In-Flight Investigation of a Rotating Cylinder-Based Structural Excitation System for Flutter Testing

Vernon, Lura

doi:10.2514/6.1993-1537

Cited by 10 publications

(6 citation statements)

References 1 publication

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“…All thise evidence points to limitations of the potential theory to model the aerodynamic damping. Research on aeroelastic damping estimation from flighttest data by Vernon [42] indicated that forced excitation yields higher damping than natural excitation by atmospheric turbulence: for wing bending, damping ratios estimated from forced excitation were often twice the values from data where the atmospheric turbulence was the only input. Peeters et al [43] found higher damping ratios by forced excitation in comparison to turbulence excitation.…”

Section: Damping Ratiomentioning

confidence: 99%

Experimental Validation of a Flight Simulation Model for Slightly Flexible Aircraft

Silvestre

Luckner

2015

AIAA Journal

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The paper presents a methodology for modeling the coupled flight dynamics with aeroelasticity in the time domain. The equations of motion are based on linearized mean-axes formulation. Unsteady, incremental aerodynamics due to elastic deformations are modeled in the time domain, applying the strip theory and a indicial function. The methodology is demonstrated with a prototype of the utility aircraft Stemme S15. Comparisons between the simulation and the flight-test data regarding the added aeroelastic dynamics have indicated that the model is suited for the flight control law and aircraft design, and that care must be taken in modeling the control surface lift slope for lowaspect-ratio lifting surfaces. Nomenclature A SIM ∕A FT = ratio of acceleration amplitudes from simulation and from flight test b = wingspan, m c = chord, m c = wing aerodynamic mean chord, m F C A , F NC A = vectors of circulatory and noncirculatory aerodynamic forces, N F ext = vector of external forces, N G = gravity acceleration vector, m∕s 2 J = inertia tensor, kg · m 2 l C , l NC = circulatory and noncirculatory lift per unit span, N∕m M C A , M NC A = vectors of circulatory and noncirculatory aerodynamic moments, N · m M ext = vector of external moments, N · m m = mass, kg m C , m NC = circulatory and noncirculatory pitch moments per unit span, N · m∕m n e = number of elastic modes O A G = global aerodynamic reference frame (origin at the aircraft center of gravity) O A L = local aerodynamic reference frame O B G = global body reference frame (origin at the aircraft center of gravity) O B L = local body reference frame O I = inertial reference frame p = position of a mass element relative to the center of gravity, m p d = elastic displacement (p − p r ), m p r = undeformed position of a mass element relative to the center of gravity, m p, q, r = nondimensional angular rates Q η = vector of generalized loads, N ⋅ m R = position of a mass element relative to the origin of O I , m R 0 = position of the center of gravity relative to the origin of O I , m r EA = position vector of the elastic axis of a wing section relative to the origin of O B L , m S = reference (wing) area, m 2 S 1.1 : : : S 7.1 = accelerometers of measurement set 1 S 1.2 : : : S 7.2 = accelerometers of measurement set 2m∕s V = velocity vector, m∕s w f 3∕4 = downwash caused by elastic displacements at the three-quarter-chord, m∕s X = 1 α β p q r T X flex = vector of states in the flexible model X RB = vector of states in the rigid-body model x AC , x EA , x 3∕4 = x positions of the aerodynamic center, the elastic axis, and the three-quarter-chord in O B L , m α L = local angle of attack, rad β L = local sideslip angle, rad γ EA k = equivalent kth modal torsion at elastic axis positive in pitch down, rad Δϕ = response phase difference between flight test and simulation, deg η = vector of modal amplitudes Λ= dihedral angle, rad λ 1 , λ 2 = aerodynamic lag states, m/s μ = diagonal matrix of modal masses, kg · m 2 ξ = diagonal matrix of structural modal damping ratios ξ SIM ∕...

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Section: Damping Ratiomentioning

confidence: 99%

Experimental Validation of a Flight Simulation Model for Slightly Flexible Aircraft

Silvestre

Luckner

2015

AIAA Journal

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“…2 The version utilized for this project used a single exciter on each wingtip. 5 Aerodynamic forces are generated by the wingtip exciter that consists of a small xed aerodynamic vane forward of a rotating slotted hollow cylinder. Rotating the cylinder varies the forces on the vane.…”

Section: Excitation Systemsmentioning

confidence: 99%

Comparison of Aeroelastic Excitation Mechanisms

Lind

Freudinger

Voracek

1998

Journal of Aircraft

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“…28 A wingtip excitation system is implemented on this aircraft to excite structural modes over a range of frequencies. 29 Responses to this excitation are measured by accelerometers at the leading and trailing edges along the wings.…”

Section: Simulation Aircraft Modelmentioning

confidence: 99%

Flutterometer: An On-Line Tool to Predict Robust Flutter Margins

Lind

Brenner

2000

Journal of Aircraft

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Robust utter margins can be computed for an aeroelastic model with respect to an associated uncertainty description that describes modeling errors. An on-line implementation to compute these robust margins is considered. The on-line approach generates uncertainty descriptions at test points and can account for time-varying errors in the model. A utterometer is introduced as an on-line tool to indicate a measure of distance to utter during a ight utter test. Such a tool is formulated based on robust utter margin analysis. A ight test of an F/A-18 is simulated to demonstrate the performance of the utterometer. This tool is clearly more informative than traditional tracking of damping trends and provides accurate information about the true utter margin throughout the ight test. The simulation demonstrates characteristics of the utterometer that could improve ight test ef ciency by increasing safety and reducing ight time for envelope expansion. Nomenclature P = plant model P nom = nominal plant model P rob = robust plant model P true = true plant model q = dynamic pressure W in = weighting matrix on input uncertainty D = uncertainty operator D A = parametric uncertainty affecting state matrix D in = dynamic uncertainty affecting plant input dq = perturbation to dynamic pressure l = structured singular value

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In-Flight Investigation of a Rotating Cylinder-Based Structural Excitation System for Flutter Testing

Cited by 10 publications

References 1 publication

Experimental Validation of a Flight Simulation Model for Slightly Flexible Aircraft

Experimental Validation of a Flight Simulation Model for Slightly Flexible Aircraft

Comparison of Aeroelastic Excitation Mechanisms

Flutterometer: An On-Line Tool to Predict Robust Flutter Margins

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