Brandon
08-03-2007, 06:01 PM
I made some spread sheets for a vehicle dynamics class and thought some of you might want to play with them.
They would be awesome for building a shifter cart. They would give you a great platform to start from and then dial in components on the track. You could also put in your car info but the results may not be quite as accurate. Also most of the units are in metric so you might have to do some converting.
Here's one for braking (right click save as)
http://www.drenfam.com/mr2/b/braking.xls
Here's one for acceleration and climbing. There's a chart that shows the acceleration (g's) vs speed. Above the traction line, the wheels are spinning. This spreadsheet was based off of a Super Bee (?).
http://www.drenfam.com/mr2/b/ac.xls
I'll try to sum up what some of the varibles are.
Braking:
m = mass
L = wheelbase
b = distance from front wheels to the center of gravity (COG)
h = height of the COG from the ground
rfront = radius of front tires
rrear = radius of rear tires
Dc = caliper piston diameter
W = weight (mass * gravity)
Amc = area of the master cylinder (MC)
Gfront/rear = gain front/rear [function of Dc, Rc, and mu-pad(how sticky the pads are)]
Lp = length of brake pedal
Lr = dist between pivot point of brake pedal and pivot point of the MC
Lmc = Distance between MCs. This spreadsheet utilizes dual MCs, one for the front and one for the back. Between them is a balance bar. You adjust the balance bar to proportion the braking.
Dmc = diameter of the MCs
mu-pad = coefficient of friction for the brake pads
Rc = radius of the center of the caliper piston in relation to the center of the wheel
mu-P = coefficient of friction between the tires and the ground
betta = ratio of front braking to rear so that all 4 wheels lock up at the same time.
Fb,f = force on the car from the front brakes
P,f = pressure in the front brake lines. I think this is in MPa
Fmc,f = force on the front MC (N)
Fr = force on both MCs, this is also the force required by the brake pedal at location Lr.
Lb = the setting for the balance bar location
Fpedal = force on the pedal
Wow that was a lot more than I thought.
If this peaks anyone's interest then I'll do more. I have a few more speadsheets too good for swaybars and cornering.
On the AC spreadsheet, the HP input is a formula but you can easily put in points from a dyno chart.
They would be awesome for building a shifter cart. They would give you a great platform to start from and then dial in components on the track. You could also put in your car info but the results may not be quite as accurate. Also most of the units are in metric so you might have to do some converting.
Here's one for braking (right click save as)
http://www.drenfam.com/mr2/b/braking.xls
Here's one for acceleration and climbing. There's a chart that shows the acceleration (g's) vs speed. Above the traction line, the wheels are spinning. This spreadsheet was based off of a Super Bee (?).
http://www.drenfam.com/mr2/b/ac.xls
I'll try to sum up what some of the varibles are.
Braking:
m = mass
L = wheelbase
b = distance from front wheels to the center of gravity (COG)
h = height of the COG from the ground
rfront = radius of front tires
rrear = radius of rear tires
Dc = caliper piston diameter
W = weight (mass * gravity)
Amc = area of the master cylinder (MC)
Gfront/rear = gain front/rear [function of Dc, Rc, and mu-pad(how sticky the pads are)]
Lp = length of brake pedal
Lr = dist between pivot point of brake pedal and pivot point of the MC
Lmc = Distance between MCs. This spreadsheet utilizes dual MCs, one for the front and one for the back. Between them is a balance bar. You adjust the balance bar to proportion the braking.
Dmc = diameter of the MCs
mu-pad = coefficient of friction for the brake pads
Rc = radius of the center of the caliper piston in relation to the center of the wheel
mu-P = coefficient of friction between the tires and the ground
betta = ratio of front braking to rear so that all 4 wheels lock up at the same time.
Fb,f = force on the car from the front brakes
P,f = pressure in the front brake lines. I think this is in MPa
Fmc,f = force on the front MC (N)
Fr = force on both MCs, this is also the force required by the brake pedal at location Lr.
Lb = the setting for the balance bar location
Fpedal = force on the pedal
Wow that was a lot more than I thought.
If this peaks anyone's interest then I'll do more. I have a few more speadsheets too good for swaybars and cornering.
On the AC spreadsheet, the HP input is a formula but you can easily put in points from a dyno chart.