Why Do Helicopters Hover One Skid Low?
I’ve been requested so much occasions why helicopters hover with one skid low. Helicopters with a counter clockwise rotating rotor system hover left skid low and helicopters with a clockwise rotating rotor system hover proper skid low.
Now there are two elements to think about with a view to clarify this phenomenon. The primary one is what we name translating tendency or tail rotor drift. This issue causes a sideways pull on the fuselage of the helicopter and within the case of a counter clockwise rotating rotor system this pull will probably be to the suitable. To elucidate it very briefly it’s the results of the tail rotor pressure appearing on the tip of the tail growth counter appearing the torque response which needs to rotate the fuselage clockwise.
With a purpose to counter this sideways pull leads to the second issue that is tail rotor roll. To counter the sideway motion to the best the cyclic must be positioned barely to the left which can tilt the Complete Rotor Thrust to the left thereby inducing a horizontal element of Complete Rotor Thrust to the left appearing on the identical degree because the aircraft of rotation.
Now usually in small helicopters the tail rotor which produces a pressure to the fitting when viewing the helicopter from the again acts under the aircraft of rotation. This pressure which counter act the torque response varieties a pair with the horizontal drive to the left which was the results of tilting the cyclic (Complete Rotor Thrust) to the left. To place it a bit easier think about a horizontal line with one drive appearing to the left and above the road and one other drive appearing to the fitting and under the road. The 2 forces appearing towards one another and never on the identical line will produce a rolling second.
As I discussed that is only a temporary rationalization for a not so straight ahead aerodynamic precept.
One final remark with regards to tail rotor roll is that it’s most outstanding through the hover off track as a result of it’s associated to the quantity of torque that the helicopter develops. That’s the reason a counter clockwise rotating helicopter tends to float to the proper because it transitions from ahead flight again to the hover as a result of energy or torque is slowly utilized because the velocity decreases.