Author Topic: can I move a crossmember?  (Read 509 times)

schines

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can I move a crossmember?
« on: Nov 25, 2017 »
A question for the engineer types. I built my IILS fuselage to plans except that I made the toe brake mod to the rudder pedals that Scott P. and a few others did. After the discussion about bolts through the landing gear stressing the longerons, I decided to re do the gear attach points for the strap type attachment. The bushings would be welded to the outside of the crossmembers at station 35 1/2 and 41 1/2 instead of between them.  The question is, Could I move the crossmember at station 35 1/2 back about an inch (I haven't measured it yet) to line up with the front edge of the gear? This would eliminate the need for a spacer between the bushing and gear and, more importantly, give me a little better foot position on the pedals. Anyone see any problems with this?
Scott

eschrom

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Re: can I move a crossmember?
« Reply #1 on: Nov 26, 2017 »
Hi Scott,

I don't see what it would hurt. Hard to believe the original design was optimized down to the last inch.

Ed

Mytonic

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Re: can I move a crossmember?
« Reply #2 on: Nov 26, 2017 »
Imho,  sounds like you plan on using the bolts to hold the gear in place from sliding foward or backward but if you weld bushings outside of those cross members there still going to be a space between the gear and the bolts and the gear can still slide around. bushings have a greater contact area and are snug against the gear

schines

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Re: can I move a crossmember?
« Reply #3 on: Nov 27, 2017 »
Thanks Ed. I guess I'll just do it then.

Mytonic,
I meant that I would extend the bushings to the strap so the bushings would be the stops, but the more I look at the plans, I think I will just use the spacers. I don't see why the plans only call for three though. Also not sure why the plans call for 3 bushings 2" long and one 2-3/4". One bushing is the stop?

Mytonic

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Re: can I move a crossmember?
« Reply #4 on: Nov 27, 2017 »
ACORDING TO THE PLANS I HAVE, THE FRONT BUSHINGS ARE 2" AND THE REAR BUSHINGS ARE 2 3/4. I BELIEVE THE REAR BUSHINGS ARE LONGER SO THE BOLT HEAD CLEARS THE VERTICAL DIAGONAL X-MEMBER

JondorB1

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Re: can I move a crossmember?
« Reply #5 on: Nov 30, 2017 »
Mytonic,

I was curious which plans you have; maybe a change was made.  I have the 2LS plans (around 2001) and all the gear mount bushings per plans are 2" long.  This is a problem for the aft bushings since the bolt heads did scratch the diagonals (I sanded them smooth and painted them).  Looking at my aft bushings, it seems they would have needed to be at least an inch longer to clear the diagonals.

Jon

Mytonic

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Re: can I move a crossmember?
« Reply #6 on: Dec 01, 2017 »
My stretch plans are "revised 99' " those plans show 2" bushings for bolt on gear. My 82' 2L plans show 2" and 2 3/4" for strap on gear

JondorB1

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Re: can I move a crossmember?
« Reply #7 on: Dec 01, 2017 »
Mytonic,

Thanks!

Jon

 

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