Post on 03-Jan-2016
Quantum
Racingand
The Physics of Racing
42
BGSU Society of Physics Students[
[
Department of Physics and Astronomy
Bowling Green State University
Outline• Grand Prix of BGSU• Quantum Racing
– Why?– 2005 Team– Kart
• Construction• Testing• Race Day
• Physics of Racing– Center of Mass/Weight Shift– Tires– Steering– Corners– Engine– Gears
• Kart race– Bring motorsports to BGSU Campus– Promote clean Energy (E85)
Grand Prix of BGSU
Why should SPS go racing?
• Real life application of Physics– Hands on experience– Brings the physics to life
HAVE FUN WITH PHYSICS!!
Quantum Racing Team
Crew ChiefMatt Hodek
DriverJen Bradley
Crew MembersRyan HendersonBilly Schmidt
ScorerRyan Loreck
Track WorkerIan Nemitz
Kart ConstructionPurchased a base racing chassis
Build a safety cageKart Construction
Engine and Clutch
Kart Construction
Kart Testing
• Several Driver training and kart testing sessions.– Improve driver skill
and familiarity with kart
– Adjust kart to provide best kart for the driver.
Data Acquisition
• Alfano – Records:
RPM
Head Temp
Wheel Speed
G-force
Lap times
– 10 hz ~90 min– 24-40 hrs (lap only)
Laptimes
20
24
28
32
0 10 20 30 40 50 60
lap
tim
e (s
)
velocity
30
35
40
45
50
13 14 15 16 17 18 19 20 21 22
seconds
ft/s
ec
acceleration
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
13 14 15 16 17 18 19 20 21 22
sec
ft/s
ec^
2
The Physics of RacingAn Introduction
How the kart moves
What makes it move
COM and Weight Shift
• COM (Center of Mass)– Very important
• Where it is• How to change it
• Weight Shift– Effects handling of car
• (de)acceleration• Cornering
Accelerating
Grip
De-accelerating
Tires!• FRICTION!!
• Traction Circle– Limited traction
available
• Slip Angle
• Relies heavily on weight transfer
Accel
brake
left right
Right Front Tire
Steering Casterforward
Kingpin
Inclination
Scrub Radius
Turn
Raiselower
Lifted off the ground
COM Shift
Steering
SteeringTurn
Raiselower
Lifted off the ground
Ackerman Steering
Chassis setup and Tires• Determines how the weight is transferred
to each wheel under different conditions
Understeer Oversteer
Front Grip
Rear GripFront Grip
Rear Grip
More grip:Decrease tire pressureStiffen Chassis sectionsMove weight towards wheel
Less grip:Increase tire pressureFlexable Chassis sectionsMove weight away from wheel
Corners
Goals: • widest arc possible• Keep speed up• Retain as much
momentum as possible
Outside - worst
Inside - better
Apex - Best
R
vmF
2
Corners
How the kart moves
What makes it move
Engine
• Fluid Mechanics– Air flow – Volumetric efficiency
• Mechanical Engineering– Converting combustion
Into mechanical force
•Thermodynamics–Compression –Combustion
axel_rpm
clutch_rpm
thclutch_tee
axel_teethgear_ratio
Gears
Higher Ratiomore torqueless top end speed
Lower Ratioless torquemore top end speed
32 teeth
16 teeth2:1 gear ratio
On going StudiesThe Advanced Physics of Racing
Topics of Study• Thermodynamic model of the engine
• Air cycle• Fuel-air cycle• Air capacity• Ambient conditions
• Dynamical model of the Chassis• Chassis flex• Harmonic Oscillation
Measured Hp/torque curves
•Comparison to Experimental data
•Smoothing Data
•Clutch issue
rpm vs torque/(hp)
0
1
2
3
4
5
6
7
8
9
10
0 1000 2000 3000 4000 5000
rpm
ft lb
s (h
p)
tormaxhpmax
rpm vs torque (hp) delta=20
y = -7E-10x3 + 5E-06x2 - 0.0073x + 1.954
R2 = 0.8577
y = -5E-10x3 + 3E-06x2 - 0.0054x + 1.5618
R2 = 0.8122
01
23
45
67
89
10
0 1000 2000 3000 4000 5000 6000
rpm
ft lb
s (
hp
) tormax
hpmax
Poly. (tormax)
Poly. (hpmax)
Simple Air Cycle Model
• Assumptions– Air is an ideal gas, fuel is not part of the charge– Each cycle draws full charge regardless of rpm – The combustion is complete
ηfQMΚ
JH.P. ca
p
T
PtdisplacmenrpmM a
3.532
60
Predicted HP (air cycle w/gasoline)
0
2
4
6
8
10
12
14
16
18
20
0 2000 4000 6000
rpm
HP
50% eff - 18.25 ft lbs
40% eff 14.6 ft lbs
30% eff 10.95 ft lbs
20% eff 7.3 ft lbs
21% eff 7.7 ft lbs
actual - 8 ft lbs @ 2500 rpm
HP vs RPM
0
1
2
3
4
5
6
7
8
9
0 1000 2000 3000 4000 5000 6000
rpm
HP
calculated hp 22% eff f=.11
recorded hp delta=20
Fuel-Air Cycle
• “An idealized process using as its working medium real gasses that closely resembling those used in the corresponding engine.“
• Not a ‘thermodynamic cycle’• Assumptions
– No chemical change before or after combustion– After combustion, the charge is in chemical
equilibrium– All processes are adiabatic– Velocities of the charge are negligable
Thank You
Any Questions?
SourcesTaylor, Charles F. The Internal-Combustion
Engine in Theory and Practice. 2nd ed. Vol. 1. Cambridge, Massachusetts: The M.I.T. P, 1985.
Beckman, Brian. "The Physics of Racing." SCCA CalClub Newsletter.
Quantum
Racing42