[rebel-builders] Float Attachment Fix
Posted: Sun Feb 19, 2012 4:17 pm
Hi John
I only did the external doublers because I did not want to open up the
floor enough to bolt a doubler onto the bulkhead web which I think would
have been preferable. 99% of the reason for the shape of my doublers
is indeed aesthetic and of course weight minimization. The other 1% is
that in general I like to taper down such doublers so that the strength
and flexibility diminishes gradually instead of suddenly where the
doubler ends. ie. less stress concentration in the bulkhead where the
doubler ends. It really isn't tapered enough to achieve that anyway in
this case.
Ken
John Peterson wrote:
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I only did the external doublers because I did not want to open up the
floor enough to bolt a doubler onto the bulkhead web which I think would
have been preferable. 99% of the reason for the shape of my doublers
is indeed aesthetic and of course weight minimization. The other 1% is
that in general I like to taper down such doublers so that the strength
and flexibility diminishes gradually instead of suddenly where the
doubler ends. ie. less stress concentration in the bulkhead where the
doubler ends. It really isn't tapered enough to achieve that anyway in
this case.
Ken
John Peterson wrote:
I have just completed a rear float attachment fix which was caused by improper riveting of the floor side panels by the original builder. Upon inspection, the floor rivets were drilled too close into the former, ie right next to the inside edge which affected the strength of the fuselage former and ultimately caused a wrinkle with a hard landing.
With the advise of Wayne O'Shea and thanks again Wayne for the assistance on this, we were able to laminate the former going over the rear strut attachment, down across the cutout section and into the floor bracing. Worked out excellent and we bolted it all together with 3/16" bolts.
Two things from this - one is taking care to be sure when riveting the inside floor and side panels to be sure they are properly aligned on the inside. I know it may be a simple thing for some but in this case, it was the root cause of the problem.
Secondly, we areputting on the outside skin and doing the tie in with the upper part of the fuselage former, I think this is one of the Ontario mods. My question is when doing this over lap piece, is there any advantage to making it come to a point(not a sharp point but approx. 2" at the top) vs. just making it straight up the whole width of the piece that is used to overlap., in essence a rectangular piece. I have seen the ones done on Garry Wrights and Kens a/c and they are both tapered going up. Is that taper necessary for strength or is it a matter of looks.
Appreciate the help on this question
Thanks in advance
John Peterson
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