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1、BRITISH STANDARD BS 185-4: 1969 Incorporating Amendment No. 1 Glossary of Aeronautical and astronautical terms Section 4: Aerodynamics UDC 001.4:629.7.015:533.6 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 This British Stand
2、ard, having been approved by the Aerospace Industry Standards Committee, was published under the authority of the Executive Board of the Institution on 31 July 1969 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference ACE/1 Draft for comment 67/19252 ISBN
3、 580 05940 5 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This docume
4、nt comprises a front cover, an inside front cover, pages i and ii, pages 1 to 16 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publicatio
5、n Amd. No.Date of issueComments 1033November 1972 Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 BSI 12-1999i Contents Page Section 4. Aerodynamics1 Subsection 41. General1 Subsection 42.
6、Stability and control4 Subsection 43. Performance5 Subsection 4445. Fluid motion7 Subsection 46. Model testing13 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:
7、00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 BSI 12-19991 (Notes on the arrangement and scope of the glossary are contained in the Foreword to Section 1.) Section 4. Aerodynamics BS M 31, “Symbols for flight dynamics”, lists the recommended terms, with explanatory text and symbols, to be used i
8、n mathematical analysis and is designed to meet a more specialized need than is this glossary. However, care has been taken to ensure that, as far as is possible, there is no conflict between the glossary and the other standard. Subsection 41. General No.TermDefinition 4101aerodynamic centreThe poin
9、t about which the rate of change of pitching moment with incidence is zero. 4102aerodynamic twistVariation of the zero-lift line along the span of a wing or other aerofoil. (Cf. 5228.) 4103airspeedThe speed of an object relative to the ambient undisturbed air. angles 4104angle of attack ANGLE OF INC
10、IDENCE The angle between a reference line in a body (for an aerofoil the chord is usually used) and the projection of the velocity relative to the ambient undisturbed air on to the place of symmetry. NOTENot to be confused with rigging angle of incidence, 5236. 4105effective angle of attackThe angle
11、 between a reference line on a body and the mean direction of a non-uniform disturbed airstream ahead of the body. 4106angle of downwash/upwash The angle between the projections on to the plane of symmetry of the local and undisturbed flow directions. 4107angle of sideslipThe angle between the direc
12、tion of the undisturbed flow and the plane of symmetry. 4108angle of sidewashThe angle between the projections of the local and undisturbed flow directions on to a plane perpendicular to the plane of symmetry and parallel to the undisturbed flow. 4109area rule, sonicThe approximation that the wave d
13、rag at the speed of sound is the same for all bodies with the same longitudinal distribution of cross-sectional area. In particular, it is equal to that of a body of revolution of that area distribution. 4110area rule, supersonicA method of estimating the wave drag in inviscid supersonic flow for sm
14、ooth bodies in terms of the areas of sections taken obliquely at the Mach angle. 4111autorotationContinuous rotation of a body resulting from the action of air forces and not sustained by control inputs. (See also 5728.) axes 4112body axesA system of rectangular co-ordinate axes fixed in the aircraf
15、t, usually with the origin at the centre of gravity. The x-axis is usually forward of and in (or parallel to) the plane of symmetry, the y-axis is to starboard, and the z-axis perpendicular to these so as to form a righthanded system. 4113aerodynamic-body axes WIND-BODY AXES Body axes in which the x
16、-axis coincides with (or is parallel to) the projection on to the plane of symmetry of some datum velocity of the origin relative to the ambient undisturbed air. 4114principal body axesBody axes that coincide with the principal axes of inertia through the centre of gravity. 4115longitudinal axesThe
17、x-axis of a system of body axes in which the xz-plane is the plane of symmetry. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 2 BSI 12-1999 No.TermDefinition 4116normal axisThe z-axis of a system of body axes in which the xz-
18、plane is the plane of symmetry. 4117transverse axis LATERAL AXIS The y-axis of a system of body axes in which the xz-plane is the plane of symmetry. 4118cross-wind axisThe straight line through the centre of gravity perpendicular to the lift and drag axes. The positive direction is to port. 4119drag
19、 axisThe straight line through the centre of gravity parallel to the direction of the undisturbed flow. The positive direction is downstream. 4120lift axisThe straight line through the centre of gravity in the plane of symmetry and perpendicular to the drag axis. The positive sense is in the dorsal
20、direction. 4121centre of pressureThe point on some reference line (e.g. the chord of an aerofoil) about which the pitching moment is zero. draga 4122cooling dragDrag associated with the cooling of the power plant, etc. 4123form dragFor shock-free flow, the normal-pressure drag less the vortex drag.
