lift of the aircraft wing equals the weight of the
values. This cuts out the possibility of damaging
aircraft. Such a condition prevails in level flight.
aircraft as a result of excessive stresses. The
The hand turns to +3 g when the lift is three times
accelerometer shows the load on the aircraft
the weight. The hand turns to minus readings
structure in terms of gravitation (g) units. It
when the forces acting on the aircraft surfaces
presents information that lets the aircraft be
cause the aircraft to accelerate downward.
maneuvered within its operational limits.
The accelerometer operates independently of
The forces sensed by the accelerometer act
all other aircraft instruments and installations.
along the vertical axis of the aircraft. The main
The activating element of the mechanism is a mass
hand moves clockwise as the aircraft accelerates
that is movable in a vertical direction on a pair
upward and counterclockwise as the aircraft
of shafts (fig. 6-42). A spiral-wound main spring
accelerates downward.
dampens the vertical movement of the mass. The
The accelerometer indications are in g units.
force of the mass travels by a string-and-pulley
The main indicating hand turns to +1 g when the
Figure 6-42.-Accelerometer mechanical schematic.
6-36