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Panther Racing

2009 Florida Tech FSAE Team

Preliminary Design Report

October 22, 2008

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Table of Contents 1.1 Introduction ............................................................................................................................... 9

1.1.1 Purpose ................................................................................................................................... 9

1.1.2 Goals .................................................................................................................................... 10

1.1.3 Background .......................................................................................................................... 11

1.1.4 Team Organization ............................................................................................................... 11

1.1.5 Scheduling............................................................................................................................ 12

1.1.5.1 Milestones and Deadlines ................................................................................................. 12

2.1 Chassis .................................................................................................................................... 13

2.1.1 Introduction and Purpose ..................................................................................................... 13

2.1.2 Goals .................................................................................................................................... 13

2.1.3 Background .......................................................................................................................... 13

2.1.4 Design Objectives ................................................................................................................ 14

2.2 Formula SAE Rules and Regulations ..................................................................................... 14

2.3 Chassis Design and Analysis .................................................................................................. 17

2.3.1 Chassis Design Introduction ................................................................................................ 17

2.3.2 Design Analysis ................................................................................................................... 18

2.4 Budget ..................................................................................................................................... 20

2.5 Scheduling............................................................................................................................... 20

2.5.1 Gantt Chart ........................................................................................................................... 20

2.5.2 Milestones and Deadlines .................................................................................................... 20

2.6 Conclusions ............................................................................................................................. 21

3.1 Suspension .............................................................................................................................. 21

3.1.1 Introduction and Purpose ..................................................................................................... 21

3.1.2 Goals .................................................................................................................................... 21

3.1.3 Background .......................................................................................................................... 22

3.2 Design Objectives ................................................................................................................... 22

3.2.1 Suspension Definitions ........................................................................................................ 23

Shock absorbers, and travel ................................................................................................... 23

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Ground Clearance .................................................................................................................. 23

Wheelbase and Track Width.................................................................................................. 23

Kingpin Inclination and Scrub Radius ................................................................................... 23

Camber................................................................................................................................... 24

Caster ..................................................................................................................................... 25

Toe ......................................................................................................................................... 26

3.3 Design Analysis ...................................................................................................................... 27

3.3.1 Braking Analysis .................................................................................................................. 29

3.3.1.1 Braking Calculations ......................................................................................................... 31

3.4 Detailed Drawings .................................................................................................................. 34

3.5 Budget ..................................................................................................................................... 35

3.6 Scheduling............................................................................................................................... 35

3.6.1 Gantt Chart ........................................................................................................................... 35

3.7 Conclusions ............................................................................................................................. 36

4.1 Drivetrain ................................................................................................................................ 36

4.1.1 Introduction .......................................................................................................................... 36

4.1.2 Purpose ................................................................................................................................. 36

4.1.3 Goals .................................................................................................................................... 36

4.1.4 Background .......................................................................................................................... 37

4.2 Design Objectives ................................................................................................................... 37

4.3 Design and Analysis ............................................................................................................... 38

4.3.1 Drivetrain Analysis .............................................................................................................. 38

4.3.2 Engine Choice ...................................................................................................................... 40

4.3.3 Transmission Analysis ......................................................................................................... 42

4.4 Detailed Drawings .................................................................................................................. 45

4.5 Budget ..................................................................................................................................... 46

4.6 Scheduling............................................................................................................................... 47

4.6.1 Gantt Chart ........................................................................................................................... 47

4.6.2 Milestones and Deadlines .................................................................................................... 47

4.7 Conclusions ............................................................................................................................. 48

5.1 Driver Interface ....................................................................................................................... 49

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5.1.1 Introduction and Purpose ..................................................................................................... 49

5.1.2 Goals .................................................................................................................................... 49

5.2 Design Objectives ................................................................................................................... 49

5.3 Driver Interface Design and Analysis ..................................................................................... 49

5.3.1 Accelerator and Clutch Pedals ............................................................................................. 49

5.3.1.1 Engineering Specifications ............................................................................................... 49

5.3.1.2 Design History .................................................................................................................. 50

5.3.1.3 Engineering Analysis ........................................................................................................ 50

5.3.1.4 Material Study ................................................................................................................... 51

5.3.2 Brake Pedal .......................................................................................................................... 51

5.3.2.1 Engineering Specifications ............................................................................................... 51

