A Method for Determining Drag Coefficients from Observed Position Data PDF Download
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Author: R. G. Barker
Publisher:
ISBN:
Category :
Languages : en
Pages : 36
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Book Description
A method is presented for computing the aerodynamic drag of a body in free flight. Polynomial least squares smoothing of position data is used for the first estimate with an optional provision of improving these results by matching arc length. All values thus obtained from one or more drops are then used to obtain a single least squares fit with the drag coefficient formula of T.S. Walton and Daniel Shanks. The nonlinear portions of this fitting problem are solved with good results using a quadratic minimization routine provided the data cover a sufficient Mach number range. This method is both fast and accurate. It replaces a procedure which was more expensive in computer time and in the required efforts of experienced personnel. (Author).
Author: R. G. Barker
Publisher:
ISBN:
Category :
Languages : en
Pages : 36
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Book Description
A method is presented for computing the aerodynamic drag of a body in free flight. Polynomial least squares smoothing of position data is used for the first estimate with an optional provision of improving these results by matching arc length. All values thus obtained from one or more drops are then used to obtain a single least squares fit with the drag coefficient formula of T.S. Walton and Daniel Shanks. The nonlinear portions of this fitting problem are solved with good results using a quadratic minimization routine provided the data cover a sufficient Mach number range. This method is both fast and accurate. It replaces a procedure which was more expensive in computer time and in the required efforts of experienced personnel. (Author).
Author: Stephen A. Whitmore
Publisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 36
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Book Description
This paper develops a real-time method based on the law of the wake for estimating forebody skin-friction coefficients. The incompressible law-of-the-wake equations are numerically integrated across the boundary layer depth to develop an engineering model that relates longitudinally averaged skin-friction coefficients to local boundary layer thickness. Solutions applicable to smooth surfaces with pressure gradients and rough surfaces with negligible pressure gradients are presented. Model accuracy is evaluated by comparing model predictions with previously measured flight data. This integral law procedure is beneficial in that skin-friction coefficients can be indirectly evaluated in real-time using a single boundary layer height measurement. In this concept a reference pitot probe is inserted into the flow, well above the anticipated maximum thickness of the local boundary layer. Another probe is servomechanism-driven and floats within the boundary layer. A controller regulates the position of the floating probe. The measured servomechanism of this second probe provides an indirect measurement of both local and longitudinally averaged skin friction. Simulation results showing the performance of the control law for a noisy boundary layer are then presented.
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Category : Astronautics
Languages : en
Pages : 636
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Category : Materials
Languages : en
Pages : 504
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Category : Aeronautics
Languages : en
Pages : 328
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Author:
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Category :
Languages : en
Pages : 352
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Category : Aeronautics
Languages : en
Pages : 296
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Category :
Languages : en
Pages : 482
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Category : Environmental engineering
Languages : en
Pages : 538
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Author: Thomas G. Piercy
Publisher:
ISBN:
Category : Boundary layer control
Languages : en
Pages : 44
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