Peter Cowan/Lexy Cameron wrote:

the bending moment created by my airplane hung on a davit 8' from the

wall? I want to be able to

do float installation and removal.
If you can discuss details with me contact me at: peterc@pipcom.com
Many thanks

Somebody will need a drawing of the garage Peter.

Actually all you need is a column inside the garage,
two  holes in the wall and cables anchored in the ground
out side the back of the garage. Got eight feet of clearance
behind the garage?

Hello Paul.
Here is roughly what I'm proposing.
The 2x4 and 2x2 steel tube is sitting around here. The 750 lbs at 92" will
handle my S7 lifted at cg while the 1500 lbs would do a rotary 170 from the
engine mount.
Thanks for any suggestions you may have.
Peter
peterc@pipcom.com

Oh OK I see. I thought the airplane was inside the building.
I was wrong.
 
The short answer is the building is not designed for that load.
The long answer is it depends on how well the sheet metal siding
is fastened to the studs and how well the studs are fastened to
the sills.

What you have there is a 2,600 ft pound bending moment around the point
where the crane arm is fastened to the column.

I would skip weld two pieces of the 2 x 4 steel tube together to form 
a 4 x 4 column and move it over to the corner of the building.
You will have to brace it in bending with a truss.
You might be able to weld enough steel to the column to take
this bending moment but a truss is the safe way to do it.

Attach it to the corner of the building as far up as you can.
Eight or ten feet. That will stabilize it lateraly. Then brace it from the 
top of the column on the outside of the building with a steel cable 
and anchor it at least 12 feet behind the the column more or less 
in a plain parallel with the building wall.

You can then use the 2 x 4 steel tubing for the crane arm
with a cable running at a 45 degree angle three or four feet up 
to the top of the column.

Better yet here is my suggested sketch along with your sketch.
You can use steel tubing or chain for just about everything where cable
is called out with perhaps the exception of the long cable
running 12 feet back along side the building.
The loads in the cable are roughly up to 1200 pounds.

Paul Lamar
 
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