- This topic has 10 replies, 6 voices, and was last updated 13 years, 6 months ago by
greywolves.
greywolves.-
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Bret Packard
Anyone ever tried one of these? They have them for Pro54 and Pro38 hardware apparently. I was thinking it looks like it would work for a threaded forward closure.
https://aeropack.net/webstore/product.asp?productid=353243224569305
Would be pretty handy if they work well. I can’t see how it attaches, but everything I’ve ever gotten from Aeropack has been top notch.
new2hpr
Looks like it threads into the charge well of the plastic front closure (delay/ejection holder). Haven’t used one, but thanks for the heads up. Must get!
-KenJeffrey Joe Hinton
Aeropak has taken the next step with retention and minimum diameter motors – see their website for details – http://aeropack.net/min_dia_retainers.asp
I haven’t used them yet but certainly got me thinking….
Bret Packard
So why do you need the retainer, instead of just screwing an eyebolt into the closure that linked above (also by aeropack)?
new2hpr
In their description, the part that screws into the closure is intended only for motor retention. I would guess that the plastic closure would not hold up to the stress of a hard recovery jerk (such as those that open non-welded eye bolts). The mount gives a solid recovery anchor, and a stud to thread the motor onto. Unfortunately, this takes up more airframe length than it really should.
I wish Cesaroni would just come out with a fully reusable front closure piece for the Pro29,38,54 series cases made of aluminum with a solid anchor thread. Wouldn’t be that tough of a piece for a person to make, though getting it certified would be another matter.
-Ken
Dr_J
In their description, the part that screws into the closure is intended only for motor retention. I would guess that the plastic closure would not hold up to the stress of a hard recovery jerk (such as those that open non-welded eye bolts). The mount gives a solid recovery anchor, and a stud to thread the motor onto. Unfortunately, this takes up more airframe length than it really should.
We tested them to over 200 lbs pull-out force, but didn’t think that would be enough for it to act as recovery harness attachment point. Therefore the restriction for motor retention only.
I wish Cesaroni would just come out with a fully reusable front closure piece for the Pro29,38,54 series cases made of aluminum with a solid anchor thread. Wouldn’t be that tough of a piece for a person to make, though getting it certified would be another matter.
There are many options, including:
* Use a spacer modified as anchor point (posted on Rocketryplanet).
* We recently started selling the threaded Pro54 closures (with smoke) to dealers. These can be used with all 54’s.Jeroen
Bret Packard
Thanks for chiming in Dr J. Threaded closures would be awesome. Any plans to make these for Pro38’s as well? Are they reuseable? Any info you guys have published on them that you could link would be awesome. Thanks!
Steve Jensen
My method is sort of funky. I just scrape out the smoke charge, drill through the delay firing hole, and put a 1/4 inch threaded forged eye bolt through it. I place a large washer and nut on this and cover the nut/washer with epoxy, filling the smoke charge area. You can recover the eye bolt after launch.
I’ve used this up through Pro54 6G XL on moderately heavy rockets (25 pounds) and seen in excess of 10g’s at deployment. So far, so fine.
I’d worry about stripping the threads on the plastic. That’s why I use a nut and forged eye bolt.
I’ll take a gander at the new threaded closure offered by Cessaroni.
Joe, ya got any?
greywolves
Hey,
I built my motor retainer just like the areo-pak, on my Kestral build. EXCEPT I used 2-3/32″ FG bulk plates, and a two section of 54 mm FG coupling, I think the were 3/4″ long. I sandwiched the two bulk plates between the two couplings. The surface area for attaching the couplings inside the airframe really makes a strong bond. Everything heavy scratched. The bulk plates have 1/4″ hole. Using a fender washer on each side with lock washer and nuts. Set an 1/4″ eye-bolt at the right height so you can just screw your motor in. Just another idea.
Steve Jensen
as it is easy to install, does not require modifying the motor casing plastic end bit, and doesn’t rely on the threads holding the shock cord assembly to the air frame.
PS. Heard a rumor that you’re bolting to Dorothy and Toto Land?
Bret Packard
new2hpr
Jeffrey Joe Hinton
Dr_J
Steve Jensen
greywolves
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