Aerodynamics%20and%20Velomobiles

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Aerodynamics and Velomobiles
The 2005 Great Midwestern Velomobile and HPV
FestivalEastern Iowa Environmental Innovators
Organization (EIEIO) Nickolas Hein 11 June
2005
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Wind Resistance
Speed 33 (CdA)1/3
Speed (mph)
Full Fairings
Partial Fairings
Unfaired Bikes
Effective Frontal Area - CdA (sq ft)
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Acceleration Equation for Human Power

• (Acceleration as a fraction of Gravity)
• ag (P/W) - m - g - (.5rV2)
• V (W/CdA)
• Vmph (P/W) or V 138 Low Speed
• g
  WSlope
• Vmph ?2P ?1/3 or 33 High
  Speed
• ?rCdA ? (CdA)1/3

Power Rolling Fric. Slope Wind Resistance
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Drag Effect of Openings in the Fairing
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Coast-Down TestsRepresentative Hill
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Fairing Layout
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Speeds for Streamlined vs. Unfaired Vehicle
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1
Vehicle 1 Unfaired Upright Vehicle 2 Hypothetical Faired Streamlin
Weight 25 lb Weight 50 lb
CdA 4 sq ft CdA 1 sq ft
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Plotted Results
Streamlined (blue) and unfaired (red) vehicles
starting uphill from rest.
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Phase Plot
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Phase Plots
Phase Plots for Unfaired and Fully-Faired
Vehicles - Constant Pedalling
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Aerodynamic Fairings for Velomobiles
Objectives -gt Performance Objective Utility Objectives Methods
Design Low Drag Low Sideforce Downforce Cooling Textbooks Rules of Thumb Simulation
Construction Verify Design Quick Cheap Modifiable Light Appearance Durability Rigid Sheet (Coroplast) Tube Frame and Fabric Foam Pad Fiberglass Vacuum Forming
Testing Resolve unpredicted problems Minimize Drag and separation Handling Qualities Coast-down test Smoke Tufts and
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Weights of Construction Materials

• Solid Materials (lb / cu ft)
• Steel 500
• Aluminum 140
• Oak 40
• Spruce 20
• Plastic 10-40
• Foam 1-6
• Balsa 6

• Sheet Materials (lb/sq ft)
• Kevlar/Nomex 1
• Lexan (2 mm) 1
• Coroplast .125
• Foam/Glass .06
• (Typical fairing has about 40 sq. ft. of total
  area)

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Conclusions
That concludes this presentation. Questions?
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Bibliography

• 1) Design of Ground Vehicles - J Y Wong. c1993.
  Hardcover, 2nd ed., 464pp. Publisher John Wiley
  Sons, Incorporated. (Available from Barnes
  Noble or Amazon.com for 100-110). Recommend
  getting this from a library.
• 2) Theory of Wing Sections - Ira H. Abbott and
  Albert VonDoenhoff. c1959. Dover Publications
  (Available from Barnes Noble or Amazon.com for
  12-15). Recommend getting buying this book.
• 3) Human Powered Vehicles - Edited by Allan
  Abbott and David Gordon Wilson. c1995. Publisher
  Human Kinetics (800-747-4457). (Amazon.com lists
  it as being back-ordered at 45 so try getting it
  directly from the publisher instead.) Recommend
  buying this book.
• 4) Foundations of Aerodynamics - Arnold M. Kuethe
  and Chuen-Yen Chow. 5th Edition c1997.
  Publisher John Wiley Sons. (Available from
  Barnes Noble or Amazon.com for 90-100).
  Recommend getting this from a library, any
  edition will do, I reference page nos. from the
  3rd edition.
• 5) Bicycling Science - Frank Rowland Whitt and
  David Gordon Wilson. 2nd Edition c1982
  Publisher MIT Press. Recommend buying this in
  the newest edition.