The 24mm motor retainer sets include instructions. More elaborate instructions are provided here, for those who prefer lots of pictures. The retainers are precision-machined from aluminum and are anodized. They are made in the USA. They can be used with Estes D/E motors and Aerotech 24mm RMS reload and single use motors. For model rocket motors with a thrust ring, no engine block is needed. For other motors, you can install a motor block, or friction-fit the motor.

Installation for a new model rocket

The Rocketarium motor retainers can be used with Estes-style BT50 tubes and other 24mm motor tubes, such as Aerotech, LOC, and others. The retainers will easily slide onto Estes-style tubes. For others, you may need to sand the bottom 1/4" until a fit is achieved. Before sanding, you can mark the motor tube at 1/4" and add a wrap of masking tape. This can prevent sanding where no sanding is needed.

For Estes-style types, simply rough up the tube, removing some of the glassine, using 60-80 grit sandpaper. For other tubes, sand with 60-80 grit sandpaper until a good fit is achieved. The fit should not be too tight. A fit that is too tight could deform the motor tube. To test the fit, slide the retainer body onto the tube and insert a motor. The motor should slide in and out easily.

Apply a thin layer of high-temperature epoxy to the inside surface of the retainer body section that slides onto the motor tube.

Apply a layer of high-temperature epoxy around the sanded part of the motor tube and remove the masking tape. JB Weld epoxy (15 hour cure) is recommended. Follow the directions provided with the epoxy for correct mixing of resin and hardener.

Install the motor retainer body. Remove any excess epoxy. Partially insert a rocket motor to ensure the fit is correct. Remove the motor and set aside. Let the epoxy come to a full cure. Once the epoxy is cured, continue building the rocket as usual. Install the aft centering ring and then the forward centering ring. Glue the motor mount into the rocket.

Installation for an existing model rocket

The motor retainer body requires 1/4" of motor tube sticking out of the rocket. More is OK, less may not allow for a secure bond.

Start by removing the motor hook. If the motor tube is painted, sand away the paint.

If needed, sand the motor mount to ensure a proper fit with 60-80 grit sandpaper.

Also rough up the inside surface of the motor retainer body with 60-80 grit sandpaper. Sand only the area that slides onto the motor tube. Note that you are not trying to increase the diameter. Merely rough up the smooth surface for a better epoxy bond.

Apply epoxy and install the retainer body.

Notes

Each 24mm model rocket retainer set will add 7 grams (+ the weight of the epoxy) to the aft end of your rocket. This will affect the stability margin of the rocket. Nose weight may be needed to ensure stable/safe flights.