motor retention on rockets with motor size adapters?

[billdz]

Hi,
I have a 4" LOC Expediter, which takes a 54mm motor, and I have the 38mm and 29mm adapters. I'm wondering what is the best way to retain motors in all 3 sizes. A 54mm retainer would secure the adapter but not the smaller motor. Is there some kind of retainer that can secure all 3 sizes, or do I need a retainer on the adapters themselves to secure the smaller sized motors?

I see that some types of retainers require the drilling of holes in the aft motor mount and the insertion in the holes of PEM nuts. My rocket and the adapters have already been built and I'm a little reluctant to be drilling holes now.
Thanks for any ideas,
Bill

 

[jd2cylman]

AeroPack. Boom! All adapters nest into themselves. So If you installed a AeroPack retainer, then you can use the 54-38 and the 38-29 adapters and retain your 29mm motor in your 54mm mmt. Pricey, but totally worth it for SECURE retention of smaller motors in larger motor mounts. And yes, the 24mm would also nest in and work if your rocket was light enough for the CTI 24 6 grain... https://www.wildmanrocketry.com/ShowProducts.aspx?Class=515&Sub=821

 

[michaelrmonteith]

I have the HAMR-KS from PML. I haven't got a chance to see how well it performs. But seems to be a pretty good design.

https://publicmissiles.com/product/motorretainers

Michael

 

[qquake2k]

This is how I do it. It requires tee nuts or some such in the centering ring, but it is a LOT cheaper than AeroPack retainers and adapters.

https://www.rocketryforum.com/showthread.php?57027-New-upscale-Freefall-XL&p=675770#post675770

 

[jimzcatz]

Tape... Masking tape friction fit. Easiest thing next to the Aeropack mentioned by Adrian.

 

[billdz]

Masking tape is tempting due to the low cost but I assume it is not that reliable, otherwise people would not be spending big bucks on the Aerotech and other commercial retainers. I see a few people use hose clamps, not sure if that is better.

 

[dhbarr]

Masking tape is tempting due to the low cost but I assume it is not that reliable, otherwise people would not be spending big bucks on the Aerotech and other commercial retainers. I see a few people use hose clamps, not sure if that is better.

Word of caution on hose clamps, fairly easy to overtighten.

And your initial assumption may be flawed: spending lots of funds and increasing complexity for little-to-no discernable benefit are a hallmark of any hobby ( see also overbuilding ). 😀

 

[jimzcatz]

Masking tape is tempting due to the low cost but I assume it is not that reliable, otherwise people would not be spending big bucks on the Aerotech and other commercial retainers. I see a few people use hose clamps, not sure if that is better.

Mistaken. Tape is very reliable when done right. That's all we had in the early days

 

[MClark]

If the motor is longer than the adapter use the masking tape above the adapter.
Better than a friction fit although as stated a correctly done friction fit is reliable.

M

 

[chris m]

Why use masking tape when you can use a aero pac at 10 times the cost

 

[pyrobob]

Masking tape has worked for me since the early 90's. It's not as sexy as the motor retainers but still works nonetheless.

 

[Bat-mite]

Why use masking tape when you can use a aero pac at 10 times the cost

Why drive a car when you can walk at zero cost?

 

[Steve Shannon]

Mistaken. Tape is very reliable when done right. That's all we had in the early days

Plus 1, especially if the case extends past the forward end of the adapter, then just wrap tape around it ahead of the adapter tube.