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Aviation History
1945
1945 - 0290.PDF
FLIGHT FEBRUARY 8TH, 1945' velocity before contact with the ground is made. Altitude can be lost even more quickly in the low-speed glide if the wings are rocked from side to side about 15 deg. and rather quickly, or if S-turns are made. A certain amount of yawing occurs if the wing is rolled back from a bank just before the turn has developed. Finally, one of the best ways of adjusting the approach nicely seems to be to make the time-honoured yo-deg. turn, which can be cut short, or stretched, as required. Of course, all of these manoeuvres require a certain amount of piloting skill, and there has been an indication from some users of the aircraft, mostly instructors, that some means for steepening the glide SIMPLER path while flying straight andat normal approach speed LC. O N T would be desirable. In general, , the experience has been that pilots who ily the Ercoupe. a fair amount and become fami- liar with it have no difficulty in getting into small fields and have no particular desire for flaps or other means of glide control. Pilots who are just starting on Ercoupes are likely to want somtf extra form of glide control, however, particu- larly if they nave previously been relying on sideslipping to help their approaches. Also, there is not much doubt that beginners and pilots who fly only occasionally would be helped in approaching to small fields by an effective glide control, and the thought is growing that the advantage may be sufficient to offset the complication of an added control to operate. In this connection we have experimented with spoilers hinged on the upper surfaces of the wings of an Ercoupe but have not produced an arrangement that received unani- mous approval by the pilots who/have flown it. One dis- advantage was that if the air speecl was held below about 75 m.p.h. when the spoilers were applied in the landing approach, the glide path steepened but the nose of the aircraft stayed at about its original level, momentarily obstructing the view of the spot on the field at which con- tact was to be made. The aircraft can be held off in the conventional manner until it loses its flying speed. This practice is preferred by some pilots in order to reduce the ground run, and is always advisable in case of rough terrain. Brake-on Landing After landing, the brakes may be used as desired. In an emergency they may be applied before the landing is made, but this procedure is not recommended as standard prac- tice on account of the tyre wear involved. During the landing run the brakes should be released if slippery terrain or loose gravel is encountered and a tendency to skid is noticeable, as in the case of an automobile. If the aircraft without rudder pedals is being landed in 11 strong cross-wind, it must be pointed up-wind sufficiently to keep the flight path in line with the runway, and it will approach the ground with the wings level but with the nose crabbed upwind. This should not alarm the pilot for, with the stable tricycle gear, contact with the ground made in this manner is> quite satisfactory, because the stability of the gear will automatically change the heading of the aircraft so that it continues down the runway, provided the nosewheel is left free to caster. In making cross-wind landings it is well to set the aircraft on the ground very definitely, but; not at high speed, and to move the. control wheel forward somewhat in order to •hold the nose down and reduce- the lift on the wing as contact is made. Under strong cross-wind conditions some pilots prefer to glide straight to the ground without pulling the control wheel back to flare of! the glide path before contacting the ground. This ensures making a definite contact. It is also helpful in some cases to set the brake on about half-way before making contact, and possibly to apply it strongly just after contact is made. This tends to hold the nose down and the wing at a low angle of attack and also cuts down the speed to that of a reasonable taxi-ing value as quickly as feasible. Another important point in a cross-wind landing is that the aircraft should be given its h«ad with very light if any lateral pressure on the control wheel at the moment that contact is made. This permits the stable castering tendency of the nose-wheel to act, and the aircraft will change its heading slightly so that it lines up with the direction of its motion along the ground. One point that deserves clearing up in this matter is that in a properly-made cross wind landing with th*e aircraft crabbed at contact (following the ground course desired, but with the nose crabbed into the wind) and the nosewheel free to caster, the rear wheels do not receive a side load of FLYING any substantial magnitude, as has been thought by some en-N U E D) gineers and pilots. The longi- tudinal drag of the main wheels, behind the centre of gravity, causes the aircraft to change its ground path. The only factor that resists this turning of the machine about its vertical axis (not in its course of travel) is its own moment of inertia at>out its vertical axis, and. the change in heading is ordinarily accomplished in less than a second and without apparent strain. If the course of the aircraft's travel is changed at the moment of contact, as it is when the nosewheel is held in position ,^ whether neutral or ue- flected, a large lateral force occurs and difficulty may follow. If, however, the nose-wheel casters properly, the cross-wind landing appears to be an effortless and natural manoeuvre. Landing Accidents Accidents in landing which have caused damage to the machine can be divided into three groups: those due to poor piloting technique at contact, landings on poor terrain, and collisions with objects in fhe landing/ approach. Under the classification of piloting techr ique there have been an average of five accidents annually which caused damage to the aircraft for each 100 machines operating. None of these cases involved any injuries to the occupants. In nearly three-fourths of these cases the nose gear or its supporting members were damaged, whereas only one-sixth of them involved damage to the main gear. Obviously in these landings the nose gear has been receiving harder treatment than it was designed for, and in order to alleviate the situation the nose gear and its snpports are being sub- stantially strengthened. About one-fourth of the poor technique landings involved overshooting or undershooting, and might possibly have been helped by a glide control. The same proportion of bad landings involved levelling off too high, losing flying speed from 20 to 40 feet above the ground, and striking' the ground with the nose well down while the aircraft was regaining flying speed. In the second group of landing accidents, those involv- ing poor terrain, landings were made on surfaces ranging from extraordinarily rough open fields to fields filled with stumps or large rocks. These also involved an average of about five aircraft annually for each 100 operating, and the relative damage to the nose gear and main gear units was about the same as for the poor-technique landings. Some of the rough open field cases might have occurred without any damage if the strengthened nose gear had been in use, but if landings are made into stumps, rocks, and ditches, a substantial amount of damage appears inevit- able. In these landings there was only one minor injury, which is probably an indication that the aircraft's structure affords the occupants substantial protection. One-third of the landings on poor terrain were forced landings, half of which were caused by engine failure. One- fourth of the landings were caused by undershooting or overshooting at a regular flying field, a type which might be reduced by a good glide control. One aircraft per year out of 100 operating collided with some object during the approach to a landing, although no injuries were incurred. One struck electric light wires that were difficult to see, causing the aircraft to contact
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