One of the problems noticed with the reinforcing plate on steel
fenders is that a heavy plate simply moves the stress points to the
perimeter of the plate and doesn't really solve the problem. Here's
an idea I've been toying with that would certainly be worth
considering for your fiberglass fenders. I haven't tried it yet but
plan to on my current hanger queen (62 +4 4 seater).
Imagine building up about 3 or 4 layers of material between the fender
bracket and the fender as follows (added thickness would have to be
compensated for by adjusting the height of the bracket:
Fender ======================== Fiberglass
Slip sheet -------------- 6" dia x 1/32" UHMW film
Layer 1 ============== 6" dia x 1/8" polycarbonate sheet
Slip sheet -------- 4" dia x 1/32" UHMW film
Layer 2 ======== 4" dia x 1/8" polycarbonate sheet
Plate ====== 2" dia x 1/8" steel plate
Bracket == Fender brace
The idea is to provide a variable flexing support (similar to the
differing leaf lengths on leaf springs). The surface between the
fiberglass and the slip sheet needs to be as smooth as possible since
a certain amount of flex results in sliding motion.
If more flexability is desired, the polycarbonate pieces can have
radial slits to change the bending mode from a simple plate to radial
cantilevers (similar to the spring plate in a clutch). The shape can
also be altered from round to oblong or a rounded rectangle to
redistribute the loading along the fender line.
Another variation would be to make the transition more gradual with
many more sheets that are much thinner. It is also conceivable to
bond the sheets together using a rubber based adhesive that allows a
high degree of flex however I believe simply capturing them in place
would be sufficient.
David wrote:
>
> Got a idea that I would like to toss around. I am now fitting fiberglass
> wing to my Mog and I am looking for a way to attach them at the wing lights
> to prevent them from cracking during normal use. Normally plates are
> welded on steel wings at the wing light attaching point. On fiberglass
> wings, I was contemplating making a steel sandwich with fiberglass. I plan
> to place a steel plate between two layers of fiberglass, the top layer being
> the
> bottom side of each wing, and the bottom layer of fiberglass , being the
> fiberglass resin that is directly applied to each steel plate.
>
> If you have any comment, I would love to hear from you.
>
> Regards,
> David
--
"Entropy Happens!"
Michael D. Miles, PE Consulting Design Engineer
(503) 292-1234, FAX: (503) 292-1105, PGR: (503) 423-4040
email: mdmiles@home.com
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http://members.home.net/mdmiles
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