Indicators as a Means of Improving Aircraft-Engine Performance 320012
OPTICAL, balanced-pressure, electrical and sampling-valve indicators are discussed with particular reference to their shortcomings.
Sampling-valve indicators possess the advantage of simplicity, as compared with the balanced-pressure type, and make a permanent record on ordinary indicator paper.
The sampling or averaging type and the electric or instantaneous type each has fields of usefulness not covered by the other. The electric indicator is claimed to be the most satisfactory device for transient and qualitative work such as combustion study, but the sampling type is said to be better suited for engine development, valve-timing studies, supercharging and similar work.