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

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