WIX Archives

Re: Corsair mainspar

Posted by Richard Allnutt on Wed Jul 31, 2002 05:33:08 PM

In reply top Re: Corsair mainspar posted by Rob Mears on Tue Jul 30, 2002 05:42:46 AM

re. the Silberman -4 corsair main spar. I spoke with Tom Reilly and Ricky Reaves (the technician who did the work). Apparently they got an FAA approved modification to make the spar caps out of a couple of layers of Aluminum stock, rather than the single layer. The same overall thickness was preserved, so they used thinner stock to make up the layers. These layers were made out of 2024 T-3 aluminum, and were formed in a heavy duty hand brake, simply inching the aluminum through the brake and gently adding slight bends to it until it was the right shape. Since they used T-3 aluminum they therefore did not need to heat treat the caps.... so it is do-able, for a reasonable cost, and with little compromise to the original design. Hope this helps.

Richard

: From what I understand, the size of the commonly available
: aluminum stock needed to create the spars is not cut larg
: e enough to equal the pieces used in the original design.
: Custom forgings are required to make this work.
:
: Secondly,from what I unsderstand those pieces then have to
: be rolled into shape to create the inverted-gull shape of
: the spar. The factory responsible for the original produ
: ction pieces had mammoth custom tooling to complete this j
: ob, the likes of which is not still extant AFAIK. To the
: best of my knowlege these are the two main hurdles one has
: to overcome.
:
: Tom Reiley of course reproduced a main spar for the Silber
: man "F4U-4" (now owned by Jim Frye). Mr. Reiley actually
: deviated from the original design, managing to reproduce
: an airworthy mainspar using different techniques that were
: approved by the FAA. I spoke with him just after his com
: pletion of the unit, but I don't really recall the minute
: details in his description of the work.
:
: Nice to know that it can be done though :) I can think of
: two or three F4U projects right now that could use a spar
: to get them kick started.

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