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Fuselage Jigging Problems

ericwolf

Well Known Member
I hope that all of you RV-8/8A slow builders can help me out with this one. I am in the process of mounting the bulkheads and longerons in the jig. I have all of the bulkheads mounted except for the F-804 wing wenter section.

I have made the two bends in the longeron angles, but when I slide them in the bulkheads, I have some issues.

1) After clamping the longerons to the firewall weldments, I temporarily placed the forward F-804 in the jig and noticed that the longerons had to bow outward significantly at the upward (as jigged) bend to accomodate the width. I can't find a good top view in any of the drawings that helps me out.

2) This may be related to my issue with #1, but I found no need for a twist between the F-804 and the firewall as the instructions say. I noticed that I will need to clamp the longeron at a significant angle at the F-804 to fit its contour. When this is done, the longeron seems to fit the angle of the weldment rather well. This further confuses me.

3) The aft 804 bulkhead appears to be the same width as the forward bulkhead. This doesn't make sense to me since the longerons taper in from front to aft and there is a distance (although small) between the bulkheads.

4) I can't find mention to this in the instructions, but I assume that the longerons should be primed before mounting to the jig. Is this right?

Thanks in advance for the help.
 
fuselage jig

Eric,

It has been awhile, but I remember being very confused, until I had all the bulkheads mounted. At that point I knew that my bends, twists, etc were not just right, so I removed each longeron and made final adjustments to fit. It actually was fairly simple at that point to take one out, make a small asjustment and put it back in. Once they were there, I never had another problem, and the skins went on with no problem.

Marshall Jacobson 80749

final wiring!!
 
pre-bent longerons

never have I sweared (sworn?) up such a storm of foul language than when cocking around with those #@$%&* longerons. tax prep time comes close, but. . . . . I would like to see (and pay accordingly) pre-bent longerons. it seems to me that it is fairly nuts attempting to effect a precise bend in a piece of metal, to within some-odd thirty-seconds of an inch, by beating the **** out of it in a vise or by other similarly primitive methods. mine are still not bent just right, but the encouragement from those who have gone before have given me hope.
 
My longerons look different now

grover said:
never have I sweared (sworn?) up such a storm of foul language than when cocking around with those #@$%&* longerons. tax prep time comes close, but. . . . . I would like to see (and pay accordingly) pre-bent longerons. it seems to me that it is fairly nuts attempting to effect a precise bend in a piece of metal, to within some-odd thirty-seconds of an inch, by beating the **** out of it in a vise or by other similarly primitive methods. mine are still not bent just right, but the encouragement from those who have gone before have given me hope.
Wow, this is a blast from the past. If I can offer some additional encouragement from the guy who originally asked this question, here is what my longerons look like now...
20060507fairingsinstalled12uf.jpg

Keep at it, and if you need any pointers, don't be afraid to ask.
 
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