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FLIGHT INSTRUCTOR'S MANUAL   97

TAKE-OFFS

   As a general rule the student should, after the first few flights, be allowed to follow through on the controls during take-offs and landings, and, after he has had instruction in taxiing and climbs, will be ready for instruction in take-offs.
   Each airplane will have its own best angle, or height of the tail above the ground, for the take-off. This angle will be the one best suited for quick development of the speed and control necessary to enable the ship to leave the ground. This angle will rarely be achieved in practice, but it is the goal toward which to strive. However, varying conditions may make a difference in the requirements of take-off technique. A rough field, all call for different technique, as will smooth air as contrasted with strong, gusty wind.
   For the normal take-off on a smooth field or surfaced runway, the tail should be raised until the thrust line is parallel to the ground, since this position will give the quickest acceleration due to the minimum drag of the whole structure.
   During take-offs from soft or rough fields, the tail should be some-what lower in order that a maximum of lift will be gained as soon as possible. This will prevent bouncing in the case of rough fields, and the wasting of power by plowing through the mud or soft earth in soft fields. The tail skid must be free from the ground and the angle not too steep, or the purpose will be defeated by too much drag being present and the actual take-off retarded rather than accelerated.
   Take-offs in a strong, gusty wind will require that the tail will be raised and an extra margin of speed obtained before the ship is allowed to take off, since a take-off near the stalling speed may result in serious lack of control when the aircraft encounters strong gusts or other turbulent air currents.
   Smooth use of the throttle is important, particularly in the case of high horsepower engines, since peculiarities of take-off characteristics are accentuated in proportion to the rapidity with which full power is developed.
   With an airplane of normal stability characteristics, and the stabilizer set for level flight or cruising r. p. m., the airplane at full throttle will assume the correct angle for the take-off of its own accord with the controls in the neutral. Therefore, with the stick full forward to raise the tail at the start, back pressure is rapidly built up as speed is gained and the stick must be allowed to come back as rapidly as it will with the tail remaining in the approximate desired position. When neutral is reached, the airplane will continue the take-off without further effort on the elevators.
   However, if the stabilizer is set nose heavy, it will be necessary to pull the stick back or the thrust angle may incline into the ground and the ship actually nose up until the propeller tips touch the ground; or, if tail heavy, continuous forward pressure will be necessary and the more the speed increases the more pressure it will be necessary to exert, until normal speed is attained.
   Efforts to accelerate the take-off, or pull the ship off the ground without regard to the speed attained, will result in decreased performance and delay the take-off. In the case of small fields the longest runway should, of course, be used unless the wind is of