The daily star-mirror. (Moscow, Idaho) 1911-1939, 1923-07-30

Some aeronauts prefer to call tnee<
motorless aircraft "sailplanes" instead
OF elders, which Is the term more com
monty applied. a. J. Nordman. inven
tor of the craft that recently made
several flights over golf links neal
Bayside, refers to his machine as q
sailplane.
Downward Air Currents.
Glider pilots have to guard In par
ticular against the downward air sur
rents. 1t is obvious that in the total
of all air movements over the earth's
surface the speed and volume OF the
rising currents equal the speed and
volume Of the falling currents. The
falling currents are what, in the pto-
neer days Of aviation, were known as
"air pockets" regarded with dread
The slow-fying airplanes of those days,
like the Dewo1tine flying fiivver, were
more subject to downward eddies of
wind and were less safe for that rea-
| son. The faster plane is moving
| through the air, the less effect will 1t
feel in reaction to air eddies, or
This fact is somewhat of an obstacle
to the future popularity of flying fiv-
vers, which must be a relatively slow
craft when not gliding, if it is to COM
bine the elements of gliding and of
powered flight.
The flying flivver's power equipment
Is just sufficient to give the craft a
10
aid Of catapult or any other starting
device. And in the air the motor makes
it possible to continue flight in aerial
conditions that do not permit power
less gliding. She flying flivver driver
can fly in still air, or even In moderate
downward currents, and seek out areas
favorable to gliding. This the glider |
Of course cannot do. When the flying |
flivver pilot reaches an area In which |
the air is rising, he can throttle down
or even perhaps "kill' his motor, and
fly his wasplike machine as a glider.
A regular airplane can do the same
thing, to be sure; but not nearly so
well. The larger motor Of the Ordi-
nary plane makes that much more
dead weight. And the relatively small
er wing area Of the airplane built for
speedy flight is incapable of gliding
without closing altitude at a much
faster rate than the slower glider or
flying f1ivver, and CORRESPONDENCE los
ing the advantage Of the upward air
currents. In this instance, the slow
ness Of the flying f1ivver and the glider
is the essential factor.
Important Difference.
The gliding angle" is the ratio of
the horizontal distance through which
a flying machine glides, or volplanes,
to the vertical distance it lowers itself
in doing so; meanwhile retaining its
flying speed" or normal rate at which
it remains under full control of the
pilot. The ratio of six to one is a con-
sentative average figure for airplanes.
That is to say, an average airplane
with its motor shut off at an altitude
of 1000 feet can volplane a horizontal
distance of 5000 feet under control
before it comes to land
An efficient glider has as good an
angle of glide as an efficient airplane.
But the important difference is that
he glider travels more slowly. AS
suming in the foregoing case, for in
stance, that the airplane would nor
nally glide to the earth, through the
5000 feet from height of 1000, in
)ne minute, the glider, with the same
gliding angle, but much less speed.
night take two, or even three, minutes
no !
erence is due to the varying flying
peed. The flying speed of an
irplane or glider is the mini
mum speed it must maintain in
rider TO fly forward on level under
I'LL control. It is, therefore, practi
ally the same as the speed of the
raft at the moment it takes off, when
he speed just begins to provide 'lift''
nough to overcome the weight of the
Machine. Flying speed not only varies
18th different types of planes accord
lg to design and ratio of wing area
} weight but also varies from time to
me in an individual plane, according
} loading and to the condition of the
ings and other essential parts at the
oeed of so miles an hour with pilot
NY aboard will necessarily require
slightly higher flying speed with q
passenger also aboard Mere Ia
,eed must be attained to supply er
e additional lift. A plane with it's W
ings newly tuned up to afford max ia
lum efficiency will gradually require W,
higher flying speed thereafter, as the gr
ngs sag and warp out of best align
emit under the strain of usage. F
Flying Speed.
Flying speed in general is governed
the ratio Of wing area to weight.
lie larger the total wing surface is in Sill
oportion to the weight Of the air. dis
Inc or glider, the less is the flying As
eed. The less number Of pounds An
at each square foot OF wing surface I'M
S to sustain the slower the wing An
lst pass through the air. The object
d1... rt,.... L.. l. |