DICTIONARY OF AVIATION 169
and motion of clouds and in other surveymg^work ; a cloud?
camera. photogrammetry ^ota'gcsemi-tj;! n. [also spelt fotogra-m-
metry] the use of the f otogrammeter ; the art of mesuring
fotograms or bird's^eye^view fotografs taken from airships. piano-wire pi'aeuo/waiz n.
1. a kind of slender steel wire of great strength such as used for the musical strings in pianos, often employd in airshipconstuction.
2. one of the stays or braces made of such wire, as in an aeroplane flying^machine.
phugoid 'fiou^eid adj. [also spelt fugoid] like flight; flights like; of or related to a flight?path.
phugoid chart, a chart or drawing showing a complete se- ries of fugeid curvs.
phugoid curve, a curv showing the form of a flightepath. phugoid equation, the equation of the flightepath of an aircraft.
phugoid oscillation, the oscillation, or periodic uplands down swinging which eften characterizes flight; the waver- ing, or alternate fluctuation of the flightepath of an air* craft.
phugoid plane, the vertical plane passing thru the curv of the flightepath of an aircraft.
phugoid theory, the theory relating to longitudinal sta- bility and the form of the fugeid curv or flighfcpath.
phugoid 'fiou,geid n. a fugeid curv.
inflected phugoid, a fugeid having the form of an in- flected curv.
pilot 'pai-tet n. one who steers or directs the course of an airship; a steersman; a helmsman; an air^pilot; an aero- naut; an aviator.
pilot 'pai-lat tr. conduct as a pilot; direct the course of (an airship) ; steer ; guide.
pilot-balloon 'pai-lat-ba^oun n. a small unmand auxiliary balloon (sometimes attacht to a main balloon) allowd to rise in advance of the main balloon in erder to ascertain the direction of the overhed air^currents.
pilot-chart 'pai-lat^tjarzt n. a chart for the use of pilots, showing wether^conditions, sterm^paths, etc.
pilotess 'pai-19-tis n. a female pilot ; a woman air^pilot.
pilot-kite 'pai-J3t,kait n. the first, upper, and smaller kite in a series of superposed kites (such as that described by Wenham in 1866), sent up in advance and used to lift the others or help sustain them in the air. compare draftzkite.
pinfeather 'pin,fed9z n. [also spelt pinfether] one of the
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