ESDU 81027 provides data giving the mean force coefficients for plane lattice frames of conventional geometry. They are applicable to the calculation of wind loading (or other fluid loading) on lattice support structures for cable and pipe runs and sign gantries and on multiple frame structures in unclad building frames, roof structures and simple bridges. The data apply for frames of flat-sided or tubular members (smooth or rough surfaces) and allow for the effect of ancillaries such as gusset plates, ladders, cables and meshes. The effects of yaw and incidence of the flow can be accounted for as can also the effects of shielding in multiple lattice frames. Data for solidity ratios from 0 to 1 are given and for tubular members the effect of Reynolds number is quantified. Guidance is also provided for tapered frames and frames of mixed member sections in both uniform and shear flow. Data for tower-like lattice structures are provided in ESDU 81028.