The Feat of Flying the Atlantic

Radio Record, Volume III, Issue 52, 11 July 1930, Page 10

The Feat of Flying the Atlantic

Did Kingsford Smith Choose the Best Path? ,

(By

A. B.

CHAPPELL

M.A.)

FEW folk, seemingly alittle air-weary, may tuke little note of Kingsford Smith’s crossing the Atlantic. There have been, you know, so many exploits in the air of late; there are Kingsford Smith’s =" previous achievements; this is "only one more." ‘These folk remain unstirred. But most of us are not like that, and this feat means much. When this achievement is understood, it ranks very high in the triumphs of aviation. It has been rightly hailed as fully worthy of being bracketed with the wonderful flight across the Pacific, which no one else has attempted. To have two such flights to his credit, even when nothing is said of the other successes of his brief career, stamps Kingsford Smith as an airman of unquestionably great skill and courage, and power to inspire associates. I do not intend to dwell in detail on this particular exploit. About it you have probably read quite as much as I have. But for a few minutes I wish to speak of one or two things that. make it remarkable, and so shed light: on the trans-Atlantic flight in general, and the westward crossing in particular. ‘ One thing in passing. This success earries. Kingsford Smith and _ the Southern Cross well on the way. right round the globe. He set out across the Pacific from Oakland, California, So he came to Australia.. After the crossing to ang from New Zealand, he went to England. Now, crossing the Atlantie, "he has landed on the American Continent. His intention is to cross the United States to California, landing at Oakland, the starting point of the Pacific venture. Thus he will have put a girdle round about the earth in the Southern Cross. Nor will that fact be all. When he talked of taking the Pacific flight he had great difficulty in "raising the wind," as we say, for the venture. By many, it was deemed too hare-brained an idea to back. Men of means, though deeply interested in aviation, were reluctant to help him. His courage, however, was shown in persevering with his project in .spite of every obstacle. Now, all going well, he will land in the Southern Cross at Oakland to a thunderous welcome. His one-time critics will be finally confounded, and the few ready to help will have their full vindication. He himself will have won more than a triumph in aviation; his will be a great moral victory. That is much. L=t us turn to trans-Atlantic flight in general. There have been many crossings through the air. Of these the list lately published has given reminder. It is an interesting record. But the thing especially notable is that the west-to-west crossing has been

often done, and the east-to-west only once before, when Baron von Huhenefeld and Major Fitzmaurice landed in Labrador and had to be rescued from a dangerous plight. The east-to-west venture is evidently the more hazardous. Why is this westward crossing so difficult, in'comparison with flight the other way? To casual thought, the very opposite should obtain. The spin of the earth is from west to east. This makes our succeeding day-dawns, the sun, in our way of speech, rising every twenty-four hours in the east. All places, that is, travel eastward. There was, consequently, in earlier days-when balloons were inventeda notion that if one wanted to go westward it should be possible to go straight aloft, stay there awaiting the arrival below cf the western plece sought, and then descend on it. The formula was something like this: "Op you go, wait; down you come; there you are." This inviting idea, like many other inviting ideas, left some things out of account. Before we consider them, let us take some precise facts. The circumference of the earth is nearly 25,000 miles. The earth’s rate of spin, varying from a maximum at the equator to zero at a a a a ay a ae

the poles, amounts to more than 1000 miles an hour at the equator. This means that, at the equator, a _ place 1000 miles to the westward of another will arrive at the spot occupied now by the latter in less than an hour from now. . According to the inviting idea once held, therefore, to go aloft and stay for —

an hour in one spot of space would be, relatively tg the earth’s spin, to travel westward more than 1000 miles, and would make travel westward in the air a simple matter, and travel eastward a very vexing stern chase. Taking London. and New York as illustrative points, nearly five hours is the time difference. New York, to speak precisely, being 74 degrees west of London, takes 4 hours 56 minutes to reach the point formerly occupied by London. To go by air from London to New York would therefore seem to mean taking a journey, as measured by earth-span, twice 4 hours 56 minutes less than the journey from New York to London-9 hours 52. minutes less-nearly ten hours less. No wonder the east-to-west journey through the air, against the spin of the earth, has been casually thought. easier, because it is made theoretically shorter by the earth-spin. _ OW for the things left out of account. First is the fact that the earth’s atmosphere, denser and denser at the lower levels and always subject to gravitation, clings to the earth, and, in general, goes with the earth’s spinning surface. I emphasise those words 2

