It is better to bank too little than too much; too little results in skidding which may be easily cured; too much results in side slipping inward and if the tail surface is too great in this latter case, a spiral dive may result—so look out for over banking.
It is better for the beginner in banking to move his ailerons first and then move the rudder; for if he moves the rudder first there will be skidding outward, forward speed will drop and a stall may result. On high angles of banking, over 45°, it should be noted that the elevators are now more nearly vertical than horizontal and operate as a rudder; similarly the rudder’s function is reversed, and to turn down the rudder will be used.
Damping in an Airplane.—Above have been mentioned the restoring forces which tend toward airplane equilibrium. Now these restoring forces tend to push the machine back to equilibrium and even beyond in exactly the same way that gravity causes a pendulum to swing about its point of equilibrium. This can sometimes be noticed in the case of an automobile when travelling at high speed along country roads where a sort of slow oscillation from side to side may be noticed due to the forceful maintenance of equilibrium of the body in its forward motion. This oscillation in an airplane would be serious unless there were means of damping it out and these means are: first, the wings; second, the tail surfaces; third, the weight and inertia of the machine itself. Regarding inertia it should be said that a machine with weight distributed far from the center of gravity, such as the double-motor airplane has a large tendency to resist the rolling motions associated with lateral stability. But from the same sign airplanes with large moment of inertia are difficult to deviate from any given attitude, and therefore have the name of being “logy.” The proper proportioning of an airplane’s parts to secure first, the restoring forces; second, the proper damping force; third, the proper amount of moment of inertia, is a very delicate matter and beyond the scope of the present chapter.
CHAPTER IV
FLYING THE AIRPLANE
Starting Off.—The first thing to do before starting off in an airplane is to inspect carefully everything about the machine and assure yourself that it is in perfect condition.
When all is ready to start turn the machine directly against the wind; this is done in order that the rise from the ground may be more quickly made with the assistance of the wind under the wings, and it has a more important advantage in the fact that if you try to get off the ground across the wind the machine will be very hard to balance. Birds also take the air directly against the wind even though for the moment this carries them in a direction toward some supposed enemy, and it is a fundamental principle in airdromes. Keep the machine pointed into the wind for the first 200 ft. of altitude (and similarly in landing face the wind when within 200 feet of the ground). In case the engine should fail before a height of 200 ft. is reached, never turn down wind as this is extremely dangerous.
Assistance will be had for the start from the mechanics, or if away from the airdrome from bystanders. Have each assistant in his proper place before starting the engine; one is to start the propeller and the rest to hold back the machine until ready to let go.
(From “How to Instruct in Flying.”)
Fig. 32.—Airplane in flying position just after starting.