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UAS Airframe and Powerplant Design
Published in Douglas M. Marshall, R. Kurt Barnhart, Eric Shappee, Michael Most, Introduction to Unmanned Aircraft Systems, 2016
As the name implies, the distinguishing characteristic of a flying wing is that this design features a single horizontal lifting surface, although vertical members in the form of winglets, wingtip endplates, and vertical stabilizers may be present. UAS Winglets (Insitu ScanEagle) function as they do on manned aircraft to reduce tip vortices and induced drag. Extending below the wing, wingtip endplates are often provided at the tips of sUAS flying wings (e.g., the Gatewing X100 and the IAI Malat Mosquito) to decrease induced drag (parasite drag will be increased) and to protect the underside of the aircraft during a landing. True vertical stabilizers installed on UASs are an attempt to overcome, to some degree, the inherent directional instability of a flying wing design. Although vertical stabilizing airfoils are relatively uncommon on a UAS, one example is that of the WASP III Battlefield Air Targeting Micro Air Vehicle (BATMAV). (Due to directional instability and a lack of computerized stability augmentation systems, vertical stabilizers were also incorporated in the design of early manned flying wings, such as the Northrop YB-49. Figure 10.7.) Control and possibly stabilizing inputs are accomplished through differential movement of elevons (a portmanteau of aileron and elevator) installed on the trailing edge of the wing. The fuselage may be clearly discernable (Institu ScanEagle) or nonexistent (Skywalker X8). According to Gundlach (2012, 120), when conventional aircraft are defined under the broadened definition in which the categories of twin-boom and conventional forward-wing aircraft having an empennage/tail assembly are conflated, “[f]lying wings are the second most prevalent UAS configuration.”
UAS Airframe Design
Published in R. Kurt Barnhart, Douglas M. Marshall, Eric J. Shappee, Introduction to Unmanned Aircraft Systems, 2021
Michael T. Most, Michael Stroup
As the name implies, the distinguishing characteristic of a flying wing is that this design features a single horizontal lifting surface, although vertical members in the form of winglets, wingtip endplates, and vertical stabilizers may be present. UAS Winglets (e.g., Insitu ScanEagle) function as they do on manned aircraft to reduce tip vortices and induced drag. Winglets reduce lift distribution drop-off at tips and use vorticity to create a component of lift in the thrust direction. Vorticity instead occurs behind the wing or at the end of the winglets. Extending below the wing, wingtip endplates are often provided at the tips of sUAS flying wings (e.g., the Gatewing X100 and the IAI Malat Mosquito) to decrease induced drag (parasite drag will be increased) and to protect the underside of the aircraft during a landing. True vertical stabilizers installed on UASs are an attempt to overcome, to some degree, the inherent directional instability of a flying wing design. Although vertical stabilizing surfaces are relatively uncommon on a UAS, one example is that of the WASP III Battlefield Air Targeting Micro Air Vehicle (BATMAV). (Due to directional instability and a lack of computerized stability augmentation systems, vertical stabilizers were also incorporated in the design of early manned flying wings, such as the Northrop YB-49 Figure 10.8). Control and possibly stabilizing inputs are accomplished through differential movement of elevons (a combining of aileron and elevator into a single moveable surface) installed on the trailing edge of the wing. The fuselage may be clearly discernable (e.g., Institu ScanEagle) or nonexistent (e.g., Skywalker X8). According to Gundlach (2012, 120), when conventional aircraft are defined under the broadened definition in which the categories of twin-boom and conventional forward-wing aircraft having an empennage/tail assembly are conflated, “[f]lying wings are the second most prevalent UAS configuration.”
Safety Control System Design against Control Surface Impairments
Published in Xiang Yu, Lei Guo, Youmin Zhang, Jin Jiang, Autonomous Safety Control of Flight Vehicles, 2021
Xiang Yu, Lei Guo, Youmin Zhang, Jin Jiang
In a modern aircraft, for instance, several elevons are configured on the wings to provide necessary control functions for pitch and roll motions. However, if malfunctions occur in some elevons, the FTC is able to use the remaining redundant actuators to counteract the failures. Hence, the elevons constitute a set of redundant actuators.
Robust Adaptive Control Laws for a Winged Re-entry Vehicle
Published in IETE Journal of Research, 2022
Asha P. Nair, N. Selvaganesan, V. R. Lalithambika
The adaptive controllers described in the following sections control the rotational dynamics of the vehicle. The translational dynamics is being controlled by a guidance system. To do the control design, perturbation dynamics equations are taken around an operating (trim) point. Then the vehicle dynamics naturally decouples into longitudinal and lateral–directional modes. The longitudinal dynamics describe changes in forward, vertical and pitching motion of the vehicle. The longitudinal dynamics can be further decomposed into short-period and phugoid dynamics. The phugoid mode represents the dynamical interchange between the altitude and airspeed and is much slower than the short-period dynamics. Hence this can be neglected during the controller design. The short period describes the faster coupling between the vehicles’ angle of attack and the pitch rate. It can be written as where α is the angle of attack, V0 is the trimmed velocity, Zα is the force coefficient w.r.t α, Zq is the damping force, Zδe control force coefficient with respect to elevon deflection, Mα moment coefficient, Mq is the moment due to aerodynamic damping, and Mδe is the moment per degree deflection of the elevator. δe is the elevator deflection that provides the control moment.