"in general," for they are important. There are several qualifications to be considered. The actual happenings are not so simple. But the general fact should be borne in mind as lying hehind all seemingly contradictory facts. The earth’s atmosphere, then, in general, and as a basie fact, goes with the earth. This suggests atmospheric

resistance, not aid, in the east-to-west crossing. If the earth’ rotated in an actually unmoving atmosphere,. there would be felt at the equator a steady wind from the east, met (and so in effect moving) at more than 1000 miles an hour-a prodigious rate, caleulated to keep the equatorial region wonderfully cool. HAT this region is. anything but wonderfully cool awakens us to look out for other atmospheric facts, What are they? They can best. be instanced by what are known as trade been taken into account ‘by shipping in the days of sail. In broad belts north and south of the equator, running to the imaginary lines of the Tropics of Cancer and Capricorn-that is, to about the 20th parallel of latitude north and the 20th parallel south of the equator respectively-these trade winds blow from these lines to the equator. This is explicable, in general, by the rising of heated air from the equatorial region, the colder. air from north or south rushing in: to take. the place of the heated, rising air. But the direction of this inrushing air is not either due south to the equator or due north to it, as the case may be. The winds from both north and south are deflected backward, in effect,:by the spin of the solid and globular earth, rotating in this region at its most tremendous speed. The "cling" of the atmosphere is the. more easily overcome by reason of its being heated and rising, as well as by reason of the high rate of the earthspin. The result is that in the northern equatorial region the trade winds blgw from the north-east and in the southern region from the south-west. These trade winds are essentially ocean winds, for land surfaces create local conditions greatly affecting and even negativing them. Our thought about these winds is an essential preparation for what more closely concerns the crossing by air of the Northern Atlantic, away from this equatorial region: What happens beyond that equatorial region, and how is it affected by what happens within it? At abdut the 20th parallel a contrary and compensating movement of the atmosphere is noted. Outside of this limit, anti-trade winds blow with considerable regularity, the degree of . regularity being higher where the ocean spaces are wider. They get their name "anti-trades" from their moving in a direction contrary to that taken by the trade winds. In the North Atlantic and North Pacific they blow from the south-west, while in the southern regions of these oceans they blow (we note this related fact now only to forget it at once) from the north-west. These anti-trade winds, note carefully, mainly arise from the upper \ winds, prevailing winds that have long.,/

earth-and he always carried radio. Other aviators as courageous, but less enterprising, have set out for long trans-oceanic flights with only nautical instruments as their navigational guide-and many have not been heard of since.. Contrary to popular belief, navigation on flights such as those Kingsford Smith has completed is an all-important consideration. Days, even weeks, have to be spent in deciding upon the most favourable route, and in plotting it accurately. Seasonal winds, prevailing and forecasted weather conditions, and other factors as important, all these have to be considered to ensure an even chance of success. In the accompanying article the writer tells of the difficulties in adverse weather conditions and in navigation that’ Kingsford Smith and his companions had to contend with, and how they overcame them. K SMITH has conquered the oceans of the

Seo currents of air ascending from. the equator; they have not merely. lost their heat up there-they have become chilled extremely and much heavier, and'come back to earth. But they cannot come directly down, oecause of the continual rising of the heated upward currents, nor make contact with the earth again within the region of the steady trade winds. But beyond the Tropics of Cancer and Capricorn where there is in each case a belt of intervening calm, they make themselves felt in that portion of them which goes to make the south-west and anti-trades.. Their density and. the slawer rate of. the earth-spin in those latitudes give them .a "cling’-hence _ their easterly direction, made northf easterly by. their point of origin and \. the: globular shape of the earth.

