Page:Dictionary of aviation.djvu/194

 170 DICTIONARY OF AVIATION

pin^like ungrown fethers of a bird, as it is before it has burst its confining sheath and expanded its vanes; any young undevelopt fether as it first pierces the skin. pinion 'pinjan n.

1. the distal or terminal segment of a bird's wing; the outer part of a bird's wing, borne on the nianus or hand and consisting commonly of ten primaries, the primary coverts, and the alula or bastard wing; also, the anterior border of an insects's wing.

2. a wing, especially with reference to flight.

3. the outermost fether, or any flight^fether, of a, bird's wing; a pinion^f ether.

pinion-bone 'pmJ3n,boon n. any one of the several bones of the pinion, hand, manus, or distal joint of a bmTs>wing.

pinion- claw 'pinJ9n,k;Lc: n. a horny claw borne by the in- dex or pellex of certain birds.

pinion-feather 'pmJ9n,fed9z n. one of the fethers en the pinion of a bird's wing; the outermost fether, or any flight? fether, of a bird's wing; a pinion.

pirouette ,pizu'et n. a quick, short turn or whirl, as of a flying^machine.

pirouette ,pizu'et intr. perform a pirouette; turn or whirl quickly.

pitch pit$ v.

1. tr. plunge, throw, or hurl downward thru the air.

2. intr. plunge with prow or hed downwad thru the air; also, rise or fall alternately at bow and stern; plunge in a longitudinal direction : distinguisht from roll.

pitch pitS n.

1. an act of plunging hed foremost.

2. the height to which a bird of prey soars before swoop- ing down upon its victim*: as, to fly a *pitch.

3. the constant distance between fixt points or lines, as between any two successiv convolutions or threds of a screw propeller, or between any two successiv turns of a screw propeller considerd as moving in a solid nut, nies- sured in a direction parallel to the axis.

straight pitch, the pitch of an aerial propeller the angle of whose blade^surface remains constant, so that the dif- ferent portions of the blade tend to advance thru the air at different velocities : distinguisht from uniform pitch.

uniform pitch, the pitch of an aerial propeller the angle of whose blade^surface varies from hub to tip in such a manner that all portions of the blade tend to advance thru the air with uniform velocity : distinguisht from straight pitch.

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