21、4124lift-dependent dragThe difference between the drag at a given lift coefficient and the drag at some specified datum lift coefficient. 4125normal-pressure dragDrag arising from the resolved components of the pressures normal to the surface. 4126post-exit dragThe force in the drag direction deduce
22、d from the resolved components of the normal pressures on the outside of the equivalent post-exit streamtube. 4127pre-entry dragThe force in the drag direction deduced from the resolved components of the normal pressures on the outside of the pre-entry streamtube. 4128profile drag BOUNDARY-LAYER DRA
23、G Drag associated with losses in total pressure and total temperature in the boundary layers. It is the sum of the form drag and the skin-friction drag. 4129ram dragThe force, acting in the downstream direction, which would arise if the momentum of the internal flow at infinity of a body were destro
24、yed. It is the effective sink drag of an air intake. 4130sink dragDrag arising from the removal of fluid from the flow. 4131spillage dragThe difference between the drag at a given intake flow and the drag at some specified intake flow. 4132skin-friction drag SURFACE-FRICTION DRAG Drag arising from t
25、he resolved components of the tangential forces on the surface of a body. 4133wave drag SHOCK-WAVE DRAG Drag arising from the formation of shock waves. 4134vortex drag TRAILING-VORTEX DRAG Drag arising from the formation of trailing vortices. Formerly called induced drag. 4135external surfaceA surfa
26、ce that forms a boundary of the external flow. flows 4136datum intake flowThe intake flow that would occur if the boundary of the pre-entry streamtube were unaffected by the presence of the intake. 4137external flowThe flow of fluid which passes around a body. a See also 4141. Licensed Copy: sheffie
27、ldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 BSI 12-19993 No.TermDefinition 4138full intake flowThe intake flow that occurs when, with a pre-entry compression body in position, the boundary of the pre-entry streamtube is unaffected by the presenc
28、e of the remainder of the intake. If there is no pre-entry compression body, then full intake flow is the same as datum intake flow. 4139internal flowThe flow of fluid which passes through a duct of a body. forces 4140cross-wind forceThe component of the total aerodynamic force in the direction of t
29、he cross-wind axis. 4141dragaThe component of the total aerodynamic force in the direction of the undisturbed flow. In powered flight, contributions to this component arising from thrust are excluded. 4142liftThe component of the total aerodynamic force in the direction of the lift axis. 4143longitu
30、dinal force AXIAL FORCE The component of the total aerodynamic force along the x-axis (or longitudinal axis). 4144normal forceThe component of the total aerodynamic force along the z-axis (or normal axis). 4145transverse force LATERAL FORCE SIDE FORCE The component of the total aerodynamic force alo
31、ng the y-axis (or transverse axis). 4146thrustThe aerodynamic force attributed to the propulsive system. 4147post-exit thrustThe force in the direction of motion deduced from the resolved components of the normal pressures on the inside of the post-exit streamtube. 4148pre-entry thrustThe force in t
32、he direction of motion deduced from the resolved components of the normal pressures on the inside of the pre-entry streamtube. 4149ground effectThe effect of the proximity of the ground or other surface on the aerodynamic qualities of an aircraft. 4150hinge momentThe moment about the hinge axis of a
33、 control or other hinged surface due to aerodynamic forces. 4151industrial aerodynamicsAerodynamics of non-aeronautical engineering applications, such as buildings, bridges, stacks, vehicles, duct flows, fans, ventilation, combustion. 4152interferenceThe aerodynamic influence of bodies on one anothe
34、r. 4153internal surfaceA surface that forms a boundary of the internal flow. 4154limiting velocityThe steady velocity attainable by an aircraft along a straight flight path at any specified angle to the horizontal under given atmospheric and propulsive conditions. 4155post-exit streamtubeThe hypothe
35、tical streamtube, extending from the body to infinity downstream, that is assumed to separate the internal flow from the external flow in the absence of mixing. 4156pre-entry streamtubeThe streamtube extending to the entry of a ducted body from infinity upstream and separating the internal flow from
