Wing Post Socket Mounting in a Rolled Motor Stick

From: calgoddard <calgoddard_at_yahoo.com>
Date: Thu, 19 Jul 2007 23:08:51 -0000

Thanks all for the advice.

I ended up determining the best estimate for the CG by mounting the
prop, putting on a 2.0 gram rubber motor and taping the wing posts
to the side of the motor stick (MS) but without flying, just
balancing the plane on a thread.

I rolled some wing post sockets, then determined the drill size that
would make the right size mounting hole. I tested the drill on some
similar balsa and determined it was sharp enough to cut through
without splitting.

I then made a drill jig with two inch long diameter brass tubes to
guide the drill. The tubes were held between two 1/16 inch balsa
sheets glued to opposite sides of a balsa frame. The tubes were
spaced apart the proper chord dimension to match up with the wing
posts. The drill fit snugly in each tube without slop but could be
easily twisted.

The drill jig had legs to grip opposite sides of the rolled MS
without damaging the same. I taped the jig to the MS after
alignment to ensure it would not rotate.

I then hand twirled the drill bit in each tube, and was able to
neatly cut through the MS. I held a piece of scrap balsa against the
bottom of the MS to ensure a clean lower hole with no break out or
cracking. When the drill jig was removed I had two aligned,
diametrically extending holes with no damage to the MS. This was
nice since it took me a few hours to make my first rolled MS.

It was then easy to glue the sockets in the MS with Duco cut 50%
with acetone. The wing posts slid into the sockets just fine. I
then put some wash in on the inboard TE of the wing.

I will see how my guess on the CG location works tomorrow when I fly
the plane for the first time.

This is pretty basic stuff for you F1D guys, but may help anyone
just making their first indoor plane with a rolled MS.

I did come in .4 grams below my target weight for the plane, and
this was made possible by use of the rolled MS. This allowed me to
use really hard wing posts. I hate it when those things break.
Received on Thu Jul 19 2007 - 16:12:20 CEST