These finished laminated wing spars for the Pitts S1-SS are ready to use. Laminated spars are made up of vertically-stacked sections of spruce which have been laminated together using a vacuum process. The result is a spar that weighs virtually the same as a solid spar, but which has several decided advantages over solid spars.
While the FAA officially considers a properly laminated wooden member to be "as strong" as a solid one, destructive load testing on many spar samples has demonstrated that our vertically-laminated spars exhibit no less than approximately 25% greater strength before breaking than does a solid spar. In fact, some of our test samples had over 50% greater strength! (Interestingly, this testing also showed that the laminated spar samples broke in stages, layer-by-layer, and often retained similar strength to a normal solid spar even after the first layer failed!)
A more practical advantage to using a laminated spar is that it is much more resistant to warping due to environmental factors than a solid, single-piece spar. This helps you build a straighter airplane. Finally, since each layer is much thinner than a solid, single-piece spar, it is also significantly less likely that the spar will contain any hidden defects.
Optionally, we will also scarf the inboard ends of the upper wing spars and provide matching splice plates, which will let the builder avoid having to make difficult and critical angled cuts in the spars. If you want us to scarf your spars, please select this option above when ordering. Otherwise, the spars will be provided somewhat longer than necessary to allow the builder to scarf the ends.
Each layer is made of the finest available spar-quality aircraft spruce and the spar is glued, drilled, and handled just like a solid spar would be. This set includes the forward and rear spars for all wing sections. Priced per set.
SHIPPING NOTE: Due to their size, spar sets cannot be shipped via UPS and must be shipped via motor freight (FOB Palm Bay, FL). There is a nominal crating charge as well.