Stability in theory, in the laboratory and in the air: William Ellis Williams’ campaign for proof positive (1904–1914)

Abstract

The equations that determine the stability of aircraft were formulated at Bangor, Wales, over the first two decades of the twentieth century, a formulation that was to prove as fit for purpose in characterizing the stability of aircraft today, as for the aeroplane allsorts that took to the sky in the wake of the Wrights' Flyer. While these equations are commonly identified with George Hartley Bryan, this does disservice to the contributions of others at Bangor. Not the least of these was William Ellis Williams, whose achievement in identifying photographically the modes predicted by theory is little recognized. Williams later went on to construct what was in all likelihood the first aeroplane designed solely for research to be built in a university department, making the first airborne measurement of pressure distribution across aircraft wings in his Bamboo Bird, in 1913, an achievement not hitherto afforded due credit in the literature.