RMS-75/3840 Reload Kit Assembly and Safety Tips

Quick answer

Assemble the AeroTech RMS-75/3840 reload kit by first gathering the required RMS-75/3840 motor hardware, then installing the forward seal disc (75FSD) and following the standard RMS loading procedure. Always verify the forward seal disc is seated properly to prevent gas bypass.

Assembly steps

1. Inspect all parts: Check the reload kit for any damage or missing components. Verify you have the propellant grains, forward seal disc (75FSD), nozzle, O-rings, and any included spacers. Missing parts will cause a motor failure; do not proceed if anything is damaged or absent.
2. Prepare the motor case: Clean the inside of the RMS-75/3840 aluminum case with a dry cloth. Apply a thin layer of AeroTech lubricant or silicone grease to the O-rings and the threads of the forward and aft closures. Lubrication prevents O-rings from rolling out of their grooves during assembly.
3. Install the forward seal disc: Place the 75FSD into the forward end of the motor case with the flat side facing the propellant grains. Press it firmly to seat it against the case shoulder. An incorrectly oriented seal disc can cause hot gas bypass and motor failure.
4. Load the propellant grains: Insert the propellant grains one at a time, ensuring they are oriented correctly per the reload kit instructions. Use the supplied spacer if included. Grains must be aligned end-to-end without gaps for proper burn progression.
5. Install the nozzle and aft closure: Place the nozzle into the aft end of the case. Screw on the aft closure hand-tight. Do not use tools. Over-tightening can damage the nozzle threads or O-ring.
6. Install the forward closure: Screw the forward closure into the forward end of the case hand-tight. Ensure it seats fully against the seal disc. A loose forward closure can cause the motor to separate from the rocket during flight.
7. Final safety check: Inspect the assembled motor for any gaps or misalignment. Confirm that the forward seal disc is not visible and that both closures are flush with the case ends. If anything looks off, disassemble and re-inspect before attempting to use the motor.

Product highlights

• AeroTech L850W-PS RMS-75/3840 Reload Kit (1 Pack) - 12850P: The AeroTech Reloadable Motor System RMS is an aluminum cased reusable motor in kit form that is assembled by the user. You will need AeroTech RMS-75/3840 motor hardware to build and complete the motor. This means you cannot fly the reload kit alone; you must own or purchase the separate RMS-75/3840 hardware set before assembly.