Date:  Thu, 12 Jun 1997 03:27:48, -0500
Subject:  Re: ECAR results

The electric car race went great! Sonnesyn and Morris Park teams were there
in force with their vehicles. Turnout was maybe 50 people (did anyone keep track)?

I'm not sure if anyone was planning to write an official report. But I can
give you a few off-the-cuff comments from my point of view.

Background

Each team started earlier this year with the same starting materials. We
provided them with a farm feed cart kit, two motors, a circuit breaker, and
a battery.

The cart consisted of four pieces of steel that bolted together to form a
2' x 3' rectangle. One piece had an axle sticking out each end, and two 24"
bicycle wheels to fit on it. The third wheel was a 10" caster, like a giant
version of a chair caster.

The 12 volt permanent magnet motors were car heater/air conditioner fan
motors. The batteries were 12 volt 45 amp-hour deep-cycle sealed lead-acid
type. They weighed about 45 lbs, and are like a car battery, except sealed
so they won't leak even upside down or with a hole is punched in them. The
batteries were used, and donated by John Wayland of E-Car Engineering in
Portland OR.

The 20 amp circuit breaker was an energy limiting device, both for safety
and to keep speed down. I mounted the circuit breaker, a voltmeter (to
indicate battery state of charge), and a regulator under a clear plastic
cover on each battery. The regulators, donated by Rich Rudman of Manzanita
Micro in Seattle WA, keep the batteries from being ruined by overcharging.
The cover keeps budding scientists from shorting the battery to see what happens.

Pre-race countdown

For the past couple months, teams at Morris Park and Sonnesyn had been
working on their entries. Rick Cash was mentoring the students in Eileen
Johanson's 5th grade class at Sonnesyn, and I was doing the same for Joe
Rossow's 4th graders at Morris Park.

The week before the race was a time of frantic activity. Neither team had
their car running. I visited both schools on several days for many hours to
help them with last-minute efforts.

Morris Park

Morris Park's car, the "Road Runner", was initially farther along. The
students had been working steadily, if sometimes chaotically, so that they
now had a rolling chassis.

Instead of using the farm cart frame, they had cut the frame/floor out of a
sheet of 3/4" plywood; it was a coffin-shape about 6' long, 1' wide at the
ends, and 2' wide in the 'shoulders'. To make it less flexible, they had
cut and bolted pieces of angle iron to the edges from some metal shelving.
The seat was recycled from a garden tractor.

The rear axle was used as-is from the farm cart, with its two 24" bicycle
wheels. A couple pieces of plywood were bolted on vertically, with another
piece attached horizontally to hold them upright. The motors were attached
to the vertical parts. A 1" diameter wheel went on each motor shaft, with a
slice of rubber tubing over it for traction. These wheels then rubbed
against the bike tires to spin them.

Brakes consisted of a 2x4 attached to the floor with door hinges. Another
piece of 2x4 was screwed to it as a handle. When the handle was raised, the
first 2x4 pivoted against the back wheels to stop them.

The front axle was from the farm cart, but with a couple pieces of threaded
rod welded into the ends as axles so two wheels could be used. A dad
brought in his wire welder, and the kids had a ball carving up steel and
sticking it together (I wonder how many other 4th grade classrooms have
taught welding)? A couple front wheels from a garden tractor went on the
front axles.

A bolt through the center provided a pivot for the front steering. The
class initially steered by pulling on a rope tied to each end of the front
axle. But they were determined that their car had to have a steering wheel.
The lawnmower skeleton yielded one, which was bolted to a piece of steel
rod. The steering rope was wrapped around and duct taped to this rod.

The first test drives were on Monday. They were burning rubber in the
halls, and crashing into walls! The little rubber rollers were slipping on
the tires so much that they smoked, and the steering rope kept slipping and
falling off so they couldn't steer. Interestingly enough, none of the test
drivers bothered to see if the brakes worked.

The motor team found that it was important to get the little rubber wheels
straight, and sitting squarely on the tire. Things had to be just right;
too little pressure and it slipped; too much and it wouldn't go. Lots of
experiments followed with tire pressure, extra screws, springs, etc.

The steering team faced a daunting task. They tried rope, copper wire,
bicycle chain, electrical conduit; all they could think of. Everything
either slipped, or stretched, or fell off. They finally settled on a baby
carriage wheel (with the tire removed) on the steering shaft, added a
couple nylon pulleys so the rope followed the desired path (more or less),
and hoped for the best. A second rope was retained as an emergency backup.

Now for wiring. Initially, the motors were wired in series to the battery.
An "engineer" ran along behind the car and switched the circuit breaker on
or off to control power. They eventually decided this was a little less
than ideal.

Experimenting with the wires, they found that loose connections and short
circuits made lots of fun sparks. Also, that the motors went a lot faster
if they wired each one directly to the battery (in parallel instead of in
series). But connecting them both at once tripped the circuit breaker. We
drew circuits on the board, and the concept of a switch formed. Aha! We can
use a separate switch for each motor.

One of the girls (Mona?) discovered a way to wire one switch to turn on
both motors in series (low speed), and a second switch to connect one motor
across the battery (high speed). She doggedly worked right through lunch,
and well into the afternoon to rewire the car, successfully defending it
against all other "helpers".

