10: Flight Instruction and Maneuvers

Taxiing

Takeoffs

Turns

Turbulence and Wind Correction

Approaches and Landings

Rectangular Course

Turns Around a Point

S-Turns

Eights-On-Pylons

Stalls and Slow Flight

Steep Turns

Chandelles

Lazy Eights

Flight by Reference to Instruments

Helicopter Operation

Gyroplane Flight Operation

Glider Flight Operation

Taxiing

When taxiing a tricycle-gear airplane in a strong quartering tail wind, the elevator should be held in the neutral or down position, and the aileron on the side from which the wind is blowing should be down so the air flowing over it will force the wing down. When a tricycle-gear airplane is taxied in a strong quartering head wind, the elevator should be held in the neutral position, and the upwind aileron should be up.

Before starting the pretakeoff check, the airplane should be positioned out of the way of other aircraft. It is recommended that the airplane be as nearly as possible headed into the wind, to obtain more accurate operating indications and to minimize engine overheating during run-up.

Takeoffs

For a soft- or rough-field takeoff, the airplane should lift off at as low an airspeed as is possible, and immediately after liftoff, the nose should be lowered to pick up speed before leaving ground effect.

For a short-field takeoff, the pitch attitude for minimum drag is used. The airplane should accelerate as rapidly as possible until the best angle-of-climb speed, VX, is reached, and then rotate. The liftoff speed for a short-field takeoff is greater than that used for a soft- or rough-field takeoff.

Turns

There are four flight fundamentals involved in maneuvering an airplane:

  1. Straight-and-level flight
  2. Turns
  3. Climbs
  4. Descents

In a coordinated turn, centrifugal force exactly balances the horizontal component of lift. Increasing the rate of turn without using rudder increases the horizontal component of lift without an opposing increase in centrifugal force, and the aircraft slips to the inside of the turn.

In a right descending turn, the torque is decreased, and a slight amount of left rudder pressure is used to keep the nose from yawing excessively. If too much left rudder is used, the horizontal component of the lift will be greater than the centrifugal force, and the aircraft will slip to the right.

The student pilot in a side-by-side aircraft is sitting to the left side of the longitudinal axis about which the aircraft rolls. This causes the nose to appear to rise when making a correct left turn and appear to descend in a correct right turn. The student will have a tendency to dive to compensate for the apparent rising nose in a left turn and to climb to compensate for the apparent descent during a right turn.

Adverse yaw, caused by the induced drag from the down aileron, causes the nose of an aircraft to initially move in the direction opposite the desired direction of the turn. This is a slipping-turn entry, and more rudder pressure should be applied for the amount of aileron pressure being used. If the rudder is applied too soon, it will cause the nose of the aircraft to move in the direction of the turn before the bank is started.

To recover from an unintentional nose-low attitude during a steep turn, the pilot should first reduce the angle of bank with coordinated aileron and rudder pressure. Then back elevator pressure should be used to raise the aircraft’s nose to the desired pitch attitude. After accomplishing this, the desired angle of bank can be reestablished. Attempting to raise the nose first by increasing back elevator pressure will usually cause a tight descending spiral and could lead to overstressing the aircraft.

The deflection of the turn needle is dependent upon the rate of yaw. If a constant angle of bank is maintained in a coordinated turn, the rate of yaw and therefore, the displacement of the turn needle, will increase as the airspeed decreases. If a constant 30° angle of bank is held in a coordinated turn, a reduction in airspeed will cause an increase in the rate of turn and a decrease in the radius of the turn.

Maintaining a constant load factor, or G, while increasing the airspeed in a coordinated turn will increase the radius of the turn.

Turbulence and Wind Correction

When flying in severe turbulence, wing loading can be minimized by setting the power and trim to obtain an airspeed at or below the design maneuvering airspeed, maintaining a wings-level attitude, and accepting the variations in airspeed and altitude that will occur.

When flying straight-and-level and following a selected ground track, the preferred method of correcting for wind drift is to head (crab) the aircraft sufficiently into the wind to cause the aircraft to move forward into the wind at the same rate the wind is moving it sideways. This crab angle should be established by coordinated use of the controls.

