1. That the lifting power of a large machine, held stationary in a wind
at a small distance from the earth, is much less than the Lilienthal
table and our own laboratory experiments would lead us to expect. When
the machine is moved through the air, as in gliding, the discrepancy
seems much less marked.
2. That the ratio of drift to lift in well-balanced surfaces is less at
angles of incidence of five degrees to 12 degrees than at an angle of
three degrees.
3. That in arched surfaces the center of pressure at 90 degrees is near
the center of the surface, but moves slowly forward as the angle
becomes less, till a critical angle varying with the shape and depth of
the curve is reached, after which it moves rapidly toward the rear till
the angle of no lift is found.
4. That with similar conditions large surfaces may be controlled with
not much greater difficulty than small ones, if the control is effected
by manipulation of the surfaces themselves, rather than by a movement of
the body of the operator.
5. That the head resistances of the framing can be brought to a point
much below that usually estimated as necessary.
6. That tails, both vertical and horizontal, may with safety be
eliminated in gliding and other flying experiments.
7. That a horizontal position of the operator's body may be assumed
without excessive danger, and thus the head resistance reduced to about
one-fifth that of the upright position.
8. That a pair of superposed, or tandem, surfaces has less lift in
proportion to drift than either surface separately, even after making
allowance for weight and head resistance of the connections.
[Illustration]
Public-domain text, read in full here on John Shaqi.
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