Flight dynamics model for preliminary design of PrandtlPlane wing configuration with sizing of the control surfaces

Abstract

This paper deals with the evaluation of the flight dynamics response of aircraft with a PrandtlPlane configuration by means of simple models to be used during the preliminary design. The study is completed by method that allows an initial sizing of the elevator and the aileron in such the way adequate requirements can be achieved: this analysis becomes important when the control surfaces can be located in both the front and the rear wing. The flight dynamics model is carried out considering the aircraft rigid, the steady aerodynamics, and separating the longitudinal and the lateral-directional motions. In this way classic equations are considered; for both the phugoid and the short period, equations are extended taking also the Zq derivative into account because of the non-conventional wing configuration. The force derivatives are extrapolated through a VLM solver whose the reliability of the results has been proven. The sizing methods have been applied to a test case derived from the project IDINTOS; as general results, the study remarks the possibility to obtain proper longitudinal dynamic response with a reduced longitudinal Stability Margin because of the very high values of the aerodynamic damping M q.

Conceptual design of PrandtlPlane civil transport aircraft

“…In analogy with experimental results shown in Oliviero et al., 9 the elevators can be designed to be counter-rotating and generate a pure pitching moment: in this way, the pitch control effectiveness is improved and the variation of vertical force due to elevators deflection is minimized. This solution increases the safety of flight, as, for example, in the event of a low altitude pull up maneuver (landing aborted).…”

“…In fact, although drag reduction is the main advantage of the PrP, other interesting benefits have been found for different aircraft categories. Previous studies have shown that the PrP has a smooth stall behavior and post-stall is characterized by only a partial reduction of maneuverability and controllability, 8 pitch control can be obtained by using counter-rotating elevators (on both front and rear wings) which can introduce a pitching moment without perturbation to lift, 9 the pitch damping is higher than in the case of a wing-tail configuration, with benefits in terms of comfort and safety. 10 In addition, as summarized in Cavallaro and Demasi 11 and Frediani et al., 12 the PrP configuration can be adopted for aircraft of very different dimensions, such as Light Sport Aircraft, ultra large airliners, freighter aircraft, 13 or “cryoplanes.” 14…”

Preliminary stability analysis methods for PrandtlPlane aircraft in subsonic conditions

“…Whereas all the models provide a poor estimation of b -derivatives, the flat fuselage model is much more accurate in predictingaderivatives, and hence its choice represents the best compromise for the conceptual design phase. As detailed by Oliviero et al (2016), the research activities carried out during the project "IDINTOS" have provided both numerical and experimental results concerning the aerodynamics and flight mechanics of the PrP configuration in subsonic flight (Cipolla et al, 2016). Given the data shown in Figure 5 (Oliviero et al, 2016), at trim condition (a = 1°, b = 0°), the following accuracy factors can be calculated:…”

“…As detailed by Oliviero et al (2016), the research activities carried out during the project "IDINTOS" have provided both numerical and experimental results concerning the aerodynamics and flight mechanics of the PrP configuration in subsonic flight (Cipolla et al, 2016). Given the data shown in Figure 5 (Oliviero et al, 2016), at trim condition (a = 1°, b = 0°), the following accuracy factors can be calculated:…”

“…Comparison of results from wind tunnel tests and AVL analyses for the ultralight PrP "IDINTOS"(Oliviero et al, 2016) …”