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196      U.S. CIVIL AERONAUTICS AUTHORITY

DOUBLE SNAP ROLLS

A double snap roll is a single roll repeated before recovery. About 20 percent more speed is required than in the single roll. The nose should be steadied slightly above the horizon and throttle fully opened. The nose is pulled slightly toward the side of desired roll with a slight amount of rudder, followed by sharply pulling the stick full back and applying full rudder. Allow the airplane to rotate two full turns. Recovery is made as in the single roll. About one-quarter turn before recovery, full opposite rudder is applied and the stick eased forward. When near level flight on the original heading, the stick is snapped forward. The airplane is thus placed in its original attitude.
 
THE SLOW OR AILERON ROLL

The principal purposes of this maneuver are:

1. The further development of control use analysis and proper coordination of the controls to obtain a desired result rather than their use in a mechanical manner or with any conception of a fixed relationship of the pressures to be exerted on each. 

2. The overcoming of the instinctive aversion of the average student to inverted flight. 

3. The development of the ability to think and control physical reactions in a normal manner while "looking up" at the ground. 

4. The further development of orientation under adverse circumstances and during any attitude of the airplane. 

In executing this maneuver the ailerons are the primary motivating control, the rudder and the elevators being merely trimming controls to maintain the correct position of the nose and prevent turning. 

If this conception is not perfectly clear, errors may be made by trying to force rolling action by means of the elevators or rudder, or both. Such efforts will blanket or nullify the effect of the ailerons, since at lowered speeds the rudder and elevators are relatively more effective than the ailerons. Most of the errors in the execution of this maneuver result from such improper use of one or the other, or both, of the trimming controls.

This maneuver, like the slow half roll, can be executed during a climb, straight flight, or in a dive or a glide, the only difference being in the degree of rotation about the longitudinal axis, which is a half revolution in the half roll and a full revolution in the complete roll. 

In starting and executing this maneuver, an axis point should be selected on the horizon and the nose held on this point while the airplane is rolled around its longitudinal axis. 

With most aircraft the nose may be held level throughout the maneuver, but with some it may be necessary to start a very shallow climb before the roll is started. From either position, with the throttle fully advanced, apply the ailerons and rudder as though a steep turn were to be started, with the pressure on the ailerons accentuated in such a manner as to obtain the maximum rolling moment with a minimum of turning effect. As the bank approaches 45° and the airplane starts to turn, the elevators must be eased forward to prevent the turn and the rudder eased off to maintain the