forward motor closure as recovery attachment point

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jkovac

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I'm building my first DD rocket, a Madcow Tomach 2.6" FG with a 54mm motor mount. The instructions state that the forward motor closure eyebolt is to be used as the recovery attachment point. In searching threads about this I have seen some postings that say using the forward closure for recovery attachment is fine, while others state it is a bad idea, as the forward closure is not robust enough. Does anyone have any input on this? I am also trying to figure out how CTI and Aerotech hardware and available accessories might compare on this point.
 
Aerotech has a threaded forward closure (no ejection charge well) that is intended to accept an eyebolt. The metal forward closure is plenty strong and has been used by many flyers. I don't know about putting an eyebolt into the Cesaroni 54mm forward closure. I have their XL 54mm motor for use in my Kestrel, but I haven't gotten around to figuring out my recovery attachment point. I dimly recall people using the forward closure, but I don't know any details. Sorry I can't be more help.
Aeropac makes a recovery point that is designed to epoxy into the airframe ahead of the motor. That's probably similar to what I will do.

[emoji1010] Steve Shannon, P.E. [emoji1010]
 
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I don't think CTI even makes a threaded forward closure in 54mm. I could be wrong.

There are lots of threads about how to make a Y-harness and epoxy it to the MMT. You could also think about installing a baffle and attaching an eye bolt or U-bolt to that. Or, consider putting a 3/16" eye bolt in the .23" of CR space you'll have.
 
I don't think CTI even makes a threaded forward closure in 54mm. I could be wrong.

There are lots of threads about how to make a Y-harness and epoxy it to the MMT. You could also think about installing a baffle and attaching an eye bolt or U-bolt to that. Or, consider putting a 3/16" eye bolt in the .23" of CR space you'll have.

Yeah they do. Have one sitting on my workbench.
 
I use motor deployment as a backup on many of my DD flights. You can't do that if you use an eyebolt on the forward closure as your only harness attachment point. Just pointing out the obvious.

I have seen at least three large rockets lawn dart due to deployment failures. The three failures I have seen where we had a reasonable idea of the failure were due to two battery failures (two guys new to DD and one team failed to secure the battery properly and one used a really cheap battery that failed) and one ejection charge not prepared properly (mine).
 
Thanks all for the replies. Regarding the CTI 54mm threaded forward closure, that's the one I've seen some posts on stating it is not robust enough to be used as a recovery attachment point. But I don't get why else they would make a threaded forward closure one can attach a eyebolt to.
 
Thanks all for the replies. Regarding the CTI 54mm threaded forward closure, that's the one I've seen some posts on stating it is not robust enough to be used as a recovery attachment point. But I don't get why else they would make a threaded forward closure one can attach a eyebolt to.

They make the threaded forward closure for minimum diameter motor retention. It may be strong enough to use as recovery anchor, but do you want to gamble? I'd just pair that with the Aeropac min dia retainer or a home-built version (bulkhead plate with eyebolt through it.
-Ken
 
They make the threaded forward closure for minimum diameter motor retention. It may be strong enough to use as recovery anchor, but do you want to gamble? I'd just pair that with the Aeropac min dia retainer or a home-built version (bulkhead plate with eyebolt through it.
-Ken

Thanks Ken. This is probably a dumb question, but what is the purpose of the threading if it is not to put an eyebolt in for recovery attachment? Or maybe I am confusing "threaded" with "tapped"?
 
It's exactly as Ken said, for motor retention only. Unless there's a different part I'm not aware of, it's not CTI that sells this threaded adapter, it's Aero Pack, and they sell it to go with their minimum diameter retainers (see here, retainers at the top of the page and the CTI "Delay/Eject-Closure Adapters" about 3/4 of the way down), which hold the motor in the rocket from the top rather than securing it from the bottom like their non-MD retainers do. AeroTech had a solution for their motors with their tapped forward closures (and FCRRA for their 38mm RAS system, which even lets you do motor-eject along with a MD retainer), but CTI didn't, so Aero Pack filled the gap. But even the website linked above clearly state "Adapters are for retaining motors to Aero Pack bulkhead retainers only and not to be used for attaching recovery hardware." And believe me, after you thread one onto the motor the first time I think you'd have to be pretty crazy to think that it would be sufficient for recovery attachment anyhow. :)
 
CTI makes a plugged forward closure. It looks exactly like the normal closure but the top doesn't have a charge well and there are 1/4-20 threads in its place. I don't know that I'd trust it on a heavier rocket, but it worked fine on my 2 lb rocket.
 
