The disc is made from a sheet of 9mm 1.9# EPP foam.
The openings are 5.75 inches in diameter, and the motors are about
230mm
apart. For the design I drew circle shapes in Photoshop and
tweaked their size and position until it all fit evenly -- see here for PDF files.
The multiple-pages version can be printed onto standard 8.5"x11"
letter-sized sheets, and the sheets trimmed and taped together.
(When printing, set "Page Scaling" to "None".) I
attached the sheets to the foam with double-sided tape and simply cut
along the lines to create the frame. (The outermost circles on
the openings are the ones to
cut along.)
The 0.9mm strips are glued (with CA) into the foam for support.
The 5.0mm x 0.6mm strips are used for the motor-mount supports, with
these lengths:
motor-mount to motor-mount struts: 5-1/16" (5.0625")
motor-mount to disc edge struts: 3"
The three "legs" on the bottom are 1.5" tall, 0.75" square, and made
from two layers of the 9mm 1.9# EPP foam. The rear fins
are made from the same EPP foam and painted blue for better
orientation in flight, with the bottom fin also serving as the rear
"leg".
I reversed the shafts on the 1811
motors to allow the props to be positioned in line with the
foam. The small grub screws on those motors need a 0.9mm
driver. That size can be hard to find; see here
for a driver; this kit has it (also here). I used a vice and the socket piece
from a socket driver to push the shafts through to the other
side. Care needs to be taken not to bend the can. The other
grub screws need a 1.3mm driver.
In my build I connected the motor mounts to the 5.0mm x 0.6mm carbon
strips with CA glue and thread, making sure that they were straight and
level. Using 3D-printed "joiner" pieces would probably work
better, so I had a friend make some; see
here for details. I glued the 5.0mm x 0.6mm
carbon strips to the foam with CA.
