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Aviation History
1934
1934 - 0866.PDF
868 FLIGHT. AUGUST 23, 1934. Private Flying ACROSS COUNTRY To the novice, navigation often appears to be an affair involving complicated calculations and a knowledge that can only be gained by prolonged study. Actually, however ^ the principles necessary for normal cross-country operations are simple This article is intended for the novice and deals with many of the problems that are likely to worry him in the extreme. How NOW that club instruc-tion has reached sucha state of perfection v the embryo pilot who feels a sense of helplessness when the clearly marked railway line fails to turn up at the psychological moment is something of a. rarity. Nevertheless, there are all manner of things to l>e thought of in one's early point-to-point flights, and if these can be at least partially settled on the ground then so much the better. If he has a clear mental plan of operation then the novice will not be quite so perturbed if his map blows away down the fuselage, or if he finds himself quite suddenly in thick weather. Confidence and routine are the secrets of mental com- fort when the entire landscape bears no apparent resem- blance to that depicted on the map. The first will prevent you from being "rattled," and the second will enable you to pick up your course again. Routine starts on the ground, so plan everything care- fully and unhurriedly. Draw your track boldly on the map and write the magnetic course (or the true course plus deviation) beside the line. Such a figure will be in- valuable if bad weather sends you home again—mental calculations are difficult to carry out in the air. I prefer to draw my track in red or black ink, knowing that the folds of a cheaper map wear through soon enough in any case. In due course experience will enable you to obtain a fair idea of wind speed and direction by watching the wind sock, but information is obtainable at most aerodromes, and, armed with this, a velocity triangle can be drawn or a course and drift calculator operated. The simplest way to treat a velocity triangle is to visualise the wind as blowing the machine away a certain distance in the hour before, so to speak, starting an hour's flight in still air. EXTENSION FOR PICKING UP TRACK five degree lines " help the pilot to judge necessary alterations to course. MAGNETIC The simplest form of " velocity triangle," in which the wind is imagined as blowing the machine away from the starting point. •j... 1.) . Actually, however careful you may be, corrections will have to be made in the air. East winds have a little habit of changing their direction higher up, and west winds of increasing their velocity. From the diagram or the C.D.C. the actual ground speed can be judged, and, if the track is marked at suitable time intervals, according to the length of the flight, you will know exactly where you are at any moment. But more of this later. Certain additions to a plain track line on the map will be found to be ex- tremely useful. An exten- sion "behind" the start- ing point will enable you to pick up your track on the other side of the aerodrome, so that, as you pass over the circle, all will be set and fair. "Five-degree lines," too, should be drawn a little distance on each side of the track from the starting point, so that you will more easily be able to judge the amounl of drift and readjust so accurately that no more course alterations are necessary. For instance, after five minutes' careful compass flying the machine may pass over a certain landmark some miles off the track. One or other of the lines will then give you a perfect visual idea of the number of degrees of your drift. If, while still in home country, you proceed to fly across to a landmark shown on your track line, then you can make the neces- sary alteration with confidence. The time taken in getting back to the track may appear to be wasted, but it is at least a sure method for the beginner. RUDDER BAR " Pressing the compass, the needle reacts to pressure. ' How rudderA really useful thing to remem- ber is that if you are altering course to the right then you must add, and if the track is on your left then you must subtract the number of degrees of error. I always found that the best way of changing course was to "push the compass " —in other words, to press the rudder in the direction in which I required the needle to move. Later on, the rudder corrections will be made quite automatically. Compass movements often mystify the novice, even though he may have been told all about " northerly turn- ing error." The crux of the matter is that the compass reading can be relied upon completely so long as the machine is, and has been, flying steadily. For all normal 1 purposes it is enough to note that the needle lags well behind the turn on northerly courses—as much as 40 degrees in a 90-degree gentle turn—and that it tends, perhaps, to go ahead on southerly courses. Actually, however, the compass can be treated as a perfect turn indicator whenever the machine is flying southerly. Even on northerly bearings it is possible to turn with accuracy by compass through wide angles. As the pupil of "blind flying" discovers, very accurate changes can be made with the help of a turn indicator and a memor- ised series of corrections. The initial temptation to compare map and landmarks continuously from the moment of leaving home, if per- sisted in, can, on long flights, become most wearing to the nerves. After all, lakes, reservoirs and woods show
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