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Aviation History
1917
1917 - 0657.PDF
JUNE 28, 1917. 1JGHT) helmsmen or pilots, and their position in regard to fixed points on sea, land or in the air, easily ascertained. I cannot at the present moment give any more precise indications at present of these new developments, which promise to be of the greatest assistance in the navigation of the air in the future. In fact, when perfected they will deprive night fog and cloud of most of their dangers. Over the sea lightships will be usable with the same code of lights always turned upwards. There may also be on land small captive balloons at moderate altitudes illuminated at night to indicate locality to the upper levels. Gradient Pointers. Now we come to some minor, but still important, points, such as to how mountains are to be surmounted. You will remember that I expressly mentioned that the " levels " should be measured from the surface of the planet, not from sea-level calculations. It follows, therefore, that when you have to cross passes through mountains, such as the Hima- layas, Alps, Pyrenees, or, to come nearer home, to fly over such mere pimples in comparison as the Pennine Range, the Cheviots or the Grampians, there will have to be some signs to show that you are nearing " rocks." To indicate rises in the ground underneath, I suggest signs similar to those I show you in these diagrams. Of course, to save motor spirit (probably distilled by then from coal direct, and no longer petrol), the lowest passes through mountain chains will be selected. The world's traffic lanes will, therefore, not be at the same altitude all over the world reckoning from the sea-level. They will vary except over flat countries. Let us take an instance near home, the nearest route from New- castle to Edinburgh—over Carter Fell into Scotland—will which I attended on behalf of Great Britain some ten years ago in Paris, and which allotted to each country specified lettering—GB standing for Great Britain, F for France and D for Germany. Pilot certificates granted by responsible countries will be recognised as valid by all those countries which signify their adherence to an international agreement, in the same way as motor drivers' licences are now recognised everywhere. Weather and Wind all-important. Almost the most important of the subjects which will have to be considered in relation to the world's air routes is how weather and wind conditions will affect flying over the surface of this planet. The prevalence of trade winds is known to you all, and how they blow with unvarying regularity and strength in certain directions in certain seasons. But what is less generally known is the almost permanent existence," of areas of high barometrical pressure (sometimes called anti- cyclonic systems) in different parts of the world. These systems, though they contract and expand, have a more or less continuous effect upon the weather and winds of the world. I have not space to deal at length with this interesting subject, worthy of a separate lecture altogether, except as regards some special features over Europe, Western Asia and Northern Africa. Before these charts of pressure and winds can be properly understood there are two points that" must be grasped : Firstly, that wind always blows parallel to the lines of the isobars, that is, the lines of equal pressure ; and, secondly, that the circulation of the wind is clockwise in high- pressure or anti-cyclonic areas, and anti-clockwise in low- pressure or cyclonic areas. This is known as the Buys Ballot Law, which in the southern hemisphere equally applies in LANDING PLACES TO BE CIRCULAR & CONVEX. ••<A?tilAffS, ^itftUS i'-: LANDING AT NIGHT SEARCHUGHT TO POI1T UPWIND. N YORK "GRADIENT POINTERS" *»OHT STARBOARD I DIRECTION POINTERS" BY tilSHT .•ct.ua. •003 n IDENTIFICATION MARKS • GOVERNMENT AIRPLANES MlNTtl) IN NATIONAL COLOURS GREAT BRITAIN CROSSED LIKE UHION JACK The World's Air Routes and their Regulation. necessitate a rise of just under 1,600 ft. Without proper warning, and on a misty day or dark night, an aeroplane flying to the east of the point where the border is crossed might collide with the Great Cheviot, which is nearly 3,000 ft. high, or nearly touch Carter Fell itself to the West of the pass. There must be, therefore, indications of gradients similar to the gradient posts of railways. You will see in the diagrams how I propose that ascending and descending gradients should be made clear. These would be white patches by day and their outlines illuminated by night. Then you may legitimately ask at what level will your need for higher altitudes for your levels begin. I suggest that all altitudes from sea-level to 250 ft. should be considered as negligible. Above that every 250 ft. will be indicated by large figures giving the average altitude of the ground below —500, 750, 1,000 and so on. It will be desirable, in planning regular routes, to avoid isolated high hills or groups of hills small in area, such as Hindhead or the Malvern Hills. All routes will follow so far as possible flat country for meteoro- logical reasons as well as I shall show presently. How Aircraft should be made Identifiable. Now I come to the problem of how planes shall be designated and made identifiable. First of all there will be the nationally- arranged colours of each country for those engaged in official services. Then I propose that all private planes shall be white and commercial planes red, to distinguish them, the one from the other. All planes, official and private, will be lettered and numbered, as decided by some inter- national conference, such as that which settled for all countries the regulations for international motor car touring, an opposite sense. -Now you will observe that the weather of Western Europe, with which we are mostly concerned, is largely governed by two factors—the tendency to a low- pressure trough more or less all the year round between Greenland and Iceland, and the high-pressure area, which is permanent, though varying in area near the Azores. It is the combination of these two areas which produces the great preponderance of westerly and south-westerly winds over these islands and the Eastern Atlantic. There is another seasonal high-pressure area in the Sahara over North Africa, between the West Coast and the Sudan, during the winter time, as has just been proved by Major Lyons, the President of the Royal Meteorological Society, in a recent paper. Then there is a nearly constant area of high pressure north of the Himalayas, over Southern Siberia and Turkestan. The low- pressure systems in the European and Western Asian areas are more seasonal and variable in character. There is a trough of low pressure, which lies between the Persian Gulf and the Western Himalayas, between May and October, which is the origin of the south-west monsoon so strongly felt in the Arabian Sea and over the western and northern parts of India. Then, nearer home, there is another area of low pressure generally prevalent over the Adriatic, the Northern Mediterranean and the Balkan States, which is characteristic rather of the winter than the summer months, producing a tendency to westerly winds in the Mediterranean and corre- sponding easterly winds to the northwards of the Carpathians. Now, these systems and the consequent tendencies to a permanent direction of wind either all the year round or at certain well-defined seasons, have a most important bearing on the world's air routes. And the lesson to be drawn i6 657
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