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Aviation History
1934
1934 - 0505.PDF
FLIGHT, MAY 24, 1934 14 13 IE II 10 9 8 7 b 5 A 3 e 0 t 4 6 OF F 1— AL T jf j/ f Z A MINUTtS 8 10 IE Ul 16 18 t- y CUIMBTtMt A k 8 C IE 14 16 18 MINUTtS SPtCD M.P.H. 130 lit 134 136 138 WO \ N \ / / / / /\ L \ V \ LA MAXIMUM I 1 \ h -THOUSAND S 130 OJ IM Ot 08 WO 3PEED M.PM. 14 3 E 1 0 9 ft 7 5 4 3 1 0 COMPARATIVE FLIGHT TRIALS : Curve A relates to the " Phoenix " installation in a Westland " Wapiti " (gross weight 4,896 lb.). Curve B represents the standard " Wapiti " with " Jupiter " VIII.F (gross weight 4,810 lb.). engine in the " Wapiti " aircraft is so remarkable that, in spite of the fact that this machine was a standard two- seater general-purpose type, identical with the many " Wapitis " supplied by the Westland Works to the R.A.F. and foreign governments, it was decided to obtain the maximum ceiling under officially observed conditions. The effect of altitude on the functioning of the compres- sion-ignition type of engine and the ceiling it was possible to obtain has been a matter of conjecture for some years past. At one time it was considered that this ceiling might be of the order of 15,000 to 18,000 ft., but these figures have actually been exceeded both in Germany and America, and now the " Phoenix " crude oil engine has attained a recorded height of 28,000 ft. The " Wapiti " general-purpose machine used weighed, complete with pilot, oxygen apparatus and full equipment, 4,564 lb. Although the recorded height attained of 28,000 ft. is subject to official calibration and confirma- tion, it would appear certain from an examination of the barograph that an altitude of 27,000 ft. has been exceeded, and that the previous record has been beaten by a sub- stantial margin. Fuel consumption is naturally an outstanding character- istic of the compression-ignition type, and in this respect the " Phoenix " installation showed an improvement of 35 per cent, over the standard "Jupiter VIIIF." " Wapiti " installation at the same normal cruising speed. The foregoing remarks and tests deal with the compres- sion-ignition engine, particularly from the performance or 1—5 e 1 i i a £ "* * « no 90 ao 70 60 5O kJ u •—» ALTITUOC - TWOUSANOS Of TCT s k ALTITUDC - THOUSANDS OF FtET >>, ' EO 0^4 & to . (t 14 * » a RELATIVE POWER LOSS AT ALTITUDE : Curve 1, a non-supercharged petrol engine. Curve 2, a supercharged petrol engine. Curve 3 the " Phoenix " Diesel engine. The first two curves are based on Air Ministry correction factors, the last on Westland flight test data. military point of view, but for civil purposes the questionof fire risk is of paramount importance as the moral effect of a fire, even though the fatalities were actually due tothe preceding crash, is very bad indeed. The possible causes of fire after a crash are many, and while the actual cause is usually difficult to expose pre- cisely, there is no doubt that the exhaust system is fre- quently the origin, and this danger is accentuated on many new types of civil aircraft using closely-cowled high-output engines. In the case of compression-ignition engines, the fire risk is very greatly reduced as, quite apart from the greater safety characteristics of the fuel used and the elimination of the electric ignition system, the operating temperatures of the engine, and particularly of the exhaust system, are much lower than on the corresponding type of petrol engine. Evidence of this greatly reduced fire risk is available from published data on actual flight experiences with compression-ignition engines in the U.S.A., which show that besides several major crashes with 100 per cent, free- dom from fires, cases have occurred on certain types during their development, where minor mechanical breakdowns during experimental flights have resulted in fuel being sprayed continuously on to the exhaust system and engine installation, with no sign of fire despite the continuance of the flight under these conditions to a suitable landing ground. While this reduction in fire risk will quite probably prove the factor deciding the adoption of the compression-ignition engine for civil aircraft, the substan- tial saving in operating costs shown in the present relative fuel prices is an additional incentive from commercial considerations. COCKPIT PROTECTION Transparent wind screens have been used with good results on a Westland " Wallace." Both pilot's and gunner's coupes can be either fully closed or fully open, according to the conditions encountered. The gunner's hood, when closed, still leaves him complete freedom for bombing, wireless, etc. 505 ;
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