Evening star., 1917-09-09
A. B. c. of AVIATION.

For the Information Of those inter-
ested in aeronautics the following
| nomenclature has been prepared as
guide by Motor Age. with a view to
eliminating the duplication of terms.
the erroneous use Of terms and con-
| fusion Of terms. and with a view to
defining the principal terms which
| have come into use in the development
Of aeronautics. In the preparation Of
| this nomenclature only those terms
| which are new and peculiar to this
| subject have been defined. 1t is taken
from the report of the national ad-
| visory committee for aeronautics.
Aerofoil-A thin winglike structure.
fiat or curved, designed to obtain
reaction upon its surfaces from the
| air through which 1t moves.
lAeroplanes-See airplane.
| Aileron-A movable auxiliary surface
used for the control of rolling mo-
| and aft axis.
Aircraft-Any form of craft designed
/ for the navigation of the affair
, planes. balloons, dirigibles. helicop-
| ters kites kite-balloons ornithopters.
gliders, etc.
Airplane-A form Of aircraft heavier
| than air which has wing surfaces for
| eustentation, with stabillzing sur
faces rudders for steering and
| power plant for propulsion through
! the air The landing gear may be
| suited for either land or water use.
Pusher-A type of airplane with
the propeller. or propellers. in
rear of the wings.
Tractor-A type Of airplane with
| the propeller. or propellers. in
| front Of the wings.
Air-speed meterAn instrument de-
signed to measure the velocity Of an
| aircraft with reference to the air
| through which 1t Is moving.
Altimeter-An instrument mounted on
| an aircraft to indicate continuously
| its height above the surface of the
Anemometer-An instrument for meas
| uring the velocity of the Wind or air
currents with reference to the earth
| or some fixed body.
Angle:
OF attack-The angle between the
direction of the relative wind
and the chord of an aerofoil, or
the fore and aft axis Of a body.
Critical-The angle of attack at
which the lift is maximum.
Gliding-The angle the flight path
makes with the horizontal when
flying in still air under the in
fuence of gravity alone.
Aspect ratio-The ratk of spread to
chord of an aerofon.
Axes Of an aircraft-Three fxed lines
of refernce, usually centroidal and
mutually rectangular.
The principal longitudinal axis in
the plane of symmetry usually par
allel to the axis of the propeller. Is
called the fore and aft axis, or iongi-
tudinal axis; the axis perpendicular
to this in the plane of symmetry Is
called the vertical axis; and the third
axis, perpendicular to the other two,
is called the athwartship axis. or
transverse or lateral axis. In math-
ematical discussions the first of these
axes is called the X axis. the second
the 2 axis and the third the axis.
Ballonet-A small balloon within the
ho1 ri fcrfh 70
control the ascent or descent and
| maintain pressure on the outer en-
| velope to prevent reformation. The
| baIlonet is kept inflated with air at
the required pressure, under the con-
! tfol of blower and valves.
Balloon-A form of aircraft comprising
| gas bag and a car. whose susten-
| tation depends on the buoyancy Of
| the contained gas. which is lighter
Captive-A balloon restrained from
free fight by a cable attaching
it to the earth.
Kite-An elongated form of cap
tive balloon. fitted with tail ap-
pendages to keep 1t headed into
the wind and deriving increased
lift due to its axis being inclined
to the wind.
Bank-To incline an airplane laterally-
that is, to rotate it about the fore
and aft axis. Right bank Is to in
cline the airplane with the right
Banking rudder-see Ai1eron.
Barograph-An instrument used to
record variations in barometric pres
sure. In aeronautics the charts on
which the records are made are pre-
pared to indicate attitudes directly
instead of barometric pressure.
Biplane-A form Of airplane in which
the main supporting surface Is di-
vided into two parts one above the
other.
Body Of an airplane-A structure,
usually inclosed, which contains in
q stream-line housing the power
plant. fuel, passenUers, eto
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