A fixed angle of three to five degrees,
however, will only be sufficient for very light puffs
of wind and to mount the wings so that the whole wing
may be moved to change the dihedral angle presents
mechanical difficulties which would be better avoided.
"The objection of mechanical impracticability applies
to any plan to preserve the balance by shifting weight
or ballast. The center of gravity should be lower than
the center of the supporting surfaces, but cannot be
made much lower. It is a common mistake to assume
that complete stability will be secured by hanging the
center of gravity very low on the principle of the
parachute. An aeroplane depends upon rapid horizontal motion for
its support, and if the center of gravity be far
below the center of support, every change of speed or
wind pressure will cause the machine to turn about its
center of gravity, pitching forward and backward dangerously.
Preserving Longitudinal Balance.
"The birds maintain longitudinal, or fore and aft balance,
by elevating or depressing their tails. Whether
this action is secured in an aeroplane by means of a
horizontal rudder placed in the rear, or by deflecting
planes placed in front of the main planes, the principle
is evidently the same. A horizontal rudder placed well
to the rear as in the Antoinette, Bleriot or Santos-Dumont
monoplanes, will be very much safer and steadier
than the deflecting planes in front, as in the Wright or
Curtiss biplanes, but not so sensitive or prompt in action.
Pages:
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133