NATOPS Ch 11

Question 1

Static Rollover

Answer 1

Static rollover angle is the angle at which the helicopter will tip over on its side if it is parked on a very steep embankment. The static rollover angle of the MH-60R is approximately 28 degrees. It occurs when the helicopter cg is directly over the longitudinal axis passing through the tail gear and either main gear ground contact points.

Question 2

Critical Rollover

Answer 2

Critical rollover angle is the maximum lateral angle of slope that can be negotiated in a takeoff or landing. At this angle, full lateral cyclic input is required to trim the wheels level with the slope without sliding. With left wheel uphill and brakes on, this angle is approximately 12 degrees.

Question 3

Dynamic Rollover

Answer 3

Dynamic rollover is an insidious dynamic condition that can occur during takeoff or landing with one wheel on the ground and can result in destruction of the helicopter.

The main contributor to dynamic rollover is the buildup of angular velocity of the helicopter cg about the wheel touching the ground. When the angular velocity about the wheel is greater than can be countered with full opposite cyclic, the helicopter will roll over. This situation can happen in less than 2 seconds.

A rolling motion to the right is made worse by the tail rotor. Conversely a rolling motion to the left is decreased as the tail rotor provides deceleration.

Lateral control is only 1/5 of the control experienced while airborne, and aircraft response will be sluggish. If lateral cyclic cannot be displaced far enough to tilt the lift vector outside the wheel tread, then even full opposite cyclic will add to the rolling moment. Smooth reduction of the collective is the most effective means of recovery.