Multiplex 100" span Glider conversion to electric (cont'd)

[Frank v B]

Started this in the midst of Covid and am now handling the conversion to electric.  The original post was https://temac.ca/smf/index.php?topic=7929.0
The fuse is fibreglass.  The wings are balsa covered foam.

Conversion:
- picked a motor- A Turnigy  3536-1100 kv.  A 400 watt motor (2 or 3S).  This plane will weigh about 4 pounds so need about 280 watts (70 watts per pound).
- picked a prop.  Found a 10 x 6 folder with a 1 5/8" metal spinner.

How to:
- held the spinner at the nose and moved it back until the spinner diameter approached to fuse diameter.  Drew a line with a pencil.
- Cut the nose off with a razor saw.
- sanded the nose with a block sander until the diameters matched.
- will make a firewall using scrap balsa until it fits, then use this template to cut out the proper plywood firewall.

F.

[Frank v B]

How to make the firewall and fit the motor.

1) Make a template:  made a 3/32" thick balsa form and drilled a hole for a skewer which split the piece.  Glued it back together and braced it on the back.  Filed and sanded it until it fit.  Photo 92 and 94
2) transfer the shape to 3/16" plywood.  Cut it out.  Photo 96.  To figure out the mounting holes,  I put toothpicks in the mounting holes, trimmed them short, applied a drop of dark paint to the toothpick end and pushed the new firewall onto the coloured toothpicks. Photos 97,98.  The paint spots on the back located the holes.  Drilled them through.  Attached the motor.  Photo 01.
3) Glue the firewall in place.  Applied 5 minute epoxy to the edge of the firewall and inside the front edge of the fuse.  Pushed the motor in from the back, attached the spinner and applied two 1/16" spacers between the fuse and spinner.  Letting it cure. Photo 03

Frank

ps: had to figure this out.  A practice run.  Have to do the same with my newer purchase- a 12' span 9 pound glider that will have the same nose-ectomy to install a Power 32.

[Frank v B]

Finished!!

Note the nose is elongated (egg-shaped) with the top being higher than the diameter of the spinner. Drilled two holes for air circulation.  Small enough not to weaken the firewall...I hope.

Queue the next project, a .46 sized Mustang.

Frank