Figure 89. Coupling network for use with bridge-type gages.
Figure 90. Moving film oscillogram record of travel and thrust vs time .
separation or at. the end of stroke. It is unnecessary to
e. Accelerometer.
Commercially
available
modify a propellant actuated device to adapt it to use of
accelerometers recommended for use in connection
a load cell. The load cell does require a somewhat
with propellant actuated devices are of the straingage
complicated mounting, however, since it must act as a
type. When a small mass in the accelerometer is
structural link between the device to be tested anti a
accelerated, a force is developed which, when
rigid mass fixed to the earth.
measured, indicates acceleration.
Electrically,
(5) Care must be taken in using load cells
accelerometers are similar to the strain gages
with propellant actuated devices, since
mentioned previously, except that the accelerometer
they are essentially static measuring
must, move with the load instead of being stationary.
devices.
While they have performed
Consequently, it must have long flexible leads and
admirably on propellant actuated devices,
possibly disconnects. If used on a free-flight device, it
repeated use, shock overloads, and
may be damaged by the high deceleration encountered
excessive rise times will change the
calibration of the cell or ruin it.
101
