DICTIONARY OF AVIATION 235
trochoidal ,to'koi-di, 'tOO,koi-dl adj. pertaining to or hav- ing the nature of a tjocheid : as, *tocheidal curvs, a *tr.o- cheidal wave.
trochoidal plane, see under plane.
truss tAs Ir. tie, bind, fasten; adjust, draw, make fast or stiffen as with a tjuss.
truss tr,As n. a stiff frame; a combination of beams, posts, and struts of wood, steel, or other material, constituting a rigid or unyielding frame, as that of the planes or wings of a double-deckt aeroplane flying-machine.
truss-wire / tjAs,waic . one of the wires of a tuss, as in an aeroplane flying-machine.
tryout 'tai,aut n. the action or process of trying out, as of a flying-machine; a tr,ial or test.
tube-whistle 'tguu^iuisal n. a light wind-blown whistle made of bamboo tubes placed side by side, such as the Chi- nese sometimes attach to the tail of a flying pigeon.
turbulence 'tBzbju-lans n. the state or condition of being turbulent; disturbd state; agitation, commotion, as of the air.
energy of turbulence, the energy of the turbulence, agi- tation, or commotion of a fluid, as the air; energy of wind- fluctuation ; turbulence-energy.
motion of turbulence, the motion of a fluid, as the air, when in a state of turbulence or agitation ; the movement of a fluid in commotion; motion of wind-fluctuation.
velocity of turbulence, the velocity of the motion of tur- bulence of a fluid, as the air; turbulence-velocity.
turbulence-energy 'tB-bjulans^naz-dsi n. the energy of the turbulence, agitation, or commotion of a fluid, as the air; energy of turbulence; energy of wind-fluctuation.
turbulence-velocity 'tBzbjulons-vi^osi-ti n. the velocity of a fluid in a state of turbulence or agitation; velocity of turbulence; velocity of wind-fluctuation.
turnbuckle 'tB:zn,bAk3l n. a screw device for connecting or drawing together two parts of a wire or metal red; a wire-tightener consisting of a right-hand and a left-hand screw, used for keeping taut the wire stays of air-craft; a strainer : as, an open *turnbuckle.
turning-point 'tBznirj,pomt n. the point or place in the air or atmosfere at tuhich an airship turns, or changes or re- verses its course, as in order to return to its starting-point.
turtle 'tBztl n.
turn turtle, turn upside down ; capsize : said of an airship.
twilight 'ttuai,lait n. the light from the sky when the sun is below the horizon at morning and evening; the illumma-
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