. Automotive industries . isnot accompanied by any appreciable change in the quan-tity of charge supplied. In contrast, Fig. 2, to typifythe foreign construction, is assumed to be so designedthat the leaning of the mixture is always accompaniedby an increase in the amount of charge supplied. Thiscan be effected by interconnecting the throttle with adevice for altering the size of the fuel orifice or, asshown in the figure, by an auxiliary throttle which ad-mits a very lean mixture of pure air. For this auxiliarythrottle to be effective, the carbureter throat must offera considerable restrictio
. Automotive industries . isnot accompanied by any appreciable change in the quan-tity of charge supplied. In contrast, Fig. 2, to typifythe foreign construction, is assumed to be so designedthat the leaning of the mixture is always accompaniedby an increase in the amount of charge supplied. Thiscan be effected by interconnecting the throttle with adevice for altering the size of the fuel orifice or, asshown in the figure, by an auxiliary throttle which ad-mits a very lean mixture of pure air. For this auxiliarythrottle to be effective, the carbureter throat must offera considerable restriction to air flow. The important dif-ference between the two types is that in the one shownm Fig. 1, the change in power produced by a mixturechange is due almost entirely to the change in power- •Technical Note No. 39 of the National Advisory Committee Eoiuitics, abbreviated. Based on tests made bj Hi- AutomotivePowej Plant Section, Bureau of Standards. DIAGRAMATrC ILLUSTRATIONS OF TWO METHODSOF VARYING FUEL TO AIR producing ability of a unit weight of the mixture, whilein the other type there is always the additional effect ofthe quantity change necessary to bring about the changein mixture quality. Fig. 3 indicates the economy that is possible with thetype shown in Fig. 1. The curves shown in full lines arebased on tests of an 8-cylinder aviation engine at analtitude of 5000 ft. and a speed of 1600 It will benoted that a decrease in the specific fuel consumption ofover 15 per cent is secured when the mixture is leaned,until there is a decrease of 10 horsepower in 150, 7per cent. Unquestionably then, so long as this type ofcontrol has sufficient range, its proper handling will re-sult in a marked fuel saving. Will it receive such hand-ling? To realize how unlikely this is, it must be remem-bered that continuing the mixture impoverishment willultimately result in a blowback in the carbureter, alikely cause of fire. Knowing that safety depends on notreaching
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectaeronautics, bookyear