5.3.2.2 Design History .................................................................................................................. 51

5.3.2.3 Material Study ................................................................................................................... 51

5.3.3 Steering Wheel ..................................................................................................................... 52

5.3.3.1 Engineering Specifications ............................................................................................... 52

5.3.3.2 Design History .................................................................................................................. 52

5.3.3.3 Material Study ................................................................................................................... 53

5.3.4 Steering Rack ....................................................................................................................... 53

5.3.4.1Engineering Specifications ................................................................................................ 53

5.3.4.2 Design History .................................................................................................................. 54

5.3.5 Driver’s Seat ........................................................................................................................ 54

5.3.5.1 Engineering Specifications ............................................................................................... 54

5.3.5.2 Design History .................................................................................................................. 54

5.3.5.3 Material Study ................................................................................................................... 54

5.3.6 Instrumentation .................................................................................................................... 55

5.3.6.1 Engineering Specifications ............................................................................................... 55

5.3.6.2 Design History .................................................................................................................. 55

5.3.7 Safety Equipment ................................................................................................................. 56

5.3.7.1 Engineering Specifications ............................................................................................... 56

5.3.7.2 Material Study ................................................................................................................... 57

5.4 Engineering Drawings ............................................................................................................ 57

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5.5 Budget ..................................................................................................................................... 57

5.6 Gantt Chart .............................................................................................................................. 59

5.7 Conclusion .............................................................................................................................. 59

6.1 References ............................................................................................................................... 60

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List of Figures

Figure 1 - Formula Team Chain of Command .............................................................................. 12

Figure 2 – Helmet Clearance [1] .................................................................................................. 16

Figure 3 - Solid Works Rendering of Chassis Regulations .......................................................... 17

Figure 4– First Chassis Design Model .......................................................................................... 19

Figure 5– Redesigned Chassis ...................................................................................................... 19

Figure 6– Chassis Sub-Team Gantt Chart .................................................................................... 20

Figure 7 - Diagram of Kingpin Inclination and Scrub Radius [4] ................................................ 24

Figure 8- Camber [5] .................................................................................................................... 25

Figure 9- Caster [6] ....................................................................................................................... 26

Figure 10- Toe Angles [7]............................................................................................................. 26

Figure 11- Example of Double Wishbone with Pull rods [8] ....................................................... 27

Figure 12- Plan View of Arning Four-Link [9] ............................................................................ 28

Figure 13- Wilwood Brake Caliper from Side Mount Car ........................................................... 29

Figure 14– Upright from Side Mount Car .................................................................................... 29

Figure 15– Center Locking Wheel off of 2005 Side Mount Car .................................................. 30

Figure 16– Front Suspension Drawing ......................................................................................... 34

Figure 17– Gantt Chart Suspension Sub-Team ............................................................................ 35

Figure 18— Cutaway of differential (Torsen T-1) [11] ................................................................ 39

Figure 19- Drive Train Prototype Florida Tech 2003 Car ............................................................ 40

Figure 20–(a)Pro E model of CRF450R Engine Model ............................................................... 40

Figure 21– Actual CRF450R[12].................................................................................................. 41

Figure 22- Dyno chart for the CRF450R ...................................................................................... 44

Figure 23- Detailed Drawing of the Torsen T-1 Differential [12] ................................................ 45

Figure 24– Gantt Chart for Drivetrain Sub-Team ......................................................................... 47

Figure 25. Side-mount car pedal setup ......................................................................................... 50

Figure 26- Wilwood Dual Cylinder brake assembly [2] ............................................................... 52

Figure 27- Steering wheel of the side-mount ................................................................................ 53

Figure 28- Steering Rack of the side-mount ................................................................................. 54

Figure 29- Tillet T8 Racing Seat [1] ............................................................................................. 55

Figure 30- Summit Racing gauges ................................................................................................ 56

Figure 31- Wilwood Pedal [2] ...................................................................................................... 57

Figure 32– Gantt Chart Driver Interface Sub-Team ..................................................................... 59

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List of Tables

Table 1– Competition Event’s Points Breakdown [1] .................................................................. 10

Table 2– Formula Team Deadlines ............................................................................................... 12

Table 3– Minimum Material Requirements [1] ............................................................................ 16

Table 4– Material Selection Chart for Chassis Construction [3] .................................................. 18