Sonnesyn

When I first visited Eileen Johanson's 5th grade class a week before the
race, they had assembled the 3-wheel farm cart, but without a front wheel.
The Sonnesyn students had also decided that "real cars have 4 wheels".
Accordingly, a rusty coaster wagon had been scrounged to provide the front
wheels and steering.

They felt a belt drive was the way to go. They had laboriously stripped all
the spokes out of two 20" bicycle wheels, and had them welded to each of
the farm cart's 24" wheels as a pulley. The plan was to use bicycle inner
tubes or rubber hose as a belt.

They had cut a piece of plywood to use as a floor on the cart, and planned
to use a classroom chair as the seat.

The leftover caster wheel was borrowed from Morris Park, so they had two
identical wheels for the wagon axle. The wagon's front axle and steering
assembly was bolted under the front of the cart. Initial human-powered
(crash) testing revealed that the wagon handle wasn't very steer-able. So
they cut off the hand grip and bolted on a bicycle handlebar.

Caliper brakes from a bicycle were installed on the back wheels with an
amazing piece of inventive woodworking. They worked pretty well!

Sonnesyn also tried to use the circuit breaker on the battery as the only
on/off switch. They put the battery under the seat in a wire "in" basket so
the driver could reach the switch (with only a little fumbling).

The belt drives were a major problem. Pulleys for the motor's 5/16" shaft
are scarce. I supplied some for flat belts, but they never got around to
ordering the belts. Inner tubes were the wrong length. Rubber hose worked,
but they couldn't join the ends; knots fell off the pulleys, staples worked
loose, etc. Running out of time, they finally got in motion with a couple
of car V-belts, and plastic electric fence insulators pounded onto the
motor shafts as pulleys.

There was so much fighting and arguing over names and colors early in the
project that Rick had told them they couldn't name it or paint it until it
actually ran. So the last order of business was to name it the "Stinger"
and give it a black and yellow striped paint job, complete with a little
stinger on the back.

At the last minute, it was discovered that Sonnesyn's battery had gotten
dropped somewhere along the way; it had a shorted cell and was now a 10v
battery. I tried and failed to get another, and so had to but two new ones.
Dave Petersen at Batteries Plus sold us two similar batteries at cost. I
picked them up friday evening, and worked well into the wee hours charging
them, making covers, and putting circuit breakers, voltmeters, and
regulators on them.

And they're off!

Race day, May 31, was absolutely beautiful, sunny and warm. You couldn't
ask for better weather. The athletic track at Armstrong High School was new
and in perfect shape. The surface was granulated rubber; smooth and
slightly resilient.

Greg Gustafson arranged for a bus to transport students and spectators to
the school track. Furious last-minute modifications were still underway.
Morris Park found a piece of plastic coated steel wire in Sonnesyn's midden
heap. It was perfect for the steering; it didn't slip or stretch, and
didn't fall off. In turn, Sonnesyn liked Morris Park's series-parallel
motor switch, and quickly added a toggle switch to provide this 2-speed operation.

At last, it was time. By 10am, both teams were rarin' to go, with helmets,
seat belts, and other safety equipment ready and in place.

The first event was a drag race; a 100 yard dash down the straightaway.
Morris Park leaped ahead, but Sonnesyn had a power failure. It was quickly
fixed, and they made a separate run. The times (going from memory) were
Morris Park 68 seconds, Sonnesyn 92 seconds.

The next event was a handling test. Parking cones were placed in the track
to require S turns every 10 yards or so, plus a figure 8 in the width of
the track in the middle of the course. Morris Park was worried; the Road
Runner's longer wheelbase meant it could barely turn sharp enough. But they
successfully completed the course, only hitting two cones and missing the
figure eight in the middle.

Sonnesyn's Stinger was having problems. The v-belt slipped in the plastic
pulley, causing it to melt and slip even more. And there was no provision
for adjusting belt tension. So they were not able to complete the course.

The third event was an endurance race; see which car could go the farthest
in an hour. Each car would go halfway around the track, change drivers, and
continue. Morris Park got started while Sonnesyn worked on emergency
repairs. They replaced the pulleys, and added duct tape and rubber hose to
improve friction. Stinger got started a few laps behind, and was making
good time until the pulleys failed again.

Meanwhile, the Road Runner was piling up laps. They found they could use
high speed with light drivers, but heavy ones (like teacher Joe Rossow) had
to stay in low or the circuit breaker would trip. After giving all their
team members a turn at the wheel, they magnanimously invited the Sonnesyn
team members to also take turns. At the end of the hour, they had completed
(I think) 22 laps, with power to spare.

After a wave of the genuine Indianapolis checkered flag (provided by Rick
Cash), the big electric car race was over. Trophies were presented to each
team. And we all chowed down on the pizza and cold drinks provided by Greg
Gustafson. The perfect way to end a perfect day.

Closing

Sorry if I write too much about the technical stuff, and not enough about
the people stuff. (I am an engineer, after all :-)  But there are so many
wonderful stories and moments that I hope some of the other participants
will share their memories, too!

Lee Hart