Technical Paper
Concept Development of a Pneumatically Driven, Fixed Root Circulation Controlled Helicopter
2007-09-17
2007-01-3828
Circulation control technologies have been applied to fixed wing aircraft for approximately four decades. During those early tests an increase in lift coefficient of nearly four times the unaltered airfoil was achieved. Applying these or similar technologies, particularly inducing the coanda effect through blowing slots to rotorcraft blades, can enhance the performance of the helicopter. The increase in lift coefficient of the rotor blade provides more options to the designer, including decreasing the rotor diameter, decreasing the rotor speed, increasing the payload capacity, or a combination of all three. By either reducing the diameter and/or the rotor speed the blade tip speed can be reduced, thus allowing a higher forward flight speed. Retreating blade stall can also be reduced by applying circulation control to the leading edge of the rotor blade.