US AAF TM 1-210: Elementary Flying - Acrobatic Phase

62. General.--a. Although many modern airplanes are restricted as to speed, rpm, and violent use of the controls, the elementary student should have some knowledge of the execution of acrobatic maneuvers. This knowledge can be applied when flying unrestricted types of airplanes and is of great assistance in improving his orientation and safe recovery when suddenly confronted with unusual and inadvertent airplane attitudes.

b. For these reasons the course includes a few basic acrobatic maneuvers description of which follows. It is recommended that these maneuvers not be taught until the student is well advanced in his intermediate maneuvers. Early use of acrobatics often frightens a timid student so much that he never fully recovers his confidence.

63. Loop-a. General-The normal loop is the easiest acrobatic maneuver to perform since compliance with a few simple instructions will assure reasonable success. Because of its simplicity and the limited. ability required, the loop is commonly the first acrobatic maneuver taught. Its greatest value is as a morale and confidence builder and as a fundamental maneuver upon which more difficult ones are based.

b. Execution-From straight and level flight, throttle set at cruising rpm, ease into a shallow dive to obtain speed in excess of cruising as soon as sufficient speed has been obtained, ease, back on the stick so that the airplane starts up on the arc of the circle. As response is obtained from the elevators and the airplane assumes the new direction, ease throttle to the fully advanced position in order to obtain the maximum power available. Maintain the airplane on the are of circle by constantly increasing the pressure exerted upon the elevators. As the airplane reaches the partially inverted position, throw the head back in order to observe when the nose crosses the horizon. When well started on the downward path, ease throttle to well below cruising setting in order to prevent undue loss of altitude and excessive increase in speed. As the airplane swings on its upward path, fully advance the throttle and use the elevators in the manner to regain altitude. As speed decreases due to climb, recover from the climb and resume level flight. Set throttle at normal cruising rpm.

c. Remarks.--(1) The necessary initial speed required to complete the maneuver can only be determined through trial and error. In a type with which the pilot is unfamiliar, or if several successive loops are to be performed, it is best to obtain considerable excess speed. However (when more information is obtained as to the looping characteristics of the airplane), the initial speed should be reduced to the minimum necessary to perform the maneuver.

(2) At the start of the maneuver, smooth, positive pressure on the elevators will effect the initial change in direction with the minimum loss of speed and insure that the outline of the loop will be as near perfect circle as possible. Violent use of elevators causes rapid loss of speed and prevents smooth completion of the maneuver. The rate of movement of the elevators is determined by the resistance met. This resistance should be appreciable throughout the maneuver.

(3) For accuracy of performance a distant object should be used upon which to orient the maneuver. This is best accomplished by diving at a definite ground objective during the period when speed is being obtained. This method will demonstrate any errors in rudder use as well as accidental misuse of the ailerons. For example, at the start of the loop the arc of travel passes through the distant objective; on completion the objective is to the left of the flight path. Obviously, the plane of the loop has been tilted to the right and the error is due to one or both of the following:

(a) Right wing lowered during the first portion of the loop. This usually occurs during the pull up and is due to the tendency to pull toward the right shoulder rather than straight back.

(b) Excessive pressure exerted on right rudder pedal or pressure maintained after the necessity for it has passed.

(4) After the student has executed several successive loops sufficient information should have been obtained to isolate his particular fault and permit corrective action to be taken. At the top of the loop when the horizon is visible the ailerons should be used if the wings are not level.

(5) The throttle should not be retarded until the nose of the airplane has definitely started on its downward path. It should then be retarded well. below cruising rpm but not fully retarded. It should not be advanced until the nose of the airplane has definitely started on its upward path during the phase when altitude is being regained. If the throttle is opened during the period when the nose of the airplane is pointing toward the ground, the loss of altitude will be far greater than necessary. Proper handling of the throttle supplements the use of the elevators and will materially aid in the performance of good loops.

64. Slow roll-a  General.--(1) The slow roll is an acrobatic maneuver which is used mainly for demonstration purposes. Its principal value as a training maneuver is to help the pilot overcome instinctive resentment to inverted flight, -and to teach him a safe method of recovery therefrom. It has some value as a means of teaching the student the use of controls during inverted flight and in addition requires coordination, timing, and a sense of orientation.

(2) In this maneuver the ailerons are the major actuating controls, the rudder and elevators aiding the roll mainly in preventing any decided change in direction. This conception (ailerons the major control) is important as most of the errors committed during the performance of the maneuver are due to attempting to force rotation by means of the rudder or elevators.

(3) During the slow roll the airplane revolves about its longitudinal axis through an arc of 360°.

b. Execution.--Select a distant object as a point of reference and maneuver the airplane so that it appears to rotate on the point selected.