CTI makes a plugged forward closure. It looks exactly like the normal closure but the top doesn't have a charge well and there are 1/4-20 threads in its place. I don't know that I'd trust it on a heavier rocket, but it worked fine on my 2 lb rocket.

I bought one of the threaded forwards. It looks like they make one out of the plastic forward closure, place a threaded insert it and it has a smoke grain.
So I guess if you want tracking smoke AND an eyebolt attachment then you have to buy that extra fwd everytime. I'd make one out of aluminum, thread it and forget about the tracking smoke.
You could bore it the same size as an old Kosdon 54mm forward, then you could load an Aerotech smoke grain and a series of greased o-rings around the smoke.
That way you would have a one that is reusable.

I am not sure I would trust that plastic CTI forward with a 20 pound or more booster section.
 
I presume that you got the 54mm version of it. I got a similar DX3. I planned from the beginning to also fly with 38mm motors using an adapter, possibly using motor ejection. Thus I needed a solution too. I used 1/2" kevlar epoxied to the MM. Check it out here
 
CTI makes a plugged forward closure. It looks exactly like the normal closure but the top doesn't have a charge well and there are 1/4-20 threads in its place. I don't know that I'd trust it on a heavier rocket, but it worked fine on my 2 lb rocket.

Interesting. Where would one buy this? I never saw anything like that listed on CTI's website or anyone who sells CTI reloads like BAR, I guess I haven't looked in the right place.
 
In searching threads about this I have seen some postings that say using the forward closure for recovery attachment is fine, while others state it is a bad idea, as the forward closure is not robust enough. Does anyone have any input on this? .


Been using them for years, actually making my own by simply self tapping a 1/4 E-bolt into touch hole after emptying the BP. It's more than robust enough. You would have to pull out the forward closure from the case.

Thanks all for the replies. Regarding the CTI 54mm threaded forward closure, that's the one I've seen some posts on stating it is not robust enough to be used as a recovery attachment point. But I don't get why else they would make a threaded forward closure one can attach a eyebolt to.

Some one not knowing do-do would say those things. See my first reply above. [this is how rumors get started]

It may be strong enough to use as recovery anchor, but do you want to gamble? I'd just pair that with the Aeropac min dia retainer or a home-built version (bulkhead plate with eyebolt through it.
-Ken

What did we do before the Aero-Pac adapter? I've been around long enough ......used the eyebolt.
Why are you gambling? Designed & approved by CTI, more than ample for minimum diam. use.
See my first reply again.

I am not sure I would trust that plastic CTI forward with a 20 pound or more booster section.

Not made for that, if rocket weights that much, should be a recovery harness somewhere. It's minimum diam..


Interesting. Where would one buy this? I never saw anything like that listed on CTI's website or anyone who sells CTI reloads like BAR, I guess I haven't looked in the right place.

Wildman, Ken Allen, has them, probably any major CTI dealer. I 've purchased from both.
I don't even know where to look on web. I think 12.00 It's a call & ask thing. Now after talking to Jeroen,I just make my own for .29 cents as mentioned above.

BUT: K-300 come with them. Several other 54 long burns may.
If flying a motor with threaded hole and NOT using it for recovery, be sure to PLUG that hole with a bolt or glue or risk possible blow by if delay grain burns faster than motor. [heck THAT never happens does it...lol]
When purchasing one for use be sure to check diameter & fit. Ones for long burn are smaller diameter due to liner is thicker [long burn XXX] LB threaded closure will be sloppy loose in regular motor!

Older units just fit in.
Newer units have an extra O-ring on lip that fits INSIDE liner to seal better. Most 54's now have that feature where needed.

Remember these are minimum diameter specific. Anything larger should use a harness.
Happy flying!
 
I've used the threaded forward Aerotech enclosures
for harness attachment point many many times...
I've used and enjoyed the 38's and the 54's so much / often
that I asked a buddy to make me a 29,, I gave him the
29 forward and he tig welded a piece of aluminum rod and drilled it and tapped it...
This is what got me started in caring really cool hard to find hardware. ..
I carry the eyes for these enclosures...
Check em out on my site....

https://onebadhawk.com/welded-stainless-steel-eyes.html

Teddy
 
Thanks again to all for the input here. One additional question: What do you prefer to use to fix the eyebolt into the closure threads? Threadlock? Epoxy?
 
Thanks again to all for the input here. One additional question: What do you prefer to use to fix the eyebolt into the closure threads? Threadlock? Epoxy?

I always use a dab of blue ( removable ) threadlock on this harness attachment eye...
On all of the hardware when I assemble my ebay as well for that matter...
Works great,, no nuts loosen up on their own ever,, but you can certainly take them apart when you need too...

Teddy
 
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