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 Thorp T-18
 Fuselage & Empennage
 Cross Member behind seat - structural?
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dickwolff

Canada
182 Posts

Posted - 06/03/2010 :  13:55:12  Show Profile
I am considering an airplane that looks pretty good in a lot of respects, but I noticed that the cross member behind the seats, over the top front of the baggage compartment, was made discontinuous to improve access. He did a nice job with a hinged hatch and all, but I haven't seen many Thorps where that was done. I wonder if that piece is a structural member.

Any thoughts?

Jim Mantyla

Canada
126 Posts

Posted - 06/03/2010 :  19:52:43  Show Profile
Hi Dick,

I assume the cross member is the one that is shoulder height and the seat back leans against. If this is missing, I would think that a lot of the fuselage rigidity would be lost. Has the builder compensated for this in other ways? Maybe pictures would or sketches would help us to understand what exactly the modification is.

Jim Mantyla
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Doug S

USA
27 Posts

Posted - 06/04/2010 :  10:35:35  Show Profile  Visit Doug S's Homepage
99KK (built by Ken Knowles) has an aluminum tube with pull pins on the ends that spans the top of the bulkhead (think shortened elevator push/pull tube. I have had the plane since '96 & not noticed any extra flexing or any undue fretting at the mount points. It does have some doublers on the bulkhead.
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Tim Brown

Canada
84 Posts

Posted - 06/04/2010 :  10:44:48  Show Profile
How about a picture!

I am 6'1" and for one would love to be able to "tilt" the seat backward about 10 degrees or so, that bulkhead is in the way; if its modifiable I would love to see how its been done.
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Doug S

USA
27 Posts

Posted - 06/05/2010 :  06:53:13  Show Profile  Visit Doug S's Homepage
I'll see about a pic Sunday. The bulkhead still comes up full height on the sides, so tilting the seatback is not accomplished. I'm a SF (short fellow) if you want to see how to make a big guy fit, contact Bob Highley (fytrplt)
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Bill Williams

USA
336 Posts

Posted - 06/09/2010 :  15:19:58  Show Profile
This cross member is a must. Anyone that eliminates it, is changing the structural integrity of the fuselage.
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fytrplt

USA
182 Posts

Posted - 06/09/2010 :  16:25:23  Show Profile
Notice in the picture that the seat back at least an inch and a half thick. Mine is about 1/2" of foam on a standard (plans) type seat back. I am 6' 1" and have fit nicely for 2400+ hrs. The bottom of the panel must not go below the 42 BL and you don't need a lot of side padding. That cross member is structural. It is there to contain the crew in the event of an incident or worse. Besides, most folks use it to get in and out of the plane. BTW, mine is beefed up.

Bob Highley
N711SH
SN 835
KLAL
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