(1) From level flight with throttle fully advanced, ease the airplane into a shallow climb. Apply ailerons and rudder as in the beginning of a steep turn but accentuating aileron action in order to obtain the maximum rotating effect with the minimum turning effect consistent without slipping. As the airplane responds to these controls and the bank approaches an angle of 45°, ease the stick forward at a rate such as to prevent turning (ailerons still being used in the manner required to obtain maximum effect), and gradually reverse the rudder at a rate which maintains the desired attitude of the nose. After the airplane rolls well past the completely inverted position the rudder is gradually eased to a neutral position, the rate of movement still that which maintains the desired attitude of the nose, elevators still forward and in a position which maintains the desired attitude and the ailerons full on in the direction of rolling. As rolling is continued the rudder is eased toward the side of original application. Pressure upon this control is gradually increased so that the maximum effort is used as the airplane returns to level flight. Throughout, the maneuver the ailerons are fully applied in the direction of rolling. Up to a bank of approximately 45°, the elevators are used as in any turn. From this position to approximately 45° before completely inverted flight the stick must be forwarded to prevent the nose from swinging in the direction of banking. From this position until approximately 45°  past the completely inverted position, the stick must be forward to prevent the nose from lowering. From approximately 15° past the completely inverted Position, until approximately 45° before completion (in the maneuver, the stick must be forward to prevent the nose from swinging  in the direction of banking. From approximately 45° before completion of the maneuver until completion, the stick must be eased toward the pilot in order to maintain level flight.

(2) As soon as the bank is well started the rudder must be eased to a neutral position to keep the turning moment to the minimum possible without slipping. From approximately 45° to well past the 90° phase, definite pressure must be exerted on opposite rudder to aid in maintaining level, longitudinal flight. From well past the 90° phase until well past the completely inverted position, opposite rudder must be used to prevent the nose from swinging. From well past the completely inverted position until approximately 45° before completion of the maneuver, the rudder must be eased toward the direction of original application in order to maintain level flight. From this phase to completion of the maneuver, pressure must be exerted on the rudder in the direction of original application to prevent the nose from swinging.

c. Remarks-.--(1) From the foregoing it will be noted that during the periods that the rudder is used to maintain level flight, the elevators are used to prevent the nose from swinging, and when the elevators are maintaining level flight, the rudder is used to prevent the nose from swinging.

(2) Very little trouble will be normally encountered with rolls to the left, mainly due to control movements being more natural and being aided somewhat by the torque of the engine. However, rolls to the right require considerable attention until proper control habits have been formed as all movements seem awkward and physical efforts are difficult to time and coordinate.

(3) Prior to attempting rolls, as well as other acrobatic maneuvers, the safety belt should be tightened sufficiently to hold the pilot firmly in the seat.

d. Common faults.--(1) A common fault is failure to select a definite point upon which to orient the roll. It is easy to become disoriented even when a definite point has been selected, but without such aid, memory is forced to play a large part in performance. A definite point upon which to focus attention tends to divert the mind from too much concern or feeling of discomfort in inverted flight.

(2) Leaning away from the bank at the beginning of the maneuver reduces the effectiveness of all movements. Better results will be obtained if the body is permitted to roll. with the airplane which insures full use of controls and well timed, coordinated pressures,

(3) Relaxing pressure on ailerons prevents proper performance. This fault occurs most frequently during the last phase of the roll at the time when the elevators are being returned to neutral. The ailerons are the last controls upon which efforts should be relaxed.

(4) Failure of the student to maintain forward pressure on the stick usually occurs at the completely inverted phase of the roll. This results from the feeling of insecurity which is apt to develop, the reaction being to reach for something to make the pilot's position more secure. Relaxation upon the elevators is usually accompanied by relaxation upon the ailerons which results in slowing or stopping rotation. A snug fit of the safety belt and confidence in it will usually remedy this fault.

(5) If the rudder. is used in an attempt to force rotation and not to maintain the attitude of the nose, skids and slips will be induced which will reduce flying speed and oppose aileron action to such extent as to prevent any semblance of performance. At the 270° phase, premature and positive application of the rudder (in direction of rolling) will cause decided slipping and definitely prevent smooth completion. In contrast, comparatively slow, well timed pressures on the rudder will aid in producing excellent results.

65. Immelmann turn.--a. The Immelmann turn is a composite maneuver consisting of the first half of a loop and the last half of a slow roll. In this maneuver the airplane reverses direction 180° with a gain in altitude depending upon the speed and power available.

b. The speed required is about 20 percent above top speed in level flight and is in excess of that required for a loop.

c. The maneuver is started as a loop. When in the completely inverted position, ease forward on the stick to hold level inverted flight and at the same time apply aileron pressure to start rotation. Aileron and rudder action is continued as in the last half of a slow roll.

