Thread: Electrathon - A Different Kind of "Hotrod"

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If you have been following my roadster build thread, you may have noticed a mention of something called Electrathon. This is something that I got involved in about six years ago with my students. Electrathon is a competition for purpose-built electric powered vehicles. These are not little toys or R/C cars; they are 3 or 4-wheeled vehicles that you can get in and drive. These also are not the $100,000+ solar experimentals that race across country every Spring. An Electrathon car may be built from a kit or completely scratch built. Although the kits can get pricey, depending on options, I have seen some very good competitive cars built from scratch for around $500! The final cost depends greatly on the ingenuity of the builder.

Although Electrathon is a great project for high school kids, it is not limited to them. Anyone who posesses a valid driver's license can participate in Electrathon. The races are "enduro style" which means that we race for a specified length of time (usually one hour). Whoever completes the greatest distance (most laps) in the designated time is the winner.

After the initial expense of obtaining or building a car, the upkeep and maintenence is really cheap. Most of the cars run bicycle tires in the $12 to $20 price range; how long they last depends on the surface we race on. Lube the chain, charge the batteries, slap on a couple of fresh tires and go race. At the end of the day we usually have spent $30 - $40. When I was racing stock cars, that wouldn't fill the fuel tank and tires were $110 each. Electrathon is just good cheap fun...

I recently sold one of my cars and have undertaken, with a couple of my students, to build a new one to replace it. Follow along on this thread and see how we do it. For more info on Electrathon cars and events, check out the Electrathon America website: www.electrathonamerica.org

The pic below is the start of a race a few years ago...

great looking cars and a great project.

Sounds like a great project and one I will watch with interest. I was involved in a high-school solar-electric car project some years ago with my daughter, but these were small, remote controlled cars that the students had to design and build. They were supplied with a solar panel and could build it any way they chose. Her team actually won the regional competition held at a nearby university.
This looks much more interesting and useful.
I'm sure that with your fabrication skills, your car will be a winner or at least technically interesting.

Thank you both. The cars are technically interesting and sometimes aesthetically appealing, too. Most of all, they are a blast to drive. Being an old stock car racer, I am accustomed to combustion engines that have to turn up some RPM's to generate horsepower. Boy, did I have a lot to learn when I started playing with electric motors! I still have a lot to learn...

Resto - I have heard of a competition similar to what you describe. It's called the "Sun Day Challenge". It's for kids in 8th grade and younger, I think...

The objective in Electrathon is to complete the most laps in a given amount of time (usually 1 hour). We are limited to 67 pounds of lead-acid Gel Cell or AGM batteries or we can use two batteries off the approved list (My team uses two Optima batteries) wired in series for a 24 volt system. Each car must also carry a 180 pound payload (payload is defined as the driver plus ballast, if necessary, to equal a minimum of 180 pounds).There are races held at real racetracks occasionally, but most of the courses we run on are temporary parking lot venues. All you need is somebody to race against and a place to do it and you can hold an Electrathon race.

Innovation and ingenuity are the name of the game in this sport. Although most of the cars are capable of speeds in excess of 40 or even 50 mph, because of the tightness of the short courses and the need to conserve the limited battery power, race speeds are usually only in the 24 to 28 mph range which makes this a fairly safe sport. Even so, competition is sometimes close and fierce. Here are some typical cars:
Pic 1 is a Blue Sky Designs Aerocoupe. This is a very popular kit car. It is of the "cycle car" type, meaning it has two wheels up front and one in the rear. They are aerodynamic, light, mechanically simple, and very reliable. They ain't cheap, though.
Pic 2 is a front-wheel-drive car. Note the motor is mounted on the front fork. Batteries are behind the driver and the driver sits well back in the car. This is a tricycle design (one front wheel, two rear). Tricycle style cars have a tendency to roll over if the weight is not kept centered between the rear wheels. If you've ever ridden a three-wheel motorcycle, you know what I mean.
Pic 3 is one of my team cars. This is a cycle car style and the driver reclines way down low. It was originally built with independent front suspension, but I recently converted it to rigid suspension for better reliability and less weight.
Pic 4 is one I built for myself. this is the car that I just sold recently. It is cycle car style and includes a six-speed derailleur.
Pic 5 is the dominant car in this area right now. It ain't pretty, but it's fast. It is powered by a 1 hp Scott motor, uses a six-speed derailleur in the rear, and the chassis is suspened and linked to the steering so that it leans into the turns.

Those are really cool!!! i interested in this thread! I might build one to run around the neighborhood in.

Damn I really like those little cars. Makes me wish I was young again. I'd love to drive one, only thing is it would have to be built to hold a much greater payload than those do.

If I had any skills I'd try to build one, but it would have to be quick because I would want to run it on the expressway.

HRD - Build one! Then you can come and race with us. I tooled the orange one around my neighborhood a few times. It really drew some curious looks. I'm sure it would have generated a mess of questions if I had stopped anywhere long enough.

Bob - You don't have to be young or small. I'm 61 years old and 227 lbs.
The reason I'm building myself a new car is because I outgrew the other one! We have a few of us "larger" guys who are wanting to race, so we are going to start a "heavy" class with a 225 pound "payload" minimum weight. As for running on the expressway.., you might get run over; these things sit so low you would be hard to see.

Sounds like a blast! It would be a shame to restrict these to the students just because 'we' happen to be a little "mature" (ie. heavy.)

