• Integrated flight/thrust vectoring control for jet-powered unmanned aerial vehicles with ACHEON propulsion

      Cen, Zhaohui; Smith, Tim; Stewart, Paul; Stewart, Jill; University of Lincoln (2014-07-29)
      As a new alternative to tilting rotors or turbojet vector mechanical oriented nozzles, ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle) has enormous advantages because it is free of moving elements and highly effective for Vertical/Short-Take-Off and Landing (V/STOL) aircraft. In this paper, an integrated flight/ thrust vectoring control scheme for a jet powered Unmanned Aerial Vehicle (UAV) with an ACHEON nozzle is proposed to assess its suitability in jet aircraft flight applications. Firstly, a simplified Thrust-Vectoring (TV) population model is built based on CFD simulation data and parameter identification. Secondly, this TV propulsion model is embedded as a jet actuator for a benchmark fixed-wing ‘Aerosonde’ UAV, and then a four “cascaded-loop” controller, based on nonlinear dynamic inversion (NDI), is designed to individually control the angular rates (in the body frame), attitude angles (in the wind frame), track angles (in the navigation frame), and position (in the earth-centered frame) . Unlike previous research on fixed-wing UAV flight controls or TV controls, our proposed four-cascaded NDI control law can not only coordinate surface control and TV control as well as an optimization controller, but can also implement an absolute self-position control for the autopilot flight control. Finally, flight simulations in a high-fidelity aerodynamic environment are performed to demonstrate the effectiveness and superiority of our proposed control scheme.
    • Multifunctional unmanned reconnaissance aircraft for low-speed and STOL operations

      Trancossi, Michele; Bingham, Chris; Capuani, Alfredo; Das, Shyam; Dumas, Antonio; Grimaccia, Francesco; Madonia, Mauro; Pascoa, Jose; Smith, Tim; Stewart, Paul; et al. (SAE International, 2015-09-15)
      This paper presents a novel UAS (Unmanned Aerial System) designed for excellent low speed operations and VTOL performance. This aerial vehicle concept has been designed for maximizing the advantages by of the ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle) propulsion system, which has been studied in a European commission under 7th framework programme.This UAS concept has been named MURALS (acronym of Multifunctional Unmanned Reconnaissance Aircraft for Low-speed and STOL operation). It has been studied as a joint activity of the members of the project as an evolution of a former concept, which has been developed during 80s and 90s by Aeritalia and Capuani. It has been adapted to host an ACHEON based propulsion system. In a first embodiment, the aircraft according to the invention has a not conventional shape with a single fuselage and its primary objective is to minimize the variation of the pitching moment allowing low speed operations. The shape with convex wings has been specifically defined to allow a future possibility of enabling stealth operations.Main objective of the design activity has been focused on low speed flight, very short take off and landing, and a control possibility by mean of two mobile surfaces in the front canard, which allow changing the pitch angle, and allows an almost complete plane control in combination with an ACHEON variable angle of thrust propulsion system. The design considers has been specifically to allow flying at a speed which is lower than 12 m/s with an high angle of attach (over 7°), without losses in terms of manoeuvrability and agility. These features allow innovative uses such as road monitoring, and police support and are characterized by a breakthrough performance level.A complete optimal sizing of the aircraft has been performed, together with an effective performance analysis, which allows identifying the strong points and the potential problems of the project. An effective energy analysis has been performed also. An effective prototyping is expected in about one year.