SteveD
Joined: 09 Jan 2006
Posts: 50
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 Posted: Thu Jan 19, 2006 3:15 pm Post subject: Panel vibration mounts |
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Jos,
Thanks for the question regarding my panel mounts. About two weeks
ago Jos saw me online and IMed me with a question about my panel mounts
http://www.europaowners.org/modules/gallery/albums/Panel/
DSCN3938.sized.jpg 4403K13 and 4403K27 http://www.mcmaster.com/
The simple question was "Steve, I don't see any loading data in
tension. If you have a sudden acceleration or acceleration stress
over time, are you going to be wearing your panel?"
The learning curve was more like a roller coaster. An email to
McMaster carr said. "Item number 4403k27 is not rated for tension at
all. The mount is designed for compression applications only."
My heart sunk, Then back to the catalog, how could I be so wrong?
Wait... I wasn't, the catalog clearly gives shear loading data.
So I contacted the manufacturer. Good news, the manufacturer
recommended two types of mounts. The first was a wire rope type some
thing like this Mcmaster part 62225K3. Then they recommended the same
type I was installing. I asked about the fact that there was no
tension data, their reply was it's "not rated for tension, because if
we did some one would hang the panel from the ceiling". Ok, give me a
number I said. The mounts can handle shear loading rating in
acceleration. No problem. Meaning that for a short duration,
acceleration of one G the panel won't fall off.
So 35 to 40 lb panel 3 mounts at 15 lb max shear load each will hold
my panel at one G in all directions. I have ten load bearing mounts
so I'm good for 3.75 g before I hit the safety stops.
But I was warned that too many mounts could actually be worse than
none. Depending on the vibration rate and arm of motion, to many
mounts could setup a feed back loop and the panel shake it self to
pieces.
SO.... It's not that I don't have enough mounts it's I may have to
many. The plan is this, remove mounts until I have 1.5g load rating.
Install stops so I have only max deflection, vertical .150",
Compression .09", and 0 in tension. The stops should be easily made
with a bolt some spacer tubing and a couple of washers.
I'm also going to take a couple of the mounts to work and have the
lab test them until destruction... just to be sure.
Photos will be posted when I get it built.
Keep the questions coming,
Steved
When I ask the AP at our EAA meeting, he said the mounts looked just
like the ones in his Cessna 150.......
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