Quick answer
Assemble the AeroTech RMS-75/7680 motor hardware by lubricating the closures, installing the forward seal disc, and threading the aft closure. Reload kits are sold separately and are not cross-compatible with mid power RMS products.
Why this hardware set matters
The AeroTech RMS-75/7680 Complete Motor Hardware Set includes the aluminum case, forward seal disc, forward closure, aft closure, and Super-Lube grease. This reusable hardware supports 75mm high power reload kits, but the reloads themselves are not included—you must purchase them separately.
One common confusion: High Power RMS reload kits (75mm) are not compatible with Mid Power RMS products (e.g., 29mm or 38mm). Always verify the reload kit diameter and length match the hardware before assembly.
Assembly steps
- Lubricate the closures: Apply a thin layer of Super-Lube grease to the O-rings on the forward and aft closures. This ensures a proper seal and prevents the closures from seizing in the case after firing. Too little grease causes leaks; too much can attract debris. Use just enough to coat the O-ring surface.
- Install the forward seal disc: Place the 75mm Forward Seal Disc into the motor case from the forward end. Ensure it sits flat against the internal shoulder. This disc contains the propellant grain and prevents hot gas from bypassing the nozzle. If the disc is cocked or missing, the motor may fail to pressurize correctly. Double-check it is fully seated.
- Thread the forward closure: Screw the forward closure into the forward end of the case. Hand-tighten firmly—do not use tools. The closure holds the seal disc in place and seals the forward end of the motor. Over-tightening can damage the threads or O-ring. Stop when you feel firm resistance.
- Insert the reload kit: Load the 75mm high power reload kit (sold separately) into the case from the aft end. Follow the reload kit’s instructions for grain stacking and nozzle placement. The aft closure will secure everything. High Power RMS reload kits are not compatible with Mid Power RMS hardware. Verify the reload label says 75mm before assembly.
- Install the aft closure: Screw the aft closure into the aft end of the case. Hand-tighten until snug. The aft closure holds the nozzle and seals the rear of the motor. A loose aft closure can cause a blow-by during ignition. Check that it is snug but not over-tightened.
Product facts
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AeroTech RMS-75/7680 Complete Motor Hardware Set - 7576M: Includes aluminum motor case, 75mm Forward Seal Disc, 75mm Forward Closure, 75mm Aft Closure, and 1cc Super-Lube grease. You have all the reusable components needed for multiple flights; only the reload kit (propellant grain and components) must be bought each time.
AeroTech RMS-75/7680 Complete Motor Hardware Set - 7576M
