method of keeping 29mm motor in from ejection charge?

[rocketsonly]

Hey all. What's the most common method for keeping a 29mm motor from shooting itself out after the ejection charge? Friction fit? For some reason a engine hook doesn't sound right.
Thanks.

 

[cls]

masking tape works just fine. I used masking tape for a J420 last Saturday, fwd and aft retention.

you can make motor clips in a variety of ways - we use 1/4" and 1/2" brass strips, which are screwed on to the aft ring. put some T-nuts on the inside of the aft ring.

 

[DynaSoar]

Originally posted by rocketsonly
Hey all. What's the most common method for keeping a 29mm motor from shooting itself out after the ejection charge? Friction fit? For some reason a engine hook doesn't sound right.
Thanks.

Most common is apparently masking tape. I won't trust it. I'll take the weight hit rather than risk having happen what someone else says hasn't happened to them; it HAS happened to others.

AT uses heavy clips. I like them, but they're very stiff and some people have had them break at the bottom tab, making them hard to open. Some people make their own like it.

There's several commercial motor retainers, best known is the SlimLine. They go on the end of the tube and have c-clips, treaded caps, or whatnot to keep the motor in.

The threads cut from a piece of 1.25" dia. male threaded PVC can be glued over the tube (use heat-proof epoxy like JB Weld). A 1.25" PVC bushing screws on it. A 1" E-clip stuck inside the bushing, and you've got a screw-on/off engine retainer for about $2. Regular "schedule 40" PVC like you find at every hardware store works fine. "Schedule 80" is lighter but harder to find.

 

[lalligood]

Comparable to the Slimline is the Aero Pack. I chose to use the Aero Pack on my PML Phobos because Slimline had not come out with their screw-on retainer (old version required snap rings). Both are Expensive (yes, with a capital 'E')and perhaps overkill...but MAN, DO THEY LOOK GOOD! And indestructible solution.

Another inexpensive alternative is Kaplow Clips. Consists of a couple of blind nuts (also called t-nuts) mounted into the aft CR. Metal clips & screws go into the blind nuts & retain the motor. All parts shoudl only cost a couple of bucks at your local home improvement store. Do a search here on TRF for more information on them.

Masking tape works well too. You just have to learn (sometimes the hard way) how much it takes to retain the motor casing... It's the cheapest solution of all & it's universal