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  • 1.
    Jansson, Natascha
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Stenfelt, Gloria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Steady and unsteady pressure measurements on a swept-wing aircraft2011Report (Other academic)
  • 2.
    Jansson, Natascha
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Stenfelt, Gloria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Steady and unsteady pressure measurements on a swept-wing aircraft2014In: Aeronautical Journal, ISSN 0001-9240, Vol. 118, no 1200, p. 109-122Article in journal (Refereed)
    Abstract [en]

    Steady and unsteady pressure measurements are conducted for a tailless aircraft model. The main aim with the presented experimental work is to investigate the difficulties and possibilities involved in using an available pressure sensing system for accurate unsteady pressure measurement. The experimental procedure which is utilised for unsteady pressure measurements is described in detail. In particular, the importance of synchronised timing is recognised. For a harmonically varying pressure a small time delay in the measurement chain can result in a significant phase shift. Also, difficulties and uncertainties that are still present are pointed out. The results from these experiments are compared to numerical results based on unsteady potential flow theory. In general, the experimental and computational results show similar trends. Especially good agreement is found for the steady pressure measurements. For the unsteady pressure measurements a possible Reynolds number dependency is found for the considered test conditions.

  • 3. Silva, W. A.
    et al.
    Ringertz, Ulf Torbjörn
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stenfelt, Gloria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Eller, David
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Keller, D. F.
    Chwalowski, P.
    Status of the KTH-NASA wind-tunnel test for acquisition of transonic nonlinear aeroelastic data2016In: 15th Dynamics Specialists Conference, American Institute of Aeronautics and Astronautics Inc , 2016Conference paper (Refereed)
    Abstract [en]

    This paper presents a status report on the collaboration between the Royal Institute of Technology (KTH) in Sweden and the NASA Langley Research Center regarding the design, fabrication, modeling, and testing of a full-span fighter configuration in the Transonic Dynamics Tunnel (TDT). The goal of the test is to acquire transonic limit-cycle- oscillation (LCO) data, including accelerations, strains, and unsteady pressures. Finite element models (FEMs) and aerodynamic models are presented and discussed along with results obtained to date.

  • 4.
    Stenfelt, Gloria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Aerodynamics and lateral control of tailless aircraft2012Doctoral thesis, comprehensive summary (Other academic)
  • 5.
    Stenfelt, Gloria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    An experimental study on the stability and control of a tailless aircraft2009Licentiate thesis, comprehensive summary (Other academic)
  • 6.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Aerodynamics of a Tailless Wind Tunnel Model2009Report (Other academic)
  • 7.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Design and construction of aeroelastic wind tunnel models2013In: IFASD 2013 - International Forum on Aeroelasticity and Structural Dynamics, 2013Conference paper (Refereed)
    Abstract [en]

    The design and building of accurately scaled aeroelastic wind tunnel models is difficult, time consuming and very costly. With the increasing usefulness of computational methods for predicting aeroelastic phenomena, few complex models have been built in recent years. New fighter aircraft projects are also becoming more and more scarce, and transport aircraft have essentially the same configuration since half a decade. This also significantly reduces the need for aeroelastic wind tunnel models. However, there still is an interest in the results from aeroelastic testing. In some cases new and radical configurations may warrant wind tunnel testing and in other cases complex phenomena arising in flight testing may need carefully performed experiments to resolve problems. However, there is definitely a trend towards building models and performing testing in the support of the development of computational methods. The developments in computer technology do not only improve the computational methods for aeroelasticity. Modern Computer Aided Design and Manufacturing techniques can significantly improve the quality and efficiency of the design and build process for aeroelastic models. There have also been some recent improvements in measurement techniques which have proven very useful for testing of aeroelastic wind tunnel models. The paper will present some new design and build techniques developed for the manufacturing of a large scale wind tunnel model of a canard delta wing fighter aircraft configuration. In the build process fiber-reinforced composites will be used, hence, challenges and possible solutions concerning the ability to produce a model with well defined material properties and fiber angles will be discussed. Further challenges arise when both measurement equipment and adjustable control surfaces should be attached inside the model using techniques that are possible to describe with computational methods. In addition, equipment, such as pressure taps, and control surface mechanics need to fit and function in a flexible structure. As a result, the above requirements will lead to necessary compromises in the design, hence, the paper will present the choices taken during the build process and for which reasons. The use of an optical positioning measurement system will also be discussed for both the validation of model properties and non-contact measurement of model deformations during wind tunnel testing.

  • 8.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Design and construction of aeroelastic wind tunnel models2015In: Aeronautical Journal, ISSN 0001-9240, Vol. 119, no 1222, p. 1585-1599Article in journal (Refereed)
    Abstract [en]

