For the rocketry hobbyist:
A number of the mid-power rockets, such as the G and H class rockets from Public Missiles and LOC Precision, have a bare engine tube with instructions on how to use many layers of masking tape on each launch to hold the engine firmly. It seemed inelegant to me for a motor of that size to depend on tape to avoid a couple of catastrophic failure modes. So I jerry-rigged a stable motor mount that has to be incorporated from the beginning of the rocket build. It works especially well for engine clusters; running the screw down the center of 3 engine tubes can secure 3 engines with one bolt.
The wing nut holds the engine from the rear, and adjusts for measurement error. I pass the headless screw through a hole drilled through the rear disc and epoxy it to the motor tube. I drill a pair of holes at one engine’s length up the tube and epoxy a straightened paper clip through the center of the motor tube. This holds the motor from the other side.
While making these mods, I place another paper clip through farther up to secure a wad of steel wool to capture the ejection charge sparks (so I won’t have to use fireproof paper on every launch).
Given the screw sticking down from the bottom, the motor tube should be mounted a bit higher in the airframe if you want the rocket to be freestanding on a flat floor. That may require planning around the fin placement. It was not a problem for this LOC Precision Norad.
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