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  #1  
Old 11-16-2021, 09:31 AM
bsbarnes10 bsbarnes10 is offline
 
Join Date: Sep 2019
Location: Texas
Posts: 48
Default Bending longeron to fit F-01234?

To All,
I've got the longerons trimmed and the angle opened up (using a hydraulic press and 3/4" bar stock die, no vise or hammering) and now it's time to match drill the the holes from F-01234-L/R into the longerons F-01255-L/R.

On plans page 23iS/U-02 Rev. 2, Figure 2 shows the longeron cross section with F-01234 overhanging the edge by 0.025" I assume this overhang is supposed to be consistent for the whole length of F-01234?

When I lay F-01234 on the longeron and set the overhang at either end, it is all wrong in the middle (i.e. negative gap) as shown in the photos below. It looks like the longeron has more curve than the F-01234's. My plan is to drill the first hole(s)and then work my way along the length of the part, putting some force on the longeron to slightly straighten it to match the curve of the F-01234. Is this correct?

Thanks,
Bruce



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  #2  
Old 11-16-2021, 09:41 AM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by bsbarnes10 View Post
Is this correct?
Yes.

The bent longeron is factory formed from a straight piece of angle extrusion. Every batch of material can bend slightly different, so it is not expected to match up perfectly.

That is why the text in the manual says -
NOTE: When match-drilling F-01255-L-1, start at the forward end and move aft, initially drilling every
other hole and placing clecos as drilling progresses. Periodically check edge alignment
(confirming .025 inch minimum overhang) and adjust as needed.

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  #3  
Old 11-16-2021, 01:29 PM
bsbarnes10 bsbarnes10 is offline
 
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That's what I thought but I appreciate the confirmation!

Thank you,
Bruce
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  #4  
Old 11-17-2021, 10:48 PM
StrictlyEXperimental StrictlyEXperimental is offline
 
Join Date: Mar 2006
Location: Layton,Utah
Posts: 8
Wink beware of spring back

I just finished this step and am match drilling the sides to the longerons. Even though I thought I nailed it, the side is a little bit proud at one point just forward of F-01205B-R-1. I guess it won't be a perfect airplane after all. Anyway, some force had to be applied and now I see the words: .025 MINIMUM overhang. Could be a little slop in the clecos and I will get the overhang back with the CS4-4 rivets in place. Wonder what the bad effect is of not having a perfectly uniform overhang?
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  #5  
Old 11-17-2021, 11:42 PM
daveyator daveyator is online now
 
Join Date: Jan 2011
Location: adelaide, south australia
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The overhang covers the top of the side skin. A little too much and you could shim the side skin out slightly. Not enough and the skin will stand proud. Cosmetic, but won’t look so good. Worth getting right if possible.
Cheers DaveH
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