The wing’s pitching moment determines the aircraft’s forward CG limit. The steeper the curve, the farther aft the neutral point will remain. For a given set of parameters, the wing’s lift curve determines how far the neutral point moves forward as alpha increases. To combat this, the wing’s airfoil should have the steepest lift curve possible. This moves the neutral point forward and decreases the stability margin. The canard is a flapped airfoil and its lift coefficient (CL) increases at a faster rate than the wing as their angle of attack increases. In short, the following airfoil qualities had a major affect on pitch stability and CG range: A pattern developed in the aircraft’s response to different airfoils. Why would Burt specify an older, draggier airfoil for the Long-EZ? I learned the answer while investigating the Cozy wing using Airplane PDQ. The E1230 is a forward loaded, turbulent flow airfoil with higher drag than the GAW1. Burt then designed the Long-EZ in 1978 and selected the Eppler 1230 airfoil, which he also modified to reduce pitching moment. He modified the cusp to reduce its pitching moment, but the section remained a modern (at the time) laminar flow, high-lift airfoil. Airfoil Design “Airfoil optimization requires the application of science, intuition, and perseverance” When Burt Rutan designed the Vari-EZ in 1974, he selected NASA’s GA(W)-1 airfoil for the wing.
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