In the power test of No. 6, the following data were obtained:
- W = weight of aerodrome = 20,450 grammes.
- θ = angle of lift = 19° 30′.
- Distance of CG from center of rotation = 198.2 cm.
- Distance of center of thrust from center of rotation = 186.3 cm.
As the propeller thrust and the weight of the model are forces acting in opposite directions at known distances from a center of rotation, letting L equal the “dead lift,” we may express the equation thus:
W sin θ × 198.2 = L × 186.3,
L = 198.2186.3 × sin 19° 30′ × 20,450,
L = 7,263 grammes “dead lift.”
The flying weight of Aerodrome No. 6 was 12,064 grammes, and the per cent of this weight lifted was, therefore,
7,26312,064 = 60.3.
This was much more than was necessary for flight, but in order to insure successful flights and avoid delay, the rule was made in 1895 that no aerodrome was to be launched until it had previously demonstrated its ability to generate enough power to maintain for at least two minutes a lift of 50 per cent of the total flying weight. At the same time other important data were obtained, such as the steam-pressure, the time required to raise sufficient steam, the total time of the run, and the general working of the boilers and engines.
As will easily be seen, these tests afforded a most satisfactory basis of judging what the aerodromes might be expected to do in actual flight if the balancing were correct.