Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1915-07-10
Que OF tho Days Best Cartoons.

WASHINC;TON. July 9.-Some pha,cs
OF fore and-aN or longitudinal euui-
lnrium in dying are discussed by Or.
brv,!le Wright in a recent publication
Of the Smithsonian Institute. entitled
Stability OF Aeroplanes." Mr.. Wright
says that hIng machine is balanced
IN three NEUTRALITY-SUSPICIOUS. an inasi-
nary axis fore and aft in its line Of
motion. referred 10 as lateral euuiiih-
rum. about another axis extending in
a lateral direction from tip to tin Of
the wings, known az .0re-and-ar or
LONGITUDINAL equilibrium, and about n
vertical axis. which is generally re-
ferrcd to as steering. although it's most
important function is that OF lateral
equilibrium. Although a beginner finds
most difficulty in mastering the lateral
control. II is his lack OF knowledge
81 certain features OF the fore and AIT
equilibrium which leads to most OF the
serious accidents.
In an ideal dying machine the CEN
ter or gravity would lie III the line
OF the center of resistance to forward
moN cIncnt. and also in the line or
thrust. but in practice this is not al
WAYS feasible. since the machine must
tie built 10 land safely as we'll as TO
ny. I'm nEinC, Il low center OF gravity
that tx. one below the center OF sup
port. causes an oSciliatiuS movement
about the lateral aNis like that OF Il
pendu!uln.. which tends to form a dis
turbtnS turning movement. On the
other hand. u hiGh center OF gravity
tends to cause the machine to roll over
in landing. and consequently "a com
promise is adopted.
The two principal methods used in
preserving re-and-aft equilibrium
have been the shifting OF weight so az
10 keep the center o. gravity In line
with the changing center OF lit. and
the utilization OF auxiliary surfaces,
known as elevators to keep the cen
ter Of pressure in line with a fixed
center OF gravity. The first method
has been found impra ctica BILE on ac-
count u! the !mpossibility OF shifting
large weights quickly enough. but the
second is used in most OF the modern
dying machines.
Flying machines of the latter type
should have their auxiliary surfaces
located in the front or rear. and as
far AS possible from the main hearing
planes, because the greater the dis
lance the greater is the leverage, and
consequently the smaller the amount
Of surface required. No part Of either
tn" main surface or auxiliary surface
should be exposed on tncr upper sides
III any way 10 create a downward
pressure fuI maintaining equilibrium.
since SuCh pressure requires twice
the propeller thrust TO overcome II
that an euual-carricd weight would re-
uuire.
me doWnWaro pressure OF air rs used
TO some extent, however, on account
OF its adaptability. in producing more
or less inherent stable atroplanes. MIR.
Wright describes an inherently stable
aeroplanc as one in which equilibrium
is maintained by an arrangement OF
surface SO placed that when a current
OF air strikes one part OF the machine.
creating a pressure that would tend
TO disturb the equilibrium, the same
current striking another part creates
balancing pressure in the opposite
direction This compensatinS or cor
rcctinG pressure is secured WITHOUT the
mechanical movement OF any part OF
tho machine. While this system will
control ma chine to some extent. il
depends 50 much on variation in course
and speed as to render il inadequate
to meet the demands Of a practical fly
ing machine.
In. order TO secure greater dynamic
efficiency and greater maneuVering
ability. auXlliary surfaces mechanical