This review covers both the 24mm motor retainer and 18/24mm motor adaptor.
The 24mm motor retainer is a two piece anodized aluminum assembly consisting of a base and a screw on cap. The motor adaptor includes two pieces as well - the adaptor body and a retainer ring.
I decided to retrofit the 24mm retainer on two of my rockets with 24mm motor mounts: a Dynastar Stonebreaker and an Arapahoe-E clone.
For the Stonebreaker, I needed to remove the motor clip. I cut the clip in half and fished out the upper half of the clip. This was a bit tricky, but I was able to completely remove the clip. The exposed motor tube needed a fair amount of sanding to fit into the retainer base. Once I was satisfied with the fit, I installed the retainer base using JB Weld. I used a paper towel to remove any JB Weld that oozed into the motor tube, and I sanded the inside joint once it had dried. I test fit both a motor and the 18/24mm adaptor, and they fit perfectly!
The Arapahoe-E was a bit trickier installation since the rocket has a full balsa tailcone. After eyeballing the tailcone for a bit, I used a sharp hobby knife to remove the lower 1/2" of the tailcone. The hard part was removing only the balsa without damaging the motor tube. Once the motor tube was exposed, I sanded the end until I was able to fit the motor retainer. As with the Stonebreaker, I used JB Weld to attach the retainer base. The inside joint required only light sanding for the motor and adaptor to fit.
Both of these retrofits were not difficult at all. Installing the retainer on a new build should be easier since you wouldn't have to cut/remove parts like I did.
I left the motor retainers unpainted - I like the look of the black retainer on the end of the rocket. I rated the construction and finishing as a 4 due to the sanding and fitting required to attach the retainer. The parts themselves were a truly a 5!
I've flown the Stonebreaker twice on Aerotech's 18mm D13-4W reload. I built the motor per instructions, then inserted the adaptor into the motor mount. I then installed the motor, adaptor ring, and screwed on the retainer cap. Wow! Super simple.
I've flown the Arapahoe-E once so far on Aerotech's 18mm D13-7W reload. Same sequence of events.
Both flights were awesome! The Rocketarium motor retainer and adaptor made using the 18/20 motor super easy! Cleanup was also easy - I used baby wipes and a paper towel to clean the retainer cap and adaptor ring after the flight. I will definitely fly more reloadable 18mm motors!
The Rocketarium retainer and adaptor are a great addition to the mid power flyer's toolbox. I really like the security (knowing the expensive RMS motor won't kick out) and the ease of use (slide in motor, screw on cap). Definitely a winner!