|CHAPTER 6. Flight Manuevers
Gliding turns have a signifi cant increase in descent rate than straight glides because of the decrease in effective lift due to the direction of the lifting force being at an angle to the pull of gravity. Therefore, it should be clearly understood that the steeper the bank angle, the greater the descent rate.
In gliding turns, the decrease in effective lift due to the direction of the lifting force being at an angle to the pull of gravity make it necessary to use more nose-up pressure than is required for a straight glide. However, as discussed earlier for steeper turns, airspeed must be maintained well above stall speed which increases during turns or the WSC could stall in the turn.
When recovery is being made from a medium or high banked gliding turn, the pitch force which was applied during the turn must be decreased back to trim, which must be coordinated with the roll back to level.
In order to maintain the most effi cient or normal glide in a turn, more altitude must be sacrifi ced than in a straight glide since this is the only way speed can be maintained without power. Attention to the front tube angle with the horizon and the reference point on the front tube provide visual reference of attitudes while gliding. [Figures 6-17 and 6-18]
Common errors in the performance of descents and descending turns are:
Pitch and Power
No discussion of climbs and descents would be complete without touching on the question of what controls altitude and what controls airspeed. The pilot must understand the effects of both power and pitch control, working together, during different conditions of fl ight.
As a general rule, power is used to determine vertical speed and pitch control is used to determine speed. However, there are many variations and combinations to this general statement. Decreasing pitch and diving do provide a quicker descent but is not typically used as a fl ight technique for long descents. Changes in pitch through moving the control bar forward and backward are used for maintaining level fl ight in rising and falling air, and pulling back on the control bar is used for a steep approach technique to lose altitude; however, these techniques are used only for short durations and not the primary altitude control for the WSC.
The throttle is the main control used for determining vertical speed. At normal pitch attitudes recommended by the manufacturer and a constant airspeed, the amount of power used determines whether the aircraft climbs, descends, or remains level at that attitude.
Steep Turn Performance Maneuver
The objective of the steep turn performance maneuver is to develop the smoothness, coordination, orientation, division of attention, and control techniques necessary for the execution of maximum performance turns when the aircraft is near its performance limits. Smoothness of control use, coordination, and accuracy of execution are the important features of this maneuver.
The steep turn maneuver consists of a level turn in either direction using a bank angle between 45° to 60°. This causes an overbanking tendency during which maximum turning performance is attained and relatively high load factors are imposed. Because of the high load factors imposed, these turns should be performed at an airspeed that does not exceed the aircraft’s design maneuvering speed (VA). The principles of an ordinary steep turn apply, but as a practice maneuver the steep turns should be continued until 360° or 720° of turn have been completed. [Figure 6-19]
An aircraft’s maximum turning performance is its fastest rate of turn and its shortest radius of turn, which change with both airspeed and angle of bank. Each aircraft’s turning performance is limited by the amount of power its engine is developing, its limit load factor (structural strength), and its aerodynamic characteristics. Do not exceed the maximum bank angle limitation in the POH. For example, a maximum 60° bank angle is a limit used by many manufacturers.
The pilot should realize the tremendous additional load that is imposed on an aircraft as the bank is increased beyond 45°. During a coordinated turn with a 60° bank, a load factor of approximately 2 Gs is placed on the aircraft’s structure.
Regardless of the airspeed or the type of aircraft involved, a given angle of bank in a turn during which altitude is maintained always produces the same load factor. Pilots must be aware that an additional load factor increases the stalling speed at a signifi cant rate—stalling speed increases with the square root of the load factor. For example, a light aircraft that stalls at 40 knots in level fl ight stalls at nearly 57 knots in a 60° bank. The pilot’s understanding and observance of this fact is an indispensable safety precaution for the performance of all maneuvers requiring turns.
Before starting the steep turn, the pilot should ensure that the area is clear of other air traffi c since the rate of turn is quite rapid. After establishing the manufacturer’s recommended entry speed or the design maneuvering speed, the aircraft should be smoothly rolled into a selected bank angle between 45° to 60° and the throttle increased to maintain level fl ight. Always perfect the steep turn at 45° and slowly work up to higher bank angles. As the turn is being established, control bar forward pressure should be smoothly increased to increase the angle of attack. This provides the additional wing lift required to compensate for the increasing load factor.
After the selected bank angle has been reached, the pilot fi nds that considerable force is required on the control bar and increased throttle is required to hold the aircraft in level fl ight—to maintain altitude. Because of this increase in the force applied to the control bar, the load factor increases rapidly as the bank is increased. Additional control bar forward pressure increases the angle of attack, which results in an increase in drag. Consequently, power must be added to maintain the entry altitude and airspeed.
During the turn, the pilot should not stare at any one object. Maintaining altitude, as well as orientation, requires an awareness of the relative position of the forward tube and the horizon. The pilot must also be looking for other aircraft mainly towards the direction of the turn while glancing at the instruments to make sure the airspeed and altitude are being maintained. If the altitude begins to increase or decrease a power adjustment may be necessary to maintain the altitude if the bank angle and speed are maintained. All bank angle changes should be done with coordinated use of pitch and throttle control.
The rollout from the turn should be timed so that the wings reach level fl ight when the aircraft is exactly on the heading from which the maneuver was started. While the recovery is being made, forward bar pressure is gradually released and power reduced, as necessary, to maintain the altitude and airspeed.
Common errors in the performance of steep turns are:
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