Installing a screw-on motor retainer on a kit

[Luzwingnut]

Resurrecting an "old" post.... BUT??? Using a bit of VASELINE on the retainer threads while gluing the assy. to the MMT will also inhibit any glue from adhering to the threads and/or centering ring. EASY and idiot-proof. Ask me how I know.

 

[Tractionengines]

Resurrecting an "old" post.... "Again".... but quick question about using LOC Precision 29mm aluminum retainers. When the retainer nut is tightened down on a Econojet motor there is about .030" of fore/aft play. This seems like a bad thing. Motor movement within the retainer would shock load the thrust ring and the retainer.
Or are the aluminum type designed to have some play for thermal reasons? I know the Estes 29mm (plastic) retainer I've used screws down tight on the thrust rings.
Thanks for your insights.

 

[flyingeagle]

Dose anyone have suggestions on aluminum motor retainers on a bt20 tube? I am ordering the Rocketarium Tank Buster 1021R that has the aluminum motor retainer included in the kit. The aft end is a BT20 that is it. There is no centering ring to glue a retainer against. The fins get glued to the BT20 BT. The aft end is smaller than the top of the rocket so if I glue on the retainer included in the kit it is going stick out past the main BT20 tube. Won’t this cause drag?

 

[mh9162013]

Won’t this cause drag?

Based on what you've described, I believe so.

As for a motor retainer for a BT-20 tube using 18mm engines, there's not much you can do to avoid the problem with retainer "sticking out." If you want a retainer with a BT-20 tube that doesn't stick out, you'll want to use a smaller engine, such as the Estes mini 13mm engines. You can take parts from certain Estes kits to make a retainer system for 13mm engines that work with most BT-20 main body tubes.

 

[T-Rex]

Unless you plan to use an Aerotech 18/20 reload case, that retainer is useless. Estes BP motors have no thrust ring for the retainer to hold. Personally, I would install a thrust ring in the tube (like an Estes model does) and then just use masking tape to friction fit the motor. (Yes you can add a thrust ring to an Estes motor with tape and super glue. I would still probably friction fit it into the model and leave the retainer off.)