Chapter 11. HELICOPTER FLIGHT MANEUVERS

From the foregoing chapters in this handbook, it should be obvious that the variable factors of wind, temperature, humidity, gross weight, and structural differences of various helicopter models greatly affect the operation of the helicopter. Even when flying the same model helicopter, two flights are seldom exactly alike to the pilot because of variation in wind and density altitude. Therefore, it is practically impossible to prescribe helicopter attitudes for the performance of each flight maneuver since this handbook should generally apply to all helicopters having the characteristics set forth on page 1. Attitudes, airspeeds, altitudes, and power settings will vary to suit the weather, the particular helicopter, and the loading. For example, on a day with a 20-MPH wind and a 1,000-foot density altitude, a certain nose-low attitude and power setting will be required to hover and to initiate a departure from a hover to commence a normal takeoff; the following day, with a no-wind condition and a 2,500-foot density altitude, both the nose attitude and the power setting for hovering and initiating a departure from the hover may differ considerably in degree from the previous day. Obviously, then, it would be impossible for the handbook to outline a specific nose attitude and power setting for departure from a hover. Therefore, this chapter does not detail each and every attitude of a helicopter in the various flight maneuvers, nor each and every move a pilot must make in order to perform a given maneuver.

VERTICAL TAKEOFF TO A HOVER

A vertical takeoff (or takeoff to a hover) is a maneuver in which the helicopter is raised vertically from the surface to the normal hovering altitude with a minimum of lateral and/or fore and aft movement.  The higher the density altitude, hovering altitude should be lower.

TECHNIQUE:

1. Head the helicopter into the wind, if possible.
2. Place the cyclic stick in the neutral position.
3. Be sure that the collective pitch stick is in the full down position.
4. Increase the throttle smoothly to obtain and maintain proper hover RPM.
5. Raise the collective pitch. Use smooth, continuous movement, coordinating throttle to maintain proper RPM setting. As collective pitch is increased and the helicopter becomes light on the skids, torque will tend to cause the nose to swing to the right unless the pilot adds a sufficient amount of left pedal to maintain a constant heading.
6. As the helicopter becomes light on the skids, make necessary cyclic stick corrections to ensure a level attitude (for the existing load and wind conditions) on becoming airborne, pedal corrections to maintain heading, and collective pitch corrections to ensure continuous vertical ascent to normal hovering altitude.
7. When hovering altitude is reached, adjust throttle and collective pitch as required to maintain proper RPM and altitude. Coordinate pedal changes with throttle and collective changes to maintain heading and use cyclic as necessary to maintain a constant position over the spot. Remember - collective pitch controls altitude, cyclic pitch controls attitude and position.
8. Check engine and control operation, manifold pressure required to hover, and note cyclic stick position. Cyclic stick position will vary with amount and distribution of load and wind velocity.

COMMON ERRORS:

1. Failing to ascend vertically as the helicopter becomes airborne.
2. Pulling through on the collective after becoming airborne, causing the helicopter to gain too much altitude. This, in turn, necessitates comparatively large throttle and collective pitch changes.
3. Overcontrolling the pedals, which not only changes the heading of the helicopter but also changes RPM, thus necessitating constant throttle adjustment.
4. Reducing throttle rapidly in situations where proper RPM has been exceeded, which usually results in violent changes of heading to the left and loss of lift resulting in loss of altitude.

HOVERING

Hovering is a maneuver in which the helicopter is maintained in nearly motionless flight over a reference point at a constant altitude and on a constant heading. The maneuver requires a high degree of concentration and coordination on the part of the pilot. When hovering, a pilot holds the helicopter over a selected point by use of cyclic control; maintains altitude by use of collective pitch control; and maintains a constant heading by use of antitorque pedals. Only by proper coordination of all controls can successful hovering flight be achieved.

Control corrections should be pressure rather than abrupt movements. A constant pressure on the desired pedal will result in a smooth rate of turn; pronounced movements tend to jerk the nose around. If the helicopter tends to move forward, a slight amount of back pressure on the cyclic control stick will stop the forward movement. Just before the movement stops, back pressure must be released or the helicopter will come to a stop, and start into rearward flight. Avoid waiting out helicopter moves; make all corrections immediately. Stopping and stabilizing the helicopter at a hover requires a number of small corrections to avoid overcontrolling.

The attitude of the helicopter determines its movements over the surface. While the attitude required to hover varies with wind conditions and center-of-gravity location, there is a particular attitude which can be found by experimentation to keep the helicopter hovering over a selected point. After this attitude has been determined, deviations can be noted and necessary corrections made before the helicopter actually starts to move from the point.