Approaches and Landings

If the crab method of drift correction has been used throughout the final approach and round-out, the crab must be removed the instant before touchdown by applying rudder in order to align the aircraft’s longitudinal axis with its direction of movement, and switching to the wing-low method of crosswind correction. The motion of the aircraft and its longitudinal axis should be parallel with the runway. A properly executed crosswind landing requires timely and accurate action. Failure to accomplish this results in severe side loads being imposed on the landing gear and imparts ground-looping, or swerving, tendencies.

The final approach for a short-field landing over obstacles is made at a steep approach angle and close to the aircraft’s stalling speed. Initiation of the round-out, or flare, must be judged accurately to avoid flying into the ground, or stalling prematurely and sinking rapidly. If the approach speed is correct, there will be no floating during the flare, and there will be sufficient control to touch down properly.

When flying at speeds below L/DMAX, thrust is inversely proportional to airspeed. As angle of attack is increased, airspeed decreases and more thrust is required to maintain a given airspeed. For these reasons, the throttle controls rate of climb or descent, and airspeed is controlled by the angle of attack.

A downwind landing, using the same airspeed as is used on a normal upwind landing, will result in a higher approach ground speed with the likelihood of overshooting the desired touchdown point. The ground speed at touchdown will be higher than normal, and the ground roll will be longer.

Specific information in the aircraft flight manual regarding the approach airspeed and the use of flaps always takes precedence over any rule of thumb. But if specific information is not known, a good rule of thumb for indicated airspeed during a turbulent-air approach is to use the normal approach speed plus one-half the wind-gust factor.

When the decision is made to discontinue an approach and perform a go-around, takeoff power should be applied immediately and the airplane’s pitch attitude changed to slow or stop the descent. After the descent has been stopped, the flaps may be partially retracted or placed in the takeoff position, as recommended by the manufacturer. If the flaps are fully extended at low airspeed when using full power, the airplane is likely to have poor controllability. Although the need to discontinue a landing may occur at any point in the landing process, the most critical go-around will usually be one started at a point very close to the ground. Nevertheless, it is safer to make a go-around than it is to touch down while drifting or while in a crab, or than it is to make a hard drop-in landing from a high round-out, or a bounced landing.

Unless otherwise specified in the airplane’s operating manual, it is generally recommended that the flaps be retracted, at least partially, before retracting the landing gear. There are two reasons for this: First, on most airplanes, full flaps produce more drag than the landing gear; and second, in case the airplane should inadvertently touch down as the go-around is initiated, it is most desirable to have the landing gear in the down-and-locked position.

If a pilot focuses on references that are too close, or if they look directly downward, the references become blurred, and reactions will be either too abrupt or too late. In this case, the tendency is to overcontrol, round-out high, and make a full-stall “drop-in” landing. When the focus is too far ahead, accuracy in judging the closeness of the ground is lost, and the consequent reactions will be slow since there appears to be no necessity for any action. This is likely to result in a nose-first touchdown. Excessive airspeed on final approach usually results in the aircraft “floating.” If the pilot misjudges the rate of sink during a landing and thinks the aircraft is descending faster than it should, there is a tendency to increase the pitch attitude and angle of attack too rapidly. This action not only stops the descent, but actually starts the aircraft climbing during the round-out in a condition known as ballooning. To correct for slight ballooning, hold a constant landing attitude and allow the airplane to gradually decelerate and settle onto the runway. If the ballooning is severe, the throttle may be used to cushion the landing.

Rectangular Course

For best results when planning a rectangular course, the flight path should be positioned outside the field boundaries just far enough that they may be easily observed from either pilot seat by looking out the side of the aircraft. The closer the track of the aircraft is to the field boundaries, the steeper the bank necessary at the turning points. See Figure 10-1.

Figure 10-1. Rectangular course

Turns Around a Point

When flying turns around a point, the airplane wings will be in alignment with the pylon only during the time the airplane is flying directly upwind or directly downwind. At all other points, a wind correction angle will keep the wings from pointing directly at the pylon.

If the student is instructed to not exceed a 45° bank in a turn around a point maneuver, the best place to start is the point where the bank angle will be steepest, which is when flying downwind. Throughout the remainder of the maneuver, the bank will be shallowing out.

The ground speed will be equal where the airplane is flying with the same headwind component. The angle of bank will be the same only where the airplane is flying directly crosswind. See Figure 10-2.