Looking at the examples you have shown and the fact that the dominant car has no aerodynamics, do you think that lower weight is more important than lower wind resistance? Or is it a better motor/driveline efficiency that contributes to it's success?

I think you are right about the "Sun Day Challenge"......and it may well have been grade eight rather than high school. Memory is a bit hazy at times.

Originally Posted by RestoRod

...Looking at the examples you have shown and the fact that the dominant car has no aerodynamics, do you think that lower weight is more important than lower wind resistance? Or is it a better motor/driveline efficiency that contributes to it's success?

I think that's exactly it. At the low speeds we compete at most of the time, low friction and driveline efficiency is probably the key. That car was built by a father/son team, Dana & Lance Barlow, from south Florida who won the Human Powered Vehicle national competition a few years back. They definitely know a bit about making things light and friction free. Of course it doesn't hurt that Lance is an extremely competent and experienced driver... They have a body planned for the car, but haven't built it yet. There is a race scheduled for Five Flags Speedway in Pensacola on April 18. I don't know if the Barlows plan on running that race, but I would bet that if they're there, the car will have a body on it...

OK, this is supposed to be a build thread, so lets get to it. If I seem wordy it's because I want to explain everything as best I can to those who have never been exposed to this type of thing before...

First thing is to decide which type of car to build. Of course, we could build a conventional 4-wheel car, but since friction is a consideration, eliminating the rolling friction of one tire on the ground seems to be the way to go. The simple fact that probably more than 99% of all Electrathon cars are 3-wheeled lends credence to that practice. So.., with that in mind the next consideration is whether to make our 3-wheeler a cycle-car or a tricycle.

Folks who have ridden old Harley Servicar 3-wheelers know that those things will dive right over the front wheel and flip over at relatively low speed. The problem is that the high center of gravity (CG) transfers forward and outside the triangle formed by the three contact patches of the wheels. In order to stabilize a tricycle in a corner, it is necessary to get the CG down low and between the rear wheels so it won't dive over the front wheel. To do that we need to stretch the wheelbase and move everything down and rearward. The winningest team in Electrathon, Cloud Electric, successfully uses the tricycle configuration, but up in the Northwest they run mosly on long courses or ovals.

On the tight parking lot "road courses" we run most of the time here in Florida, quick handling is important. With a cycle-car configuration we can keep a shorter wheelbase for quick steering response, move the CG around pretty much at will to put components where we want them, and still not worry about the car having a tendency to roll over. I have video of one of the Kennedy High School cars from Iowa actually smoking the rear tire in a tight turn and all 3 wheels stay firmly on the ground. So, it is a cycle-car style that we will build here.

I have an advantage in that I have done this before. The car below (also pictured in my initial post) was originally conceived by my students, the design refined by me and a former teaching assistant, and built by my students and me. That was in 2004. Since then, this car has proven itself to be reliable, consistent, and driver-friendly. The new car I am building here is similar to this, but with a few refinements I have learned along the way.

When we designed the car above, I put a student on a table with his legs sretched out straight and a board under his back. I propped the board up with books untill he could easily see over his toes. Then I started taking measurements. I did a similar process with the orange car, but I propped up the "driver's" knees with a bar to simulate the front axle under his knees and then propped up his back until he could easily see over them. In both cases I did a quick diagram with measurements. Then it was time to start building...

The next step is to acquire something to build with. Some of the well-healed teams in the Northeast use some pretty exotic materials in their builds like carbon fiber and Kevlar, but I'm on a budget here so we'll stay a bit more conventional. I made a trip to the local Lowe's and picked up some EMT conduit. I got four 10-foot pieces of 1/2 inch and two pieces of 3/4 inch. I also grabbed a roll of aluminum "kick panel" from the area where they have siding and porch screen stuff. The aluminum is .025" thick, 16 inches wide and 10 feet long. All together it was $45.

This looks very interesting JR. I being older- also appear to be the lightweight of group. At 5'5" I don't even make 140 lb. Does that mean I could add a spare batt. for ballest? Honest officer I have no idea how that "ballest" became part of electric grid.

I'll be following this build. Looks like fun for you and the students.

Earl

I did some poking around in my old files this morning and came up with this diagram I sketched back when we built the car above. It oviously is not to scale and the human form is not reclined as much as the dimensions indicate, but it gave me some measurements to work from. With a student stretched out on a long table (he was 6'3"), we used a piece of plywood and a stack of books to support his back at the desired angle. Then we started taking measurements. I measured from the bottom of his shoes to approximately where his tialbone would be contacting the table. I measured the height of the plywood at the top of his shoulders so I could make the seat back. I measured to the front of his shoulder so I would know how high to make the sides. I measured to the top of his head so I would know how high to make the roll bar. Etc, etc.

I'm sure I must have made a preliminary sketch of the frame before I started building, but it apparently did not survive.

Neat thread Jim. During construction are you using aluminum for the frame? Not sure what emt is. Also while racing do you use certain gears most often or all of them? Could you put a small alternator in there for braking to reverse generate power when braking?

Jim wrote:

As for running on the expressway.., you might get run over; these things sit so low you would be hard to see

So were the early formula 1 cars. If it was fast enough with good maneuverability, size wouldn't be that important. Scoot right under that semi, yee ha!.

Now where can I get three electric motors to drive each wheel and the computer to hook it all up?? Could be a minature Eliici.

http://www.evworld.com/news.cfm?newsid=10772