3" Fiberglass Build Analysis Paralysis/Recovery harness mount in the fincan

[Banzai88]

OK, so my latest build project is a 3" fiberglass vehicle with a 54mm motor tube. I intend this to be my basic 'workhorse' go-to 3"/54mm rocket, so it'll see a lot of use.

The issues comes to recovery harness mounting in the fin can.

1) Teddy's (OBH) method of 3/16" welded eyes, and perhaps doing a Y harness.

2) Just doing a pin/single loop a-la MAC kits.

3) Traditional CJ/Wildman style of kevlar strap/loop.

What to you prefer and why? What spec of kevlar do you use?

 

[Tim51]

OK, so my latest build project is a 3" fiberglass vehicle with a 54mm motor tube. I intend this to be my basic 'workhorse' go-to 3"/54mm rocket, so it'll see a lot of use.

The issues comes to recovery harness mounting in the fin can.

1) Teddy's (OBH) method of 3/16" welded eyes, and perhaps doing a Y harness.

2) Just doing a pin/single loop a-la MAC kits.

3) Traditional CJ/Wildman style of kevlar strap/loop.

What to you prefer and why? What spec of kevlar do you use?

I've never built an FWFG kit (and given the slowness of my CW BF2021 order, I don't suppose I ever will...but that's another story ). However: I've used both (1) and (3) on various builds, and haven't had a problem with either. I can see why the 'starting' weight of an FWFG kit would entail avoiding adding more with metal hardware, but I tend to only use the epoxied strap technique when space is too tight for eyes or ubolts.
For straps I've tended to use the widest kevlar practicable.
Good luck with the build, and please post pictures. It's a fact that pictures posted on TRF ensure perfect recoveries.

 

[Jmhepworth]

I use CJ’s method with a Y harness on fiberglass almost exclusively. It just works. With a 54mm mount inside a 75mm tube, it’s not likely you can get a welded eye in there. And unless your hands and arms are smaller than mine are, I don’t see how you could get in there to attach a quick link to it.

On size, I go big. I know it’s overkill, but I use 3/8” tubular kevlar on even a 54mm body tube rocket (e.g., the Wildman Junior series). I use the same size on a 6” body tube with a 98mm mount. The only problem with using thick Kevlar is that it takes up room that you might want for the rest of the recovery stuff. And it weighs a bit more.

 

[rfjustin]

Traditional Kevlar loop where the loop is above the top of the booster. I like to have (2) contact points on the airframe if possible. For a 3" bird, I recommend this: https://wildmanrocketry.com/collections/kevlar/products/kevlar-3-8

 

[SDramstad]

Eye bolt screwed into the tapped forward closure with the shock cord tied to the eye bolt.

 

[Onebadhawk]

Sorry,
I never saw this thread before..
In a 3" airframe with a 54mm mount my 3/16" Welded polished eye fits perfect..
I'll attach pics of options..
This attachment point is built into the rocket / inaccessible..
For that reason I keep the attachment point short enough so it doesn't reach out of the booster..
What wears against the edge of the booster should be the harness,, you can access..
Not the attachment point that is permanent and not accessible..



My 1/4" Tubular Kevlar is for 3" Airframes..
My 3/8" Tubular Kevlar is for 4" Airframes..
I oversize the material on these and keep them short so they don't reach out of the airframe..
That makes a 3" Airframe with a 54mm mount a
3/16" welded polished eye and 3/8" Tubular Kevlar just a bit shorter then the
distance from the top centering ring to the top edge of the booster..

These are the neatest, most professional looking attachment points there are, period..

Teddy

 

[KenECoyote]

Sorry,
I never saw this thread before..
In a 3" airframe with a 54mm mount my 3/16" Welded polished eye fits perfect..
I'll attach pics of options..
This attachment point is built into the rock / unsevisable..
For that reason I keep the attachment point short enough so it doesn't reach out of the booster..
What wears against the edge of the booster should be the harness,, you can access..
Not the attachment point that is permanent and not accessible..
View attachment 545428View attachment 545429
View attachment 545430

My 1/4" Tubular Kevlar is for 3" Airframes..
My 3/8" Tubular Kevlar is for 4" Airframes..
I oversize the material on these and keep them short so they don't reach out of the airframe..
That makes a 3" Airframe with a 54mm mount a
3/16" welded polished eye and 3/8" Tubular Kevlar just a bit shorter then the
distance from the top centering ring to the top edge of the booster..

These are the neatest, most professional looking attachment points there are, period..

