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Willsonman's Repair Log

willsonman

Builder Extraordinare
Mentor
#1
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.
IMG_6817.JPG IMG_6815.JPG

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.
IMG_6816.JPG

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.
IMG_6818.JPG

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.
IMG_6819.JPG
 

willsonman

Builder Extraordinare
Mentor
#2
Next up is the SE5a (1/6 scale) that was built in 2014. She is made entirely from DSFB but I ripped all the paper off and did all the fun scale things. I flew her back in the early spring but quickly discovered that her rudder servo needs to be replaced. Its a bit of a chore but it is next on the list.
IMG_6820.JPG
 

JimCR120

Got Lobstah?
Site Moderator
#3
There is a nice aspect about the process of crashing and gluing numerous times other than the learned craftsmanship in repairing and desire to stop needing repairs; but when the rebuilding of a new frame does happen it's oh so clean and light, quite spiffy looking.... until that next crash of course.
 

willsonman

Builder Extraordinare
Mentor
#4
Well we are the end of another weekend and I have a report!

The Sikorsky flew without a hitch, as usual. She is so graceful and never wants to go fast with all the drag from the spar work. She went up 4 times and never had an issue... until the last landing. There was another club member with a quad and he wanted to do some chase practice. Well, right as I was landing his quad distracted me and I landed at too steep of an angle. It was not a bad thing. This showed that my lower rod was doing the work. The ply plate ripped free slightly as it broke right on the spot where the spar protrudes. No big deal. A new ply plate and It will be right as rain. Probably about 30 minutes of work.

The SE5a flew great but she lacked a lot of aileron authority. I ended up using a lot of rudder to compensate and this is not exactly the safest of situations. I think the wings have just warped and mounts have worn over the years so I think I will retire her. I hate flying unsafe airplanes. Its just as well too, the landing was looking great and then the grass touched the wheels and over she went. Broke the V-stab and rudder. I'll gut the electronics and hang her on the wall. She is still nice to look at and a reminder of how far I've come in my scale building.
 

willsonman

Builder Extraordinare
Mentor
#6
After flying the Spacewalker more, I've decided to change props. The 14x7 on the ExceedRC Monster 46 motor was working great but lacked the speed to carry through rolls and immelmans. According to eCalc, a 12x10 should give me an additional 10MPH while giving me another minute of flying time. One is on order and I believe this will be the final power setup for this airplane.
 

willsonman

Builder Extraordinare
Mentor
#7
I've also re-built the Cuda's broken wing. I realized that my power issues at SEFF were due to a magnet being thrown in the funfighter motor. I've heard of this happening and I was not surprised. I attempted to repair it but after just one flight it got thrown again. I've been looking all over for a suitable replacement that would not require me to change the ESC (30A YEP). I've been hearing good things about the Xnova motors in the quad community so I thought I would give it a shot. The funfighter motor is 1950kV and a 2000kV is about right. The current limits seems good. I'm getting more familiar with the FT store and being able to find the right motor comes down to knowing what you are looking for and using key search terms. I do have concern that the motor does not come with an X-mount but I'm hoping that the one I have for the funfighter motor will work. If not, I'll make something. I'm also concerned that the smaller dimension will mean I'll need to use a spacer to keep the 6x4 prop clear of the vertical stab. All challenges that can be easily worked.
 

rockyboy

Skill Collector
Mentor
#8
I've also re-built the Cuda's broken wing. I realized that my power issues at SEFF were due to a magnet being thrown in the funfighter motor. I've heard of this happening and I was not surprised. I attempted to repair it but after just one flight it got thrown again. I've been looking all over for a suitable replacement that would not require me to change the ESC (30A YEP). I've been hearing good things about the Xnova motors in the quad community so I thought I would give it a shot. The funfighter motor is 1950kV and a 2000kV is about right. The current limits seems good. I'm getting more familiar with the FT store and being able to find the right motor comes down to knowing what you are looking for and using key search terms. I do have concern that the motor does not come with an X-mount but I'm hoping that the one I have for the funfighter motor will work. If not, I'll make something. I'm also concerned that the smaller dimension will mean I'll need to use a spacer to keep the 6x4 prop clear of the vertical stab. All challenges that can be easily worked.
Interested to hear how this motor will work out for the Cuda - I'm looking for something a little hotter in mine. I smoked a PowerUp Zoom 400 motor in my Cuda earlier this summer (I thought it could handle a 4s... sadly not)
 

willsonman

Builder Extraordinare
Mentor
#9
Went out last night for a quick flight with the Cuda. The motor performed perfectly and came down just a touch on the warm side but nothing bad at all. I think it is a perfect match for this airplane. I did have to use a couple of 1/2" nylon standoffs that I picked up from the Home Depot. I found them in the drawers and were less than a dollar each. Longer screws too but it worked great. The X-mount from the funfighter was a perfect fit with hole alignment on the motor. Again, the motor is here:
https://store.flitetest.com/xnova-hypersonic-22072000kv-fpv-racing-motor-1-xnm-2207-2000-1/p544894