Experiments on Flying

Abstract

IF we imagine the linear dimensions of a bird increased n times, its weight will be increased n⁸ times. On the other hand, the work necessary to keep it flying will, as Helmholtz has shown, increase n⁷ times.¹ Now, we can assume that the power, that is to say, the amount of work that can be done in the unit of time, increases in proportion to the weight, or even less. Helmholtz, therefore, concluded that large dimensions are a disadvantage, and that there is a limit beyond which the power will become inadequate to the increased weight. This limit, in his opinion, is already attained in the largest birds, whose bodies appear to be constructed with the utmost economy in weight, and whose constitution and food seem adapted to furnish the highest power. And he therefore thought it improbable that man would ever be able to fly by his own power.