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Kenneth W. Iliff - One of the best experts on this subject based on the ideXlab platform.

  • aerodynamic assessment of flight determined subsonic lift and drag characteristics of seven lifting body and wing body reentry vehicle configurations
    2002
    Co-Authors: Edwin J Saltzman, Charles K Wang, Kenneth W. Iliff
    Abstract:

    This report examines subsonic flight-measured lift and drag characteristics of seven lifting-body and wing-body reentry vehicle configurations with truncated bases. The seven vehicles are the full-scale M2-F1, M2-F2, HL-10, X-24A, X-24B, and X-15 vehicles and the Space Shuttle Enterprise. Subsonic flight lift and drag data of the various vehicles are assembled under aerodynamic performance parameters and presented in several analytical and graphical formats. These formats are intended to unify the data and allow a greater understanding than individually studying the vehicles allows. Lift-Curve Slope data are studied with respect to aspect ratio and related to generic wind-tunnel model data and to theory for low-aspect-ratio platforms. The definition of reference area is critical for understanding and comparing the lift data. The drag components studied include minimum drag coefficient, lift-related drag, maximum lift-to drag ratio, and, where available, base pressure coefficients. The influence of forebody drag on afterbody and base drag at low lift is shown to be related to Hoerner's compilation for body, airfoil, nacelle, and canopy drag. This feature may result in a reduced need of surface smoothness for vehicles with a large ratio of base area to wetted area. These analyses are intended to provide a useful analytical framework with which to compare and evaluate new vehicle configurations of the same generic family.

  • flight determined subsonic lift and drag characteristics of seven lifting body and wing body reentry vehicle configurations with truncated bases
    37th Aerospace Sciences Meeting and Exhibit, 1999
    Co-Authors: Edwin J Saltzman, Charles K Wang, Kenneth W. Iliff
    Abstract:

    This paper examines flight-measured subsonic lift and drag characteristics of seven lifting-body and wing-body reentry vehicle configurations with truncated bases. The seven vehicles are the full-scale M2-F1, M2-F2, HL-10, X-24A, X-24B, and X-15 vehicles and the Space Shuttle prototype. Lift and drag data of the various vehicles are assembled under aerodynamic performance parameters and presented in several analytical and graphical formats. These formats unify the data and allow a greater understanding than studying the vehicles individually allows. Lift-Curve Slope data are studied with respect to aspect ratio and related to generic wind-tunnel model data and to theory for low-aspect-ratio planforms. The proper definition of reference area was critical for understanding and comparing the lift data. The drag components studied include minimum drag coefficient, lift-related drag, maximum lift-to-drag ratio, and, where available, base pressure coefficients. The effects of fineness ratio on forebody drag were also considered. The influence of forebody drag on afterbody (base) drag at low lift is shown to be related to Hoerner's compilation for body, airfoil, nacelle, and canopy drag. These analyses are intended to provide a useful analytical framework with which to compare and evaluate new vehicle configurations of the same generic family.

William J Crowthe - One of the best experts on this subject based on the ideXlab platform.

  • a quasi steady lifting line theory for insect like hovering flight
    PLOS ONE, 2015
    Co-Authors: Mostafa R A Nabawy, William J Crowthe
    Abstract:

    A novel lifting line formulation is presented for the quasi-steady aerodynamic evaluation of insect-like wings in hovering flight. The approach allows accurate estimation of aerodynamic forces from geometry and kinematic information alone and provides for the first time quantitative information on the relative contribution of induced and profile drag associated with lift production for insect-like wings in hover. The main adaptation to the existing lifting line theory is the use of an equivalent angle of attack, which enables capture of the steady non-linear aerodynamics at high angles of attack. A simple methodology to include non-ideal induced effects due to wake periodicity and effective actuator disc area within the lifting line theory is included in the model. Low Reynolds number effects as well as the edge velocity correction required to account for different wing planform shapes are incorporated through appropriate modification of the wing section lift curve Slope. The model has been successfully validated against measurements from revolving wing experiments and high order computational fluid dynamics simulations. Model predicted mean lift to weight ratio results have an average error of 4% compared to values from computational fluid dynamics for eight different insect cases. Application of an unmodified linear lifting line approach leads on average to a 60% overestimation in the mean lift force required for weight support, with most of the discrepancy due to use of linear aerodynamics. It is shown that on average for the eight insects considered, the induced drag contributes 22% of the total drag based on the mean cycle values and 29% of the total drag based on the mid half-stroke values.

Edwin J Saltzman - One of the best experts on this subject based on the ideXlab platform.

  • aerodynamic assessment of flight determined subsonic lift and drag characteristics of seven lifting body and wing body reentry vehicle configurations
    2002
    Co-Authors: Edwin J Saltzman, Charles K Wang, Kenneth W. Iliff
    Abstract:

    This report examines subsonic flight-measured lift and drag characteristics of seven lifting-body and wing-body reentry vehicle configurations with truncated bases. The seven vehicles are the full-scale M2-F1, M2-F2, HL-10, X-24A, X-24B, and X-15 vehicles and the Space Shuttle Enterprise. Subsonic flight lift and drag data of the various vehicles are assembled under aerodynamic performance parameters and presented in several analytical and graphical formats. These formats are intended to unify the data and allow a greater understanding than individually studying the vehicles allows. Lift-Curve Slope data are studied with respect to aspect ratio and related to generic wind-tunnel model data and to theory for low-aspect-ratio platforms. The definition of reference area is critical for understanding and comparing the lift data. The drag components studied include minimum drag coefficient, lift-related drag, maximum lift-to drag ratio, and, where available, base pressure coefficients. The influence of forebody drag on afterbody and base drag at low lift is shown to be related to Hoerner's compilation for body, airfoil, nacelle, and canopy drag. This feature may result in a reduced need of surface smoothness for vehicles with a large ratio of base area to wetted area. These analyses are intended to provide a useful analytical framework with which to compare and evaluate new vehicle configurations of the same generic family.

