Aerodynamic centre of wing-fuselage-nacelle combinations: effect of wing-pylon mounted nacelles
ESDU 77012 gives a method for estimating the forward shift of aerodynamic centre by treating the nacelle as an annular wing of diameter equal to the nacelle spanwise width. A graph gives the lift-curve slope for an annular wing as a function of its width to length ratio, the lift is assumed to act at the nacelle lip, and a correction term for the effect of the wing upwash field is added. The method is validated by comparing predictions with wind-tunnel data taken from the literature for both free-flow nacelles and nacelles with variable mass flow and is found to predict the shift to within 0.02 of aerodynamic mean chord. The wing lift-curve slope, also required in the method, is obtained from ESDU 70011 and the aerodynamic centre of the wing-fuselage combination, to which the forward shift is applied, is obtained from ESDU 76015.
The effect on aerodynamic centre due to rear-fuselage pylon-mounted nacelles is obtained from ESDU 78013.
The computer program ESDUpac A1309, associated with ESDU 13009, evaluates the chordwise position of the aerodynamic centre of wing-fuselage-nacelle combinations at subsonic speeds.
|Data Item ESDU 77012|
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