Final Exam

As you may know, I teach a class on high performance driving. What do we talk about? I present to you the final exam from the last time I taught the class. Feel free to suggest new exam questions!

Question 1: Friction Circle

Given: Miata, 1.0g grip, left-hand drive, driver is highly skilled, no passenger, track is clockwise and shaped like the letter “T”.

• Draw a circle and label the axes
• Draw appropriate dots on the friction circle
• Place the letter “A” at the location where power-on understeer might happen
• Place the letter “B” at the location where over-braking understeer might happen
• Place the letter “C” at the location where lift-off oversteer might happen
• Place the letter “D” at the location where power-on oversteer might happen
• Place the letter “E” at the location where trail-braking oversteer might happen

Question 2: 90° Corner

• Draw the geometric line (dashed)
• Draw the typical late apex racing line (solid)
• Label the entry, apex, and exit
• Place an X on the racing line where the driver should apply throttle
• Place a Y on the racing line at the position of minimum speed
• Place a Z on the racing line at the position of the highest speed

Question 3: Suspension

• Why does lowering a car reduce body roll?
• Why does stiffening the suspension reduce body roll?
• How does an anti-roll bar reduce body roll?
• What is the advantage of reducing body roll?
• Why do racers soften suspension in the rain?

Question 4: Grip

• State Amonton’s First Law of Friction and describe a flaw.
• State Amonton’s Second Law of Friction and describe a flaw.
• State Coulomb’s Law of Friction and describe a flaw.
• Slicks vs. grooved tires: what are the advantages and disadvantages?
• Wide vs. skinny tires: what are the advantages and disadvantages?

Question 5: Tire Graphs

Draw the following graphs. Label the axes.

• Coefficient of friction vs. Load
• Coefficient of friction vs. Slip Angle
• Coefficient of friction vs. Temp
• Coefficient of friction vs. Speed

Question 6: Corners

Draw the following corners: esses, chicane, carousel, 120° decreasing radius. Label the corner as Type I, II, or III.

Question 7: Puzzles

• You notice your friend drags his clutch during braking (i.e. uses the engine to help slow the vehicle). You ask him why and he claims it helps him slow down faster.
  • Is he correct?
  • How does this change braking in a FWD vehicle?
  • How about RWD?
• When cars go off track at the exit, they often end up crossing the track and crashing against the inside wall. Why does this happen?
• Cars often lose control when cresting a hill. Why does this happen?
• Label each shape below with an approximate drag coefficient. Assume the object is traveling upwards on the page.