Figure 10-2. Turns around a point

S-Turns

In a steep turn, the ground speed will be the same when the aircraft has the same headwind component. The steepest angle of bank is required at the points where the aircraft is flying downwind. The aircraft will have to be crabbed into the wind the greatest amount where it is flying crosswind.

In the first half of an S-turn, the bank should begin shallow and increase in steepness as the aircraft turns crosswind, and become steepest where the turn is downwind. If the turn is started with too steep a bank angle, the bank will increase too rapidly and the upwind half of the “S” will be smaller than the downwind half. The turn will not be completed by the time the aircraft is over the reference line. See Figure 10-3.

Figure 10-3. S-turns

Eights-On-Pylons

When eights-on-pylons are conducted at the correct altitude, the reference line will always point directly at the pylon. If the reference point moves behind the pylon, the airplane is above its pivotal altitude. The pivotal altitude for eights-on-pylons depends primarily on the ground speed.

If the rudder is misused when attempting to hold the pylon during the performance of eights-on-pylons, the airplane will either slip or skid. The airplane is above the pivotal altitude when the bank angle is too steep for the rate of yaw and the airplane is slipping. The airplane is below the pivotal altitude when the rate of yaw is too great for the bank angle and the airplane is skidding. See Figure 10-4.

Figure 10-4. Eights-on-pylons

Stalls and Slow Flight

The crossed-control stall is the type of stall most likely to occur during a poorly planned and executed turn from base to final during a landing approach. The objective of demonstrating a crossed-control stall is to show the effect of improper control technique and to emphasize the importance of using coordinated control pressures whenever making turns.

Maneuvers at slow flight are taught to develop the pilot’s sense of feel and the ability to use the controls correctly. This type of flying improves proficiency for maneuvers in which very low airspeed is required, and allows the pilot to recognize how fast control effectiveness can be lost. In-flight practice at slow flight should cover two distinct flight situations:

  1. Establishing and maintaining the airspeed appropriate for landing approaches and go-arounds in the aircraft being used; and
  2. Turning flight at the slowest airspeed that the particular aircraft is able to continue controlled flight without stalling.

Steep Turns

An airplane will stall during a coordinated steep turn exactly as it does from straight flight, except that the pitching and rolling actions tend to be more sudden. The direction an airplane tends to roll during an accelerated stall is determined by whether the airplane is slipping or skidding, or is in a coordinated turn. If the airplane is slipping toward the inside of the turn at the time the stall occurs, it tends to roll rapidly toward the outside of the turn as the nose pitches down. The outside wing stalls before the inside wing. If the airplane is skidding toward the outside of the turn when it stalls, it will have a tendency to roll to the inside of the turn because the inside wing stalls first. If the airplane is in a coordinated turn at the time the stall occurs, the nose will pitch away from the pilot just as it does in a straight-flight stall, since both wings stall simultaneously.

In a steep power turn, the bank angle is steep enough that the airplane has an overbanking tendency, and the rudder is used to prevent excessive yawing.

If the airplane begins to gain altitude in a steep power turn, the bank should be increased by coordinated use of rudder and ailerons. If the airplane begins to lose altitude, the bank should be decreased by coordinated use of the rudder and ailerons. The rudder should never be used alone to control the altitude.

Chandelles

In the first 90° of a chandelle, the bank angle is held constant, and the pitch attitude is increased at a constant rate until it reaches its maximum at the 90°-point. During the second 90°, the pitch angle is held constant, and the bank angle is gradually reduced at a constant rate until the wings come level when the 180°-point is reached. At this point, the pitch attitude should be high and the airspeed about 5 knots above a stall.

If a chandelle is begun with a bank that is too steep, the airplane will turn too fast; not enough altitude will be gained and the pilot may pitch up abruptly to compensate. If it is begun with a bank that is too shallow, the pitch angle will increase excessively, and the airplane is likely to stall before it reaches the 180°-point. See Figure 10-5.

Figure 10-5. Chandelle

Lazy Eights

A lazy eight consists of two 180° turns, in opposite directions, while making a climb and a descent in a symmetrical pattern during each of the turns. The maximum pitch-up attitude should occur at the 45°-point. The minimum airspeed and steepest bank should be reached at the 90°-point where the altitude is maximum, and the pitch attitude is near level. The maximum pitch-down attitude should occur at the 135°-point. The altitude at the 180°-point should be the same as the entry altitude.