Table 5– Chassis Sub-Team Budget ............................................................................................. 20

Table 6 - Front Suspension Geometry .......................................................................................... 28

Table 7– Initial Suspension Sub-Team Budget ............................................................................ 35

Table 8- Differential Specification [2] .......................................................................................... 39

Table 9- Engine Specifications ..................................................................................................... 41

Table 10- Graph above shows regular and custom setup for the gear box of the car[13] ............ 43

Table 11 - Drive Train Budget ...................................................................................................... 46

Table 12 Engine Budget ................................................................................................................ 46

Table 13- Parts Availabilities or Prices. ....................................................................................... 59

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Team Members:

Kyle Meier

Keith Reihl

Jeff Grubesich

Mert Candarli

Jacob Allenbaugh

Earle Jackson

Sebastien Griveau

Joachim Agou

Joel Zahlan

Talal Almoyaed

Guido Carelli

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1.1 Introduction Florida Tech Motorsport‟s history of racing teams continues this year with another Formula SAE

series team. This year the team will be going to the competition held in Michigan International

Speedway where the team will continue the traditions of the old racing teams and plans to place

well at the competition.

The design for this year‟s car incorporates revisions and new ideas that will improve the

handling and drivability. A new engine will be used instead of the standard four cylinder 600cc

motorcycle motor that has been used for all of the other formula cars, but parts from previous

cars will be taken to keep costs down and save time. We look to make this year‟s design superior

to the previous cars.

The team is comprised of 11 students all studying mechanical engineering. All design, analysis

and manufacturing will be done by the students. We continue to analyze and research to find the

best solutions to the many problems this design encounters.

1.1.1 Purpose The Formula SAE Series competitions challenge teams of university undergraduate and graduate

students to conceive, design, fabricate and compete with small, formula style, autocross racing

cars. To give teams the maximum design flexibility and the freedom to express their creativity

and imaginations there are very few restrictions on the overall vehicle design. Teams typically

spend eight to twelve months designing, building, testing and preparing their vehicles before a

competition. The competitions themselves give teams the chance to demonstrate and prove both

their creativity and their engineering skills in comparison to teams from other universities around

the world.

The competition is based on two types of events, static and dynamic. The static events provide

the judges with insight into the design process that went into building the vehicle while the

dynamic events allow the vehicle to show how well it can handle, accelerate and brake and its

fuel economy. The static events consist of a presentation, engineering design event, and a cost

analysis and the dynamic events consist of acceleration, skid-pad, autocross, fuel economy and

endurance. The point‟s breakdown can be seen in table 1 below.

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Static Events:

Event Points

Presentation 75

Engineering Design 150

Cost Analysis 100

Dynamic Events:

Acceleration 75

Skid-Pad 50

Autocross 150

Fuel Economy 100

Endurance 300

Total Points 1,000

Table 1– Competition Event’s Points Breakdown [1]

It‟s obvious that the most points come from the endurance event, so a design that can withstand

the dynamic abuse of a race car will prevail. Another interesting area of the competition is the

fuel economy event which has had an impact on some decisions that the team has made.

Students participating in the Formula series learn how to implement the ideas and theories of the

classroom into real life applications. The design of the car includes static and dynamic analyses,

driver ergonomics, cost efficiency, teamwork, and learning. The intricate design process of the

car must be done with precision and accuracy.

1.1.2 Goals The goals of our Formula team are:

Design and build an open wheel, formula style, race car

High performance in acceleration, braking and cornering

Attend competition at Michigan International Speedway

Learn and take part in the engineering design process

Have a well tested car for competition

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1.1.3 Background The Formula SAE series began as a mini-Indy style race car competition in 1979 and was held at

the University of Houston. Dr. Kurt M. Marshek conceived the competition by reading an article

out of a Popular Mechanics magazine. The series gained interest by universities across the

United States and soon by international universities. In 1980 three students at the University of

Texas decided to start another Indy style event with new rules but with minimal restrictions. The

University hosted the competitions up until 1984, and after that new concepts were added by Dr.

Robert Woods of the University of Texas at Arlington. The concept of building an all out Indy

race car was changed to one that mimicked the Mini Baja competition. The teams were to design

a race car based on an imaginary engineering firm that wanted to produce and market formula

style race cars to non-professional autocross racers. This tradition continued on and after the

1992 competition Ford Motor Co., Chrysler Corp., and General Motors formed an association to

run what is now known as Formula SAE.

