I would like to start a conversation about updating the ground clearance rule in the rules. But, first, allow me to share my experience to illustrate the contradiction in the rule book.
Back in November of 2020 on a parking lot at Plant City High School, a parking lot used almost exclusively for busses to load students, I blew a tire in the last few minutes of an hour long race and skidded across the pavement to a stop into a concrete island. See photo. I slide for 30 or more feet before I came to a stop after blowing the tire. I should have taken this as a wake up call.
In April of 2021, at Brandon High School on a 0.25 mile jogging track, I blew the right front tire at about 30 mph. This put me and my car into the fence. Like a weight on the end of a string when the string breaks, I went off on a tangent and continued straight into the barrier. You can see the moment of impact from the GoPro, the images showing the damage to the car, and the bruise on the inside of my foot where I believe the pole and foot collided.
Why did this happen? I discovered that when my tire blew in both instances, I lose steering and the ability to stop with my two front disc brakes.
You can see the GoPro video at the link below: https://www.facebook.com/1231850029/videos/10225608526739951/
In the rule book, page 8, under 10 - Wheels and Tires point #3 states: "The minimum ground clearance is to be judged by the cars ability to roll over a 2x2 that is milled to be 1˝ x 1˝. This is to prevent the vehicle from sliding on the ground in the event of failure of any or all of the tires."
My car complies with this. My car clears a 1 1/2" obstruction without issue. However, with 1.75 tires on my car, when the tire blows, the car is now about 0.25" below the rim of the wheel.
On page 16 under Stability, the paragraph states:
"A well-designed vehicle should be stable under all conditions and situations that might be encountered in a race. Competition places very high loads on a vehicle during tight cornering, even at relatively low speeds. It is therefore very important that the center of gravity of your vehicle be located below the axles. You need only a couple of inches of ground clearance on most race courses. Two to three inches is usually adequate, but make sure that you have clearance even if one, or all, of the tires are flat ( this is a rule requirement)."
Despite the assertion, there is no specification about ground clearance when the tires go flat.
Here's an image of my car from the side. This is after the repairs where the nose was brought up slightly. But still, as you draw a line from the back of the wheel well to the front of the wheel well, the rim appears to be higher than the lowest part of the car. As a result, a blown tire lays the car down on the smooth underside with only the rivets to slow me down. :)
I will say the this past weekend, I raced the car in the final race of the season and blew two tires. The first tire blew about 30 minutes into the race and was on the inside of the track. I had control the entire time and was able to steer into the infield and brake to a complete stop. I was able to swap wheels and get back out to finish the race only to have the other tire, right-front wheel this time blow. Again, I had control, steered into the infield and brought the car to a stop (once I let go of the deadman switch).
I believe what is needed is a rule that states the rim of any wheel must be lower the lowest part of the vehicle. My wheels are 16" up front and 20" in the back at the drive wheel. I run a reverse trike or cycle car design. One of the reason for the blown tires is that I used to use Maxxis Hookworms exclusively. They no longer manufacture these in 16" and I have been force to move to Big Blue Box Store kiddie tires. The last race I ran with GoodYear Tires heavy duty tire and tubes (brand new) and they still failed. Oh, and the fact that I weight 40 lbs over minimum driver weight might have something to do with it.
Just to follow up on the injury. My foot swelled pretty quickly and with help, I was able to get out of the car and stand on it. I spent two days staying off of the leg. I went back to work 3 days later and got around on it. The leg improved everyday and strength and cotroll was back to normal about 16 days post accident. The only thing that remains now is the scab from the contusion where the leg was crushed between metal parts.
Glad you recovered and did not have too much more fun as you lost tubes this weekend as well. Thank you for your assistance in allowing me to have the same experience.
There were a number of rule changes made in 2012 that took, what I felt were goal oriented rules and made new rules that were somewhat arbitrary. The original tire rule was something like the floor could not touch the ground with any single tire deflated. The new rule was that every car had to be able to roll over a 1.5 inch board.
I favored the old rule because it gave the option of looking for a performance advantage using less tall tires and a lower ride height while still staying safe. The 1.5 inch rule was arbitrary and did not guarantee safety. The counter argument is not without merit. The 1.5 inch rule is simple and clear and easy to check and enforce.
ElectrathonAmerica rules are determined by the members, so we had a vote and that was one of the rules that passed. Based on your experiences, you should write up a wording you think is better and propose it to the board. Then we can vote on it for next year.
As for the pneumatic tire rule, I wonder what the reasoning is. I think a solid tire would be too heavy and not create good grip but I do not see a safety reason for not running them. You could propose removing that restriction as well.
Sorry to hear about your bad luck. There is no max car height so if your just raise your car or went with a taller tires. It would solve the problem with your car hitting to ground when your tires go away. I think the rule the way it is is just fine and easy to test and simple.
I think Todd's experience raises the question, "What is the purpose of the 1.5 inch rule"? The rule it replaced was to make sure the vehicle's floors did not come in contact with the ground when a tire failed. Racers have learned from experience that the bottom of the vehicle coming in contact with the ground at speed can have bad results. Sometimes the floor digs in and the vehicle flips but more often, the driver losses all directional control.
To most of us, this is not intuitively obvious when designing a vehicle. The rule was there to help designers to avoid this problem.
Does the 1.5 inch rule accomplish this goal? Todd was racing a vehicle that was legal based on the 1.5 inch rule. He was unaware of the danger that his rim size put him in.
The original rule protected us from a specific danger. The current rule does not.
Does anyone have a copy of the old rule? I cannot find my old rule book.
I do not think the old rule was hard to enforce. With most Electrathon vehicles, I find it is pretty easy to judge whether the vehicle will bottom out if the tire goes flat. If it looks close, the inspector should require the team to deflate the tire and demonstrate that it is safe.
I think having the cars any lower than a 1 1/2 off the ground would be a mistake because some track are not smooth enough and could bottom out on the track, When setting up you car or if things change( like tires you can not get anymore) you may want to make changes to your car for safety sake not try to change the rule that every one else has built there cars to.
If the rule were to be changed, inspectors could just utilize a tape measure to compare the height of the lower rim edge to the bellypan of the car. No airing down of tires should be required.
Then you could set your any height you want. If it bottom out on the track would that also be a safety concern. Just raise up the spindle to comply with the rules.
I do not think there is too much to be concerned about if we go back to the Pre- 1.5 inch rules. It will not necessarily mean people will have to lower their vehicles to take advantage of the lower possible ride height. We know that running a lower ride height should lower the CG and allow the vehicle to corner better (everything else being equal) but lower ride heights often increase aero drag. This is why, traditionally, so many solar racers (such as those racing across Australia) run such high ride heights. The vehicles body displaces air and some of it flows under the vehicle. The lower the vehicle, the more restricted the air is between the body and the ground. This increases the amount of energy required to move the vehicle forward.
I was reading 'The Leading Edge' by Goro Tamai which has some guidance on how to calculate the optimum ride height. There are a lot of factors including body shape and smoothness and speed range of the vehicle. I roughly calculated the optimum for an electrathon vehicle running the tight course we run in Florida and came up with----wait for it---around 1.5 inches!
Racing is about finding the best compromise, and that can change from track to track. It is complicated and interesting and part of why racing is fun. I like that most Electrathon America rules are written to address specific risks and allow the greatest room for innovation. I do not think the 1.5 rule meets these standards.
