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New Piper Aircraft Jet The following is an example of how Surfaces can be used to analyze an aircraft from little more than a low quality drawing copied from a brochure. The following is for demonstration purposes only and may not represent actual data.

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What will be Covered… Why should you care? What is SURFACES? Model Creation Validation Samples Examples of Aerodynamic Analysis Examples of Aerodynamic Loads Examples of Stability and Control Approximate length – 1 hour.

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Why should you care? Fast and reliable estimation of aerodynamic properties. Fast and reliable estimation of stability derivatives. Fast and reliable estimation of aerodynamic loads. Fast “what if” evaluation of configurations (T-tail versus Conventional tail versus H-tail versus…). Ideal for sensitivity studies. Tailoring of stall progression. Control effectiveness studies. and more…

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What is SURFACES? Interactive environment that allows the user to design and analyze aircraft geometries. SURFACES has a multi-document interface. In SURFACES you do everything in a single program; pre-process, solve, and post-process. SURACES uses two kind of documents; a Surfaces Worksheet and an Aircraft Datasheet.

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What is SURFACES? Interactive environment that allows the user to design and analyze aircraft geometries. SURFACES has a multi-document interface. In SURFACES you do everything in a single program; pre-process, solve, and post-process. SURACES uses two kind of documents; a Surfaces Worksheet and an Aircraft Datasheet. A SURFACES Worksheet is your digital wind tunnel. A SURFACES Aircraft Datasheet is where stability and control and performance analysis takes place.

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What is SURFACES? Model Details

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What is SURFACES? Model Details

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What is SURFACES? Movable control surfaces Forces and Moments can be applied using equations Model Details Movable flaps

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Flow Solver Three dimensional Vortex-Lattice Method is used to determine the flow field. Models can be symmetric as well as asymmetric. Boundary conditions allow AOA and AOY. Three compressibility models (Prandtl-Glauert, Karman- Tsien, Laitone) Three induced drag models (surface integration, standard Cdo+k∙CL², and Prandtl-Betz). Program can take advantage of multiple processors on the motherboard and solve more than one model simultaneously.

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Validation Sample 1 Pressure distribution over a flat plate.

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Validation Sample 9 NACA R-1208 – Comparison to Wind Tunnel Tests Highly swept-back tapered wings are a good test for any code.

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Validation Sample 9 NACA R-1208 – Results from SURFACES

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Examples of Aerodynamic Analysis

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What We Don’t Know about the Piperjet Airfoils and airfoil properties CG Envelope Gross Weight / Inertias True Geometry in many areas Wing washout Wing dihedral Aileron and elevator geometry FAA Design speeds Winglet geometry FJ44 Thrust properties Ram drag point location Flap definition

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Examples of Stability and Control Angle-of-Attack Derivatives ApproachCruise Far field speed V far field 134591 Basic lift coefficientC Lo 0.85180.1277 Lift coefficientCLCL 1.32420.15201 Lift curve slopeCLCL 5.03886.21135 Drag coefficient slopeCDCD 1.77050.11453 FX variation with AOACxCx 0.06590.06183 FZ variation with AOACzCz -5.467-6.219 CG locationX cg 0.2000 Neutral point (X cg -C m /C L )X neu 0.49360.4566

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Examples of Stability and Control Angle-of-Yaw Derivatives ApproachCruise Far field speedV far field 134591 Side force derivativeCyCy -1.3417-1.26053 Dihedral EffectClCl -0.1427-0.15177 Directional StabilityCnCn 0.12660.14048

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Examples of Aerodynamic Analysis Stall Progression At S-L, 5000 lbs, 75 KEAS, Flaps UP, no yaw.

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Examples of Aerodynamic Analysis Compliance with FAR 23.77(c) at Forward CG At S-L, 5500 lbs, CG at 20% MAC, V REF =79 KEAS trim = 5.37° etrim = -17.3°

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Examples of Aerodynamic Analysis Compliance with FAR 23.77(c) at Forward CG At S-L, 5500 lbs, CG at 20% MAC, V REF =79 KEAS Minimum section lift coefficient, C L2D = -1.003

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Conclusions SURFACES –Model Creation –Flow Solver –Validation Samples The Piper Jet –Examples of Aerodynamic Analysis –Examples of Aerodynamic Loads –Examples of Stability and Control

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The End Feedback –Questions –Comments

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Validation Sample 5 When compared to 3 other VL codes and the panel code CMARC, SURFACES scores highest when determining stability derivatives. Cessna 172 - Comparison to Flight Test results.

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Examples of Aerodynamic Analysis Trim Drag in Cruise At 25000 ft, at 5500 lbs, 350 KTAS, C Do = 0.020, Prandtl-Glauert compressibility CG Location 20% MAC35% MAC trim 0.22 ° 0.13 ° etrim -1.25°-0.35° C Ltrim 0.1520 C Dtrim 0.02760.0273 Drag, lb f 1000988 V trim, KTAS348350

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Examples of Aerodynamic Load Analysis Shear Diagram at V A At S-L, 6000 lbs, CG at 20% MAC, V A = 152 KEAS

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Examples of Aerodynamic Load Analysis Moment Diagram at V A At S-L, 6000 lbs, CG at 20% MAC, V A = 152 KEAS

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Examples of Aerodynamic Load Analysis Torsion Diagram at V A At S-L, 6000 lbs, CG at 20% MAC, V A = 152 KEAS

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Examples of Aerodynamic Analysis Flow Visualization - Streamlines

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Sweep Scripts SURFACES can perform sweeps, during which selected parameters can be modified. AOA, AOY, p∙b/(2V), and others can be varied and studied. Points can even be moved during a sweep

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Sweep Scripts Once a sweep script is completed, are displayed in a tabular format,…

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Sweep Scripts …or a graph, in which any parameter can be plotted against each other. This allows the user to extract relationships as mathematical expressions.

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Sweep Scripts From time to time, many sweeps may have to be created. You can set up batch processing, which will handle the processing automatically. This allows the program to be run overnight or over a weekend.

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