  • flight determined subsonic lift and drag characteristics of seven lifting body and wing body reentry vehicle configurations with truncated bases
    37th Aerospace Sciences Meeting and Exhibit, 1999
    Co-Authors: Edwin J Saltzman, Charles K Wang, Kenneth W. Iliff
    Abstract:

    This paper examines flight-measured subsonic lift and drag characteristics of seven lifting-body and wing-body reentry vehicle configurations with truncated bases. The seven vehicles are the full-scale M2-F1, M2-F2, HL-10, X-24A, X-24B, and X-15 vehicles and the Space Shuttle prototype. Lift and drag data of the various vehicles are assembled under aerodynamic performance parameters and presented in several analytical and graphical formats. These formats unify the data and allow a greater understanding than studying the vehicles individually allows. Lift-Curve Slope data are studied with respect to aspect ratio and related to generic wind-tunnel model data and to theory for low-aspect-ratio planforms. The proper definition of reference area was critical for understanding and comparing the lift data. The drag components studied include minimum drag coefficient, lift-related drag, maximum lift-to-drag ratio, and, where available, base pressure coefficients. The effects of fineness ratio on forebody drag were also considered. The influence of forebody drag on afterbody (base) drag at low lift is shown to be related to Hoerner's compilation for body, airfoil, nacelle, and canopy drag. These analyses are intended to provide a useful analytical framework with which to compare and evaluate new vehicle configurations of the same generic family.

R Kelso - One of the best experts on this subject based on the ideXlab platform.

  • an insight into the dynamic stall lift characteristics
    Experimental Thermal and Fluid Science, 2014
    Co-Authors: Amanullah Choudhry, R R Leknys, Maziar Arjomandi, R Kelso
    Abstract:

    Abstract The article presents an insight into the dynamic stall lift characteristics through experimental work and a detailed survey of the seminal articles related to the phenomenon. Of particular interest is the dynamic stall observed on lifting surfaces as they undergo high-rate pitching motions at constant speeds up to a predetermined maximum angle of attack. The effects of several contributing parameters, such as the reduced frequency, Mach and Reynolds numbers of operation and the airfoil geometry, have been investigated. In addition, the behavior of the lift curve Slope for an airfoil undergoing constant pitch dynamic stall has been analyzed in detail to gain a better understanding of the mechanism for the unsteady case. The unsteady Lift-Curve has been broken down into stages and each stage has been analyzed separately. The aim is to obtain a deeper insight into the lift generation mechanism involved in unsteady motion of the airfoil in order to improve the design of flow control techniques to exploit the dynamic stall process for a large range of applications.

Flavio J Silvestre - One of the best experts on this subject based on the ideXlab platform.

  • experimental and numerical investigations on the nonlinear aeroelastic behavior of high aspect ratio wings for different chord wise store positions under stall and follower aerodynamic load models
    International Journal of Non-linear Mechanics, 2021
    Co-Authors: Gefferson Silva, Mauricio Vicente Donadon, Flavio J Silvestre
    Abstract:

    Abstract This study performs an experimental and numerical investigation on the nonlinear aeroelastic response of cantilever high-aspect-ratio beam-like wings with a ballast at their free tips, emulating the effects of a store. As an extent, the effects of different chord-wise ballast positions are experimentally examined for two highly flexible rectangular wings. Furthermore, the numerical model proposed brings forward a nonlinear finite element beam model accounting for aerodynamic nonlinearities, via stall and follower forces models, along with geometrical nonlinearities due to large displacements and rotations. A great variety of analyses were performed: First, the flutter boundaries of the wings were analysed; second, the limit cycle oscillation amplitudes and frequencies in the oscillating wings were evaluated; third, the coupling behavior and the nonlinear responses obtained were discussed under several attributes. The geometrical nonlinearities were taken into account by a total Lagrangian formulation based on a straightforward and consistent interpolation field in order to describe the exact kinematics of a Timoshenko’s beam. Nonlinear aerodynamic loads were computed via an unsteady strip theory in the time-domain with the Jones approximation for the Wagner’s function along with a follower aerodynamic loads assumption. Additionally, a non-usual stall model based on an experimental quasi-static stall curve for flat plates was used to interpolate the Lift-Curve Slope. The experimental and numerical results indicated a minimum flutter speed for ballast positions about of − 5 mm towards the leading edge. Next, different nonlinear post-flutter LCO behaviors were obtained for the different ballast positions tested. To conclude, the good correlation between model and experiments indicated that the nonlinear modelling approach proposed herein was capable to predict the aeroelastic behavior of the tested high aspect-ratio wings.