A conceptual study is presented on the dynamics of a proposed unmanned aerial vehicle (UAV), which is designed as a testbed for studying the influence of micro-(or partial) gravity on various biological or physical phenomena. The design option of a torque-controlled wing, free to rotate about a spanwise axis, is evaluated in terms of gust sensitivity and automatic settling at a certain g-setpoint. The complete set of nonlinear equations of motion of such a free-wing UAV are derived using Lagrange's equations. A linear aerodynamic model of the UAV is used to investigate its flight dynamics, gust sensitivity, and ability to fly micro-and partial gravity flights. Comparison to a similar fixed-wing UAV shows considerably decreased gust sensitivity. NomenclatureC m = dimensionless moment coefficient about the center of gravity of the fuselage c = cosinē c = mean aerodynamic chord F = generalized force f = position of the fuselage center of mass g = Earth's gravitational acceleration H = transfer function h = position of the intersection of the hinge lines of both wing halves L = Lagrangian function lw = position of the left wing half center of mass M = moment m = mass n = load factor p = angular velocity component of the fuselage along the x f axis q = angular velocity component of the fuselage along the y f axis q = column vector of generalized coordinates R = transformation matrix between two reference frames r = angular velocity component of the fuselage along the z f axis rw = position of the right wing half center of mass S = power spectral density s = angular velocity component of the wing halves along their hinge axes s = sine T = kinetic energy t = tangent t = time u = geodetic velocity component of the center of mass of the fuselage along the x f axis V = potential energy v = geodetic velocity component of the center of mass of the fuselage along the y f axis v = velocity ; A.M.Kraeger@lr.tudelft.nl. w = geodetic velocity component of the center of mass of the fuselage along the z f axis w = column vector denoting the center of mass of the wing halves in wing fixed axes x = in combination with index: x coordinate of the element indicated by the index; without index: x-position coordinate of the fuselage center of mass in geodetic reference frame y = in combination with index: y coordinate of the element indicated by the index; without index: y-position coordinate of the fuselage center of mass in geodetic reference frame z = in combination with index: z coordinate of the element indicated by the index; without index: z position coordinate of the fuselage center of mass in geodetic reference frame α = angle of attack = hinge axis dihedral angle γ = flight path angle δ e = elevator deflection δW = increment in virtual work δq = incremental virtual displacement δ w = angular deflection of the wing halves ζ = damping θ = pitch angle = hinge axis sweepback angle σ = standard deviation ϕ = roll angle ψ = heading angle Ω = skew symmetric matrix ω = column vector of (angular) velocity components ω 0 = undamped natura...
This paper presents a study on a possible control concept for micro-or partial gravity flight of conventional aircraft that can be implemented in any aircraft with a minimum in effort. The method makes use of a conventional pitch rate controller to track the continuously changing pitch rate along the desired micro-or partial gravity trajectory. As a first step towards automatic flight this principle is used to design a micro-and partial gravity flight director. The flight director has been experimentally evaluated in a fixed base manned simulation and its performance checked against other flight director principles. Pilots unanimously pointed out this flight director as their favorite one and it also showed the best performance. A baseline version will be implemented and flight-tested in the Delft University Cessna Citation research aircraft in the near future.
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