REDUCE VIBRATION DAMAGE ON YOUR RC PLANE’S COWLING

Whether your cowling is plastic or fiberglass, it suffers from the effects of
vibration, especially at the attachment points. With replacement cowlings
costing $50.00 or more on many planes, a little effort here will reward you in
extra life for your cowlings. Nothing will totally eliminate the problem, but
these few things will definitely reduce vibration damage significantly.
1) Always make sure your prop is properly balanced-stop vibration at it’s source
whenever possible.
2) Use rubber bonded washers at the attachment points. I use the #4 size for
most cowlings, with #2 or #4 screws. On the larger gas powered planes I use
the # 6 washers-see picture #1. The rubber backing bonded on the washers
absorb much of the vibration at the attachment points. They are available at
microfasteners.com, in bags of 20 for about $4.oo.
3) You can strengthen the cowling by attaching small ply disks inside your
cowling at the attachment points (picture #2). I use round disks rather than
squares, to prevent stress points that might occur at the corners of the
squares.
I like to use 1/32 ply, and use a hole saw I made from ½ inch brass tubing to
cut the disks. To make the hole saw, just sharpen one end of the tubing by
running a #11 Xacto blade around the inside edge of the tube. Although not
totally necessary, you can then use a ziz wheel on your Dremel to cut small
teeth in the end of the tube- this makes the cutting a little easier. If you have
access to a drill press, you can cut any number you need in a matter of
minutes. (picture 3)
Fit your cowl and drill holes for the attachment screws as you do normally.
Then take the disks, and epoxy inside the cowling at the screw holes. If the
cowl fits tightly, you may have to sand a small amount of material from the
attachment blocks. Re drill your holes through the ply disks and attach the
cowl.