If a lazy eight is started with too rapid a roll rate, the 45°-point may be reached before the maximum pitch-up attitude is reached. If the climbing turn portions of a lazy eight are entered with banks that are too steep, the turn rate will be too fast for the rate of climb, and the 180° change of direction will be reached with an excess of airspeed. See Figure 10-6.

Figure 10-6. Lazy eights

Flight by Reference to Instruments

The turn-and-slip indicator and the turn coordinator have a inclinometer built into their display that shows the relationship between the centrifugal force and the horizontal component of lift that acts on the airplane in a turn.

In a coordinated turn, the horizontal component of lift and the centrifugal force are equal but operating in the opposite directions, and the ball stays in the center of the glass tube. When entering a turn, the horizontal component of lift should exactly balance the centrifugal force to keep the ball centered. If, while rolling into a right turn, the ball moves to the outside (to the left), the centrifugal force is greater than the horizontal component of lift, and the right rudder pressure should be slightly relaxed to allow the ball to return to the center. If, while rolling into a right turn, the ball moves to the inside (to the right), the horizontal component of lift is greater than the centrifugal force and more right rudder pressure is needed to center the ball.

The pitch attitude of an airplane is the angle between the longitudinal axis of the airplane and the actual horizon. In straight-and-level flight, the altimeter is the primary instrument for pitch control.

When entering a constant airspeed climb from straight-and-level flight, the attitude indicator is the primary pitch and supporting bank indicator. The heading indicator is the primary bank indicator and the turn coordinator is the supporting bank indicator. When establishing a level, standard-rate turn, the primary bank instrument for the beginning of the turn is the attitude indicator, and after the turn is established, the primary bank instrument is the turn coordinator.

In an unusual attitude, it is possible for the attitude indicator to exceed its limits and become unreliable. The airspeed indicator and altimeter can be relied upon to give pitch indication to initiate a recovery from an unusual flight attitude.

If the airspeed is increasing or is too high, reduce power to prevent excessive airspeed and loss of altitude. Correct the bank attitude with coordinated aileron and rudder pressure to straight flight by referring to the turn coordinator. Raise the nose to level flight attitude by smooth back elevator pressure. All components of control should be changed simultaneously for a smooth, proficient recovery.

During attitude instrument training, the pilot must develop three fundamental skills involved in all instrument flight maneuvers:

  1. Instrument cross-check.
  2. Instrument interpretation.
  3. Aircraft control.

When executing an ILS approach, the pilot must keep the aircraft on the electronic glide slope. This requires the ability to establish the proper rate of descent for the ground speed. As ground speed increases, the rate of descent required to maintain the glide slope must be increased; as ground speed decreases, the rate of descent required to maintain the glide slope also decreases. By first cross-checking the instruments and then interpreting them, the pilot is able to precisely control the aircraft to a successful landing.

Helicopter Operation

Helicopter Controls

The collective pitch control simultaneously changes the pitch of all of the main rotor blades. It is connected through appropriate linkage to the throttle cam, so that the engine power is automatically increased as the collective pitch lever is raised and decreased as it is lowered. The collective pitch control should be used:

  1. To correct for loss of lift during level turns at altitude.
  2. To maintain desired engine power.
  3. To correct a high rotor RPM during autorotations from altitude.

When taxiing a helicopter, the collective pitch controls starting, stopping, and the rate of taxi speed. The higher the collective pitch, the faster will be the taxi speed.

As collective pitch is increased to check the descent in a flare, autorotative descent, and landing, additional right pedal is required to maintain heading due to the reduction in rotor RPM and the resulting reduced effect of the tail rotor.

During a powered approach to a hover, the angle of descent is primarily controlled by collective pitch, the airspeed (and the ground speed) by the cyclic control, and heading on final approach is maintained with pedal control.

As you accelerate to effective translational lift, the helicopter will begin to climb, and the nose will tend to rise due to increased lift. At this point, adjust collective pitch to obtain normal climb power, and apply enough forward cyclic stick to overcome the tendency of the nose to rise.

During crosswind taxi, the cyclic stick should be held into the wind a sufficient amount to eliminate any drift.

If a helicopter experiences complete power failure during cruising flight, the collective pitch control should be lowered to reduce the pitch on all main rotor blades so that the proper rotor RPM can be maintained.

