Great Britain, 1867. J. W.
Butler and E. Edwards, patent an aeroplane probably based on
some recollection of their school-boy days, when they threw
paper arrows in class. The stability of these Iittle
projectiles is quite good fore-and-aft, because the
supporting surfaces increase in area while the intensity of
the pressures diminish toward the rear, but the power
required is great, and there is probably no aviating merit
in this form.
Butler and Edwards' Delta
planform jet of 1867
The form here shown
above is the simplest, the top planes being set at a slight
dihedral angle, in order to procure lateral stability.
Butler and Edwards' dual
Delta planform jet of 1867
Butler and Edwards also
proposed to combine the planform in a variety of ways,
superposing the sustaining planes, or (fig. 2), placing two
machines side by side, or both, and bracing between by
The motive power was to be
placed in a car, forward of the centre of figure, and
capable of being moved forward and back, so as to shift the
centre of gravity to correspond with the centre of pressure
at varying angles of flight.
The power was to consist
in jets of steam issuing against the air in the rear; but,
suspecting that this would be enormously wasteful, the
patentees reserved the right of using screw propellers,
driven either by the reaction of jets of steam issuing from
curved arms (Hero's aeolipile) or by an ordinary
steam-engine, in which case the steam was to be exhausted
and condensed back into water, in cells formed by doubling
the surfaces of the planes and thus providing hollow spaces.