66. Half roll and reverse.--a. General.--When accuracy, precision, and smooth flying are insisted upon, the half roll is one of the most difficult maneuvers to perform. As a training maneuver, care should be given to it as it requires good coordination, blending of the controls, and precision throughout.

b. Description.--In this maneuver the airplane is rolled about its longitudinal axis until it is completely inverted, held there momentarily, and then rolled back to level flight. The roll out is in the opposite direction to the roll in.

c. Execution.--The execution is the same as that described in a slow roll except that the rudder and ailerons are neutralized momentarily in the inverted position and the procedure continued as for a slow roll in the opposite direction.

d. Comments.--This maneuver is considered of more value than the half roll with diving recovery for the following reasons:

(1) The modern "clean" airplane gains so much speed in a diving recovery that it is not believed satisfactory for training purposes.

(2) The recovery from unintentional inverted flight, particularly at low altitudes, would necessarily be made by rolling out.

(3) It requires complete orientation in the inverted position in order to perform the last half satisfactorily.

e.. Common errors.

Poor coordination and timing.

Loss of orientation.

Holding airplane on its back. Other errors same as those encountered in slowrolls.

67. Snap roll---a. Execution.--The snap roll should be executed at the speeds specified in technical orders pertaining to the type airplane being used. The airplane is first placed in a slight climbing angle, followed by full movement of the stick to the rear and slightly in the direction of the roll. At the same time full rudder is applied in the direction of the roll. Recovery is started by neutralizing the stick when in the inverted position, with full recovery accomplished by judicious rudder reversement as the level position is reached.

b. Comments.--(1) Care should be taken to execute the roll as smoothly as possible as it is a maneuver to develop rhythm and orientation.

(2) The time spent on this maneuver at any one time should be limited as the necessarily sudden and extreme use of controls may tend to cause mechanical performance.

68. Vertical reverse.--a. General.--The verticalreverse is a training maneuver belonging to the spin or snap roll family and as such, during its performance, the movements of the airplane are rapid but controlled. The maneuver has the following useful training purposes:

(1) Requires good performance and understanding to steep turns.

(2) Accentuates errors resulting from either violent and poorly timed effort or overcautious effort.

(3) Demands perception as to gain or loss of speed and prompt physical responses.

(4) Requires trained responses rather than impulsive erratic reactions.

(5) Requires orientation during rapid movements of the airplane.

(6) Accentuates the value of timing efforts,  especially that of relaxation, when at reduced flying speeds.

b. Execution..-The vertical reverse is a quick change from a right to a left steep turn or vice versa. From a turn with a bank in excess of 45° apply firm pressure on the rudder pedal in the direction opposite to turning, and as soon as the airplane starts to respond pull straight back on the stick. As the airplane responds to these controls, apply ailerons firmly in the direction of rudder use, still continuing the backward movement of the stick and firm pressure on the rudder pedal. The airplane will start up in a steep climb swinging in the direction that ailerons and rudder are being used. Before flying speed is materially reduced, start easing forward on the stick, still continuing efforts on ailerons and rudder. As the airplane approaches the desired angle of bank gradually relax efforts on all controls, timing this action so that it is completed when the airplane has assumed the desired attitude. Correct small errors in the new turn with light, well directed efforts.

c. Comments-(1) When properly performed it should be possible to resume flight without any break in the rhythm of turning or, in other words, the airplane should not suddenly stop and then resume turning as gross errors are corrected.

(2) The instructor should emphasize that smooth performance requires positive control movements and well timed, gradual relaxation of the controls.

(3) The initial steep turn should be well executed otherwise errors are carried into the maneuver and their cumulative effect is to destroy performance. The common tendency is to anticipate the reverse before the turn is well started. When this is done, such gross errors result that it is better to start the maneuver over again.

(4) Upon completion of the maneuver, speed is materially reduced. At this time violent pressure, if applied to the ailerons in order to reduce the angle of bank, or to the elevators to prevent the nose falling, will result in further diminishing the available speed and consequent loss of control. Under these conditions, if control abuse is carried to an extreme the airplane will either fall into a spin, or lose considerable altitude before recovery can be made. To stop the airplane in the desired attitude properly time relaxation of the controls. This last is the only positive and unfailing method to be used but because of its simplicity it is seldom done.

(5) After the peak of the maneuver has been reached, maintaining pressure back on the stick will result in the start of a spin and such rapid rotation and loss of control that all semblance of a vertical reverse will be lost. The student should be cautioned that when extremely rapid rotation takes place at this phase of the maneuver it is undoubtedly due to this cause, and he must completely relax on all controls and then, after the airplane has freed itself from control abuse, regain control.

(6) Due to the possibility of accidental spins, vertical reverses should be practiced by the student at an alitude well above 2,000 feet.

(7) The most common fault is the tendency to bring violent back pressure on the elevators after the sudden direction change resulting in a stall or spin. With practice the average student can make continuous reverses, changing direction 180the airplane will without excessive loss of altitude.