DESIGN PROPOSAL AND WING BOX MANUFACTURING OF A SELF-LAUNCHING SOLAR-POWERED SAILPLANE

Abstract

A preliminary study for a powered sailplane capable of taking-off and climbing to 500 m powered by batteries stored (solar) energy and maintaining a level flight by taking advantage of direct sun radiation only is reported. The final configuration of HELIPLANE has a 24m rectangular wing span with two brushless motors, each one powering a propeller blade of 2 m diameter. A 13kW power would be available, during the take-off and climbing, both by 400N of nickel-cadmium rechargeable batteries as well is by the 30 m^2 of 17% efficiecy solar cells. A T-tail configuration with a horizontal stabilizer having 6m span has been chosen. The most important structural elements are made of CFRP in order to reduce the sailplane mass. A 6 meter long wing-box has been manufactured by using a graphite/epoxy pre-preg and cured by autoclave cycles. Shear - bending- torsion tests have been carried out up to the failure load. A good correlation hasbeen obtained between the theoretical and experimental structural results. Compression flange and sandwich panels showed a good post-buckling behaviour of load 25% greater than buckling load. Failure has occurred, at a bending moment of 19 kNm, by debonding of the spar from the skin panel because of a poor bonding.