Transcript stanpope.net

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
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Based on information presented
at the author's website at ...

Pinewood Derby Design
http://stanpope.net/pwdesign.html

Learn to Build a Winner
http://stanpope.net/lbw_apl.html
Copyright © 2009 by Stan Pope
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Basics
Copyright © 2009 by Stan Pope
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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
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Quickest:
Accelerate early
Attain maximum velocity
Hold speed through finish line

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Make or Break
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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
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Assure Ground Clearance.
Failure:
Grinding stop
Dramatically flying off the track
If you can't get to the finish line,
you can't win!
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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.
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Top 10 in district
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Make sure that the wheels are
in balance,
in round,
moving freely,
well lubricated,
minimum turning weight, and
correctly aligned.
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Maximize weight vs. wind drag.
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Optimize weight distribution.
As the center of gravity moves
farther back in the car, there is
more energy available to be
converted into speed.
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Some Guidelines
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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
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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
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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)
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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)
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Fundamental Energy Equation
Potential Energy at start
minus
Lost Energy
leaves
Kinetic Energy at finish
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In other words ...
Start with as much potential
energy as you can, and
waste as little of that energy
as possible.
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Copyright © 2009 by Stan Pope
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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

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Closing
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Admonitions
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Hot Lead:
Severe burns possible
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Lead:
Lead is Poisonous
Lead often has nasty additives
Minimize contact.
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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
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Rules change from time to time.
Review the rules carefully each year.
Especially check the
“boundary conditions.”
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Don't believe everything the
“experts” tell you!
Smile, say “Thank you,” and
go home and check it out!
Copyright © 2009 by Stan Pope
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Help your builders get the most
out of their efforts.
Share what you have learned.
Copyright © 2009 by Stan Pope
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Good Racing!
Copyright © 2009 by Stan Pope
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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
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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
http://www.openoffice.org
Copyright © 2009 by Stan Pope
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