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Aviation History
1931
1931 - 0255.PDF
FLIGHT, .MARCH 13, 1931 METEOROLOGY AND AIR NAVIGATION ON Wednesday, March 4, before the Royal United ServiceInstitution, Lt.-Comm. J. W. Josselyn, R.N., gavea very interesting lecture on meteorology and its bear-ing on air navigation. He started by pointing out th, difference between air pilotage and air navigation and sine that he would deal mainly with air navigation. When tht aircraft was flying chiefly over the sea, out of sight of land from which one could fix one's position, meteorological conditions he said affected air navigation very greatly. On such long flights as, for example, that made by Col. Lindbergh across the Atlantic, it did not matter very much if the pilot was several miles out on reaching the other side, but in short flights where contact had to be made with the fleet at definite points, accurate navigation was absolutely essential. This accuracy, he said, depended very greatly on the knowledge of meteorological conditions in order to keep an accurate knowledge of the aircraft's track and ground speed. He then outlined methods used to determine the direction and strength of the wind, such as pilot balloons, smoke shells or the drift of the aircraft. The wind, he said, follows very definite laws and does not as the Bible would have it " bloweth where it listeth " and, provided these laws are known, can be forecasted with a large degree of accuracy. Comm. Josselyn then dilated at some length on the difficulty of defining visibility and its bearing on the navigation of aircraft. He described how fog is brought about by the precipitation of moisture when the temperature of the air is brought below its dew point and how this precipitation is aggravated in districts where the air contains a large proportion of salt or sulphur particles such as round our coasts and over industrial districts. He quoted a case as an example of the advisability of the meteorological officer working in close conjunction with the navigating officer which happened in H.M.S. Furious in the North Sea. In the event in question the meteorological officer noted that the temperature of the sea was practically the same as the dew point of the air and therefore he confi- dently expected the visibility to decrease. The next morning he found, much to his disgust that this forecast was totally wrong, since during the night a warm current of water had come up for the south and had thereby warmed the air instead of cooling it and causing fog. A further weather condition which, he said, affects air navigation, is the presence of bumps, particularly those of the vertical variety, since they alter, very materially, the course and speed of the aircraft. Several examples of the synoptic weather chart were shown on the screen indicating how the meteorologist can forecast the wind and weather through the shifting of areas of high and low pressure. Examples of warm and cold fronts were also shown and it was explained how the wind always veered after the passage of a cold front. From this the lecturer emphasized the importance of the intelligent use of a strut thermometer as an aid to air navigation. He said that if the pilot was warned that he would encounter the passage of such a front during his flight his strut thermometer would indicate to him that particular passage and he could then allow for the change of wind. Records were shown of several transoceanic nights, notably those of H.M. airship R.34 and of Col. Lindbergh and one or two others, and the methods by which they checked their drift, as, for example, in the case of R.34, by the white horses on the waves and by dropping Holmes' lights ; their ground speed by their shadow on the breaking wave tops ; their height by the angle subtended by their shadow, knowing the altitude by the sun, in which case barometrical changes were also deduced. In the case of Col. Lindbergh's flight, he pointed out that although a landing was made within three miles of the intended position, the aircraft was actually 250 miles out in its D.R. position, since although the wind did not shift it had increased in force and Col. Lindberg arrived 21- hr. before his scheduled time. In answer to questions raised during the following dis- cussion, Comm. Josselyn said that the white caps caused by breaking waves did not actually travel along but remained in their original position on the surface of the water except in so far as they were moved by the drift, due to the wind, the actual wave motion being wholely under the surface of the water. With regard to the measurement of the wind, he said they usually used the drift and range method, whereby bearings were taken on a smoke bomb which had been dropped some minutes previously. Rear-Admiral H. P. Douglas, the Hydrographer of the Navy, who was in the chair, said that those present would be interested to know that the Admiralty was by no means neglecting this side of science. He informed them that a committee was already investigating the question of defining visibility. He also announced that a series of meteorology courses had been instituted for officers and said that 15 officers had gone through the course last year and he expected some 30 to do so this year. As a further evidence of the Admiralty's foresight, he said there was a chart. No. 5073. which had been compiled from reports sent in by some 40 of H.M. ships showing the distribution of the upper air currents and temperature over the ocean in order to determine the most suitable routes and heights for aircraft to follow on long journeys. A Simple and Useful Helmet BURCH'S of 33, Bedford Street, Strand, are the makers of an extremely simple flying helmet, which is admirable for general use. This is called the Instructor's Helmet, but is equally suitable for anyone else, as its great merit lies in the speed and ease with which it can be taken off, the simple two- ring fastening being very easily manipu- lated even with cold fingers. We ourselves have used one of this .; type for a consider- able number of i months and have • nothing but praise for it. Lloyd's Register Cricket Club 37th Annual Reunion Dinner LLOYD'S Register Cricket Club held their annual dinner at the Mayfair Hotel on Saturday, February 28. Mr. Andrew Scott, President of the Club, was in the Chair, and tnere were many prominent people in aircraft present, including Sir George Higgins, Chairman of Lloyd's Register, ^r. Handley Page, Lt.-Col. H. Outram, Capt. A. G. Lamplugh. Lloyd's Register are finding that their Aviation Depart- ment is getting a rapidly increasing amount of work, and Mr. L. J. Hill, senior surveyor, reports that the number of aircraft owners who have their annual surveying done for renewal of C. of A. through his department is a very satis- factory one. The Chairman proposed the toast of " Our Club and Patrons," while Sir George Higgins replied, and in doing so anticipated the day when the aviation side of Lloyd's Register would become more important than the shipping side. Mr. Handley Page also replied giving one of his characteristic forceful speeches. The toast to the Mem- bers w.is proposed by Mr. A. L. Sturge, and to the Chairman by Mr. Scrutton. Interspersed between the toasts were several very good variety turns, whose excellence added greatly to the pleasure that all those present took in the dinner. D. Napier & Son THE directors of 1). Napier & Son, Ltd., announce that their Annual Report, which will be issued shortly, will show (subject to audit) that the net profits for the year ended September 30, 1930, amounted to /169.905 7s. 'id. They have decided to recommend at the forthcoming annual general meeting that :—A final dividend be paid to the ordinary shareholders on the books of the company on March 23, 1931, of 10 per cent, (less income tax) in respect of the year ended September 30, 1930, making, with the interim dividend, 15 per cent, for the year. They also give notice that the ordinary share transfer books will be closed from March 23- to April 1, 1931, both days inclusive. Irvin Air Chute Demonstrations IT is pointed out to the Editor that the Irvin Air Chute of Great Britain, Ltd., have not engaged Mr. John Tranum as their parachute demonstrator, as inferred in a paragraph published in our last issue. He has arranged to jump during the coming season for Capt. Barnard's Air Tours, Ltd., and for this purpose he will use Irvin air chutes. 239
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