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Aviation History
1938
1938 - 1711.PDF
FLIGHT. c JUNE 16, 1938. Typical of the towns on the Midnight Sun Airway run, Trondhjem (right), which is still five hundred miles from the most northerly point of the service, Tromso. (Below) One of the Junkers Ju.52 used by D.N.L. Its appearance as a floatplane is distinctly improved, the '' bootss' balancing the bulk of the machine rather more adequately than the normal wheel undercarriage Above is the Sikorsky S.43 in flightnear Oslo ; this machine was originally purchased for a pro-jected service to America via Iceland. On the left is an aerialview of the airport at Stavanger taken at the time of the officialopening, in May last year. Nevertheless, the 86 has never been more than twenty minutes late on its run and the passengers like it. Since the service was first inaugurated the 86 has made more than 120 crossings in the hands of Capt. E. A. Starling with Mr. Milnes as radio operator and assistant navigator. Between them a very simple but adequate method of radio navigation has been evolved. Quite obviously over such a distance pin-point accuracy is not essential, and even if at the midway point the machine is as much as thirty miles to the north or south of its true track the loss of time over the whole journey is a matter of seconds or, at the most, minutes. Taking the outward journey as an example, QTEs, ortr ue back bearings, are obtained at regular intervals from the Woolsington radio station—every quarter of an hour in normal conditions—and Capt. Starling merely adjusts his compass course on the directional gyro to maintain these at a constant and reasonably accurate figure. When half-way across Mr. Milnes changes over to the Stavanger wavelength and obtains a similar series of QDMs, or mag- netic courses to steer. In due time a position is asked for, the stations at Sola (Stavanger) and Herdla (Bergen) pro- viding the necessary bearing intersection. This fix is noted as being, say, 200 km. from Sola, and the time is taken. Ten minutes or so later another fix is obtained, and from the pair of them the cruising speed can obviously be read off at once on a proportional calculator or slide-rule. However, the wind speed and directions can very often change considerably near the Norwegian coast, and this cruising speed provides only an approximate idea of the machine's likely time of arrival. A second pair of fixes, with stop-watch times, are taken when Lhe machine is about fifty miles from its destination. On the trip which I made a fortnight ago these second figures were, as a matter of interest. 180 km. and 125 km. at 12.41 and 12.56 hours respectively; this meant that 55 km. had been flown in fifteen minutes, providing an E.T.A. of 13.30 hours. A further fix obtained at 13.12 hours showed that this E.T.A. was approximately correct. At this moment a weather report was also obtained, indicating on that day a 300-metre ceiling with visibility of 15 km. and a barometric pressure of 1,005.4 mbs- When and if the weather at Sola is likely to develop dangerously, the crew are informed at approxi- mately the half-wav mark so that, if necessary, • the machine can return to Newcastle with ample fuel reserves. The normal endurance of the 86 is a matter of five hours, which does not permit a safe return all the way from the Norwegian coast. However, it should be possible in an emergency to reach the available military aerodrome at Oslo, and next year there should also be an aerodrome at Bergen. The coast at Stavanger is not at all typical of Norway as this is generally imagined and the approaches into Sola are excellent. In fact, Capt. Starling has had no difficulty in bringing the 86 in under a cloud ceiling of 100ft. or so. The control there has developed its own variation of the " ZZ " system, and any pilots using the aerodrome regu- larly are provided with an explanatory diagram and type- written sheet of instructions. The line of absolutely clear approach lies approximately north and south, the QDM for a straightforward arrival being 20 deg. There is not
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