Preliminary design of an unmanned Wing In Ground effect craft.

This paper describes a systematic technique for preliminary conceptual design of Unmanned Wing in Ground Effect Craft (U-WIGs). Application of the methodology to a small U-WIG to be employed in tasks like coastal patrolling, oceanography, civil protection, control and monitoring, is presented. A mission profile and numerical mission specifications on minimum payload weight conveyable, cruising speed, minimum cruising altitude and autonomy suitable for the intended craft duties are imposed. On the basis of such specifications, take off weight is estimated via the fuel fraction method. Due to the lack of statistical information for small sized unmanned WIGs, data available for UAVs are used, corrected to take into account the impact of the hydro design on structural weight. The correction to be applied is determined through a comparison of data relative to seaplanes and landplanes of similar mission specifications, largely available in the literature. Successively, wing loading and power loading are determined via a classical design space procedure on the basis of performance specifications. The required statistical relationships between performance figures and wing/power loading are obtained again by considering a correction of UAV data which takes into account hydro design. The selection of wing planform is then addressed. A comparison between two sample candidate palnforms is performed using an open source numerical code, implementing the vortex lattice method, with ground effect modeled via the method of images