The proposed Data Item provides a means of predicting the trailing-vortex drag coefficient@ CDV @ of wings with or without camber and twist@ at a given value of CL in shock-free flow. The method is applicable to wings with quarter-chord sweep angles not exceeding 45o @ aspect ratios not exceeding 12@ and linear or simple non-linear spanwise twist variations of up to 10o wash-in or wash-out. The method is applicable to both straight-tapered and cranked wing planforms where the section geometry@ including camber@ either remains unaltered or varies with spanwise location. The method is based on a theoretical analysis using inviscid spanwise loading distributions generated by the Multhopp-Richardson lifting-surface method@ obtained from ESDU 95010. As a result the trailing-vortex drag coefficient obtained by the method is the inviscid component of the total wing drag coefficient in shock-free attached flow. The viscous drag coefficient@ which may be predicted using ESDU 07002@ is the component of the total drag coefficient arising from all viscous effects. Therefore@ ESDU 07002 may be used in conjunction with the method of the proposed Data Item to predict the total wing drag coefficient at a given value of CL in a shock-free flow. Trailing-vortex drag coefficient data obtained using the Full Potential (FP) program and a post processing program@ both contained in ESDU 06016@ are compared with data obtained using the method of the proposed Data Item. There is good agreement between the two sets of data. Three worked examples illustrating the use of the method for a straight-tapered wing with cambered sections and a monotonic spanwise twist distribution@ a straight-tapered wing with non-monotonic spanwise twist and a wing with a single crank and monotonic spanwise twist@ are given.
DWN 10022-2010 history
2011DWN 10022-2011 Trailing-vortex drag coefficient in shock-free attached flow for cambered and twisted wings (Issue 6)
2010DWN 10022-2010 Trailing-vortex drag coefficient in shock-free attached flow for cambered and twisted wings. (Issue 2)