Post by gugie on Dec 27, 2013 16:49:02 GMT -4
Retract mounting platform:
I’ve spend the last couple of days working on the landing gear supports in the wing. Since we had to move the retracts out by an inch (Which left me without a support to attach the outer screws to) I was going to just epoxy in a short 3/8” x 3/8” hardwood piece to fill the gap and then sandwich this by several 1/16” strips of plywood.
The problem is that there was only one wing rib support on the inside of the wing and this was close to the wing root which wasn’t going to do much good. So this ended up being a lot more work than I thought as I had to remove all of the old retract plywood rails and then build up some wing rib retract rail supports. This was a huge challenge as it was not easy to get inside this small area. I used a Dremel metal cutoff wheel to cut away the exposed wood rails and then a bigger cutoff wheel to cut away the rail from the wing skin. This took about 4 hours for each side to remove these pieces. This kind of work should be reserved for surgeons as I blotched it in a couple of areas. Luckily it’s in an area where no one can see it. Here’s what it looked like after removing the rails.
Here’s a view from inside the wing looking up at the inside edge of the top wing skin. You can see a small amount of wood remaining which I left in place as there is a thin layer of wood skin inside the wing.
Next I cut a new ¼” plywood retract mount. I used a sheet of plywood instead of just rails as I thought it would be stronger and I could better leverage the support rails I was going to make. The small notches in the opening are for the retract motor support rod ends that stick out slightly on the sides of the retract. See red circles on second picture. The cutout for the retract unit is a good snug fit.
This mount was then clamped inside the wing and the opening was then marked. The retracts were then located with mounting holes marked and drilled.
I then added blind nuts to the backside and had to trim one side as this stuck out into the opening.
Next I had to make some retract wing rib supports. So again I had to get my fat fingers inside the wing to get some measurements in order to make sure these ribs fit snuggly, sooooo.... you guessed it my measurements weren't exactly accurate. I went through one sheet of 1/8 x 4” x 12” of lite birch plywood before I had rib supports that fit. I used nice (cheap) machinist tools that I got at Harbor Freight.
Problem was that these tools didn’t exactly fit inside the wing so it took several trial pieces before I had pieces that actually fit
I ended up making three pieces. One that went on the inside edge of the wing root rib and the other two are centered between the two blind nuts on the retract mount. Since the retract mechanism almost touches the other wing skin on the opposite side I couldn’t make this one piece like I wanted to so had to split this support rib into two pieces.
The notches on the one inner support rib are for the plywood retract tray with the circular notch being needed to clear the landing gear strut when retracted. The notches on the two outer support ribs are to clear the plywood mount as well as the wood inner wing skin.
Here’s how the two outer supports sit inside the wing:
Here’s how the one inner rib support looks:
Today I’m going to try and glue in one side. I’m a little concerned as all I have is 30 minute epoxy. I thought I had 60 minutes but can’t seem to find it. If this doesn’t set perfectly the wheels will not retract properly and I’m worried that the glue will start to set before I have a chance to set everything.
Will keep you all updated.
I’ve spend the last couple of days working on the landing gear supports in the wing. Since we had to move the retracts out by an inch (Which left me without a support to attach the outer screws to) I was going to just epoxy in a short 3/8” x 3/8” hardwood piece to fill the gap and then sandwich this by several 1/16” strips of plywood.
The problem is that there was only one wing rib support on the inside of the wing and this was close to the wing root which wasn’t going to do much good. So this ended up being a lot more work than I thought as I had to remove all of the old retract plywood rails and then build up some wing rib retract rail supports. This was a huge challenge as it was not easy to get inside this small area. I used a Dremel metal cutoff wheel to cut away the exposed wood rails and then a bigger cutoff wheel to cut away the rail from the wing skin. This took about 4 hours for each side to remove these pieces. This kind of work should be reserved for surgeons as I blotched it in a couple of areas. Luckily it’s in an area where no one can see it. Here’s what it looked like after removing the rails.
Here’s a view from inside the wing looking up at the inside edge of the top wing skin. You can see a small amount of wood remaining which I left in place as there is a thin layer of wood skin inside the wing.
Next I cut a new ¼” plywood retract mount. I used a sheet of plywood instead of just rails as I thought it would be stronger and I could better leverage the support rails I was going to make. The small notches in the opening are for the retract motor support rod ends that stick out slightly on the sides of the retract. See red circles on second picture. The cutout for the retract unit is a good snug fit.
This mount was then clamped inside the wing and the opening was then marked. The retracts were then located with mounting holes marked and drilled.
I then added blind nuts to the backside and had to trim one side as this stuck out into the opening.
Next I had to make some retract wing rib supports. So again I had to get my fat fingers inside the wing to get some measurements in order to make sure these ribs fit snuggly, sooooo.... you guessed it my measurements weren't exactly accurate. I went through one sheet of 1/8 x 4” x 12” of lite birch plywood before I had rib supports that fit. I used nice (cheap) machinist tools that I got at Harbor Freight.
Problem was that these tools didn’t exactly fit inside the wing so it took several trial pieces before I had pieces that actually fit
I ended up making three pieces. One that went on the inside edge of the wing root rib and the other two are centered between the two blind nuts on the retract mount. Since the retract mechanism almost touches the other wing skin on the opposite side I couldn’t make this one piece like I wanted to so had to split this support rib into two pieces.
The notches on the one inner support rib are for the plywood retract tray with the circular notch being needed to clear the landing gear strut when retracted. The notches on the two outer support ribs are to clear the plywood mount as well as the wood inner wing skin.
Here’s how the two outer supports sit inside the wing:
Here’s how the one inner rib support looks:
Today I’m going to try and glue in one side. I’m a little concerned as all I have is 30 minute epoxy. I thought I had 60 minutes but can’t seem to find it. If this doesn’t set perfectly the wheels will not retract properly and I’m worried that the glue will start to set before I have a chance to set everything.
Will keep you all updated.