New-York tribune., 1919-07-13

airship, or one having a stiff wood or
metal framework inside the big gas bag
to hold its shape for it. The semi
rigid airship has rigid metal or wood
en- keel or spine along its under side,
which holds it partly in shape, aided
by the expansion Of gas inside. Bal
looms and airships have appendices, too.
The appendix is a hose leading from
the bottom side of the gas bag 10 the
car and used for initiating it, or. in the
case of the old-fashioned spherical ba,-
loon, like big rubber bali. it serves
to equalize the gas pressure inside.
An aviator is an operator or pilot of
an airplane, or any heavier than air
craft. A balloon is lighterthan- ir
craft. The term aviator applies to
either man or a women who drives
airplanes. The term 'fuselage' is COM
mon, yet not wholly understood. 1t is
the body of the airplane, or the fabric
covered framework which holds the en-
gine in front, the pilots seat and pas
senger area in the centre between the
wings and then runs back to the tail.
Dope" Used on Aircraft
"The trail group is general, and it
contains, besides the rudder or rudders.
depending on the type of machine, ele-
vators in horizontal position, one on
either side of the rudder, and fins
which are vertical to the elevators and
are fixed, forming one plane with the
rudder when it is in a natural position.
The controls are the wheel or stick
for use of the pilot in guiding his craft,
the same as the wheel of an automobile
or the rudder bar of boat. A control
has three uses, where in other vehicles
such as the motor car or boat only two
uses can be found for it. The reason
is that aviators have to contend with
three dimensions. An auto or boat can
travel only backward or forward, or
sidewise. A plane canssdo these things
and besides can go either up or down.
"A hangar is shed for an airplane.
An airplane also has dope in large
quantities. Dope is a substance re-
sembling glue, etc. used in treating
the cloth surfaces of airplanes and bal
looms to increase strength, produce
tautness and act as filler to maintain
the air and prevent the fabric from
leaking or tearing. It's base usually is
cellulose. The nacelle of an airplane
or dirigible is structure to which the
wings are attached. The engine is
moored and the passengers are sta
toned in it. A nacelle never extends
back to the tail, but sometimes pro-
trudes out on front and holds the pro-
peller.
"The term pancake came into use
during the war. 1t means that an air
plane, when landing, straightens out
almost level with the ground, instead
of diving into it. In other cases the
tail is dropped lower than the. nose, so
that the wings catch the air and re-
tard the force of the descent. A pom
toon is float or buoyant construct On
attached either under the wings of a
hydroplane or flying boat or under its
body to keep it aioat. When we speak
in terms of speed, we mean air speed
or the relative speed of an ailplane in
the air, and deducting the actual speed
of the air from the distance we have
travelled. Ground speed is more com
mon. If we travel from one point to
another in ten minutes, making fifteen
miles from a to B, we say that the
ground speed was a mile and half q
minute, or ninety miles an hour. The
undercarriage of plane is the struct-
ure by which it is enabled to land; the
traces and wheels, between which a
kid bar is sometimes located"