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Solar Car Shell Design. Allison Bedwinek, Douglas Simmons, Sheldon Low, and Laura Sullivan ME 43A Fall 2004 . Project Goals. Design a shell for solar car Overall aerodynamically superior car Low rolling resistance Low coefficient of drag Incorporate solar panels
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Solar Car Shell Design Allison Bedwinek, Douglas Simmons, Sheldon Low, and Laura Sullivan ME 43A Fall 2004
Project Goals • Design a shell for solar car • Overall aerodynamically superior car • Low rolling resistance • Low coefficient of drag • Incorporate solar panels • Meets voltage/current requirements from Electrical Engineering team • Lightweight, yet strong • Material selection • Compete in the North American Solar Challenge • July 2005 race from Austin, TX to Calgary, AB, Canada
Major Specifications • Rayce Regulations • Overall dimensions • Safety • Cockpit ventilation • Driver Egress • Visibility • Nerd Girls • Frame • Solar panels • Drive train
Carbon Fiber Composites • Carbon Fiber is a form of graphite in long thin ribbons. • The fibers are used to reinforce polymers. • Carbon fiber composites are used for everything http://www.geocities.com/CapeCanaveral/1320/
Carbon Fiber Construction • A plug is made of the desired car shape, and a mold is then built off of that. • Carbon Fiber Tissue is placed in the molds while still flexible. • These molds are then pressurized and heated. The Resin in the Tissue then adheres to the carbon fiber ribbons to form one solid composite in the desired shape. www.secart.com
Research • University of Missouri-Rolla • 2003 winning solar car • Common Solar Car Features • Thin and streamline • Low to the ground • Unobtrusive windshield and canopy • Wheel fairings www.prin.edu/solar/home.php solar42.umr.edu www.americansolarchallenge.org/
Aerodynamics Conservation of Momentum • Drag • Total area • Sharp Corners • Turbulent Flow • Curve Discontinuities http://ocw.mit.edu/ans7870/16/16.unified/propulsionS04/UnifiedPropulsion2/UnifiedPropulsion2.htm
Aerodynamics • External Force: Pressure • Cross Sectional Area • Upward and Downward Pressure www.gmecca.com/byorc/dtipsaerodynamics.html#Drag
Preliminary Considerations • Car Frame • Solar Panels • 1.038 m x .527 m (2) • 1.559 m x .798 m (4) • Wheel Fairings • Turning radius of car • Only on back wheels
Design of Shell • Flat Surface Area for Cells • Flat Sides with Fillets • Leading and Trailing Edges • Curved Underbelly
Flow Analysis With Canopy Streamlines Air Density: ρ=1.29 kg/m^3 Air Velocity: U∞= 20 m/s Dynamic Viscosity: μ=1.5 X 10^-5 N*s/m^2 Pressure Velocity Pmax=264.876 Pa Umax=35.786 m/s
Flow Analysis of Sides Streamlines Air Density: ρ=1.29 kg/m^3 Air Velocity: U∞= 20 m/s Dynamic Viscosity: μ=1.5 X 10^-5 N*s/m^2 Pressure Velocity Pmax=155.613 Pa Umax=29.868 m/s
Updates • New solar panel layout • Customized modules of SunPower Corp cells built by SunWize • Significantly lighter and thinner • F16 windshield canopy • More aerodynamic design
Updates • Working with Secart LLC of Bethel, CT, a carbon composites engineering firm • Mold construction is the most labor intensive step • Plugs will be created from 3D models • Next month, begin construction of molds • Two versions of shell • 1st version – create door, add brackets
Acknowledgements • American Solar Challenge • Nerd Girls • James Seeley, Secart LLC • Prof Karen Panetta, Electrical Engineering • Prof James O’Leary, Mechanical Engineering • Matthew Heller and Rick Colombo, EE consultants for Nerd Girls