Tail Rotor Roll and lateral landing limits
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Tail Rotor Roll and lateral landing limits
The usual effects of Tail Rotor Roll (TRR) manifests itself as one skid low when hovering. Considering the lateral limits stated for landing on sloping ground I would like to know if TRR is a factor and taken into account within these limits?
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Using a S300C as an example, with a main rotor that turns CCW when viewed from above, the tail rotor creates thrust to the right. Slope landings require lateral cyclic and the amount of lateral cyclic available can determine the steepness of slope you can land on. By holding in left cyclic to counteract translating tendency we are using up some the left lateral cyclic, leaving less cyclic travel for the actual slope work on a slope that slopes down from left to right. On a slope that slopes down from right to left the translating tendency helps to hold in the upslope skip and more cyclic travel is available to keep the skip into the slope. A steeper slope can be landed on if it slopes downward from right to left for a S300C or similar helicopters.
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Slope landing limits are developed by the manufacturer and will take this sort of thing into account. The certification authority will also test it to make sure it's OK.
I know of one manufacturer who published a slope landing limit of 3 degrees - which of course is pretty useless. Turns out they meant you could land on this much slope, with 40 knots of wind from the worst side, with the worst lateral CG, and still be able to stop and start the rotors safely. I recently told them they need to reconsider their method of testing and demonstrating limitations, as there is no requirement to shut down....
I know of one manufacturer who published a slope landing limit of 3 degrees - which of course is pretty useless. Turns out they meant you could land on this much slope, with 40 knots of wind from the worst side, with the worst lateral CG, and still be able to stop and start the rotors safely. I recently told them they need to reconsider their method of testing and demonstrating limitations, as there is no requirement to shut down....
