well understood; in the case of the former the resistance is approximated by a curve a a. Fig. 1, representing the sum of a resistance following the V-square law and a constant; the latter (the dirigible) may be taken as following the V-square law implicitly. Fig. 1, b b.
_-_Fig._1.png)
Fig. 1
Fig. 1 represents approximately actual values of the resistance coefficients, in tractive effort per cent., in machines of average size as they exist to day, for the speeds given in miles per hour.[1]
One salient fact is at once evident; the greater the horse-power available for a given engine weight the greater the advantage in the matter of speed in favour of the aeroplane; the highest speed of flight of an aeroplane attained to-day (through, i.e., relatively to, the air) is already more than twice that of which
- ↑ The maximum speed attained by an airship is approximately 50 miles per hour; the maximum in the case of an aeroplane is considerably over 100 miles per hour; thus (Fig. 1) the tractive coefficient in the case of the aeroplane is actually greater than in the case of the airship. The reason for this is that the dead-load in the airship—represented by the envelope and its appurtenances—is disproportionately great, and the proportion of the weight that can be devoted to the motive-power installation is relatively smaller than in the aeroplane. Were it not for this fact the airship would have held the advantage until speeds about 60 miles per hour had been reached and the aeroplane after.
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