Hovering altitude is maintained by use of collective pitch, coordinated with the throttle, to maintain a constant RPM. The amount of collective pitch needed to maintain hovering altitude varies with wind, air density (density altitude), and gross weight. When a steady wind is blowing, very little adjustment of the collective pitch stick should be required to hold a desired altitude. Only under variable and gusty wind conditions should any great collective pitch control changes be required.

Coordination of all controls cannot be overemphasized. Any change on one control will almost always require a coordinated correction on one or more of the other controls. Hovering can be accomplished in a precision manner only when corrections are small, smooth, and coordinated.

COMMON ERRORS:

1. Tenseness and slow reactions to movements of the helicopter.
2. Failure to allow for lag in cyclic and collective pitch control which leads to overcontrolling.
3. Confusing altitude changes for attitude changes, resulting in improper use of controls.
4. Hovering too high, creating a hazardous flight condition.
5. Hovering too low, resulting in occasional touchdown.

HOVERING TURN

A hovering turn is a maneuver performed at hovering altitude in which the nose of the helicopter is rotated left or right while maintaining position over a reference point on the surface. This maneuver requires the coordination of all flight controls and demands precision control near the surface. Constant altitude, rate of turn and RPM should be maintained.

TECHNIQUE:

1. Initiate the maneuver from a normal hovering altitude by applying pedal in the desired direction of turn.
2. As the nose begins to turn, and throughout the remainder of the turn, use cyclic control to maintain position over the surface reference point. Use pedals to maintain a slow, constant rate of turn, and use collective pitch, along with proper throttle coordination, to maintain a constant altitude and proper operating RPM.
3. As the 180° position is approached, anticipate the use of a small amount of opposite pedal. As the tail of the helicopter swings from a position into the wind to a position downwind, the helicopter will have a tendency to whip or increase its rate of turn as a result of the weathervaning tendency of the tail surface. The higher the winds, the greater the whipping action.
4. As the desired heading on which the turn is to be completed is approached, apply opposite pedal as necessary to stop the turn on this heading.
5. During a hovering turn to the left, the RPM will decrease if throttle is not added; in a hovering turn to the right, RPM will increase if throttle is not reduced slightly. (This is due to the amount of engine power that is being absorbed by the tail rotor which is dependent upon the pitch angle at which the tail rotor blades are operating.) Avoid making large corrections in RPM while turning since the throttle adjustment will result in erratic nose movements due to torque changes.
6. If you wish to determine the amount of left pedal available, make the first hovering turn to the left. If a 90° turn to the left cannot be made, or if an unusual amount of pedal is required to complete a 45° hovering turn to the left, do not attempt a turn to the right since sufficient left pedal may not be available to prevent an uncontrolled turn. Hovering power requires a large amount of left pedal to maintain heading. Sufficient left pedal in excess of this amount must be available to prevent an uncontrolled turn to the right once the turn has begun.
7. Hovering turns should be avoided in winds strong enough to preclude sufficient aft cyclic control to maintain the helicopter on the selected surface reference point when headed downwind. Check the helicopter flight manual for the manufacturer's recommendations for this limitation.

COMMON ERRORS:

1. Failing to maintain a slow, constant rate of turn.
2. Failing to maintain position over the reference point.
3. Failing to keep the RPM within normal operating range.
4. Failing to maintain constant altitude.
5. Failing to use pedals properly.

HOVERING - FORWARD FLIGHT

Forward hovering flight can generally be used to move the helicopter to a specific area unless strong winds prohibit crosswind or downwind hovering. A hovering turn is utilized to head the helicopter in the direction of the desired area, then forward flight at a slow speed is used to move to the area. During the maneuver, constant groundspeed, altitude, and heading should be maintained.

TECHNIQUE:

1. Before starting, pick out two references directly in front of the helicopter and in line with it. These reference points should be kept in line throughout the maneuver (fig. 69).
2. Begin the maneuver from a normal hovering altitude by applying forward pressure on the cyclic stick.
3. As movement begins, return the cyclic stick toward the neutral position to keep the groundspeed at a low rate - no faster than normal walking speed.
4. Throughout the maneuver, maintain a constant groundspeed and ground track with cyclic stick, a constant heading with pedals, a constant altitude with collective pitch control, and proper operating RPM with throttle.
5. To stop the forward movement, apply rearward cyclic pressure until the helicopter stops. As forward motion stops, the cyclic must be returned to the neutral position to prevent rearward movement. Forward movement can also be stopped by simply applying enough rearward cyclic pressure to level the helicopter and let it drift to a stop.

