Design, manufacturing and testing of a HALE-UAV structural demonstrator

Some main activities have been developed as part of the HELINET research project which was financed in January 2000, by the European Commission, (Fifth Framework Program in the IST action), to develop a European project in the field of stratospheric platforms. From the aeronautical point of view the following items were studied: (1) the design of an autonomous high altitude long-endurance unmanned air vehicle (HALE-UAV) platform capable of remaining aloft for very long periods of time (between 6 and 9 months) using a solar-powered and fuel cell system and to gain a complete understanding of the feasibility of a near-term aerodynamic HALE concept, in particular as far as stratospheric platforms are concerned (mainly dependent on high efficiency and reliability of solar cells, fuel cells and electric motors), (2) an evaluation of the production and service costs and an assessment of the safety and regulatory aspects of the platform, and (3) the manufacturing of a scale-sized technological demonstrator and the execution of static tests on it up to the ultimate load. The first HELIPLAT (HELIos PLATform) configuration was worked out, on the basis of a preliminary parametric study. The platform was a twin-boom tail type monoplane with eight brushless motors, a long horizontal stabilizer and two rudders. A scaled-prototype was designed to demonstrate the feasibility of this configuration and to perform some structural static and dynamic tests on it. The main CFRP structures were manufactured by CASA (Spain): the principal wing and horizontal tail tubular spars, booms, vertical tail spars and some reinforced ribs. These parts were delivered to the Aerospace Engineering Dept. (DIASP) at the Politecnico di Torino (POLITO) and assembled using special joints while some other necessary parts were manufactured by POLITO-DIASP. A parallel activity was performed to define the structural test configurations and structural test frame. The manufacturing activities and the development of the structural test system is described in the first part of the paper. Static and dynamic experimental tests were performed in two phases (2003 and 2004) on the prototype and the results of the static tests are presented in this paper and compared with numerical and theoretical computations. 2007 Elsevier Ltd. All rights reserved.