21
Activating (Arming) Switch:
an external switch that prevents
the electric motor from accidentally turning on
Aerodynamics:
science of air in motion
Angle of Attack (AOA):
angle between the chord of the wing
and the relative wind that strikes the airfoil; independent of the
attitude of the sailplane with respect to the horizon
Auto-Peak:
type of battery charger that automatically shuts off
when a battery has been fully charged
Axis:
a line passing through a body about which the body
revolves
Battery Cycling:
repeated charge and discharge of a battery to
erase battery memory
Battery Memory:
term used to explain why a battery is unable
to take on a full charge because of insufficient discharging
before recharging
Capacity:
amount of charge or electricity a battery can hold
Center of Gravity (CG):
balancing point of an aircraft
Critical
Angle of Attack: angle of attack at which smooth airflow
over the top of the wing stops
Electrolyte:
a caustic material found in batteries
Harness:
a device consisting of wires, switches, and a fuse that
connects the motor to the battery
L/D:
lift divided by drag expressed as a ratio; the same as a
glide ratio (think of L/D as a glide slope, then, for a given
amount of distance, the sailplane moves forward it drops a
certain amount.)
Minimum Sink:
the speed at which a sailplane loses altitude
most slowly, expressed in feet per minute
Ni-Cd (Nickel Cadium) Battery:
a rechargeable battery used
for radio control airplanes
Penetrate:
to make progress against the wind
Pitch:
degree of nose up or nose down from level to the horizon
Relative Wind:
direction that the air molecules strike the
leading edge of the wing
SCR:
a battery designed to release a lot of energy over a short
time without being damaged
Span:
the maximum distance from wingtip to wingtip
Stall:
loss of lift resulting from exceeding the critical angle of
attack
Thermal:
rising body of hot air that can take a sailplane to a
great height
Section 13: Definitions
