文档介绍：measure motion along vertical and lateral engine axes.
4 Linear Vibration The electrical output is fed to a multi-channel recording
oscillograph, which simultaneously records on a 35mm
Overload endurance testing is a valuable technique filmstrip the instantaneous position of the pickups as a
extensively used by engine manufacturers to function of time. Later analysis allows correlation of
determine weak points in engines. The process relative phase and frequency of the pickups.
consists of running the engine at high power settings,
sometimes even higher than the rated power of the
engine, until something breaks. The defective part is
then redesigned, the engine rebuilt incorporating the
new part, and the endurance run repeated. This
procedure, though time consuming and painful, results
in robust and reliable engines.
When overload endurance testing was begun on
engine X-79, strong vibration began breaking engine
parts. W. H. Sprenkle and R. E. Gorton began a series
of tests using engine X-78 on April 26, 1938 to
investigate the nature of this destructive vibration that
had resulted in carburetor mount, air chute, and
exhaust stack failures. As was the usual practice,
obvious “easy” solutions had already been exhausted:
Steel and aluminum air chutes, each with different
vibration characteristics, had been tried
essfully. Both metal and wood props were tri