Wing Manufacturing (MonoKote)

Owned by Nathaniel Li
Last updated: 2024-10-29
3 min read

This guide will focus on the manufacturing process for the wings on Project Eclipse. The wings will be made using laser cut balsa ribs, a box tube for the spar, 3d print spacers, and a MonoKote wrap. The sections will be separated into the cutting of the ribs and wrapping of MonoKote.

TBD

  • Rib attaching to rib spacers

  • Iron temp

  • Cutting guide for small (and possibly large?) cuts

  • Fixture for holding wing (this will almost def be needed for full size wing)

  • Hobby knives

Laser Cutting Balsa Ribs

The RPC’s laser cutter has a 40" x 28" (1010mm x 710) cut bed. It cuts with a kerf (cutting width) of 0.1-0.175mm so applying a negative tolerance will most likely be needed. To determine the exact fit needed for the ribs, some trials will have to be done within that range. To get it cut, email the RPC and follow their instructions (just need a DWG of the full sheet and drop off the material).

Rib Assembly and Wrapping Monokote

Instructions are from Horizon Hobby

Tools needed:

  • Sealing iron with sock

  • Box cutter (for corners and tight spaces) [Hobby knife is recommended for precision]

  • 200 and 400 grit sand paper

Before starting, sand the ribs and any other balsa pieces with sandpaper (start with 200-grit and finish with 400-grit). A smooth surface is required for MonoKote to adhere and bond evenly. Clean off the dust when finished.

  1. Place the 3D-printed spacers at along the spar with a rib between each. Glue each rib to the connecting spacers. [TBD based on updated rib spacer]

  2. Make sure all ribs are spaced properly, aligned, and the glue has fully set.

  3. Set the iron to 300°F. Make sure to put the sock on. [Need to experiment with, higher temp = more shrinkage]

  4. If there are small geometries and bends (eg. near ailerons), follow the instructions below to apply MonoKote to them before applying the main top and bottom layers. [A cutting guide with a small straight edge will probably help here]

  5. Cut and apply MonoKote to bottom of wing:

    1. Roll out the MonoKote with the adhesive (adhesive side is dull) side facing up and cut a section large enough to cover the entire bottom of the wing. Ensure it overlaps the edges by 2-3 inches.

    2. Remove the clear backing film from the adhesive side of the MonoKote.

    3. Position the MonoKote over the bottom of the wing. Start from the center and iron outward toward the edges using your sealing iron. This ensures that the film is pre-tensioned and tightly applied without wrinkles.

    4. As you iron, pull the film taut while gliding the iron in a zig-zag motion. Make sure to go over all surfaces.

  6. When the MonoKote has been applied to the bottom of the wing:

    1. Use a box cutter to trim excess MonoKote from the edges. Aim for a 1/3” (3mm) overlap along the leading edge.

    2. Go back over any seams or loose edges with the sealing iron to ensure all parts are bonded well.

  7. Cut and apply MonoKote to the top of the wing by following steps 13 and 14. Make sure to overlap the top layer over the bottom’s leading edge by 1/3” (3mm).

  8. Sealing the wings tips is the last step.

    1. It’s best to have it held down securely with weights [possibly a fixture?] so that you can stretch and heat it.

    2. You can usually pull wrinkles out by heating and stretching. Don’t go too crazy with the stretching but usually it’s pretty lenient.

    3. To trim the tips, you can use masking tape as a guide or peel back the covering back to where it will be cut and cut along the seem.