Teddy

Teddy's stuff is top notch where it counts and he really knows what he's talking about.

Plus I've had the pleasure of meeting him in person and he is one of the nicest and most trusted people I know...that counts a lot in my book.

 

[Jmhepworth]

Teddy‘s suggestion to make sure the removable shock cord is the part that has contact with he top of the airframe, rather than the permanent Y harness, makes sense. I’m going to think about doing that from now on. In the past, I’ve used very beefy Kevlar for the Y harness because it’s permanent—3/8 tubular Kevlar in a 54mm rocket like the Wildman Junior series. That’s going to take a lot of punishment before it wears through. I really like thinner Kevlar for the shock cord (1/8” tubular Kevlar) for that same size rocket.

 

[Onebadhawk]

Teddy's stuff is top notch where it counts and he really knows what he's talking about.

Plus I've had the pleasure of meeting him in person and he is one of the nicest and most trusted people I know...that counts a lot in my book.

lol,
Thank you so much Ken..
That's awfully kind of you..
It sure was nice seeing you at the METRA launch this past..

Teddy‘s suggestion to make sure the removable shock cord is the part that has contact with he top of the airframe, rather than the permanent Y harness, makes sense. I’m going to think about doing that from now on. In the past, I’ve used very beefy Kevlar for the Y harness because it’s permanent—3/8 tubular Kevlar in a 54mm rocket like the Wildman Junior series. That’s going to take a lot of punishment before it wears through. I really like thinner Kevlar for the shock cord (1/8” tubular Kevlar) for that same size rocket.

Yes Joe..
For sure..
I always oversize one size the single sided attachment points..
And make certain that they don't reach out of the booster..
On the two sided or "Y" attachment points use the correct size material..
For "Y" attachments think "small, medium, and large..
Small-- 3" airframe = two legs of my 1/4" Tubular Kevlar and a 3/16" polished stainless swivel...
Medium-- 4" airframe = two legs of my 3/8" Tubular Kevlar and a 1/4" polished stainless swivel...
Large-- 6" ( and up ) airframe = two legs of my 7/16" Tubular Kevlar and a 5/16" polished stainless swivel...
There's also --
Extra Large-- TBD airframe = two legs of my 3/4" Tubular Kevlar and a 3/8" polished stainless swivel...
But these are absolute monsters, I don't usually mention them..

Joe,
I am 100% with ya..
For a harness, particularly a booster harness, long is everything, strong is nice too, but it's all about long..
Allowing the kinetic energy of separation dissipate on it's own, without coming to a violent stop at the end of a short harness..
If you're shocking the harness, you're shocking everything else as well,,
and my harness is just not going to be the weak link in that chain..

Man, I have a super cool pic of the eye that made me source my hardware line...

You know I can't find it, lol..

Thank you all anywhoosie..

Teddy

 

[Ulexis]

Teddy,

I need one of those kevlar Y-harness attachment points. PM me when you get a chance.

 

[Banzai88]

Thanks everyone. I have to admit that I never actually built this rocket (WM ShapeShifter 3).......because life happened for a bit and I can't find where I put the box with the parts in it anywhere in my house!

As soon as I find it, though, it's next on the build table.

 

[Banzai88]

After some discussion with Ted at OBH, this is what he makes as 'standard recommendations'. I'll be getting my act figured out here soon and placing an order!

Ted writes:
"
Small == 3” airframe..
1/4” Tubular Kevlar — 3/16” Polished Stainless Swivel — 3/16” Welded Polished Stainless Eyes…

Medium == 4” airframe..
3/8” Tubular Kevlar — 1/4” Polished Stainless Swivel — 1/4” Welded Polished Stainless Eyes…

Large == 6” airframe..
7/16” Tubular Kevlar — 5/16” Polished Stainless Swivel — 5/16” Welded Polished Stainless Eyes…

Extra Large == Minimum 8” airframe..
3/4” Tubular Kevlar — 3/8” Polished Stainless Swivel — 3/8” Welded Polished Stainless Eyes…

I can make larger then this Extra Large.."

 

[Banzai88]

 

[Onebadhawk]

NICE !!!!!!!!!!!!!

 

[Onebadhawk]

Ohh yeah,,
Somebody was referring to tight, no fit..
I'm pretty sure my 3/16" eyes will fit on both sides of a 38mm mount in a 2.6 airframe..
That's easy..
I'm fairly certain they'll fit on a 38mm mount in a 2.1" airframe..
The only real question is a 54mm mount in a 2.6" airframe..
( with my 1/4" Tubular Kevlar on them )..
That's really tight..
But I think it'd fit..
Not certain though..

