Define airfoil mac#

(1972), Mechanics of Flight, Chapter 3, (p.103, eighth edition), Pitman Publishing Limited, London ISBN 3-0 (1959), Theory of Wing Sections, Section 1.4 (page 27), Dover Publications Inc., New York, Standard Book Number 486-60586-8 ^ Abbott, I.H., and Von Doenhoff, A.E.Flight dynamics principles : a linear systems approach to aircraft stability and control (3rd ed.). ^ The Design Of The Aeroplane,Darrol Stinton 1984, ISBN 7 1,p.26.Aerodynamics for Engineering Students (5th ed.). Clancy (1975), Aerodynamics, Section 5.2, Pitman Publishing Limited, London. This is why gliders have long slender wings. Induced drag is most significant at low airspeeds. (For wings with planforms that are not rectangular, the aspect ratio is calculated as the square of the span divided by the wing planform area.) Wings with higher aspect ratios will have less induced drag than wings with lower aspect ratios. The ratio of the length (or span) of a rectangular-planform wing to its chord is known as the aspect ratio, an important indicator of the lift-induced drag the wing will create. Any shape other than a simple trapezoid requires evaluation of the above integral.

Define airfoil mac#

Note that the figure to the right implies that the MAC occurs at a point where leading or trailing edge sweep changes. In particular, the position of center of gravity (CG) of an aircraft is usually measured relative to the MAC, as the percentage of the distance from the leading edge of MAC to CG with respect to MAC itself. Therefore, not only the length but also the position of MAC is often important. The pressure distribution over the entire wing can be reduced to a single lift force on and a moment around the aerodynamic center of the MAC. The MAC is a two-dimensional representation of the whole wing. Where y is the coordinate along the wing span and c is the chord at the coordinate y. Standard mean chord (SMC) is defined as wing area divided by wing span: SMC = S b, The mean aerodynamic chord is used for calculating pitching moments. To provide a characteristic figure that can be compared among various wing shapes, the mean aerodynamic chord (abbreviated MAC) is used, although it is complex to calculate. Most jet aircraft use a tapered swept wing design. Usually, the chord length is greatest where the wing joins the aircraft's fuselage (called the root chord) and decreases along the wing toward the wing's tip (the tip chord). Many wings are not rectangular, so they have different chords at different positions. The term is also applied to compressor and turbine aerofoils in gas turbine engines such as turbojet, turboprop, or turbofan engines for aircraft propulsion. (If a wing has a rectangular planform, rather than tapered or swept, then the chord is simply the width of the wing measured in the direction of airflow.) The term chord is also applied to the width of wing flaps, ailerons and rudder on an aircraft. The chord of a wing, stabilizer and propeller is determined by measuring the distance between leading and trailing edges in the direction of the airflow. The wing, horizontal stabilizer, vertical stabilizer and propeller/rotor blades of an aircraft are all based on aerofoil sections, and the term chord or chord length is also used to describe their width. For a turbine aerofoil the chord may be defined by the line between points where the front and rear of a 2-dimensional blade section would touch a flat surface when laid convex-side up. The point on the leading edge used to define the chord may be the surface point of minimum radius. The chord length is the distance between the trailing edge and the point where the chord intersects the leading edge. In aeronautics, the chord is an imaginary straight line joining the leading edge and trailing edge of an aerofoil.