In a running takeoff in a crosswind, the ground track of the helicopter is maintained with cyclic control, and the heading is maintained with the antitorque pedals until a climb is established. Antitorque pedals are used to maintain heading during crosswind takeoffs and approaches, and right antitorque pedal is used when entering autorotation to maintain heading after the torque is lost.

If the antitorque system fails during hovering flight, quick action must be taken by the pilot. The throttle should be closed immediately without varying the collective pitch position to eliminate the turning effect. Simultaneously, the cyclic stick should be used to stop all sideward or rearward movements and place the helicopter in the landing attitude prior to touchdown. From this point, the procedure for a hovering autorotation should be followed. If the antitorque system fails during cruising flight, and a powered approach is commenced, the helicopter can be prevented from yawing to the right just prior to touchdown by decreasing the throttle to decrease the torque effect.

A slip occurs when a helicopter slides sideways toward the center of the turn. It is caused by an insufficient amount of pedal in the direction of turn (or too much in the direction opposite the turn) in relation to the amount of collective stick (power) used. In other words, if improper pedal pressure is held to keep the nose from following the turn, the helicopter will slip sideways toward the center of the turn. In a right descending turn, if insufficient right pedal is used to compensate for the decreased torque effect, a slip will result.

Takeoffs and Hovering

A downwind turn close to the ground made immediately after takeoff increases the hazards involved, if an emergency landing should become necessary.

Tall grass tends to disperse or absorb the ground effect, and more power is required to hover over tall grass, especially in zero wind conditions. Takeoff from tall grass may be difficult.

Autorotation

The pilot’s primary control of the rate of descent in autorotation is the airspeed. The rate of descent is high at zero airspeed and decreases to a minimum somewhere in the neighborhood of 50 to 60 miles per hour, depending upon the particular helicopter. If the glide is too flat, the airspeed is too high, and this can be corrected by increasing the rotor lift by applying aft cyclic pressure.

Forward speed during autorotative descent permits a pilot to incline the rotor disc rearward, thus causing a flare. The additional induced lift created by the greater volume of air flowing through the rotor momentarily checks forward speed as well as descent.

When a helicopter is flared during an autorotative landing, the rotor RPM momentarily increases because of the additional volume of air flowing upward through the rotor disc. This air increases the angle of attack of the blades and increases their lift. The horizontal component of this increased lift turns the rotor at a higher speed.

As the forward speed and descent rate near zero, the upward flow of air practically ceases, and the rotor RPM again decreases. The helicopter settles at a slightly increased rate, but with reduced forward speed. As the forward speed and descent rate decrease, the amount of air flowing upward through the rotor decreases, and the rotor RPM decreases.

The specific airspeed for autorotations is established for each type of helicopter on the basis of average weather and wind conditions and normal loading. When the helicopter is operated with excessive loads in high density altitude or strong gusty wind conditions, best performance is achieved from a slightly increased airspeed in the descent. By increasing the airspeed in these conditions, a pilot can achieve approximately the same glide angle in any set of circumstances and can estimate the touchdown point.

When making turns during an autorotative descent, generally use cyclic control only. Use of antitorque pedals to assist or speed the turn causes loss of airspeed, downward pitching of the nose, and an increased sink rate.

RPM is most likely to increase above the maximum limit during a turn because of the increased back cyclic pressure, which induces a greater airflow through the rotor system. The use of excessive right pedal pressure will require additional back cyclic pressure, which will increase the rotor RPM.

Retreating Blade Stall

Retreating blade stall in a helicopter rotor is caused by an excessive angle of attack on the retreating blade. When vibrations from a blade stall are first felt, decrease the angle of attack. Do this by reducing the collective pitch, increasing the rotor RPM, and reducing the forward airspeed. A retreating blade stall is indicated by:

  1. Abnormal two-per-revolution vibration in a two-blade rotor or three-per-revolution in a three-blade rotor.
  2. Nose pitch up.
  3. Tendency of the helicopter to roll.

Vortex Ring State

A vortex ring state is a helicopter operation in which the main rotor is operating in its own downwash. The flow of air through the center portion of the disc is upward, and the flow through the outer portion is downward.