    The design and building of accurately scaled aeroelastic wind-tunnel models is difficult, time consuming and very costly. With the increasing usefulness of computational methods for predicting aeroelastic phenomena, few complex models have been built in recent years. New fighter aircraft projects are also becoming more and more scarce, and transport aircraft have essentially the same configuration since half a decade. This also significantly reduces the need for aeroelastic wind-tunnel models. However, there still is an interest in the results from aeroelastic testing. In some cases new and radical configurations may warrant wind-tunnel testing and in other cases complex phenomena arising in flight testing may need carefully performed experiments to resolve problems. However, there is definitely a trend towards building models and performing testing in the support of the development of computational methods. The developments in computer technology do not only improve the computational methods for aeroelasticity. Modern Computer Aided Design and Manufacturing techniques can significantly improve the quality and efficiency of the design and build process for aeroelastic models. There have also been some recent improvements in measurement techniques which have proven very useful for testing of aeroelastic wind-tunnel models. The paper will present some new design and build techniques developed for the manufacturing of a large scale wind-tunnel model of a canard delta wing fighter aircraft configuration. In the build process fiber-reinforced composites will be used, hence, challenges and possible solutions concerning the ability to produce a model with well defined material properties and fiber angles will be discussed. Further challenges arise when both measurement equipment and adjustable control surfaces should be attached inside the model using techniques that are possible to describe with computational methods. In addition, equipment, such as pressure taps, and control surface mechanics need to fit and function in a flexible structure. As a result, the above requirements will lead to necessary compromises in the design, hence, the paper will present the choices taken during the build process and for which reasons. The use of an optical positioning measurement system will also be discussed for both the validation of model properties and non-contact measurement of model deformations during wind-tunnel testing.

  • 9.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    High angle of attack and sideslip aerodynamics of a tailless aircraft2011Report (Other academic)
  • 10.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Lateral Control of a Tailless Aircraft Configuration2009Report (Other academic)
  • 11.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Lateral Stability and Control of a Tailless Aircraft Configuration2009In: Journal of Aircraft, ISSN 0021-8669, E-ISSN 1533-3868, Vol. 46, no 6, p. 2161-2164Article in journal (Refereed)
    Abstract [en]

    The aerodynamics of a generic aircraft configuration known as Swing was investigated. The configuration used had two trailing-edge flaps on each wing used for control around all three stability axes included pitch, roll, and yaw. Tests are done in the low-speed wind tunnel L2000 at a freestream velocity of 30 m/s corresponding to a Reynolds number of 6.9 · 105 was applied. A NACA-66009 airfoil was used for the wing, and the outer wing section was twisted up 5° around the leading-edge point of the wing. Asymmetric deflections with the same amplitude for both flaps on each wing were applied for roll control. The deflection of the flaps was recorded with a motion capture system. The infrared light was emitted from four cameras and the light was reflected back to the cameras with a scan rate of 100 Hz and the system computed the distance to the markers. The results revealed that a sudden increase in pitch moment were observed at angles of attack above 10° and the flaps deflected with the same amplitude.

  • 12.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Yaw control of a tailless aircraft configuration2010In: Journal of Aircraft, ISSN 0021-8669, E-ISSN 1533-3868, Vol. 47, no 5, p. 1807-1810Article in journal (Refereed)
    Abstract [en]

    The yaw control of a tailless aircraft configuration is investigated. The four trailing-edge control surfaces are actuated using electrical servos which are controlled using a custom designed Ethernet interface. Measurements of the yaw moment due to sideslip and due to split flap deflections have been performed using a strain gauge balance for both sting configurations in order to estimate the sting interference effects. The mass moment of inertia J is obtained from a yaw ground vibration test using the yaw sting with a torsional spring installed. Dynamic stability is estimated by performing vibration tests in yaw with the torsional spring installed. The required control surface deflections can be large due to the low dynamic pressure when landing. The configuration uses only four flaps for simultaneous control around all three axes and necessary control surface deflections for pitch, roll and yaw need to be superimposed at all times.

  • 13.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Yaw departure and recovery of a tailless aircraft configuration2011Report (Other academic)
  • 14.
    Stenfelt, Gloria
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Ringertz, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Yaw Departure and Recovery of a Tailless Aircraft Configuration2013In: Journal of Aircraft, ISSN 0021-8669, E-ISSN 1533-3868, Vol. 50, no 1, p. 311-315Article in journal (Refereed)
    Abstract [en]

    The ability to recover an aircraft from an out-of-control condition is essential both from a safety and from an economical point of view. Investigations show that a significant amount of fatal accidents occur due to loss of control outside the tested flight envelope. For passenger aircraft, safety is of greatest importance; for military aircraft, a pilot's life can be saved by an ejection seat and the remaining loss after an accident is the cost of the aircraft. The purpose of this study was to investigate departure and recovery in the yaw degree of freedom for a tailless aircraft model. In previous studies, stability and control investigations have shown that the model is not stable in yaw for low angles of attack (AOA), and a simple control model has been implemented to handle the instability at moderate sideslip angles. An increase in yaw damping due to deflected flaps is, however, observed. To accurately simulate the departure motion for the current experimental setup by using the preceding equations, a better understanding of the friction is needed.

  • 15.
    Tomac, Maximilian
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Stenfelt, Gloria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Predictions of stability and control for a flying wing2014In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 39, p. 179-186Article in journal (Refereed)
    Abstract [en]

    The numerical simulation of a generic reduced radar signature tailless aircraft is considered. Investigation compares simulated data to low-speed wind tunnel experiments. Focus is on numerical predictions of steady longitudinal and lateral aerodynamics and influence of control surfaces on aerodynamic forces. Fully turbulent and transitional Reynolds Averaged Navier-Stokes (RANS) simulations predicted in agreement with experiment unstable pitch characteristics for low angles of attack (alpha), this was not the case for inviscid or laminar simulations. However, all simulations captured a sudden rapid increase in nose up pitch moment at higher angles of attack compared to experiments. Time accurate computations (URANS) captured non-linearity and unsteadiness in yaw moment with respect to differential split flap deflections for the studied angles of attack.

1 - 15 of 15
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