«Turn your thought to ‘the North Atlantie again, where these anti-trades blow from the south-west. London and New York are well above the Tropic ef. Cancer. The Southern Cross, therefore, had to face and fight these anti-trades, whereas on flights from west to east they: assist. There is the crux of the question: the east-to-west flight, because of these anti-trades, isa struggle against prevailing winds. In that region these ‘winds are marked by considerable variability, due to the closing in of the North Atlantic land areas, put the general drift of them, as. they go with the earth-spin but deflected by the globular shape of the earth,: is against the aviator. Now we ean see why, in those latitudes, east-to-west flight is a more trying business, as well as a much longer business, than flight from west to east. Atmospheric conditions overrule all expected gain from the west-to-east earth-spin. A west-to-east air cur7! rent prevails, its northward deflection adding still further, as I shall explain in a moment, to the aviator’s trouble. OME of you, remembering what I said about the narrow belts of calm between the trade winds and the antitrades, at about the 20th parallels, are perhaps wanting to put a question. Why-did not Kingsford Smith take that belt in the North Atlantic-known as the Cancer Calm-and- so avoid the opposing anti-trades? He had the best of reasons for not doing so. The Cancer Calm lies so far south of the latitudes of London and New York that to ‘have taken a route through it would have more than doubled the distance to be traversed. Besides being so far out of the way, it goes across a broader stretch of ocean. It might have served him had he been going from Gibraltar "to Florida, but even then not so well as a mere glance at a map might suggest. Yet you have noted, in a message from him, that he did not fly straight across, and are perhaps still inclined to think he should have tried a southerly route, nearer, if not within, the Cancer Calm. But what did that message say? That he was setting a great eircle course, This indicates the most decisive reason for his electing to take a route involving conflict with the anti-trades. This great-circle course took a line north-westward from Irelard, and curving round gradually afterward to strike the American mainland northward of New York. "Why not go _ straight across?" you may be disposed to ask. Because that would have been a longer way. No; I am not making a feeble joke.

Remember, th¢ earth is a ball, not flat like a map. To get from one place to another by the shortest road is seldom the same thing as taking the route followed by a straight line drawn between them on the map. To go from one to another place on the -.equator your shortest way is along. the equator. So, in going from one place to another north or south on the same meridian of longitude, the shortest way is straight along the meridian. But, as the earth is a ball, these journeys mean taking, not a straight _ line, but the curving route that happens to be the shortest. . Now, in the mathematical language of the navigator, the equator is a great circle, and a meridian right round

the earth, going north and south through the poles, is nearly as great--a little less only because of the flattening of the earth at the poles. [f any two directly-opposite points of the earth’s surface be taken, and a full circle, cutting the surface of the globe in half, be drawn through them, there will be another great circle. Theyre can be any number of such circles. The character of a great circle is its cutting the surface of the globe in half-sym-metrically . By "half" I mean half, not an approximately equal portion. Now, apply what is known about the two instances already mentioned-the equator and a complete meridian. The shortest way between places on them is along them, Departure from that curve will lengthen the journey. That obtains with all great circles, and the problem in navigation between distant points is to find the great circle connecting them: that is, the shortest way. On the chart it may look longer, but it is actually shorter, because the earth’s surface is one rolling curve, not a flat expanse as on a chart. To get from Ireland to New York by the shortest route, the Southern Cross had to be navigated on a greatcircle course connecting them-possible choices of altitude could not affect the route materially-and this great circle, as they both lie north, of the equator in one hemisphere, has a northward, not southward curve. Therefore, Kingsford Smith, though not hampered seriously by adverse winds on the rise of

that curve on setting out, had to face them more and more as he came toward America. Bluntly put, the position is this: to have fiown across on a ‘parallel of latitude would have taken him across a bigger bulge of the earth’s surface, and made the journey longer. So the idea of attempting the feat by way of the Cancer Calm lying to the south was, for this additional — feason, not to be entertained for a second. The distance would have made the flight impossible. There was nothing for it but to take the great-circle route and dare the adverse anti-trades to do their worst. They may not have done their worst, but they did pretty badly. ‘A last point-the fog. Heavy fog- . banks are characteristic of the Newfoundland and the mainland coast thereabouts. This is a special peril in making the east-to-west objective. Going to Hurope from America, there is little or nothing of this: the target ean be struck with more certainty of vision, should dependence on navigating instruments become, for any reason, an uncertain guide. In this flight there was a lowering of compass reliability, probably because of the violent movements of the plane. Over Newfoundland, flying became perilously blind, and but for aid derived from wireless direction signals there would likely enough have been another fatal tragedy to add to the records of transAtlantie flight.