Quick Answer

Assemble the 5.5" IRIS by dry-fitting the fin can, adapting the motor mount to your chosen motor size, then epoxying and filletting for a strong, straight build.

Why Build Order Matters

The 5.5" IRIS uses a LOC N FIN/RING system that locks fins in place, so the order of assembly directly affects alignment. If you epoxy the motor mount before dry-fitting the fin can, you lose the ability to adjust fin position without fighting the adhesive.

Take time to test-fit everything before mixing epoxy. This kit is designed to be adaptable, but only if you plan the motor mount size before you glue.

Choosing Your Motor Mount Size

The stock 75mm motor mount suits most high-power flights, but the IRIS adapts down to 54mm or 38mm with additional adaptors. Decide early based on your motor availability and expected performance. A 75mm mount gives you more thrust options, while a smaller mount reduces weight for lower flights.

If you plan to fly smaller motors, install the adaptor during assembly rather than after, to avoid unnecessary disassembly later.

Assembly Steps

  1. Dry-fit the fin can: Slide the fin can and fins onto the booster without glue to confirm alignment. Mark fin positions with a pencil. Check that all fins sit flush and square before any adhesive.
  2. Adapt the motor mount: If using a 54mm or 38mm motor, install the adaptor into the 75mm mount now. Epoxy the adaptor in place and let it cure fully. Ensure the adaptor is centered so the motor sits straight.
  3. Epoxy the motor mount: Apply epoxy to the inside of the airframe and insert the motor mount. Use a centering ring to keep it perpendicular to the airframe. Check that the mount is square before the epoxy sets.
  4. Attach the fin can: Slide the fin can over the booster, aligning with your pencil marks. Epoxy it in place, then add small external fillets at each fin joint. Wipe away excess epoxy before it cures for a cleaner finish.
  5. Cure and inspect: Let the assembly cure for the full epoxy time, then inspect all joints for gaps or weak spots. Add extra fillet material if needed. A thorough inspection now prevents failures at the pad.

Product Facts

  • 5.5" IRIS: Stock 75mm motor mount; easily adaptable down to 54mm or 38mm with additional motor mount adaptors. You can match the motor mount to your preferred motor size without modifying the airframe.

    5.5" IRIS

    5.5" IRIS

  • 5.5" IRIS: Construction details include a LOC N FIN/RING system that assures alignment is a breeze and sturdier than ever. The fin ring locks fins in place, so you get straight, strong fins with less measuring and clamping.