Devin W.C. Ryan

Building 4 Star 60 Day 18: Aileron Edge Sanding & Servos

Last night started with a bunch more sanding.  I rounded the trailing edge of both ailerons and bevelled the leading edges.  Peter already had a line made as to how far down I could for the bevel.

To bevel it I performed similar steps I did with the rudder.  Started by taking two passes with a tool that shaves off the wood, making sure to hold it at a 45° angle to start getting the bevel look. I then used a piece of sand paper that was wrapped around flat wood to go back and forth, holding at the same angle, until I sanded to the line on both sides of the edge.  Then repeated for the other aileron.

For the trailing edge of the ailerons I had it in the vice and held a loose piece of sand paper against the sides of the aileron with my thumbs rounding the paper and moving in a motion side to side as well as up and down the length.  I started with rougher sand paper and then fine to complete the look with a smoothly rounded finish.

The next thing I did was cut four hatch rails from the special-cut 1/4″x1/2″x16″ basswood stick provided in the kit.  As you can tell in the pic below there is a little ledge and this is where the servo hatch will be recessed and screwed into.  Each rail (except for the one I screwed up) is cut from the same basswood stick to be a bit over 3.5″ and then sanded until it fits snug.  Once I had them fitted we glued and clamped them into place.  For the one I screwed up (cut it too short… even measured twice, just had the wrong length in my head!) we had to cut a little piece of the excess to make up the difference.  We glued the longer piece of the two into place last night and then Peter was going to fit and glue the little piece into place before our next session.

Hatch Rails Glued
Hatch Rails Glued

Lastly for the day I worked on the servos themselves.  Since this is my first build, my LT40 is an ARF, I got to learn the process of assembly a new (unboxed) servo.  The steps involved here were:

  1. Take out the Phillips screw holding the control horn on
    • Came with a rounded one with holes that wouldn’t work well for my scenario
    • Make sure not to loose the screw as they’re specially threaded and hard to find replacements!
  2. Pull off the ’rounded’ control horn that came with
  3. Put on the appropriate control arm
    • The horns are geared on one so make sure they line up when pushing on
    • The other end is flat & recessed a bit for the screw
  4. Secure with the specially threaded screw (removed earlier)
  5. Place the rubber (for shock absorption perhaps?) pieces into the 4 slots (2 on each mounting flange)
    • Make sure rounded end that sticks out is facing out

Once the servo was assembled the next step was to cut four 3/8″x1/2″x7/8″ pieces out of the 3/8″x1/2″x6″ basswood to use as aileron servo mounts.  Using a 1/32″ shim, the size of the aileron servo, I laid the servo down on the shim and stood the basswood mounts on end against the servo.   Using one of Peters tools I marked the location of the servo mounting screws and then drilled four 1/16″ pilot holes for the screws through the pieces.  Next I used screws provided by Peter (as he doesn’t like the ones provided) to attach the servo mounts to the servos.

We mounted the servos to the hatch cover by gluing the servo mounts (on the side that allowed the servo to be raised off the hatch cover a bit to protect against vibrations) to the hatch cover and then clamping.  When doing this need to ensure:

  • Have one for the left and one for the right wing (it’d be an oopsy to have two for the one wing!)
  • That the control arm is in the center of the slot in the hatch cover both length wise and width wise
    • Peter already marked the center length wise

You can see a picture of the servos mounted to the hatch covers below.

Servos assembled and mounted
Servos assembled and mounted

This concluded another night of building as we got as far as we could, so it was time to crack out the tea :).  I’m looking forward to our next building session as we are moving at a comfortable pace and the aircraft is really starting to take shape!

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