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Aviation History
1932
1932 - 0119.PDF
FLIGHT, FEBRUARY 5, 1932 FUEL ECONOMY IT •NDER the title " Some Factors affecting the Range of Aircraft, with Special Reference to Height," a paper was compiled by A. E. Woodward Nutt, B.A., A.F.R.Ae.S., and Fit. Lt. A. F. Scroggs, B.A., D.I.C., R.A.F., and read before the Royal Aero nautical Society (with which is incorporated the Institution of Aeronautical Engineers) on January 28. The authors did not concern themselves with the effects of improved aerodynamic design on range, but confined their investiga tions to an examination of the part played by the power plant, and more specifically by the carburation and ignition. The paper dealt at considerable length with previous information on the subject, and disclosed the somewhat surprising fact that even now there does not appear to be unanimity of opinion on the subject of whether or not it " pays to fly high." The current use (or lack of use) of the altitude control by pilots came in for a certain amount of criticism, it being pointed out that probably the very name " altitude control " has kept pilots from using the device to obtain better fuel economy, often through a hazy fear that in some obscure ivay it might be bad for the engine. Ignition liming was important in securing good fuel economy, and contrary to general belief, ignition should be advanced as the throttle was closed. Results were given of a number of flight tests made with a Vickers " Venture " and a de Havilland " Stag," and the latter part of the paper outlined likely future develop ments. In conclusion, the authors summarised their paper as follows: — " At the present time fuel is wasted and range cur tailed by the use of unnecessarily rich mixtures. This is mainly due to insufficient use of altitude control " The range attainable by an aircraft to-day is largely in the hands of the pilot. Widely differing consumptions <3> <3> " Swissair " Speeding Up FROM Zurich it is reported that the Swiss air trans port company " Swissair " plans to speed up its services to Vienna in the spring. On the Zurich-Munich-Vienna route the average speed of the existing service is, owing to the halt of 35 minutes at Munich, only about 77 miles per hour. Counting in, as one should do, the time taken in travelling from town to aerodrome by car, the complete journey from Zurich to Vienna occupies something over six hours. This brings the average speed of the journey (distance 380 miles) down to something like 62 m.p.h. By putting into service new aircraft types capable of 150 m.p.h. cruising speed, and by reducing the halt at Munich from 35 to 10 minutes, the journey from Zurich to Vienna will be reduced to less than three hours. Allow ing for the time spent in cars between towns and aero dromes, the air journey from Zurich to Vienna will be reduced to nearly one-quarter of the duration of the rail way journey, and the machine, moreover, arrives in Vienna are often obtained on the same aircraft when attempting identical conditions. " In our opinion, limitation of the movement of the altitude control in aircraft might well be discontinued. " The damage that can be caused to engines by the use of weak mixtures has been greatly exaggerated. " It appears that, in general, modem water-cooled en gines may be run en weaker mixtures with safety than may air-cooled engines, " Weakening the mixture until a 3 per cent, drop in r.p.m. occurs in level flight has given the lowest con sumptions on flight tests. This is in agreement with test bench experience. " When running on weak mixtures it seems to be advan tageous to advance the ignition as the engine is throttled. " For really economical running, precise adjustment of the altitude control is required. The development of auto matic A.C. is necessary to attain these conditions in routine flying. Improvements in carburation and distribution are needed, especially with a view to improving the economy when throttled. " Under average conditions of flying, the mixture strength is so indefinite that it is impossible to predict with any accuracy the range at any height. This state of affairs is clearly unsatisfactory. The work done up to date indicates that as economy is improved, so range becomes more nearly constant with height. Theory indicates that for maximum economy range should not vary with height. " For maximum range flight should be made at a con stant indicated air speed at all heights. Hence it will always save time to fly high. " Wind, by no means a negligible factor at the present time, is likely to assume even greater importance in the future." ^> <•> some four hours before the train, giving business men that much extra useful time. The machines ordered by " Swissair " for this service are, it is reported, Lockheed " Orions," with 575-h.p. Wright " Cyclone " engines. The machine will, it is hoped, carry considerable quantities of mail, and passen ger accommodation will, therefore, be restricted to four seats. The Klemm-Pobjoy THE climb of this aircraft, which was described on page 90 of last week's FLIGHT, is in reality somewhat spectacular and not merely mediocre as the figures then quoted made it appear. It should, of course, have been 3,280 ft. in 4J min. fully loaded. The 3 and 2 having inadvertently been changed round made out the climb as only 2,380 ft. for the same period. The Pobjoy engine is only rated at 75/80 h.p., but the gearing allows the use of an efficient airscrew, which no doubt largely accounts for this excellent performance. <$> <•> <•> <$> LESSENING HEAD RESISTANCE. That the new monospar (2 Pobjoys) will be a clean aircraft is here very evident. The cut away wing- root, though by no means a new idea, has not been used of recent years and should, particularly in a twin-engined aircraft of this type, ensure effectiveness of the tail controls at all speeds. Even with the tail on the ground the pilot's view will, in this design, be completely unrestricted. (FLIGHT Photo.) Ill c2
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