Strain-Gage Loads Calibration Testing of the Active Aeroelastic Wing F/A-18 Aircraft

Lokos, William A.; Olney, Candida D.; Chen, Tony; Crawford, Natalie D.; Stauf, Rick; Reichenbach, Eric; Bessette, D.

doi:10.2514/6.2002-2926

Cited by 11 publications

(6 citation statements)

References 3 publications

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“…6 and 7, we also notice that the flexible model can predict the strains on points of the structure with very good accuracy. Thus, we can expect that by using a greater number of strain sensors, and performing a rigorous ground calibration 16 , an accurate model for the structural loads can be obtained using the methodology presented here.…”

Section: Flexible Model Identificationmentioning

confidence: 97%

System Identification of Flexible Aircraft in Time Domain

Silva

Mönnich

2012

AIAA Atmospheric Flight Mechanics Conference

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This paper proposes and demonstrates the applicability of the system identification methodology in time domain to include the effects of structural motion on the flight dynamics of an aircraft treated as an elastic body. For this end, flight tests using a highperformance sailplane equipped with special flight test instrumentation were performed. The structural motion is represented in terms of those normal modes which influence and are influenced by the rigid-body response. The coupling between rigid-body and structural motion is obtained through aerodynamic forces in terms of generalized stability and control derivatives, which are estimated using the output error method in the time domain. The conventional rigid-body stability and control derivatives as well as the deflections of the normal modes at the measurement points are estimated. The model dynamics incorporate two anti-symmetric and three symmetric normal modes. A validation analysis shows the improvements obtained by using the integrated model when compared to the traditional rigid-body approach. Nomenclature= Accelerations at measuring point , m/s 2 = Wingspan, m ̅ = Mean aerodynamic chord, m = Aerodynamic derivative representing the effect of the variable on the coefficient = Aerodynamic bias in the coefficient = Moment coefficients = Force coefficients along body axes = Lift and drag coefficients = Aerodynamic derivative representing the effect of the variable on the -th generalized load = Aerodynamic bias derivative of the -th generalized load ⃗ = Structural displacement, m = Drag efficiency (Oswald's) coefficient , = Acceleration due to the gravity, acceleration due to gravity at sea level, m/s 2 = Geometric altitude, m = Moments of inertia, kg.m 2 = Products of inertia, kg.m 2 = Aerodynamic moments, N.m = Aircraft mass, kg = -th structural modal mass, kg.m 2 = Number of flexible modes in the model = Angular rates, rad/s = Static pressure, Pa ̅ = Dynamic pressure, Pa = Generalized load acting on the -th structural mode, N.m = Air constant, J/(kg.K) 1 Guest scientist, Institute of Flight Systems, Lilienthalplatz 7, 38108 Braunschweig, Germany, on leave from DCTA -Institute of Research and Flight Tests, Brazil, epd-t@ipev.cta.br. 2 = Distance between horizontal tail aerodynamic center and the aircraft center-of-gravity, m , = Wing reference area, horizontal tail area, m 2 = Time, s = Static air temperature, K = Components of the velocity vector, m/s = True airspeed, m/s = Position of a point along the aircraft structure, m = Aerodynamic forces along the body axes, N , = Angle of attack, angle of sideslip, deg = Control deflections (ailerons, elevator, flaps, rudder), deg = Reference flaps position, deg = Position error, Pa = Pitot error, Pa = Measured strain at point = Bias of the strain measurement at point = Effect of the unitary -th structural mode displacement on the strain at point ⃗⃗⃗⃗ = Shape function of the -th structural eigenmode, m = Modal deflection at measuring point due to the -th modal displacement, m = Aspect ratio = Displacement of -...

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Section: Flexible Model Identificationmentioning

confidence: 97%

System Identification of Flexible Aircraft in Time Domain

Silva

Mönnich

2012

AIAA Atmospheric Flight Mechanics Conference

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“…9 This calibration included wing-root and wing-fold shear, torsion, and bending loads plus all wing control surface actuator hinge moments. Redundant wing load equations were calibrated using single-point, multipoint, and distributed loads.…”

Section: Instrumentation Systemmentioning

confidence: 99%

Flight Test of the F/A-18 Active Aeroelastic Wing Airplane

Clarke

Allen

Dibley

et al. 2005

AIAA Atmospheric Flight Mechanics Conference and Exhibit

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“…These strain gages were calibrated through an extensive ground loads calibration test (ref. 8). Twenty component load measurements ( fig.…”

Section: Measurements and Observationsmentioning

confidence: 99%

Shock Location Dominated Transonic Flight Loads on the Active Aeroelastic Wing

Lokos

Lizotte

Lindsley

et al. 2005

AIAA Atmospheric Flight Mechanics Conference and Exhibit

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During several Active Aeroelastic Wing research flights, the shadow of the over-wing shock could be observed because of natural lighting conditions. As the plane accelerated, the shock location moved aft, and as the shadow passed the aileron and trailing-edge flap hinge lines, their associated hinge moments were substantially affected. The observation of the dominant effect of shock location on aft control surface hinge moments led to this investigation. This report investigates the effect of over-wing shock location on wing loads through flight-measured data and analytical predictions. Wing-root and wing-fold bending moment and torque and leading-and trailing-edge hinge moments have been measured in flight using calibrated strain gages. These same loads have been predicted using a computational fluid dynamics code called the Euler Navier-Stokes Three Dimensional Aeroelastic Code. The computational fluid dynamics study was based on the elastically deformed shape estimated by a twist model, which in turn was derived from in-flight-measured wing deflections provided by a flight deflection measurement system. During level transonic flight, the shock location dominated the wing trailing-edge control surface hinge moments. The computational fluid dynamics analysis based on the shape provided by the flight deflection measurement system produced very similar results and substantially correlated with the measured loads data. NOMENCLATURE AAWActive Aeroelastic Wing AIL aileron

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Strain-Gage Loads Calibration Testing of the Active Aeroelastic Wing F/A-18 Aircraft

Cited by 11 publications

References 3 publications

System Identification of Flexible Aircraft in Time Domain

System Identification of Flexible Aircraft in Time Domain

Flight Test of the F/A-18 Active Aeroelastic Wing Airplane

Shock Location Dominated Transonic Flight Loads on the Active Aeroelastic Wing

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