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Repairing a motor mount

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les

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I've had 2 rockets where over-energetic ejection charges pushed the motor back and tore out the Estes style motor hook:(. While I could just friction fit the motor, the tube is now torn down the side (where the front part of the hook was dragged back). My only thought is to cut out the rear centering ring, glue a replacement tube over the original tube, and then a new centering ring.

Does anyone have a better suggestion?

Thanks
Les
 

jflis

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Something like that is going to be a frustration every time you fly it if you fumble with a repair (at least that's *my* experience...). I would remove the entire engine mount and replace it with a new one. You can salvage useable parts from the old mount (such as the engine hook and block).
 

Micromeister

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Something like that is going to be a frustration every time you fly it if you fumble with a repair (at least that's *my* experience...). I would remove the entire engine mount and replace it with a new one. You can salvage useable parts from the old mount (such as the engine hook and block).
I completely agree with Jim;
if you don't get the thing sealed well it can cause all kinds of headaches. replace the entire motor mount. You'll be much happier with the outcome.
 

Gillard

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i agree with the above two posts -it will look better too.
 

hcmbanjo

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I stay away from the thinner Estes BT-20 for motor mount tubing.
The older Centuri style ST-7 tubing is thicker, it might stand up better with the strong ejections. It's available through Semroc.
The Dr. Zooch kits reinforce the area right below the slit for the upper part of the engine hook. It's a simple 1/2" wide wrap of cardstock.
Cut the small slit for the bend in the engine hook, then glue the cardstock wrap immediately under that slit. Set the engine hook in the slit over the cardstock wrap and then build the rest of the engine mount as normal.
 

Luv2launch

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I have repaired motor mounts that have torn out the motor hooks.The first one was on my Super Big Bertha after its first flight on an E9 it zippered the hook, I trimmed a bit of the cardboard centering ring out around the hook so it could be removed then I just flattened out the zipper and coated it with carpenters glue on both sides to make sure it sealed the zippered portion and where the motor hook was making sure that the glue on the inside of the motor mount didn't get on the way of inserting a motor.The second time it happened was on my Fliskits US Tog which I did basically the same thing to repair minus cutting the centering ring to get the motor hook out both have flown since then with no problems at all.If the zipper isn't too bad this is a much easier fix then pulling the whole motor mount out and its less destructive to the model.
Hope this helps.
 

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