36、 the external flow. 4157scale effectThe effect upon any non-dimensional aerodynamic coefficient of a change in the size of a body, other conditions remaining unchanged. More generally, the effect of a change in the Reynolds number. a See also 4122 to 4134. Licensed Copy: sheffieldun sheffieldun, na,
37、 Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 4 BSI 12-1999 No.TermDefinition 4158sound barrierA popular term for the large changes in the aerodynamic characteristics of an aircraft approaching the speed of sound, formerly believed to make supersonic flight unattainab
38、le. 4159spillageThe amount by which the intake flow is less than some specified intake flow. 4160stallThe progressive breakdown of attached flow over an aerofoil, leading to marked changes in aerodynamic characteristics, in particular loss of lift. (Cf. 2225.) 4161terminal velocity1. The highest val
39、ue of the limiting velocity. 2. The velocity for which the drag of a freely falling body just balances the weight at a given altitude. 4162vertical thrust margin (VTM) The amount, on a VTOL aircraft, by which the vertical thrust exceeds the aircraft weight. 4163zero-lift lineA line through the trail
40、ing edge of an aerofoil section parallel to the direction of the relative air stream when the lift is zero. Subsection 42. Stability and control 4201aerodynamic dampingThat part of the damping of a system which is contributed by the aerodynamic forces and/or moments called into play by the motion. 4
41、202aerodynamic stiffnessThat part of the stiffness of a system which is contributed by the aerodynamic forces and moments called into play by the motion. 4203disturbanceA displacement from steady state conditions. 4204divergenceA disturbance which increases without oscillation (Cf. 4234.) 4205latera
42、l divergenceA divergence involving rolling, yawing, sideslipping, or any combination of these. 4206longitudinal divergenceA divergence in the plane of symmetry. 4207spiral divergence SPIRAL INSTABILITY A lateral divergence which tends to a spiral descent with increasing rate of turn. 4208instability
43、The quality whereby any disturbance from steady motion tends to increase. An aircraft is unstable if, following a disturbance from a given type of steady motions, it does not return to its initial steady motion without movement of the controls by the pilot (Cf. 4223.) motions 4209lateral motionMotio
44、n involving rolling, yawing, sideslipping, or any combination of these. 4210longitudinal motionMotion in the plane of symmetry. 4211coupled motionMotion of an aircraft involving both lateral and longitudinal motion at the same time. 4212inertia couplingCoupled motion due to the inertial properties o
45、f the aircraft. 4213manoeuvre margin with stick fixed The distance of the centre of the gravity forward of the manoeuvre point with stick fixed, expressed as a fraction of the longitudinal reference dimension. It is a measure of the displacement of the control column necessary to produce a given nor
46、mal acceleration in a steady pull-out. 4214manoeuvre margin with stick free The distance of the centre of gravity forward of the manoeuvre point with stick free, expressed as a fraction of the longitudinal reference dimension. It is a measure of the force on the control column necessary to produce a
47、 given normal acceleration in a steady pull-out. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 03:26:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 185-4:1969 BSI 12-19995 No.TermDefinition 4215manoeuvre point with stick fixed The position of the centre of gravity for which the displaceme
48、nt of the control surface required to maintain a steady normal acceleration does not depend on the acceleration. 4216manoeuvre point with stick free The position of the centre of gravity for which the force on the control column required to maintain a steady normal acceleration does not depend on th
49、e acceleration. 4217neutral point with stick fixed The centre of gravity position for which the static margin with stick fixed is zero. 4218neutral point with stick free The centre of gravity position for which the static margin with stick free is zero. oscillations 4219lateral oscillationAn oscillation involving rolling, yawing, sideslipping, or any combination of these. 4220longitudinal oscillationAn oscillation in the plane of symmetry. 4221phugoid oscillationThe long-period longitudinal oscillation involving predominantly changes in airspeed. 4222short-period longitudinal
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