Innovative Aircraft Aeroelastic Modelling and Control

The aeroelastic design of innovative aircraft wing configurations imposes the designer to deal with specific phenomena, which are not usually considered in classical aircraft definition. The design process itself, though, gives the designer several indications on how to maintain the safety standards imposed by regulations. The investigation of the basic aeroelastic principles for unconventional wings with high aspect ratios can be extremely interesting as, once introduced in a multidisciplinary design, they can be very effective in giving an early determination of the static and dynamic behaviour of the aircraft, leading to significant improvements in the configuration weight, cost, and overall performance. The paper shows some preliminary results as part of the main objectives of the In.A.Team group (Innovative Aircraft Theoretical-Experimental Aeroelastic Modelling) at Politecnico di Torino, Italy. The In.A.Team Project has the following main objectives: 1) to develop multidisciplinary analysis methods appropriate to unconventional aircrafts (highly flexible, "morphing" vehicles); 2) to develop the capability of illustrating and understanding the effects of uncertainties on the behaviour of an aeroelastic system; 3) to apply the innovative adaptive L1 control techniques to highly flexible wings, 4) to integrate theoretical analysis with commercial structural (FEM) and aerodynamic tools (CFD). 5) to design and manufacture an aeroelastic experimental-test-model. 6) to validate theoretical/numerical results by vibration and aeroelastic wind tunnel tests

Practical considerations for the design of an aeroelastic energy harvester

Achieving the optimal balance between weight and energy consumption during flight mission remains a challenge for the design of very efficient high altitude long endurance aircrafts (HALE). These aircraft are intended to have flight missions that can range from 30 to 90 days. Composite materials are used to provide the structural integrity of the aircraft while minimizing its weight. Typically composites are used in long and slender structural elements of the HALE and are the main drivers of dynamic aeroelastic instabilities, even at low speed. This is due to the higher structural flexibility they introduce. Therefore, in order to respond to the demand of HALE aircrafts of having a wider amount of energy on board, without any substantial weight penalization, an experimental piezoelectric wing have been designed with the aim of exploiting aeroelastic instabilities or any other type of induced vibrations to generate electric energy directly on board. The numerical model of the piezoelectric wing, presented in this paper, is built starting from the assumptions of the 3D Euler-Bernoulli beam theory and of the strip theory for the aerodynamic loads. A preliminary sensitivity study was carried out, over the flutter solutions, for the identification of a suitable experimental prototype, to be used for modal and wind tunnel tests. The test campaign showed a good agreement between numerical and experiments results, highlighting, above all, the encouraging results in terms of energy harvesting and in terms of the exploitation potential of the piezoelectric design in the dynamic of structures

EQUIVALENT MATERIAL IDENTIFICATION FOR COMPLETE SIMILARITY IN SCALED-MODEL TESTS

The continuous proposal and analysis of innovative aircraft configurations require wider validation activity based on testing results. The arrangement of real-scale prototype for testing campaign is often not feasible due to economic reasons. As a consequence the experiments on scaled models are frequently performed applying similarity laws. The definition of specific material and its scaling rules for a complete similarity is required in several cases particularly when composites play a predominant role on the test response. So the design of a correct scaled-model including the right material selection becomes decisive. The introduction of TRACE parameter is proposed as a method orienting the designer for the right material selection in these situations. The method is presented in a specific case of a composite plate deflected by pressure. Non-dimensional deflection is determined as a function of load parameters and TRACE according to typical material classes definition. The procedure is extended to a typical drop-test equipment on water including structural flexibility. Potentiality of the method is clarified

Progetto S55 Replica

Il Savoia Marchetti S55 è un idrovolante simbolo dei notevoli progressi tecnologici dell’Italia in campo aeronautico durante gli anni ’20 e ’30 e reso famoso da una serie di voli a lunga percorrenza da record. Nonostante la produzione toccò i 250 esemplari ad oggi non esiste nessun esemplare volante e solo uno di essi si è conservato fino ai giorni nostri ed è attualmente esposto nel museo aeronautico TAM in Brasile. Nel 2015 un gruppo di professionisti e appassionati del settore aeronautico ha avviato il progetto Replica55 coordinato dal comandante Francesco Rizzi, con l'obiettivo di progettare, costruire e far volare una replica del velivolo S55 (www.replica55.it). The Savoia Marchetti S55 is a seaplane symbol of the remarkable aeronautical know how reached in Italy in during the '20s and' 30s, and confirmed by a series of record long-range flights. Although were made about 250 aircraft, to date does not exists one flying airplane. Currently the only one remaining and preserved is exhibited in the TAM aeronautical museum in Brazil. In 2015 a group of competent and enthusiastic professionals of the aeronautics sector started the "Replica55 project" coordinated by the commander Francesco Rizzi, with the aim of designing, building and flying a replica of the S55 aircraft. (www.replica55.it)

PRELIMINARY ASSESSMENT OF A WARPING WING CONFIGURATION IN ROLLING CONTROL

The preliminary analysis and the possible advantages of a morphing solution replacing the traditional hinged aileron configuration has been analyzed in order to evaluate its energy efficiency in UAV configurations with limited payload capacity and power available for flight. The parameters considered are the wing aspect ratio, the torsional stiffness, the position and the aileron deflection and the consequent actuation rib rotation in the morphing solution. The analysis showed that the morphing solution is very advantageous in all cases requiring high rolling moments with a more evident advantage at high aspect ratios. The traditional solution still remain advantageous at low aspect ratios and low rolling moments