This year at FF I encountered a lot more people wanting to get into more complex builds. My discussions around this topic was mostly about HOW to do repairs. Most basic FTers have what I, and most everyone else, call "disposable airframes. Yes, they can be repaired with hot glue and tape but only to a point when to when it is no logner safe to fly or you crash it so hard it's just easier to make a new one. There are building tips and tricks a bit more specific to making repairs that I've never really captured.
Rather than digging up the old build threads, I'll condense all of my repairs here and go through the rationale for doing what I do to keep my models in the air. I hope there are lots of questions and, as always, I welcome feedback on what I do.
To kick this off, I'll start with the Sikorsky S-39. This airplane was scratch-built from foam on-site at Flite Fest 2015. She still does fly exceptionally well but there are a few rashes she has taken over the years. Namely, the landing gear. While the airplane is foam, I built the landing gear mounts as ply plates that seat into the foam with gorilla glue. A few years ago, I noticed that the top of the battery hatch was collapsing the foam over time so I put a carbon fiber tube as a cross brace to keep the top of the main gear mounts at the proper distance. It worked very well. Then I started breaking the gear off entirely.
The one side has had the gear rip out (the ply plate) several times on even the softest of landings. There is just not enough surface area to keep them in securely. After re-applying the ply plate, I drilled a hole in the middle of the ply plate on both sides. I ran a threaded rod through each side and cut the rod to length. Each end was secured on the outside using a lock nut. You can see these nuts below.
In this picture you can see the threaded rod on the bottom and the carbon tube at the top. There is no interference with the battery location. These structural components will firm up the gear but the oleo suspension should take more of the brunt of landings. Again, the top carbon spar prevents the top of the gear from collapsing inward, and the bottom threaded rod prevent the bottom gear mounts from ripping out.
The last bad landing also tore away the tail spine that mounts the steering wheel/rudder. I simply glued that back in with gorilla glue and used my usual aluminum ducting tape to prevent the foam from expanding where I did not want it to.
After spreading a bit of yellow paint on the ugly parts, she was on her legs and ready for another pleasure flight. I hope to get her in the air again tomorrow.
Rather than digging up the old build threads, I'll condense all of my repairs here and go through the rationale for doing what I do to keep my models in the air. I hope there are lots of questions and, as always, I welcome feedback on what I do.
To kick this off, I'll start with the Sikorsky S-39. This airplane was scratch-built from foam on-site at Flite Fest 2015. She still does fly exceptionally well but there are a few rashes she has taken over the years. Namely, the landing gear. While the airplane is foam, I built the landing gear mounts as ply plates that seat into the foam with gorilla glue. A few years ago, I noticed that the top of the battery hatch was collapsing the foam over time so I put a carbon fiber tube as a cross brace to keep the top of the main gear mounts at the proper distance. It worked very well. Then I started breaking the gear off entirely.
The one side has had the gear rip out (the ply plate) several times on even the softest of landings. There is just not enough surface area to keep them in securely. After re-applying the ply plate, I drilled a hole in the middle of the ply plate on both sides. I ran a threaded rod through each side and cut the rod to length. Each end was secured on the outside using a lock nut. You can see these nuts below.
In this picture you can see the threaded rod on the bottom and the carbon tube at the top. There is no interference with the battery location. These structural components will firm up the gear but the oleo suspension should take more of the brunt of landings. Again, the top carbon spar prevents the top of the gear from collapsing inward, and the bottom threaded rod prevent the bottom gear mounts from ripping out.
The last bad landing also tore away the tail spine that mounts the steering wheel/rudder. I simply glued that back in with gorilla glue and used my usual aluminum ducting tape to prevent the foam from expanding where I did not want it to.
After spreading a bit of yellow paint on the ugly parts, she was on her legs and ready for another pleasure flight. I hope to get her in the air again tomorrow.