Copyright © 2009 by Stan Pope Page 1 Pinewood Derby Performance Basics An introduction to making a high performance Pinewood Derby car Copyright 2003, 2009 by Stan Pope, all rights reserved.

Copyright © 2009 by Stan Pope Page 2 Pinewood Derby Design Learn to Build a Winner Based on information presented at the author's website at...

Copyright © 2009 by Stan Pope Page 3 Basics

Copyright © 2009 by Stan Pope Page 4 To win a pinewood derby race, your car must get from the starting line to the finish line before the other cars.

Copyright © 2009 by Stan Pope Page 5 Quickest:  Accelerate early  Attain maximum velocity  Hold speed through finish line

Copyright © 2009 by Stan Pope Page 6 Make or Break

Copyright © 2009 by Stan Pope Page 7 Follow your district's rules. If you can't pass inspection, you can't race. If you can't race, you can't win!

Copyright © 2009 by Stan Pope Page 8 Assure Ground Clearance. Failure: Grinding stop Dramatically flying off the track If you can't get to the finish line, you can't win!

Copyright © 2009 by Stan Pope Page 9 Assure that the car will "run" on the track. A narrow or pointed nose may not stage correctly on the starting mechanism and may not trip the finish line sensor correctly.

Copyright © 2009 by Stan Pope Page 10 Top 10 in district

Copyright © 2009 by Stan Pope Page 11 Make sure that the wheels are in balance, in round, moving freely, well lubricated, minimum turning weight, and correctly aligned.

Copyright © 2009 by Stan Pope Page 12 Maximize weight vs. wind drag.

Copyright © 2009 by Stan Pope Page 13 Optimize weight distribution. As the center of gravity moves farther back in the car, there is more energy available to be converted into speed.

Copyright © 2009 by Stan Pope Page 14 Some Guidelines

Copyright © 2009 by Stan Pope Page 15 Car as long as rules allow Rear wheels as far back as rules allow Front wheels forward almost as far as rules allow, without affecting rear wheel location

Copyright © 2009 by Stan Pope Page 16 Car's center of mass as far back as car stability allows, and car's center of mass as low as possible, but "as far back" is more important (maximize potential energy) Wheel alignment "dead-on"

Copyright © 2009 by Stan Pope Page 17 Weight as close to maximum allowed as possible Car's cross section as small as possible Wheels "in round", balanced, and all sliding contact surfaces polished and lubed (hub, bore, and inside wheel edge)

Copyright © 2009 by Stan Pope Page 18 Axle contact surfaces polished Hub contact area as close to wheel axis as possible (minimize breaking torque due to wheel-body and wheel-axle friction)

Copyright © 2009 by Stan Pope Page 19 Fundamental Energy Equation Potential Energy at start minus Lost Energy leaves Kinetic Energy at finish

Copyright © 2009 by Stan Pope Page 20 In other words... Start with as much potential energy as you can, and waste as little of that energy as possible.

Copyright © 2009 by Stan Pope Page 21

Copyright © 2009 by Stan Pope Page 22 Losses from:  Friction between wheel and axle  Friction between hub and car  Friction between hub and nail end  Air friction  Wheel vibration  Body oscillation (wheels out of round)‏  Wheel rolling friction  Wheel sliding friction on track or rail  Angular acceleration of wheels

Copyright © 2009 by Stan Pope Page 23 Closing

Copyright © 2009 by Stan Pope Page 24 Admonitions

Copyright © 2009 by Stan Pope Page 25 Hot Lead: Severe burns possible

Copyright © 2009 by Stan Pope Page 26 Lead: Lead is Poisonous Lead often has nasty additives Minimize contact.

Copyright © 2009 by Stan Pope Page 27 Melting lead is discouraged! Supply your builders with lead slugs. Hold lead slugs in pliers. Pound lead slugs into desired shape with hammer. Glue in place with 5-minute epoxy.

Copyright © 2009 by Stan Pope Page 28 Rules change from time to time. Review the rules carefully each year. Especially check the “boundary conditions.”

Copyright © 2009 by Stan Pope Page 29 Don't believe everything the “experts” tell you! Smile, say “Thank you,” and go home and check it out!

Copyright © 2009 by Stan Pope Page 30 Help your builders get the most out of their efforts. Share what you have learned.

Copyright © 2009 by Stan Pope Page 31 Good Racing!

Copyright © 2009 by Stan Pope Page 32 Use of This Presentation Permission is granted... You may use the presentation as-is within your organization. You may add, remove, or alter slides for use within your organization provided that this page is retained and that the original copyright assertion remains on all retained content.

Copyright © 2009 by Stan Pope Page 33 Technical Note This presentation was prepared using the “Impress” feature of OpenOffice.org 2.4. OpenOffice is free for individual use through a project supported by Sun Microsystems, Inc. Software is available at