Florida Tech‟s involvement in the Formula SAE Series has proven a success in building and

racing formula style cars. Florida Tech‟s highest placement in the competition was from the

2004 formula car. The car placed 43rd

out of 134 teams in competition which overcame the 80th

place finish done by the 2003 formula car. Our team this year hopes to place even higher this

year with the new motor selection and suspension design.

1.1.4 Team Organization Four sub-teams comprise our formula team which consist of suspension, chassis, drive train, and

driver interface teams. The 11 members making up the team were divided into a sub-team they

were interested in. Displayed below is the formula team chain of command.

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Figure 1 - Formula Team Chain of Command

1.1.5 Scheduling

1.1.5.1 Milestones and Deadlines The team reached a huge milestone on October 6

th, 2008 when we were able to register for the

Michigan International Speedway competition held from May 13th

to May 16th

, 2009. This was

the first major milestone the team has had. Deadlines associated with the team consist of the

following:

Action Deadline Safety Plan

Human Safety Analysis 11/7/2008

Failure Modes and Effects

Analysis 2/6/2009

Formula SAE

Structural Equivalency Form 2/1/2009

Impact Attenuator Data 3/1/2009

Design Report & Design Spec

Sheet 3/2/2009

Cost Report 4/1/2009

Fuel Type Order 4/1/2009

Senior Design

Final Design Report 12/3/2008

Student Design Showcase 4/3/2009

Table 2– Formula Team Deadlines

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2.1 Chassis

2.1.1 Introduction and Purpose The chassis houses all the sub-systems and components of the car, and is one of the most

important aspects of the entire vehicle. The chassis must be designed to keep the driver safe if

any collisions occur and provide a stiff backbone for all of the components of the car to operate

correctly. An optimal chassis must be lightweight and rigid that allows for very little deflection

under static and dynamic conditions. If any part of the chassis fails, it would be detrimental to

the entire vehicle, so proper consideration must be done in order to not have any failures.

2.1.2 Goals The chassis sub-team has set design goals in order to produce the most optimal chassis for our

vehicle. The goals include:

Abiding by all Formula SAE rules and regulations

Obtaining a torsional rigidity greater than 2500 lbf/degree

Fit the 95th

percentile male driver

Allow all components of the vehicle to fit properly and securely

Have a weight of around 50 lbs.

Optimization using finite element analysis software, ANSYS

2.1.3 Background Spaceframe chassis design has been incorporated into racing vehicles since the dawn of racing.

The design is based on tubular or rectangular bars, triangulated to provide stiffness against the

static and dynamic loads associated with a race car. The simplicity associated with a spaceframe

allows for great design innovations and ease of maintenance.

The chassis must incorporate all the systems that allow the car to drive while keeping the driver

safe and comfortable. Safety is of the utmost concern when designing the chassis because if a

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collision does occur, one must be sure that the driver of the vehicle will not be injured; therefore,

the cockpit design is crucial to the development of the chassis.

While designing the chassis for all its optimizations and safety concerns, the engineer must also

take into consideration the rules and regulations set forth by the Formula SAE competition.

Proper reading of the rules ensures that a team will not be disqualified when arriving to the

competition.

2.1.4 Design Objectives The main design objectives for the chassis are:

Research fundamentals behind designing a spaceframe that will see forces associated

with a race car

Research chassis materials that can withstand the high performance ratings of a formula

style race car

Design a chassis that will be able to withstand the loads from static and dynamic forces

using solid modeling software

Perform static and dynamic load analysis using finite element analysis software

Optimize the chassis by lowering high stress concentration areas using better

triangulation of the frame members and gusseting

Finalize a chassis design that meets all requirements and regulations and begin testing of

the vehicle once all the systems have been implemented into the vehicle

2.2 Formula SAE Rules and Regulations The governing body presiding over the competition is Formula SAE, and they have defined an

intensive list of all the rules and regulations for the competition. The team must adhere to all

rules presented by Formula SAE in order to compete. There are some significant rules that need

to be discussed in order to show how the chassis sub-team designed the chassis, and all other

rules can be seen in „PART B – TECHNICAL REQUIRMENTS.‟ These rules include, but are

not limited to:

