appreciate these.

Given any thought to heat treating these parts and doing comparative destructive testing? DIY stuff, not the ludicrously expensive cert testing.
Might even be able to shave some % of material from them with the added strength. Don't want to make it TOO brittle. ;)
 

lakeroadster

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Very clever idea. I've used SS webbing guides as something of an equivalent, but they're a bit long and thus limited to larger diameters.

Your idea is great and I hope to see it turn into a product.

Interesting, a footman loop. Everything old is new again. I have some of these out in the barn. Henry Ford used these to attach door restraints on Model T and A Ford's.

FOOTMAN LOOP NICKEL
Part # A-162592-L | Model Year 28-31
These footman loops were used in several places on the Model T tops. Model A's used them with the rubber door check straps. They were used on all 1928-29 closed cars, and the rear doors of all station wagons. Mounting holes are 2-1/4" on center. U.S.A.
$1.50 EA


1637502446872.png Model T Door Straps.jpg 000_0033.jpg
 
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Loathing

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Genuinely provocative engineering. Wonderful stab in a direction likely to lead to great benefit to what we cyclists call "weight weenies".
I would think the altitude junkies would really appreciate these.

Given any thought to heat treating these parts and doing comparative destructive testing? DIY stuff, not the ludicrously expensive cert testing.
Might even be able to shave some % of material from them with the added strength. Don't want to make it TOO brittle. ;)

Based on the inference on the tensile strength in the opening text (tensile strength near steel), I suspect that the parts are heat treated and machined from 7075-T6 material. Most of the steel material you get as u-bolts, etc, is not heat treated, unless specifically noted to be. Just a simple metallurgist here, specializing in heat treatment :)
 

Landru

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These are coming for Black Friday.

Yes, 7075 T651. No additional strengthening required.

I'm considering a tapped version as well, so no nuts required. Would be good for lower stress, lighter weight applications.
 

manixFan

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These are coming for Black Friday.

Yes, 7075 T651. No additional strengthening required.

I'm considering a tapped version as well, so no nuts required. Would be good for lower stress, lighter weight applications.
Yes! FINALLY!! I can see using these in quite a few of my MD rockets, as well as on larger nose cones. Looking forward to the sale.

Tony
 

cautery

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These are coming for Black Friday.

Yes, 7075 T651. No additional strengthening required.

I'm considering a tapped version as well, so no nuts required. Would be good for lower stress, lighter weight applications.

Awesome!! :D:cool::clapping: I can't imagine I will find a better solution for my "min weight" build on the kit I have coming.

Not a bad idea on the threaded version..... should be a very similar file, not a lot of extra programming, one more tool... maybe 2.

I have some additional ideas for you to eval. Do you want them here or PM them to you? :)
 

Landru

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Awesome!! :D:cool::clapping: I can't imagine I will find a better solution for my "min weight" build on the kit I have coming.

Not a bad idea on the threaded version..... should be a very similar file, not a lot of extra programming, one more tool... maybe 2.

I have some additional ideas for you to eval. Do you want them here or PM them to you? :)

Feel free to send them over PM.
 

troj

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Any idea when these will be available on your website?
 
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