FLYING IN FOGS

Evening Star, Issue 20135, 27 March 1929, Page 6

FLYING IN FOGS

AVIATION DIFFICULTIES One of the grout difliculiies by which civil aviation is laced is that ol maintaining a. regular service under bad weather conditions. The problems aris* ing under this category relate to control, navigation, and landing, but it is with the first of those that wo arc now concerned (says ‘ Kiiginccriug ’). When tho pilot is deprived of his horizon the control of an aeroplane becomes exceedingly difficult. in spite of the information which can he supplied by such instruments as turn indicators. Generally, if tho rodder can he operated so as to keep the aeroplane Hying in a constant direction, most of the difficulty disappears. It should ho noted, how* ever, that observation of a magnetic) compass is practically useless from this point of view, owing to flic disturbances which arise from centrilugal force when tho aeroplane departs from a straight course. For this reason the automatic rudder control developed at the .Royal Aircraft establishment relics for its sense of direction on a free gyroscope or “ gyro azimuth.” The control consists essentially ol a pneumatic ram servo-motor, which operates an auxiliary rudder bar and is controlled by an air valve attached to the azimuth ring of a gyroscope. Tin* gyro wheel is spun at high sliced, god. its axle is sot along the line of tho required compass course. Deviation of: the aeroplane from its course entails relative movement between the azimuth ring and the aeroplane, since tho axlo of the wheel maintains a constant direc* tion in space. The consequent disturb* a nee of the valve admits compressed air to one cylinder of the servo-motor, and exhausts tho other to atmosphere, thus causing the servo-motor to apply, a correction to the rudder. To pro* vent the application of excessive judder the servo-motor is also connected to the casing of the valve, thus causing the valve to shut when the servo-motor has moved the required amount. This mechanism constitutes a “ lollow up, ,|,j and has the effect of making the rudder displacement proportional to tho deviation of the aeroplane from the de» sired course.