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„2.1 Vehicle Configuration – The vehicle must be open-wheeled and open cockpit (a

formula style body) with four (4) wheels that are not in a straight line‟ [1]

The car‟s wheelbase must be a minimum of 60 inches

„3.1 General Requirements – Among other requirements, the vehicle‟s structure must

include two rolls hoops that are braced, a front bulkhead with support system and Impact

Attenuator, and side impact structures.‟ [1]

„Primary Structure – The Primary Structure is comprised of the following Frame

components:

o 1)Main Hoop, 2)Front Hoop, 3)Roll Hoop Braces, 4)Side Impact Structure,

5)Front Bulkhead, 6)Front Bulkhead Support System and 7)all Frame Members,

guides and supports that transfer load from the Driver‟s Restraint System into

items 1 through 6.‟ [1]

The minimum material requirements states that the primary structure of the car must be

constructed of either round, mild, or alloy steel tubing with a minimum of 0.1% carbon

Figure 2 outlines how the driver must fit in the car in relation to the main roll hoop and

Table 3 provides minimum material requirements for various parts of the vehicle

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Figure 2 – Helmet Clearance [1]

ITEM or APPLICATION OUTSIDE DIAMETER X WALL

THICKNESS

Main & Front Hoops, Shoulder Harness

Mounting Bar

1.0 inch (25.4mm) x 0.095 inch (2.4mm)

or 25.0mm x 2.50 mm metric

Side Impact Structure, Front Bulkhead, Roll

Hoop Bracing, Driver‟s Restraint Harness

Attachment

1.0 inch (25.4mm) x 0.065 inch (1.65mm)

or 25.0mm x 1.75 mm metric

or 25.4mm x 1.60mm metric

Front Bulkhead Support 1.0 inch (25.4mm) x 0.049 inch (1.25mm)

or 25.0mm x 2.50 mm metric

or 26.0mm x 1.2mm metric

Table 3– Minimum Material Requirements [1]

The rest of the rules can be viewed on the Formula SAE website where there is more information

on the constraints for the vehicle. These were the more important rules that needed to be

highlighted.

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2.3 Chassis Design and Analysis

2.3.1 Chassis Design Introduction

Chassis design began with the regulations set forth by the Formula SAE rules committee, and

from those given dimensions a basic shape of the chassis was formed as seen in figure 3.

Figure 3 - Solid Works Rendering of Chassis Regulations

The cockpit, 95th

percentile male, and leg tunnel dimensions were all given information in the

2009 rules, and were modeled in Solid Works to have a visual of what to expect this year‟s

chassis to look like. Among these specifications set forth by Formula SAE, we need to account

for the incorporation of a motor, drive train, suspension components, and various other sub-

systems. Stress calculations need to be looked at to ensure optimal operation of all components

in the vehicle and ensure failure does not occur.

The American Society for Nondestructive [2] testing has set a standard for the factor of safety for

these cars at 3. With this key factor in mind, it allows the team to narrow down materials that can

be considered for the construction of the chassis. Table 2 defines a material selection chart for

determining the material for chassis construction with properties from Matweb.com [3].

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Material Candidates

Design Requirements Overall Rating

UTS Yield Strength Density

Absolute Value

Relative Value

Absolute Value

Relative Value

Absolute Value

Relative Value

AISI 4130 Steel

97.2 ksi 1.00 63.1 ksi 1.00 0.284 lb/in3

0.34 0.99

T6-6061 Aluminum

45 ksi 0.46 40 ksi 0.63 0.0975 lb/in3

1.00 0.54

AISI 1020 Steel

55.1 ksi 0.57 29.7 ksi 0.47 0.284 lb/in3

0.34 0.53

Table 4– Material Selection Chart for Chassis Construction [3]

AISI 4130 chromoly steel outranks both T6 aluminum and 1020 alloy steel drastically. This

choice of material was used in all of the previous formula cars designed by Florida Tech teams,

so its strength and durability has been tried and tested. 4130 steel comes in square and round

tubes, and we have designed the chassis around using round tubes due to the increase in torsional

stiffness seen by the constant moment of inertia around a central axis which is defined by the

following equation.

