As you move the main mounts further forward the load on the main mounts gets
higher and higher. The reason this is so is the front mount is now called
upon to hold the front of the engine down. In effect you are cantilevering
the engine off the main mounts. The loads on the main mounts are now
the sum of the engine weight plus the tension loads in the front mounts.

Perhaps the approach you should take in the Glass Goose is use one
large rear mount as far back as you can get it and two widely separated
front mounts using the 12A front cover to react the prop torque.
The single rear mount will then accept only 90% of the engine weight.
Beef up the structure a bit if the skin is thin in that area.

In that case you cpuld  use a Barry Controls 2003-12 for the rear mount.

Paul Lamar

The approximate pylon dimensions are: 16" wide (I.D.) at the aft
end of the 13B block, and down to a max of 14" wide at the
motor plate location.  (The engine sits higher than the pylon, so
width higher up is not an issue.)  Going farther forward,
there is 24" at the center of the engine.  My structural engineering
buddies say that a cantilevered bridge supporting the motor
plate area should be possible, going forward and down to the
lower wing shear web for vertical support.  However it would only
be 14" wide, giving two mounts a maximum of about 11" center-to-center.
Is this wide enough to be considered for two mounts?
If not, as Paul suggested, the motor plate area can only support a single mount.

If a single rear mount is used, how wide apart should the
forward mounts be?  As wide as possible?  Would 1"x2" 6061  be
adequate for a forward beam from the case to two mounts?

Scott Gettings

Do you have any pictures of the motor mount area Scott?
The official Glass Goose web site crashes my browser.
No way to run a business. They should fix the web site.

Do you know how to capture pictures off the web?
In NS you put the mouse pointer on the picture and press the
right mouse button and select "Save Image As.."
Find and send some pictures to me and I will do a 3D on the
motor mount.

Paul Lamar

Thanks VERY much, Paul.   There are no such drawings on the web site, 
and the plans don't include detailed drawings in this area
of the plane.  I'll check with the mfg. to see if they can
 supply such, or I'll develop much more detailed drawings from actual
measurements and send them.

Scott Gettings

 
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