Aeronautical Science Perspective Paper
Embry Riddle Aeronautical University
Rotary-wing aircraft are designed and built to fulfill a multitude of purposes and missions. Cargo, attack, transport, observation, etc. and with these different mission types come a plethora of design features. Such features include, but are certainly not limited to fully-articulated or semi-rigid rotor systems; two, three, four, or even five main rotor blades; skids, wheels; one or two engines. Yet, despite all the differences to the structure and therefore the aerodynamic properties of the helicopter, the one thing that remains constant in every aircraft are the flight controls and ...view middle of the document...
("Fundamentals of Flight," 2007) The resultant tilt of the swashplates cause the rotor to tilt, the tilt of the rotor changes the lift vector of the rotor and therefore, the aircraft moves in the direction of lift. In helicopters, the controls are rigged is such a way that when forward cyclic is applied, the helicopter moves forward, likewise for aft, etc. To accomplish this, the pitch horn is offset 90º to the rotor blade. The controls still tilt the swash plate in the same direction as the control input is made, but due to the pitch horn placement, the input to the blade occurs 90º earlier in the plane of rotation. ("Helicopter flight information: understanding," 2012) The rotor response to cyclic control input on a single-rotor helicopter has no lag. Rotor blades respond instantly to the slightest touch of cyclic control. The fuselage response to lateral cyclic is noticeably different from the response to fore and aft cyclic applications. Normally, considerably more fore and aft cyclic movement is required to achieve the same fuselage response as achieved from an equal amount of lateral cyclic. This is not a lag in rotor response; rather, it is due to more fuselage inertia around the lateral axis than around the longitudinal axis. For single-rotor helicopters, the normal corrective device for the lateral axis is the addition of a synchronized elevator or stabilator attached to the tail boom. This device produces lift forces keeping the fuselage of the helicopter in proper alignment with the rotor at normal flight airspeed. This alignment helps reduce blade flapping and extends the allowable CG range of the helicopter; however, it is ineffective at slow airspeeds. ("Fundamentals of Flight," 2007)
Newton’s third law of motion states: when a first body exerts a force F1 on a second body, the second body simultaneously exerts a force F2 = −F1 on the first body. This means that F1 and F2 are equal in magnitude and opposite in direction. ("Newton's laws of," 2012) According to Newton’s law of action/reaction, action created by the turning rotor system will cause the fuselage to react by turning in the opposite direction. The fuselage reaction to torque turning the main rotor is torque effect. Torque must be counteracted to maintain control of the aircraft; the anti-torque rotor does this (figure 1-43). In the tandem rotor or coaxial helicopters, the two rotor systems turn in opposite directions, effectively canceling the torque effect. Most rotary-wing aircraft have a single main rotor and...