Aero-Pac Motor Retention System

[PGerringer]

Wanted to give a quick review of this little gem. While a bit pricy at $25, it is still very functionable and very good looking. 2 thumbs up.

How it works:
The system is basically 2 pieces. One threaded retainer "ring" that fits over the motor tube like a collar. Then a threaded cap that screws on the ring. As with typical RMS stuff, the RMS aft closure still sits on the motor tube. Then the retainer ring surrounds both the tube and the aft closure. The retainer ring is epoxied with high heat JB Weld epoxy. Then the cap actually screws on to the ring (like a top screws on a soda bottle) and holds the RMS system firmly in place.

The good:
It seems to be a high quality product. I looked for imperfections and didn't see anything. The installation is a snap, you just have to make sure that you have enough clearance for the RMS aft closure. (see Note) When the system is installed, it looks very clean and professional.

The bad:
For what it is, it seems a little pricy. But, if that is all the bad, then it may be worth the price.

Note: When measuring how much ring should cover the motor tube it is very important to remember this. Dr. Rocket cases have a 3/8" aft closure and Aerotech has a 1/4" aft closure. If you install your motor retainer to have only 1/4" clearance inside the ring, then you will not be able to use Dr. Rocket RMS. Installing it with a 3/8" clearance leaves a 1/8" gap when using the Aerotech RMS. I'm still trying to figure out what I can use to close the gap. All in all, it is best to install the ring based on the hardware you are going to be using.

 

[Klint]

have you tryed that clay or wax stuff? I dont see the problem with haveing an 1/8 gap

 

[PGerringer]

What clay or wax stuff? Please share.

 

[jdlawren]

I had a similar gap between the motor aft closure and the motor tube when the retention cap was fully tightened. I went to a hardware store and bought a rubber O-ring that snugs over the motor case. The ring is only 1/16" thick. With it rolled all the
way down to the aft closure, the motor slips through the retainer
base and seats against the motor tube. With the retainer cap fully tightened, the O-ring squeezes down and seals the gap.
I've replaced the O-ring twice in 10 flights. It only cost 29 cents.

Joseph
NAR# 81715

 

[PGerringer]

That is a great idea... I will try that next time.

 

[dluders]

Wouldn't the 1/16"-thick RUBBER O-ring melt under the heat of the RMS motor casing? I guess if you've used that system for multiple flights, the O-ring survives somehow....

 

[PGerringer]

That was the first thing I thought. But, when building reloadable motors they include o-rings in with the grains etc. They are used to keep hot gasses inside the casing. If those o-rings survive, I can see where ones on the outside of the casing will. Although, I would expect to see some warping, thus the ratio of 1 ring per 5 flights.

 

[rstaff3]

I use an O-ring, leftover from a used motor, on my Slimline. I was worried about not leaving enough room for the snap ring, so I left a skosh too much. I agree with Phil, the one O-ring should last a long time.

 

[PAH]

PGerringer,

If this is for a 29mm setup, I have two aluminum rings you can have. One is about 1/8" thick and the other is about 3/32" thick. Both have an ID just shy on an inch and fit perfectly in a 29mm Slimline retainer. They should work with AeroPack just the same. They're machined aluminum platter spacers out of computer hard drives. If you want them I attend most Whitakers sport launches or I can mail them to you.

Paul

 

[PGerringer]

Thanks for the offer bro. Actually, I found that a small amount of space does not affect performance. The aeropack holds it in with no issues. So I appreciate your offer but I would hate to waste the rings. We will find better uses for them...

 

[KermieD]

To use that great new AMW casing, you need to make sure your 54mm Aeropack retainer was made around November of 2002 or later.

 

[PGerringer]

Ooooo, good tip. Luckily I haven't installed the retainer yet. Perfect time to test huh?