I think it's my 8th or 9th now. I'm starting to lose track.
Anyway, for this one I wanted to see how much speed I can carry through the corners on the shorter parking lot courses.
Consequently I decided on much shorter and wider wheels and tires than what I usually use. These are actually trailer tires on 8x2.75 inch aluminum mini bike wheels. I'm not sure how well they're going to work out.
I guess we'll see.
Anyway, this car is to be powered by a 3kw Golden Motor and 36v worth of lead acid batteries.
I intend to build pods to cover the front wheels but didn't get them done in time for it's first race this Saturday. I'll probably get them done eventually.
I ran my newest Electrathon car in it's first race yesterday and the results were mixed.
I built this one specifically for shorter parking lot style tracks instead of the speedway type track that my last car ran on. Consequently I made some design decisions toward that end. I moved the nearly 70 lbs of batteries forward so they were centered on the front axle in an effort to reduce the car's tendency to want to roll over on excessively fast sharp turns. For this same reason I chose to use shorter, wider wheels and tires so it would have the grip necessary to take those corners and the strength to not break the outside front wheel in the process. (i.e. taco-ed bike wheel) Race-ready, car and driver weighed in at just over 400lbs.
The track was very old asphalt that had eroded down to be exceedingly rough as the aggregate in it was very exposed. This created a cheese grater effect as the car took the numerous tight turns at 20ish mph and the limited traction caused a bit of understeer making the grater effect worse. After what I believe was 127 laps in two 1 hour races, the front tires are pretty well shot. The wheels, tires and overall design of the car proved extremely durable as I demonstrated in a crowded 180 degree turn when I ran the right front wheel completely up and over a 6" curb at about 18mph without any apparent damage.
I think the car was too nose heavy for the traction provided by that surface. I may try moving the most forward of the three batteries to behind the seat to try to achieve a better balance and reduce understeer. I did NOT notice a problem with rolling resistance with these tires as some predicted I would. I ran them at 80 psi and could maintain 24 mph on the back straight at less than 500 watts.
In the end I finished 2nd in my class out of 7 and was maybe 3rd or 4th overall. (Not sure till the results are posted) I had to pit once in each race, the first one for 10 minutes while I found and tightened a battery connection that had rattled loose (my fault) and for about 5 minutes in the second one after I knocked another connection loose after getting physically tangled up with lapped traffic. (my fault again) The lesson here is "lockwashers are cheap. Use them." One of the problems with being a one man team is that it means very little when the driver blames the crew chief for a problem.
I swapped out my 8" wheels with trailer tires for 10" wheels with scooter/moped tires. Got another race in 2 weeks, we'll see if these hold up any better.
