Graham Singleton wrote:
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>>Harnesses - the ongoing saga
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>>For those who are interested, I've posted my solution to the low harness
>>height, on todays journal at my build site. Very strong and works very
>>well...
>>
>>--
>>Jeff - A055
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>Jeff
>the geometry to avoid compression looks good. However I think the plate
>will get a strong bending load in a crash like mine. Think of a 40G load
>pulling forwards at the top of the plate. 40 times the weight of your upper
>body.
>If the plate was straight and attached at the front of the headrest
>structure it would see more compression and less bending. Putting a flange
>on the edges would help to give more strength in compression too.
>I try and think in terms of pin joints at all the corners and attach
>points, then everything has to be in compression or tension.
>Graham
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Graham,
I considered gussets on each side of the front plate, or, even a couple
of ribs on the back side of the rear plate, however my engineer friend
assures me that any load that would bend the current design forward
enough to negate its effectivness, would also rip the head rest right
off the CM. That's why he recommended the large radius. At any rate,
the deceleration that the gizmo will provide, should help avoid spine
compression. If the airplane breaks... well, it's going to need repair,
anyway, after hitting the ground and, assuming I survive at all... :)
--
Jeff - A055
Builders Log: http://www.N55XS.com
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