OTHER: Aerodynamics - Rotor Theory - Yawed Blade Element Theory

• The following is (will be) based upon my understanding of Sikorsky's Yawed Blade Element Theory as noted in ABC report 'Forward Flight Performance of a Coaxial Rigid Rotor ~ Radial Flow Effect' on page 6
• The velocity across the blade elements will be a resultant vector of forward velocity and rotational velocity at each of the blade elements.
• The angle of attack will have to be adjusted to take into account the revised vector; both angle and airspeed.
• My thought, which Sikorsky might or, might not, be including; During forward flight and at azimuths other than 90º the airflow will not be normal to the span of the blade. This means that the airflow will experience a chord length that is longer than the actual chord length of the blade. However, it will experience the actual thickness of the blade. This means that the airflow is experiencing the same airfoil except that it has a smaller thickness. In other words; the airfoil is larger, the element is narrower and the profile is thinner. For example; airflow across a NACA 0018 airfoil at 45º off the chord line, should give results as if it was flowing across an NACA (0012 * sin45) = NACA 0012.7.
• Reverse Velocity will add another set of ..............

• Nothing yet, however, existing FORM Tangential Velocity will be the foundation.

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