Harness tore a 1/4" forged eye apart...

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Onebadhawk

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I was doing a 2 hour shift at LDRS on Thursday from 2 PM to 4 PM for Safety Check / RSO......
While I was there someone brought into the Lost and Found ( same canopy )
a 4" fiberglass booster section..
If I remember correctly it was all black with black fins...
It looked like it was there because it had torn away from the top section ( av bay ) of the rocket on separation at apogee...
I was 12 or 14 ft away when it was put down on the table but immediately noticed a "Onebadhawk" harness wrapped around it,,,
so I went over to take a look.....
I certainly don't know how large the apogee echarge was but the harness was still fixed into the booster,,
the top side of the harness was the 1/4" forged eye that I had sewn the harness to at the rocketeers request...
The harness was my 7/16" Tubular Kevlar material...
The reason the 2 halves of the rocket came apart is the harness tore the 1/4" forged eye apart...
The harness looked great..............

How is it humanly possible that I didn't think too take a pic of this.........

If this was your rocket or you know who's it was there will certainly be a reward for the pic.......

Teddy
 
That does seem physically impossible. What is the test strength of the harness vs. the test strength of the eye bolt? Got to fail at the weakest point. Are you absolutely sure it wasn't a curved eyebolt that just looked like a forged eyebolt?

Ditto on the request for pictures!
 
No John,,,
Not even close.....
No eye bolt will stand up to a Kevlar harness ever...
That's not even a fair test for the eye bolt.....
This is not that big of a deal to be honest...
What's a big deal to me is to get a pic of it.....
I'd like to post it on my site.......

Teddy
 
That's crazy, those are some harnesses!
So was the bolt itself broken, or pulled through the bulkhead?

Nate
 
Good Q. I could see it being pulled through the nut and thread-stripped; but I can't imagine it breaking through the eye. Which was it, Teddy?
 
Must have been jerked sideways. Tensile strength on them is pretty amazing, but shear strength isn't that great. Then if you get a bad one (brittle or even over torque one) worse yet. Still one would not think that there would be that much force on a rocket separating, but I've seen a 1/4" regular one straightened out, on a 3lb. rocket, hard to believe until seen!!
 
Good point about shear strength. Now I get it. Could have been a bad weld or something.
 
That was the booster to my Extreme Wildman. The forged 500lb (IIRC) test strength eyebolt got ripped right at the end of the threads. What happened was that one of my altimeters fired the charges at burnout during the flight. Teddy's harness were perfectly fine after the flight! I STRONGLY recommend Teddy's harnesses as they are SUPER strong.
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Zach
 

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That was the booster to my Extreme Wildman. The forged 500lb (IIRC) test strength eyebolt got ripped right at the end of the threads. What happened was that one of my altimeters fired the charges at burnout during the flight. Teddy's harness were perfectly fine after the flight! I STRONGLY recommend Teddy's harnesses as they are SUPER strong.
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Zach

Those eye bolts appear to be castings that have been machine threaded... If so, that may be part of the problem... Eye bolt castings, steal or cast iron are much more sensitive to sudden sharp force, such as experienced when a deployment comes early or late; "much more so than an drawn steel u-bolt assembly"... U-bolts are also a better choice as there are two points of attachment which gives a more efficient distribution of stress in any direction. That being said, I use the so called, forged eyebolts sometimes, but still prefer the U-bolt assembly, especially in heavy/larger rockets... However, given the force it took to break that eyebolt, no doubt those harnesses are a first class product and darn close to being bullet proof...

Fred
 
Fred, I totally agree. I am also working on a Wildman Extreme for my L3. I was going to go with 3/8" cast and shouldered eyebolts. I thought about that a bit and changed my mind and went with 3/8" U bolts.
 
That was the booster to my Extreme Wildman. The forged 500lb (IIRC) test strength eyebolt got ripped right at the end of the threads. What happened was that one of my altimeters fired the charges at burnout during the flight. Teddy's harness were perfectly fine after the flight! I STRONGLY recommend Teddy's harnesses as they are SUPER strong.
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Zach

WWWooowwwwwwwwwww,,,,
Thank you,, thank you,,,
That's it,,
I remember the torn stud,,,
but I don't remember the split link there...
I thought the harness was sewn on the eye......
Zach,,,
Do you mind if I hijack,,, um,,, borrow these pics for my site ???

Better yet,,,
Please shoot me an email,,
I'd like to take care of you for posting this....

