Hi All,
I'm just finalizing things before I drill my longerons to the side skins (yes, some nervous times). The left side was about smack on, and the right side needed tweaking a little, which I did by setting up a temporary clamping mechanism and using a screw jack so that I didn't have to remove it from the fuselage. I've got tolerance town to about 3/64" between the top of the skin and the top of the F-770 just after the bend point, which can be reduced to about 1/32 if a small amount of preload is put on the longeron when I drill and insert the clecoes. Given that we are trying to follow a shallow but sharp bend in the skin profile with a thick piece of angle, I am assuming that a 1/32" tolerance is ok. If not, let me know and I'll pull it out and do some more whacking with the hammer.
In light of the fact that there will be a curve transition, I am assuming that I should hold the longeron flush with the F-770 skin aft of the bend point, and let it bow outwards this 1/32" or so once it is forward of the bend, before pulling it back flush again as soon as possible. Is this train of thought on the right track?
Cheers,
Tom.
EDIT: Don't use this clamp in-situ procedure for adding to the sharp downward bend. Chock the fuselage and remove the stringer (see post #9 of this thread). It is easier.
I'm just finalizing things before I drill my longerons to the side skins (yes, some nervous times). The left side was about smack on, and the right side needed tweaking a little, which I did by setting up a temporary clamping mechanism and using a screw jack so that I didn't have to remove it from the fuselage. I've got tolerance town to about 3/64" between the top of the skin and the top of the F-770 just after the bend point, which can be reduced to about 1/32 if a small amount of preload is put on the longeron when I drill and insert the clecoes. Given that we are trying to follow a shallow but sharp bend in the skin profile with a thick piece of angle, I am assuming that a 1/32" tolerance is ok. If not, let me know and I'll pull it out and do some more whacking with the hammer.
In light of the fact that there will be a curve transition, I am assuming that I should hold the longeron flush with the F-770 skin aft of the bend point, and let it bow outwards this 1/32" or so once it is forward of the bend, before pulling it back flush again as soon as possible. Is this train of thought on the right track?
Cheers,
Tom.
EDIT: Don't use this clamp in-situ procedure for adding to the sharp downward bend. Chock the fuselage and remove the stringer (see post #9 of this thread). It is easier.
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