Motor Retention

[Dbarrm]

I am building a Yank Enterprises 3” Iris. In the directions it talks about motor retention. This is my first HP rocket and have never had to worry about this so I have no idea of what to do. I don’t want to use the old friction fit method. I would like to find some way to use screws and washers to hold it in. I’m sure someone here can tell me what works best (for them of course).

Dan

 

[Justin Horne]

Some one else could describe the screws way better ( I don't know it well enough to give directions, ) but I use threaded slim-line retainers. Very sold, positive retention. Really though, friction fit is fine. Just be sure to run tape lengthwise of the case, so there is not just a 1 inch area of hold. I do it on my rockets that don't have slim-lines, works fine. Put them in very solid. To get them out, take off aft closure, pull out o ring and nossle , install closure, and use it as a place to get grip. Works for me.

Threaded slimline




Justin

 

[DynaSoar]

Originally posted by Dbarrm
I am building a Yank Enterprises 3” Iris. In the directions it talks about motor retention. This is my first HP rocket and have never had to worry about this so I have no idea of what to do. I don’t want to use the old friction fit method. I would like to find some way to use screws and washers to hold it in. I’m sure someone here can tell me what works best (for them of course).

Dan

I just saw this today: https://silent1.home.netcom.com/umrs.htm

Universal Motor Retention System

I went straight to Lowe's to get the parts, but they didn't carry the right stuff. $2 of parts plus glue. Screw closed, screw open, can't get much easier. The only down side is that if you want to keep the business end of the bird looking like a collection of plumbing parts is to either embed the pipe piece in the end (requiring modifying the aft centering ring) to sawing the piece in half and embedding it in epoxy in the aft.

I'm torn between putting one of these vs. a Slimline retainer on the Mirage I'm building.

 

[Hospital_Rocket]

Universal Motor Retention System - Dynasoar

This idea carried to the extreme is available from Aeropack

Aeropack Quick Change Retainers

Another source for those of you in the UK is Rowe's. They make one that includes a coned extension that has "cool" written all over it.

Rowwes Quick Change Retainers

In both cases a 29mm retainer runs around $25

 

[loopy]

get some blind nuts/T-nuts, drill some holes in your aft centering ring and install these in those holes with some epoxy (making sure to keep the threads clear, mind you). Now, you can use screws with washers to hold the motor in. Pretty cheap and dirty, but very effective. And a WHOLE lot less money than slimline.

Loopy

 

[Habu]

I've used the PRM described by silent1 for 29mm that DynoSoar referenced.
It works great and the price is attractive.
Use JB Weld. More heat resistant than regular epoxy.
If you look hard enough you may be able to find the appropriate size coupler in black ABS. That is what I ended up using.
Admittedly more rocket looking than the white PVC.
There is also a coduit coupler available in gray.
I have not been able to find this one myself.