Teddy
 
Those eye bolts appear to be castings that have been machine threaded... If so, that may be part of the problem... Eye bolt castings, steal or cast iron are much more sensitive to sudden sharp force, such as experienced when a deployment comes early or late; "much more so than an drawn steel u-bolt assembly"... U-bolts are also a better choice as there are two points of attachment which gives a more efficient distribution of stress in any direction. That being said, I use the so called, forged eyebolts sometimes, but still prefer the U-bolt assembly, especially in heavy/larger rockets... However, given the force it took to break that eyebolt, no doubt those harnesses are a first class product and darn close to being bullet proof...

Fred

Thank you very much Fred......
To be honest,,,
this doesn't surprise me at all....
Over the last few years I've seen my harnesses tear apart
everything from bulkheads to split links....
I've seen them tear enough things apart that it'd make you think
about the necessity of one of two things.....
Either Tubular Nylon,,, not much,, but at least a little "give"........
Or just making certain you have enough material,,, the harness is long enough.......

Oh,, and guy's ,,, take it easy with the black powder for Pete's sake.........lol...

Teddy
 
Fred, I totally agree. I am also working on a Wildman Extreme for my L3. I was going to go with 3/8" cast and shouldered eyebolts. I thought about that a bit and changed my mind and went with 3/8" U bolts.

Mark,,
If the U-bolts you got came with a steel backing plate,,,,,
Put it on.......

Teddy
 
Ahhhhhhhhh, I was trying to picture this but now I see. Wowee Teddy that is one nice job. Since Zach said it blew on ascent (Was it mach delay on an an old altimeter that was not right?:cry:) the force was likely applied at some
angle less than 90 degrees. That is not optimal for any eyebolt and it's not good for its full load in that case. If that's the original quick link, I'm surprised it didn't open up. It looks like it has been bent back into position but that
appearance might just be from the angle of the photograph. Impressive demonstration when force isn't applied in the "right" direction. Kurt
 
Kurt, the altimeters that were used in the flight were 2 RRC3's that are supposed to be Mach Immune. The rocket had been flown in this configuration before with perfect deployment events at their proper times. Yes, I am also quite surprised that the quick link didn't open up. I was very lucky and recovered all of the expensive components of the rocket and the kit is the only thing that was destroyed! The way I look at it, it's a great excuse to build another rocket! Lol

Zach
 
I just put a set of your harness's in the Intercepter 98 at LDRS Thurs.

Flew them twice.....nice fit, easy to use. First class product.
Thanks for making such nice stuff.

Highly recommend to anyone who might be thinking about it!!
 
Kurt, the altimeters that were used in the flight were 2 RRC3's that are supposed to be Mach Immune. The rocket had been flown in this configuration before with perfect deployment events at their proper times. Yes, I am also quite surprised that the quick link didn't open up. I was very lucky and recovered all of the expensive components of the rocket and the kit is the only thing that was destroyed! The way I look at it, it's a great excuse to build another rocket! LolThat's

Zach

That's still an "ouchie".:facepalm: Ummmmm, did you recover the altimeters? Ahhhhhh, I don't know if I'd trust them again unless you can be certain at to why one of them fired and can remedy that situation. Of course if they were destroyed it's easy.

Just get new ones.:wink: Kurt
 
I did recover the altimeters. However, I plan on replacing them.

Zach
 
I did recover the altimeters. However, I plan on replacing them.

Zach

Were you able to download flight data and look at the control traces? Might not be an alt problem--drag separation, payload pressure, etc. may be the culprit.
 
Kurt, the altimeters that were used in the flight were 2 RRC3's that are supposed to be Mach Immune. The rocket had been flown in this configuration before with perfect deployment events at their proper times. Yes, I am also quite surprised that the quick link didn't open up. I was very lucky and recovered all of the expensive components of the rocket and the kit is the only thing that was destroyed! The way I look at it, it's a great excuse to build another rocket! Lol

Zach

Zach,,
I'm all with ya building another rocket anyway,, but I thought the booster looked fine..
And the top half should have come down under the chute ,, no ??
Yeah ,, the quick link was twisted pretty bad in one of the pics you sent me..lol..

Teddy
 
I just put a set of your harness's in the Intercepter 98 at LDRS Thurs.

Flew them twice.....nice fit, easy to use. First class product.
Thanks for making such nice stuff.

Highly recommend to anyone who might be thinking about it!!

Thank you very much Jim,,
The material you flew is the 11/32" Tubular Kevlar..
That material tore a split link open in my Arcas in Potter last year...
Dizwolf has a pic of it,, everybody was laughing about it..lol....

Teddy
 
Teddy, yes they have steel backing plate. To not have that makes no sense.

Actually Mark,,
Even without the backing plate a U-bolt still spreads load twice what an eye does...
It's just better yet with the backing plate...

Mark,,
All the absolute best on your level 3 flight....

Teddy
 
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