Part 21 (1/2)

=Turnbuckle=--A for of a barrel into each end of which is screwed an eyebolt Wires are attached to the eyebolts and the required degree of tension is secured bythe barrel

=Thrust, Propeller=--See ”Air-Screw”

=Undercarriage=--That part of an aeroplane beneath the _fuselage_ or _nacelle_, and intended to support the aeroplane when at rest, and to absorb the shock of alighting

=Velocity=--Rate of displaceht=--Is a ravity) upon a body The standard unit of weight in this country is 1 lb, and is the force of the Earth's attraction on a piece of platinum called _the standard pound_, deposited with the Board of Trade in London At the centre of the Earth a body will be attracted with equal force in every direction It will therefore have no weight, though its ht is a measure, decreases with increase of altitude

=Web= (_of a rib_)--That vertical part of a rib which prevents it fro upwards [37_a_]

=Warp, to=--To distort a surface in order to vary its angle of incidence

To vary the angle of incidence of a controlling surface

=Wash=--The disturbance of air produced by the flight of an aeroplane

=Wash-in=--An increasing angle of incidence of a surface towards its wing-tip [38]

=Wash-out=--A decreasing angle of incidence of a surface towards its wing-tip [39]

=Wing-tip=--The right or left-hand extremity of a surface [40]

=Wire=--A wire is, in Aeronautics, always known by the na=--A wire opposed to the direction of lift, and used to prevent a surface froht [41]

=Wire, Anti-lift or Landing=--A wire opposed to the direction of gravity, and used to sustain a surface when it is at rest [42]

=Wire, Drift=--A wire opposed to the direction of drift, and used to prevent a surface froht

=Wire, Anti-drift=--A wire opposed to the tension of a drift wire, and used to prevent such tension fro the fra from the top of an interplane strut to the bottom of the interplane strut in front of or behind it It le of incidence So=--Any wire holding together the framework of any part of an aeroplane It is not, however, usually applied to the wires described above unless the function performed includes a function additional to those described above Thus, a lift wire, while strictly speaking a bracing wire, is not usually described as one unless it perfor soe It will then be said to be an ”undercarriage bracing lift wire” Itas a drift wire also, in which case it will then be described as an ”undercarriage bracing lift-drift wire” It should always be stated whether a bracing wire is (1) top, (2) botto wire,” then it should be stated whether right- or left-hand

=Wire, Internal Bracing=--A bracing wire (usually drift or anti-drift) within a surface

=Wire, Top Bracing=--A bracing wire, approxierons of fuselage, between top tail booms, or at the top of si=--Ditto, substituting ”botto wire crossing diagonally a side bay of fuselage, tail booe side bay or centre-section side bay This term is not usually used with reference to incidence wires, although they cross diagonally the side bays of the cell It should be stated whether right- or left-hand [48]

=Wire, Cross Bracing=--A bracing wire, the position of which is diagonal fro it fro=--A wire preventing distortion of a controlling surface [50]

=Wire, Control=--A wire connecting a controlling surface with the pilot's control lever, wheel, or rudder-bar [51]