Summary

ESDU 80006: this program calculates the drag increment due to rear fuselage upsweep, i.e. the difference in drag coefficient between a fuselage with an upswept rear and a fuselage without upsweep, with the cross-sectional shapes of the two fuselages (in the plane normal to the local fuselage centre-line) being the same.

The method is based on information derived from several studies of the subject carried out with wind-tunnel models representing a wide range of practical configurations.

Estimation of the difference in drag coefficient between similar fuselages with and without rear upsweep is based on the 'cross-flow drag' concept (in order to model the dependence on the angles of incidence and upsweep), using empirical corrections to compensate for the limitations of the method.

The values obtained take account of the effects of downwash generated by the aircraft wing and allow for sharp corners, or corners of small radius, on the perimeter of the fuselage section.

The method applies for Reynolds numbers (based on maximum fuselage width) up to 4.4E6, for civil and military transport aircraft cruising at subcritical flight Mach numbers.

Note: The user should consult ESDU 80006 for full specification and discussion of the aircraft configurations and flow conditions covered by the data used in the derivation of the method, and additional advice on the applicability.

Fuselage Shapes

Shape 1 Fuselages with smooth upper surfaces but with flattened lower surfaces and having corners of small radius.

Shape 2 Fuselages with smooth upper surfaces but with flattened lower surfaces and having hard chine lines.

Shape 3 Fuselages of square or rectangular cross-section with rounded corners of small radius.

Shape 4 Fuselages of smooth cross-section such as circular or elliptical.