I think if using the beam, then the mounts on the front of the engine
need to do a more substantial job of bracing against such gyroscopic loads.
...Chrissi

Cozy Mk-IV 13B Turbo
www.CozyGirrrl.com
Chrissi@BlueMountainAvionics.com

I don't follow you Chrissi. Can you be a bit more specific about
"more substantial job".

A 5/16th AN bolt with an area of .0767 has a tensile strength
of about 11,000 pounds at a stress level of 150,000 psi.
So 300 ft pounds would only stress the bolt to about 4,000 psi.
A couple of 1/4 inch bolts per side would distribute the stress
in the sheet metal joints better.

If the oil pan walls are made from .065 aluminum a section two
inches wide would have an area of .13 square inches.
The concentrated load of the bolt is distributed into
the sheet metal oil pan sides by the welded on aluminum
angle clip.

300 pounds tensile  / .13 area is a tensile stress in the
aluminum pan side walls of 2,300 psi. Not much.

I'm saying there is less likelihood of the gyroscopic twisting force resulting in stress on the
beam mount screws if the front of the engine is adequately braced to prevent such movement.

In

other words, don't take the front mount lightly. Someone may look at the beam mount

solution and

think there is only need to brace the front  to prevent up and down movement.
...Chrissi

Cozy Mk-IV 13B Turbo
www.CozyGirrrl.com
Chrissi@BlueMountainAvionics.com

The down load is by far the greatest load applied due to landing and
high G maneuvers. 6 G's or 1800 pounds download. Up load too if you are 
into high negative G aerobatics.

The 60 degree per second gyro loads are severe for gyro loads as 
that is what you would get with an accelerated stall, a spin or 
falling out of the top of a loop with insufficient airspeed.

Therefore the dual 5/16 bolt solution is a conservative solution
to the gyro load scenario on a Schertz beam.

If you want to see something scary here is the stock motor mount
for a Long EZ. Note the two 1/4 inch bolts through the 1 by 1 aluminum
angle holding the entire motor mount and engine to the airplane.

In a 6 G landing or pull-up each joint is taking about 1800 pounds
tension on the top and compression on the bottom as the vertical
spacing is only about a foot and the CG of the engine and prop
is probably two feet away from the firewall. The moment of the Lyc engine
about the firewall is 2 feet times 6 G times the 300 pound weight
of the engine or 3600 foot pounds. total tension at the top 3600
pounds. Total compression on the bottom is 3600 pounds. 1800 pounds each 
mount not counting shear load. Shear load is 1800 pounds total 
or about 450 pounds each mount.
 

Paul Lamar
 
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