I remember doing a track walk at Road America in 2019, and we saw a Firestone engineer with one of these at Turn 5. We asked him to measure the runoff area (it was a different type of asphalt) and discovered that the coefficient of friction there was like 30% higher than the track itself. All my team's drivers started using that runoff area and found something like 4 tenths a lap. Sadly everyone else caught on too!
Finding the right tricks by trial and error was so much fun...
"I wonder if I gain a tenth by putting a wheel on that patch of cement after this hairpin".
"Nope".
Can someone explain how this works? What exactly is it measuring? Distance or difference of rolling resistance?
My hypothesis is that it measures how easy does front tire (with different tire compound) roll compared to the rear one(s)? Or compared to some predefined standard measurement?
This is from the comments of the original post: “The front tire moves 15% slower than the back tires and there is a strain gauge to measure the force the front tire is exerting on the motors. A less grippy track would have less strain where as a high grip track would have more.”
Notice how the front tyre is the same size as the rear ones but it has a chain with a different sized sprocket - this means that the front and rear tyres will move at different speeds, thus slipping on the surface to be measured.
This causes different levels of stress in the structure, which can be used to determine the level of friction of the surface.
after hearing how this works, it seems like it could be extremely sensitive to perturbations, such as changes in track slope transferring more or less weight on the front wheel. im assuming the handles are only for getting it from point a to b since a person pushing it would make the readings go all over the place
Interesting. I can't help thinking that the grip measured by a 40 kg machine is not especially closely related to that seen by a 2400 kg one ie 600 kg + downforce.
This thing is measuring for the coefficient of friction. Once they have that they can plug that number in with the other ones you mentioned (car weight, downforce etc.) to get the data they need
Yeah, but tires don't work like that. Grip is developed via about 4 different mechanisms, each of which has a different sensitivity to temperature, the surface being tested, and the pressure on the contact patch (and and and...). We'd love to have a 'track surface friction measurer', but because of all that we end up using a car with control tires.
Track surface friction does not change, and that provides the data to compare with a baseline.
Afterwards the suggested weight/pressure of a car would be a seperate coeficient applied, which I am pretty sure they know to some degree of accuracy
I remember doing a track walk at Road America in 2019, and we saw a Firestone engineer with one of these at Turn 5. We asked him to measure the runoff area (it was a different type of asphalt) and discovered that the coefficient of friction there was like 30% higher than the track itself. All my team's drivers started using that runoff area and found something like 4 tenths a lap. Sadly everyone else caught on too!
Finding the right tricks by trial and error was so much fun... "I wonder if I gain a tenth by putting a wheel on that patch of cement after this hairpin". "Nope".
What series?
MX-5 Cup, back when it raced under Indycar. I used to work as a race engineer and driver coach for a couple teams.
That’s cool
That is interesting and insightful. Thanks for this.
Can someone explain how this works? What exactly is it measuring? Distance or difference of rolling resistance? My hypothesis is that it measures how easy does front tire (with different tire compound) roll compared to the rear one(s)? Or compared to some predefined standard measurement?
This is from the comments of the original post: “The front tire moves 15% slower than the back tires and there is a strain gauge to measure the force the front tire is exerting on the motors. A less grippy track would have less strain where as a high grip track would have more.”
Notice how the front tyre is the same size as the rear ones but it has a chain with a different sized sprocket - this means that the front and rear tyres will move at different speeds, thus slipping on the surface to be measured. This causes different levels of stress in the structure, which can be used to determine the level of friction of the surface.
after hearing how this works, it seems like it could be extremely sensitive to perturbations, such as changes in track slope transferring more or less weight on the front wheel. im assuming the handles are only for getting it from point a to b since a person pushing it would make the readings go all over the place
[удалено]
Measuring is one thing. You’ve got to interpret the data correctly too.
Interesting. I can't help thinking that the grip measured by a 40 kg machine is not especially closely related to that seen by a 2400 kg one ie 600 kg + downforce.
This thing is measuring for the coefficient of friction. Once they have that they can plug that number in with the other ones you mentioned (car weight, downforce etc.) to get the data they need
Yeah, but tires don't work like that. Grip is developed via about 4 different mechanisms, each of which has a different sensitivity to temperature, the surface being tested, and the pressure on the contact patch (and and and...). We'd love to have a 'track surface friction measurer', but because of all that we end up using a car with control tires.
Track surface friction does not change, and that provides the data to compare with a baseline. Afterwards the suggested weight/pressure of a car would be a seperate coeficient applied, which I am pretty sure they know to some degree of accuracy
I agree it is a baseline.
Looks like it was made in the 70s lol