Quantcast

Motor Retention in 29mm MD?

The Rocketry Forum

Help Support The Rocketry Forum:

sailmike

Well-Known Member
Joined
Jan 19, 2009
Messages
498
Reaction score
0
I'm looking for ideas on motor retention in my 29mm minimum diameter rocket. I may just get a plugged forward closure and drill and tap for a 1/8" eyebolt. Anybody got other ideas?

Thanks,
Mike
 

troj

Wielder Of the Skillet Of Harsh Discipline, Potent
Joined
Jan 19, 2009
Messages
13,962
Reaction score
192
1) Screw-on motor retention (Slimline, Aeropac, PML HAMR, whatever...) It'll add a small amount of bulk at the end, so it's a trade-off.

2) Bolt in a plugged closure

3) Cable around the top of the forward closure, the ferrule crimped close enough that the cable won't come off. Use that in conjuction with some tape, so the two work in tandem

4) Wire through holes in the rear of the fins, around the nozzle, and up through another fin.

-Kevin
 

Handeman

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
7,728
Reaction score
324
Location
Stafford, VA
A variation on Kevin's #4. I've used large paper clip wire bent into a U shape and epoxied into the fillets of the fins to wrap wire through rather then holes in the fins. Works the same way.
 

sailmike

Well-Known Member
Joined
Jan 19, 2009
Messages
498
Reaction score
0
Handeman, I like your idea, but it's too late to use it. I think I will go with #2 or 3. How well does idea #3 work?

Thanks,
Mike
 

troj

Wielder Of the Skillet Of Harsh Discipline, Potent
Joined
Jan 19, 2009
Messages
13,962
Reaction score
192
Handeman, I like your idea, but it's too late to use it. I think I will go with #2 or 3. How well does idea #3 work?
I've never done it, but know people who have, and I've not seen a problem with it.

-Kevin
 

kramer714

Well-Known Member
Joined
Jan 20, 2009
Messages
696
Reaction score
10
Mike,

I used a short section of tube coupler as a stop at the top of the motor (bonded in the body tube at the top of the motor. I drilled and tapped hole on the top of the motor and made a washer plate that is the same ID as the body tube, the washer has a hole that an eye bolt passes thru. When you tighten it up the eye bolt, it snugs against the washer and tries to pull the washer and motor together pinching the tube coupler.

I also did this with a zipper-less design where the tube coupler is regular length and is the split for the body. For this design, I turned a delrin washer that 'fits into the I.D. of the coupler to make sure it doesn't hang up during deployment.

Let me know if you need and I can take some pictures of it for you.

Is this your altitude contest rocket for Rocstock?

Mike Kramer
 

sailmike

Well-Known Member
Joined
Jan 19, 2009
Messages
498
Reaction score
0
This rocket goes too high for the altitude contest. I need to put like a 1/2A motor in it to keep it down to around 2000'!

Anyway, that's a great idea, but might only work with an I200 that I plan to put in it.

Mike
 

Jeroen_at_CTI

Well-Known Member
Joined
Apr 27, 2009
Messages
563
Reaction score
1
I'm looking for ideas on motor retention in my 29mm minimum diameter rocket. I may just get a plugged forward closure and drill and tap for a 1/8" eyebolt. Anybody got other ideas?
Bond the casing in the airframe? With Pro29 casings there is no need for forward access. Casings are relatively inexpensive as well.
 

Garoq

Well-Known Member
Joined
Jan 18, 2009
Messages
983
Reaction score
0
I'm looking for ideas on motor retention in my 29mm minimum diameter rocket. I may just get a plugged forward closure and drill and tap for a 1/8" eyebolt. Anybody got other ideas?

Thanks,
Mike
If there was enough demand we could easily produce a tapped forward closure for the 29mm RMS. Are there any other features you would like to see, such as an extended length for a longer smoke charge?
 

sailmike

Well-Known Member
Joined
Jan 19, 2009
Messages
498
Reaction score
0
I would go for the extended forward closure. One other thing that I'd like would be a built in eyebolt as part of the closure rather than something that you screw in. A built in eyebolt would be made out of aluminum and lighter than a standard eyebolt.

Mike
 
Top