Aileron Design S-1 vs. S-2 LTS

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Well-Known Member
Dec 5, 2010
Chesapeake, VA
Bottom Line Up Front:
Why do the Sonerai I Plans call for an Aileron Root Rib to made of .063 4130 sheet when the same part in the Sonerai II LTS Plans is spec’d for .032 4130?

I’m building a Sonerai 1 with a hybrid wing design using the rib spacing and spar design of the Sonerai II LTS from the root of the spar out to the outboard end of the first sheet of wing skin. The remaining outboard rib spacing will be typical for the Sonerai 1 and the overall span will be consistent with the Sonerai 1. My rationale for this is to allow for the two additional wing ribs suggested by those that fly the Sonerai 1 in the upper end of the wing loading envelop (racing/acro).

I was in the process of cutting out the root rib for the aileron using .063 stock when our local Sonerai II LTS builder asked with a puzzling look, what I was doing. He told me his rib was half that thickness and did not require heat to make the bend. When I looked again at the LTS plans, sure enough, he was correct – only .032.

According to the Specification List the wing loading on the Sonerai 1 is 9.3 lbs/sq. ft. and the loading on the II LTS is 13.6 lbs./sq. ft. At gross weight the wings of a Sonerai 1 at 6s handles 4500 lbs. The LTS wings at gross and 3.6 gs handles 4140 lbs. At a gross weight of 750 lbs., all Sonerais are rated for 6 g’s.

Like all Sonerais, this root rib has a bolt head and shank welded to it to pick up the movement of the aileron actuator levers to control the ailerons. Will the .032 material hold up on a Sonerai 1? What did a standard Sonerai II use for this rib material? The tradeoffs are ease of fabrication vs. strength?

Any thoughts.



Well-Known Member
Staff member
Oct 20, 2007
Gilbert, S. C.
John, I would go with the weight penalty here, and use the .063 sheet…My thinking….The potential for hard aileron inputs with racing are stressful and more frequent with the Sonerai 1, and that AN-4 Bolt welded to the sheet rib has a lot of bending and shear load on it, and welding the head on the backside to .032 sheet, in my opinion, is fine for sport flying, but seems a bit light for competition flying….Just my opinion….I can think of many other places I would rather save weight…….

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