Scott Gettings wrote:

Do you have any pictures of the motor mount area Scott?

Here are the second set of pictures, of another builder's 13B Glass Goose engine mounts.

Scott Gettings

This will work great. Just copy this exactly.

Paul Lamar

OK, thanks VERY much.  I'm planning on building a test specimen for at 
least the (middle) bridge mount.  Should I allocate 1,800
lbs or perhaps more at this location?  I can test a specimen 
much easier than loading the plane and installed mounts itself --
and it won't hurt to break it!

If Rick Girard is following this thread, please contact me regarding 
your 12A front cover if it is still for sale.  Thanks to
all.

Scott Gettings

The worse case download on the engine CG due to dropping it in from ten feet or
so may be 6 G. So if the all up engine weight with gear box and prop
is 300 pounds that is 1800 pounds total at the engine/PSRU/prop CG. 
If you use one mount aft and two mounts about in the middle The aft 
mount takes 1000 pounds and the two middle mounts roughly 400 pounds 
each. That assumes the prop is not generating any torque reaction 
which will add and subtract from the loads on the center mounts. 

With the four mount systems things become a little less determinate 
as it now depends on the hardness of the various rubber bushings 
as to the loads they see. The thrust load from the prop will
cause the engine to rock forward so that front mount may see
more load under those conditions and the rear mount less.

Size the rubber bushings according to the static load distrubution 
and they will take that 6G worse case download in stride.

My guess is about 100 pounds each for all the rubber bushings.
 
Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2003 All world wide rights reserved.