COMMON ERRORS:

1. Erratic movement of the cyclic stick, resulting in overcontrol and erratic movement over the surface.
2. Failure to use pedals properly, resulting in excessive heading changes.
3. Failure to maintain desired hovering altitude.
4. Failure to maintain proper RPM.

HOVERING - SIDEWARD FLIGHT

Sideward hovering flight may be necessary to move the helicopter to a specific area when conditions make it impossible to use forward flight. During the maneuver, a constant groundspeed, altitude, and heading should be maintained.

TECHNIQUE:

1. Before starting sideward flight, pick out two reference points in a line in the direction sideward flight is to be made to help you maintain proper ground track (see figure 68 above right). These reference points should be kept in line throughout the maneuver.
2. Begin the maneuver from a normal hovering altitude by applying cyclic toward the side in which movement is desired.
3. As movement begins, return the cyclic stick toward the neutral position to keep the groundspeed at a slow rate - no faster than normal walking speed.
4. Throughout the maneuver, maintain a constant groundspeed and ground track with cyclic stick, a constant heading (perpendicular to the proposed ground track) with pedals, a constant altitude with collective pitch control, and proper operating RPM with throttle.
5. To stop the sideward movement, apply cyclic pressure in the direction opposite to that of movement, and hold it until the helicopter stops. As motion stops the cyclic stick must be returned to the neutral position to prevent movement in the opposite direction. Sideward movement also can be stopped by simply applying enough opposite cyclic pressure to level the helicopter. Then it will drift to a stop.

COMMON ERRORS:

1. Erratic movement of the cyclic stick, resulting in overcontrol and erratic movement over the surface.
2. Failure to use proper pedal control, resulting in excessive heading change.
3. Failure to maintain desired hovering altitude.
4. Failure to maintain proper RPM.
5. Failure to make clearing turns prior to starting the maneuver.

HOVERING - REARWARD FLIGHT

Rearward hovering flight may be necessary to move the helicopter to a specific area when the situation is such that forward or sideward flight cannot be used. During the maneuver, constant groundspeed, altitude, and heading should be maintained. The area behind the helicopter must be carefully cleared before the maneuver is begun.

TECHNIQUE:

1. Before starting rearward flight, pick out two reference points in front of, and in a line with the helicopter to help you maintain proper ground track (see figure 69 above right). The movement of the helicopter should be such that these reference points remain in a line.
2. Begin the maneuver from a normal hovering altitude by applying rearward pressure on the cyclic stick. After movement has begun, position the cyclic stick to maintain a slow groundspeed.
3. Throughout the maneuver, maintain constant groundspeed and ground track with cyclic stick, constant heading with pedals, and constant altitude with collective pitch control, along with throttle coordination, to maintain proper RPM.
4. To stop the rearward movement, apply forward cyclic and hold it until the helicopter stops. As the motion stops, return the cyclic stick to the neutral position. Also, as in the case of forward and sideward flight, forward cyclic can be used to level the helicopter and let it drift to a stop.

COMMON ERRORS:

1. Erratic movement of the cyclic stick, resulting in overcontrol and an uneven movement over the surface.
2. Failure to use pedals properly, resulting in excessive heading change.
3. Failure to maintain desired hovering altitude.
4. Failure to maintain proper RPM.
5. Failure to make clearing turns prior to starting the maneuver.

TAXIING

Taxiing is the intentional movement of the helicopter, under its own power, while remaining in contact with the surface.

TECHNIQUE:

1. The helicopter should be in a stationary position on the surface with the collective pitch full down, and the RPM the same as that which is used for hover operations.
2. Move the cyclic slightly forward of the neutral position and apply a gradual upward pressure on the collective pitch to move the helicopter forward along the surface. Use pedals to maintain heading and cyclic to maintain ground track.
3. The collective pitch controls starting, stopping, and rate of speed while taxiing. The higher the collective pitch, the faster will be the taxi speed. Taxi at a speed no greater than that of a normal walk.
4. During crosswind taxi, the cyclic should be held into the wind a sufficient amount to eliminate any drifting movement.
5. Maintain proper RPM at all times.
   

COMMON ERRORS:

1. Improper use of cyclic stick - using the cyclic to control starting, stopping, and rate of speed.
2. Failure to use pedals for heading control.
3. Improper use of controls during crosswind operations.
4. Failure to maintain proper RPM.