A helicopter is most likely to enter a vortex ring state under the following combination of conditions:

  1. A vertical or nearly vertical descent of at least 300 fpm. (The actual critical rate depends on the helicopter’s gross weight, RPM, density altitude, and other factors.)
  2. The rotor disc must be using some of the available engine power (20–100 percent).
  3. The helicopter’s horizontal velocity must be slower than effective translational lift.

Slope Operation

When making a slope landing with a helicopter, the cyclic pitch control should be used in the direction of the slope to hold the upwind skid against the slope, while the downslope skid is let down with collective pitch.

The steepness of the slope that can be used for a helicopter landing is determined by the amount of lateral cyclic stick travel available. Each make of helicopter generally has its own peculiar way of indicating to the pilot when lateral cyclic stick travel is about to run out, and a landing should not be attempted when the pilot is getting an indication that they are running out of lateral stick control.

As the upslope skid touches the ground during a slope landing, the cyclic stick should be applied in the direction of the slope to hold the skid against the slope. With the upslope skid against the slope, the downslope skid is lowered to the ground with the collective pitch.

Rapid Decelerations

Although used primarily for coordination practice, decelerations can be used for a helicopter to make a quick stop in the air. The purpose of the maneuver is to maintain a constant altitude, heading, and RPM while slowing the helicopter to a desired ground speed. The rotor RPM will normally tend to increase during the entry and tend to decrease during the completion of the maneuver. Rapid decelerations should be practiced at an altitude high enough to permit a safe clearance between the tail rotor and the surface throughout the maneuver.

Pinnacle Approaches

During a pinnacle approach to a rooftop heliport under conditions of turbulence and high wind, the pilot should make a steeper-than-normal approach, maintaining the desired angle of descent with collective applications.

Running Landings

Adequate directional control is ensured while making a running landing in a helicopter by maintaining the normal operating RPM until the helicopter stops.

Gyroplane Flight Operation

The gyroplane rotor blade spin-up lever engages the engine to the rotor and at the same time decreases the pitch angle of the blades to minimize the engine load. For run-up, the pitch angle is 0°. During the transition from prerotation to flight, all rotor blades change pitch simultaneously, but to different angles of incidence.

The spinning rotor of a gyroplane acts as a large gyroscope, and abrupt control movement can cause damaging and excessive blade travel. When taxiing a gyroplane with the rotor blades turning, avoid abrupt control movements.

The normal landing for a gyroplane is a running, or roll-on, landing. On final approach, establish a crab angle into the wind to maintain a ground track that is aligned with the extended centerline of the runway. Just before touchdown, remove the crab angle and bank the gyroplane slightly into the wind to prevent drift. Maintain longitudinal alignment with the runway using the rudder.

Glider Flight Operation

Water ballast is used in some high-performance sailplanes to increase their cruising speed. The L/D ratio is a function of aerodynamic considerations and is independent of the sailplane weight. The added weight of the water ballast allows the sailplane to increase its lift by flying faster, rather than by increasing its angle of attack.

Rules of thumb for airspeeds to be used for various conditions are:

  1. When passing through lift with no intention of working it, the airspeed that produces the minimum sink speed should be used.
  2. To cover the greatest distance for each foot of descent when flying into a strong headwind, hold the airspeed at the best L/D speed plus 1/2 the estimated wind speed at the glider’s flight altitude.
  3. For the final approach speed, use 50 percent above the glider’s stalling speed plus 1/2 the estimated wind speed.

If a steep wind gradient exists, a pilot not maintaining adequate speed control during the turn to base and final approach to landing will likely undershoot the desired landing spot, or the glider will stall. If there is an indication of a strong thermal on the final approach to landing, the pilot should close the spoilers and dive to increase airspeed.

After attaining the proper climb speed, the pilot should smoothly increase the pitch attitude until reaching an altitude of at least 200 feet. A safe rule of thumb for pitch angle is to keep the pitch angle below 15° at 50 feet, 30° at 100 feet, and 45° at 200 feet.

When more than one glider is circling in a thermal, the turns should be made in the same direction as those made by the first glider to enter the thermal.

When slope soaring, make all reversing turns away from the ridge and into the wind. When making an off-field landing, it is nearly always best to land uphill, if possible, regardless of the wind direction. A safe off-field landing is normally ensured by maintaining an approach airspeed of at least 50 percent above the glider’s stall speed, plus 1/2 the estimated wind speed.

[10-2024]