At these settings the wings were generating so much lift that it needed minus 17 degrees of down elevator trim to fly level! After much experimentation I finally bit the bullet and modified the wing saddle to minus 1/4 degree (all I could get) and set the top wing at minus 1-1/4-degrees. The bottom wing saddle was set at plus 1/2-degree (manufacturer specs were "zero") and I initially set the top wing at plus 3/4-degrees to get it to stall first for positive stability. ![]() My Great Planes Stearman ARF does not use the Clark Y, but its' semi-symetrical wings have somewhat similar charachteristics. Anyone setting the wing(s) with the flat bottom parallel to the airframe's "zero-degree datum" is actually setting them for a plus 2-degree angle of incidence relative to the datum and 7-degrees above the zero lift angle! Some aircraft may work well there but I expect most will not. The Clark Y airfoil stalls at around 13 to 15-degrees at the reynolds number of a typical RC model and has a zero lift angle of minus 5-degrees. Your comments added the most I've read to this thread and you clearly understand the issues well. Any feedback would be helpful as the next step in the building process will be to align the center section of the bottom wing to with the fusealage. I was also hoping to be able to adjust the angle of incidence for the horizontal stab, or maybe just set it at about -1 degree to offset the climb. I was planning on having the bottom wing at a zero angle of incidence and the top wing at about 3 degrees. The other one requires slight down elevator. One of the planes requires slight up elevator for level flight. I never paid much attention to the chord line and had the bottom of the airfoil sit paralell with the horizontal stab. I have designed and built two other models that have a Clark X airfoil. Is the cord line the same as the zero lift angle? If I set the cord line parallel with the thrust line it looks like the airfoil has a negative angle of attack. Compufoil shows shows the cord line for the airfoil. I used Compufoil to generate the airfoil. Cars Īn inverted Clark Y airfoil was used on the spoilers of the Dodge Charger Daytona and Plymouth Superbird.I am designing/building an electric biplane that has a clark Y airfoil for both wings. Inexperienced modellers are more readily able to build model aircraft which provide a good flight performance with benign stalling characteristics. The Clark Y is appealing for its near-flat lower surface, which aids in the construction of wings on plans mounted on a flat construction board. Applications on model aircraft is very wide, ranging from free-flight gliders through to multi-engined radio control scale models. The Clark Y has found favor for the construction of model aircraft, thanks to the flight performance that the section offers at medium Reynolds number airflows. ![]() The Clark Y was chosen as its flat bottom worked well with the design goal of a low radar cross-section. ![]() The Northrop Tacit Blue stealth technology demonstrator aircraft also used a Clark Y. Louis are two of the better known aircraft using the Clark Y profile, while the Ilyushin Il-2 and Hawker Hurricane are examples of mass-produced users of the Clark YH. ![]() The Clark YH airfoil is similar but with a reflexed (turned up) trailing edge producing a more positive pitching moment reducing the horizontal tail load required to trim an aircraft.
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