Airspeed Indicator - P-340

CHAPTER ONE

T-34C INSTRUMENTS

Airspeed Indicator

Under standard atmospheric conditions at sea level, the airspeed indicator (Figure 15)

shows the speed at which the airplane is moving through the surrounding air mass. The

pointer is activated by the difference in pressure between static air pressure and the

impact air pressure from the pitot tube. The face of the instrument is calibrated in

knots. The airspeed indicator provides a continuous indication by which you can

maintain flight within safe minimum and maximum airspeed limits for various

performance conditions. Refer to NATOPS for additional information.

Use and Limitations. The airspeed indicator is the nose attitude crosscheck

instrument in all climbs and descents and a performance instrument in level flight. It

will give you an indirect indication of nose attitude with a constant power setting. For

any particular power setting, there is only one nose attitude that will hold altitude and

airspeed constant for any momentary weight. The airspeed is controlled by power

during level flight and by nose attitude during a climb or descent. Since the airspeed

indicator is a pitotstatic instrument, there is a slight lag (23 knots) when

accelerating or decelerating. Realize also that the airspeed indicator lags behind nose

movement in climbs and descents, so when correcting for airspeed in a climb or

descent, reference the gyro for miniature aircraft nose movement and allow sufficient

time for the airspeed to react prior to initiating another nose attitude correction.

Figure 15 Airspeed Indicator

1-8 INTRODUCTION TO BASIC INSTRUMENTS