Teddy

 

[ricky2117]

Sorry,
I never saw this thread before..
In a 3" airframe with a 54mm mount my 3/16" Welded polished eye fits perfect..
I'll attach pics of options..
This attachment point is built into the rocket / inaccessible..
For that reason I keep the attachment point short enough so it doesn't reach out of the booster..
What wears against the edge of the booster should be the harness,, you can access..
Not the attachment point that is permanent and not accessible..
View attachment 545428View attachment 545429
View attachment 545430

My 1/4" Tubular Kevlar is for 3" Airframes..
My 3/8" Tubular Kevlar is for 4" Airframes..
I oversize the material on these and keep them short so they don't reach out of the airframe..
That makes a 3" Airframe with a 54mm mount a
3/16" welded polished eye and 3/8" Tubular Kevlar just a bit shorter then the
distance from the top centering ring to the top edge of the booster..

These are the neatest, most professional looking attachment points there are, period..

Teddy

I’m building a Punisher 3…would you use something like that in it?

 

[Onebadhawk]

I’m building a Punisher 3…would you use something like that in it?

Hi Ricky,

Single sided,



or two sided,,



I need the distance from the top centering ring to the top edge of the booster..

Any attachment point should not reach out of the booster...
Something is going to wear against the sharp edge of the booster,,
that can be the built into the rocket “Y” attachment point that is very difficult to access/service,,
or what wears can be the very easy to access/service booster harness…

This is why I keep these attachments short enough so they don’t reach out of the booster…

It’s things like this that make my harness set ups outlast rocket after rocket…

When you email me it's important that you include the answers to these questions..


Hi XXXX,,
How are you ?
My name is Ted Chernok.
It’s very nice to meet you.
Yes, of course I do custom work..
I can make any configuration you need..
I’ll need to know a few specs on the rocket for us to begin.


Just answer in red right next to each item,,
It’s easiest that way..

What’s the material, fiberglass ??


What’s the diameter of the airframe ?


What’s the diameter of motor mount ?


What’s the distance from the top centering ring to the top edge of the booster ??


What's the length of the booster ??


What’s the length of the payload section ??


What’s the all up weight of the rocket, ready to fly, on the pad ??


And at apogee with an empty motor case ??


Is the rocket of a “standard “ configuration,,
separates at the booster for drogue deployment
and at the nose cone for main deployment ?


Have you started construction yet ?


When I have these answers I can make a harness setup recommendation for your rocket..


It's critically important that you understand,
You asked a question that had a grand total of a dozen words in it.
In order for me to help you the reply contains a few paragraphs that take much time and effort to put together.

I do this in order to make a correct recommendation of a harness set up for you..

If I can help, yus hollar,, lol..

Teddy

 

[danielhv]

Hi Ricky,

Single sided,

View attachment 559582

or two sided,,

View attachment 559583

I need the distance from the top centering ring to the top edge of the booster..

Any attachment point should not reach out of the booster...
Something is going to wear against the sharp edge of the booster,,
that can be the built into the rocket “Y” attachment point that is very difficult to access/service,,
or what wears can be the very easy to access/service booster harness…

This is why I keep these attachments short enough so they don’t reach out of the booster…

It’s things like this that make my harness set ups outlast rocket after rocket…

When you email me it's important that you include the answers to these questions..


Hi XXXX,,
How are you ?
My name is Ted Chernok.
It’s very nice to meet you.
Yes, of course I do custom work..
I can make any configuration you need..
I’ll need to know a few specs on the rocket for us to begin.


Just answer in red right next to each item,,
It’s easiest that way..

What’s the material, fiberglass ??


What’s the diameter of the airframe ?


What’s the diameter of motor mount ?


What’s the distance from the top centering ring to the top edge of the booster ??


What's the length of the booster ??


What’s the length of the payload section ??


What’s the all up weight of the rocket, ready to fly, on the pad ??


And at apogee with an empty motor case ??


Is the rocket of a “standard “ configuration,,
separates at the booster for drogue deployment
and at the nose cone for main deployment ?


Have you started construction yet ?


When I have these answers I can make a harness setup recommendation for your rocket..


It's critically important that you understand,
You asked a question that had a grand total of a dozen words in it.
In order for me to help you the reply contains a few paragraphs that take much time and effort to put together.

I do this in order to make a correct recommendation of a harness set up for you..

If I can help, yus hollar,, lol..

Teddy

Pm sent

 

[Onebadhawk]

Please,
all business contact via email.

Teddy