Mark bought a foam Corsair at a swap meet for a song. It has had issues with limited power output and a perpetually loose motor mount.
1) Limited Power output- 1) one magnet appears to have been chipped and the piece was loose inside the
bell. See green arrow photo 29.
2) one of the 3 wire connectors broke off. It looks about 2/3 of the strands
had broken off. It could have broken during the less than perfect landing on
its last flight. See green arrow photo 32.
2) To secure the motor- Mark had built up a plywood structure to secure the motor but it still shook itself loose.
My approach: secure Mark's reinforcement with fibreglass and epoxy and spread the load significantly via the full circumference of the large round fuselage.
step 1- take off the motor and the metal motor offset. photo 28.
step 2- dig out the firewall so it is flush with the plywood plate. Used an #11 blade. photo 30, 31.
step 3- apply diluted epoxy to the plywood and the foam around it to seal off the foam. Photo 34.
step 4- add fibreglass cloth over the entire circular firewall: foam and plywood. Add a second layer if more stiffness is required after the first layer has cured. Still to be done.
Frank
Glassing.
- add a drop of oil to the screw hole so errant epoxy will not stick to it. photo 35
- put a toothpick in each screw hole.
- cut the fibreglass cloth to size.
- add the fibreglass cloth and brush on diluted 5 minute epoxy (thinned 50% with rubbing alcohol).
Photo 37
- put the metal motor mount back in place over the toothpicks so the glass stays flat while it cures.
Photo 38
- fill the entire area with epoxy to strengthen. (reduce flex)
Frank
Installed the motor mount onto the firewall. The open structure allowed the aluminum bracket to rock left and right (rack). To stop this I added a bit of 3/32 ply (photo 39) inside the bracket opening (photo 40). It firmed it up dramatically.
Oh, yes. Re-soldered the bullet connector that broke off.
Motor mount done. Now have to check the retracts that do and don't at the wrong time. :)
Frank