Another Pipe Dream - A Fly in the Ointment

[jqavins]

I might try this one day. I had the idea to wonder if anyone makes boat tail rear closures for AT or CTI cases. The idea is to use such a thing along with an Aero Pack internal min-diameter retainer to make a 29 or 38 mm sleek demon.

After some Googling, I haven't found a tail cone aft closure for AT, but CTI does make them, but only for some sizes. They have them for 29 mm, but not for 38.

Aero Pack only makes the internal retainers for 38 mm and up. And, they need a special adapter to use with CTI cases, which Aero Pack also makes, only for 38 and 54 mm.

I could make my own internal retainer to use with an AT threaded forward closures, but I'm not willing to make my own motor parts, be it an aft closure or a CTI-AeroPack adapter.

At 54 mm, all the bits are available, but the pipe dream is to keep it really skinny, 29 mm preferably, or 38 mm at most.

Size​	Tail cone aft closure​	Aero Pack internal retainer​	Aero Pack CTI adapter​
29​	Yes​	No (I could make my own)​	No (No, I won't make my own)​
38​	No​	Yes​	Yes​

So, any bright ideas?

 

[boatgeek]

CTI 38mm motors don't have a reusable aft closure like the 29s and 54s. The closure and nozzle are all one [phenolic?] piece with threads that mate with the casing. The outside of the closure is pretty big and has ridges to grip while tightening the threads. I'm pretty sure that I've seen that CTI has given approval for cutting away all of the closure material outside the diameter of the casing. Not sure if that extends to giving it a little tail cone or not. Granted, this requires a lathe or a lot of patience, so it may not be useful to you.

 

[Neutronium95]

I'd honestly just use friction fit on a 29mm CTI motor. Glue in a bulkhead above the motor for it to push on and to anchor the shock cord to and you'll be set.

 

[mtnmanak]

Making an internal retainer for a 29mm minimum diameter rocket is pretty easy (and cheap) since the forward closures are threaded for 1/4"-20. All you need is some all-thread and some coupler nuts.

I make the internal attach point out of an eye-bolt and a couple centering rings and install the attach point to fit the longest motor I will use in the rocket:



Then cut all-thread to the right length for each motor case and JB weld a coupler nut to the end:



Voilla.

Here is a build thread I did that explains it a bit more:

https://www.rocketryforum.com/threads/29mm-minimum-diameter-dual-deploy-go-devil.165916/

 

[jqavins]

Making an internal retainer for a 29mm minimum diameter rocket is pretty easy (and cheap) since the forward closures are threaded for 1/4"-20. All you need is some all-thread and some coupler nuts.

Only on Aerotech cases. And it seems to be only CTI that has tail cone aft closures.

 

[SDramstad]

Wildman has them for 54 and 75mm Aerotech cases

 

[jqavins]

Wildman has them for 54 and 75mm Aerotech cases

By "them" I guess you mean the tail cone aft closures? But...

At 54 mm, all the bits are available [from CTI and Aero Pack], but the pipe dream is to keep it really skinny, 29 mm preferably, or 38 mm at most.

So, that would give me another option for a size I could already have done, but don't want.

 

[SDramstad]

As the philosopher Jagger said "You cant always get what you want"
Wildman makes them for the 75 and 54s. Maybe he can make one for you in a smaller size.

 

[jqavins]

Unless AT approves the new Wildman 29 mm part, would that not make it a research motor?

 

[SDramstad]

They approved the 75 and 54 he makes. Shouldnt take much for them to approve a smaller one.