Paul, I did the static load test on the S-beam today. I tested
two S-
beams using identical loads of 1700 lbs. I got this figure by
weighing just the front end of my truck on a commercial scale. The
total came to 3400 lbs. So one wheel should be 1700 lbs.
Both S-beams were fully notched to clear the dampner . One beam
had the reinforcing strips which in this case were .5"x .125" x 12"
304 SS. This beam was somewhat arched (low in the center) by the
welding. It is a junk beam and I did not feel the need to build a
fixture to hold it straight while welding. Also, it was welded in
one long pass on each side which is guaranteed to produce some
distortion. With a fixture and alternating short welds, there would
be no distortion.
The beams were stretched across small pieces of 1 x 3 plank at either
end and the truck wheel was lowered on to the center of the beam
using the fixture you designed to put the weight on the bolts. We
used mechanics clay to measure the amount the beams sagged under the
weight. I wish I had taken a picture but you can get the idea.
The reinforced beam sagged exactly .063 under the weight of the
truck. The beam without reinforcement sagged somewhat more at .145
inches. Both beams returned to their original shapes when the
weight was removed.
I am looking forward to your interpretation of these numbers. In
particular I am very happy with the performance of the unreinforced
beam as it seemed to be more than strong enough for our purposes.
That is just me guessing, of course. The last photo shows exactly
how the finished notch looks. There is plenty of material left on
both of the top flanges. Jerry
The deflection is of no consequence unless the beam does not
return to its original shape. 1700 pounds is a severe test and
only likely to occur if the airplane is drooped in from ten feet
or so. Also a 6G pull up where something else is likely to fail
first.
Great work. Looks like we over did it a bit on the reinforcement:)
Thanks again Jerry for all your help. Motor mounts
are one of the key items to make a successful rotary engine
installation.
Paul Lamar
Great, then here is my final drawing on this subject. Anyone
who has bought an S-Beam from me can return it to me for this
modification. It will be free if you pay the shippiing. Jerry
Well I am still a wee bit uncomfortable with NO reinforcement.
How about just a couple of .065" thick 4130 straps 1/4 inch
wide laid flat? Skip welded every one inch with a 1/4 inch
long weld.
Paul Lamar
You are the engineer. I felt it passed the load test o.k. without
reinforcement. But welding a little strip on each side is not a
problem if it will really strengthen the beam so let's do it. There
may be a problem finding such a strip. I would not be surprised if
it comes off the shear looking like spaghetti. Not available in the
ACS catalogue. Cold Roll might be available in that size. Would
that be acceptable? Jerry
I think shearing it will be OK Jerry. It is thin enough to twist
back into shape. You can also clamp it down to the beam.
Mild steel might be OK because I am mainly worried about
local buckling or local crippling to use a high tech term.
Paul Lamar
What about a piece of 3/16" rod ?
John
Good idea make it 1/4 inch and I would feel pretty good.
Paul Lamar
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