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98 U.S. CIVIL AERONAUTICS AUTHORITY sufficient velocity to make the effective length of a shorter one the greater. In either case, it is best to run until the last moment before attempting to "lift off" from a short field, unless it is clearly evident that the airplane is trying to get off and is being held down. Most modern airplanes require considerable run, particularly if they are clean high-speed airplanes not equipped with a constant speed or controllable-pitch propeller. In such aircraft the engine takes longer to attain its horsepower due to the pitch of the propeller holing its r.p.m. down until speed is gained. For this reason, as well as for safety's sake, which will be further discussed under "Forced Landings," all the available field should be used. There is nothing that stamps a student or a pilot as foolhardy or lacking in judgment, quite as quickly as failure to take full advantage of the size of the field when taking off. It should be impressed on the student that the resistance to the movements of the controls, as well as the airplane's reaction to such movements, are the only indicators of the degree of control attained. Instruments are not reliable indicators in this regard, and the student should be warned against such use of them. This resistance is not a measure of speed of the airplane but only of its controllability. It is possible to move the controls so violently, or through such large ranges, that these pressures are not correctly evaluated and, in the case of students with a limited sense of control feel, may not even be felt. This not only reduces the efficiency of the airplane and delays the gain of speed, but leaves such a student with no idea of what is taking place or what to do. He must wait for the reaction of the aircraft to his control pressures and attempt to sense the control resistance to pressure rather than attempt to control the airplane by movement of the controls. Balanced control surfaces increase the importance of this point, because they materially reduce the intensity of the resistance offered to pressures exerted by the pilot. Unless the student has developed much more feel than the average from the limited experience in taxiing and in stalls, the control pressures and the speed of the airplane will not be within the range of his appreciation. He will, therefore, tend to move the controls through wide ranges seeking the pressures he expects and, as a consequence, badly overcontrol, which will be aggravated by the sluggish reaction of the ship to these movements. Such tendencies should be checked and the importance of the development of "feel" stressed. The student should be required to feel lightly for these resistances and accomplish the desired results by pressing against them. This practice will enable him, with increasing experience, to finally arrive at the point where he knows when sufficient speed has been acquired for the take-off instead of merely guessing and trying to force performance. As a preparation for take-offs and landings, the student should have been required to do all the taxiing after instruction has been given in it. The amount of taxiing experience can be increased by the instructor making it a practice to land short and requiring the student to taxi up to the hangar. As the time for instruction in take-offs approaches, the student should be required to use the rudder alone during this taxiing, in order that a better conception of the results of its use alone can be acquired. The S-ing required when taxiing will increase this and also serve as a means of smoothing
