To: RW-1
This was lifted off of your website. The only thing missing is the diagram. The missing diagram shows the control inputs and gyroscopic precession results. The illustration is of a Bell swashplate. This is the same diagram that is on the two Robinson websites. Do you believe in gyroscopic precession and, if you do, please explain to me and all of the other participants how gyroscopic precession phase angle of 90-degrees applies to a Robinson helicopter that has the same control inputs as a Bell Helicopter.
Gyroscopic precession is a phenomenon occurring in rotating bodies in which an applied force is manifested 90 degrees later in the direction of rotation from where the force was applied.
Although precession is not a dominant force in rotary-wing aerodynamics, it must be reckoned with because turning rotor systems exhibit some of the characteristics of a gyro. The graphic shows how precession affects the rotor disk when force is applied at a given point:
A downward force applied to the disk at point A results in a downward change in disk attitude at point B, and an upward force applied at Point C results in an upward change in disk attitude at point D
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Forces applied to a spinning rotor disk by control input or by wind gusts will react as follows:
This behavior explains some of the fundamental effects occurring during various helicopter maneuvers. For example, the helicopter behaves differently when rolling into a right turn than when rolling into a left turn. During roll into a left turn, the pilot will have to correct for a nose down tendency in order to maintain altitude. This correction is required because precession causes a nose down tendency and because the tilted disk produces less vertical lift to counteract gravity. Conversely, during a roll into a right turn, precession will cause a nose up tendency while the tilted disk will produce less vertical lift. Pilot input required to maintain altitude is significantly different during a right turn than during a left turn, because gyroscopic precession acts in opposite directions for each.
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