PML Bull Puppy

I'm looking at getting a PML 3" Bull Puppy, and I was wondering how other folks handled motor retention? After looking at the kit
directions, the motor mount just fits into the bottom of the boat tail without any centering ring. They also have you mount the motor mount flush with the end of the boat tail. This does not leave many options for motor retention. Ideas wanted.
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When I fly mine, I take about 18 inches of florists wire, and do a loop once around the center of the nozzle. Run the ends up 180 degrees from eachother, and put a bit of a bend in the end. Then just do a few wraps of 1" masking tape around the wire/boattail.
Ben
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On 5 Dec 2005 20:28:05 -0800, snipped-for-privacy@bnl.gov wrote:

you can see what I did with my bullpup here:
http://waro.iinet.net.au/parc/motorretention.htm
In a nutshell, I sanded a slot in the boattail and epoxied some alli bar to the motor tube. The bar has holes drilled all the way down it and one in the end for a cap screw & nut - the screw goes over the end of the aft closure and prevent the motor being ejected. I then filled in the slot in the boat tail with epoxy in an attempt to make it less visible (and failed misserably). The url shows what I am talking about. It's a good solution because you can use motor adapters with it - you just need to know what distance to drill the hole.
I use this method on all my kits now. It works great, it's cheap but it doesn't look too flash...
Paul.
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Cool idea. Personally, though, (if Bob doesn't mind me mentioning this,) I use homemade Kaplow clips when in doubt about retention characteristics. They work just as good for modrocs as they do for mid powered, and they do offer symmetry.
Bob352
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I have the 2.1" Bull Puppy and I modified mine to accept the Giant Leap Slim Line motor retainer. I don't have a picture, but in a nutshell I glued the Slim Line retainer on the motor tube per guidelines. Then I sanded the inside rear of the boat tail just enough so the motor tube with the Slim Line retainer would fit through. I left about 3/8" hanging out the back and epoxied the motor mount in place following the PML instructions from there. It not only looks good but works well too!
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On 5 Dec 2005 20:28:05 -0800, snipped-for-privacy@bnl.gov wrote:

Glued an aeropac-style retainer onto the end of the motor mount, and filed open the end of the boat tail just enough to accommodate the resultant larger diameter. Looks very neat.
--
Darren J Longhorn http://www.geocities.com/darrenlonghorn /
NSRG #005 http://www.northstarrocketry.org.uk /
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Use an AeroPac retainer. It adds some drag but the Puppy really won't care. Its a screamer.
Don Brown MDRA NAR L2
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I have the 3 inch Bull Bup and its another great kit from PML. I also have a Black Brant IV from them, and it never suffers a crash. the best feature is the safety belt like shock cord, a vast improvement over stel cables. Great decal set. My only negative is like you said the engine mount. I would stand off an all thread rod about .0625 inches from the motor tude and drop in a nut and washer. Bore out the boat tail accordingly.
Dave Ketchledge
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snipped-for-privacy@bnl.gov wrote:

I found a piece of thick walled tubing that had the correct ID for a 4-50 tap. I cut three pieces about 1-1/2" long and tapped both ends. I screwed the upper end onto some 4-40 Quick Link rod from a hobby shop. The quick link rod extends through the forward centering ring and is bent over and cut off. The threaded tubing extends through the boat tail and accepts 4-40 bolts that hold on a PML retainer. Lock-tite the joint between the quick link rod and the threaded tubing so it won't come unscrewed and epoxy everything inside the boat tail.
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