– Moment of Inertia of a circle with constant cross sectional area

Utilizing the factor of safety of 3 and the Ultimate Tensile Strength of 4130 steel of 97.2 ksi, we

obtained a new UTS of 32.4 ksi, and for the Yield Strength we come to 21 ksi. These values will

be used to determine whether or not the chassis will fail at the loads seen during static and

dynamic loadings. If the chassis sees a stress greater than the Yield Strength, the chassis will

plastically deform and the structure will be compromised, but if it exceeds the UTS, then the

structure will fail. Neither of these situations should be seen when driving the car, so proper

gusseting and triangulation will be placed into the design to ensure these stresses will never be

seen.

2.3.2 Design Analysis

Designs of previous cars were looked upon for ideas about how to conceptualize a new chassis

and cars from other competing teams were looked at for more ideas. Preliminary chassis designs

took shape in Solid Works and improvements were made on these designs to incorporate the

various systems of the car. The first design, as seen in figure 3, shows a model in Solid Works

with members that conform to all the rules and regulations. The chassis uses basic geometry to

satisfy regulations and triangulation was used to provide stiffness to the overall design.

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Figure 4– First Chassis Design Model

This model allowed us to see what challenges would come about. A rendered model of the

engine was placed into the conceptual chassis design, and we soon found out that we needed to

resize and move certain members that interfered with the engine mounting. A redesigned chassis

with better placement of frame members can be seen in figure 5 below.

Figure 5– Redesigned Chassis

This new chassis design allows better fitment for the engine and suspension geometry has been

updated to incorporate a new suspension design.

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2.4 Budget

Part Part Number/Code Unit Price Quantity Price Company

4130 Steel Tubing

1'' OD x 0.095'' Wall 4130 - ALLOY TUBE

ROUND $7.89 15 $118.35 olinemetals.com

1'' OD x 0.065'' Wall 4130 - ALLOY TUBE

ROUND $6.02 70 $421.40 olinemetals.com

1'' OD x 0.049'' Wall 4130 - ALLOY TUBE

ROUND $5.80 15 $87.00 olinemetals.com

Tabs 11 GA HRPO Radius

Tab 02-105 $1.75 26 $45.50 tabzone.com

TOTAL

$672.25 Table 5– Chassis Sub-Team Budget

2.5 Scheduling

2.5.1 Gantt Chart

Figure 6– Chassis Sub-Team Gantt Chart

2.5.2 Milestones and Deadlines

Milestones already seen by the chassis sub-team include modeling a preliminary design in Solid

Works and working with this model to optimize it for all of the sub-systems. The sub-team plans

on having a chassis mock up built with conduit by the middle of November as seen on the Gantt

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chart. After a successful building of a mock up chassis, the real chassis fabrication can begin.

Deadlines associated with the chassis sub-team can be viewed in the Gantt chart above.

2.6 Conclusions

A properly designed chassis will prove to make the entire project run more smoothly and fewer

headaches will be felt by the team. Close attention to detail in the design will yield promising

fitment and results in the future of this team. More analysis needs to be done on the chassis itself,

and once that is complete or almost complete more analysis on the attachment points for the

engine, drivetrain and suspension components.

3.1 Suspension

3.1.1 Introduction and Purpose

Although the car we hope to build is not an off-road vehicle and does not have the suspension

requirements of such, suspension is still a major aspect of the efficiency of the vehicle. The

suspension system serves a dual purpose – contributing to the car's handling and braking for

good active safety and driving performance, and keeping vehicle occupants comfortable and

reasonably well isolated from road noise, bumps, and vibrations. Although these goals are

generally at odds and tuning must find the right compromise, driver comfort is not a big priority

in the flat track we must run, so our car‟s tuning will be focused on performance. With the

technology available today, an ideal suspension system for a track car will balance out the forces

experienced while turning from one side to the other and while braking from the front to the rear,

however we aim to keep the design simple and cost efficient so we will use independent wheel

system. Our suspension system will focus on providing maximum traction at all times and to

control the sway of the car during steering and braking.

3.1.2 Goals

The goals of the suspension sub-team are the following:

• Design and create a suspension system that will meet all the SAE specifications and

design objectives

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• To maximize traction so as to have maximum deliverance of power

• To cancel out the uneven weight distribution experienced during turns and braking

• Maximize vehicle performance with optimal use of suspension

• Perform well in competition

3.1.3 Background

SAE requires that we are to assume that we work for a design firm that is designing, fabricating,

testing and demonstrating a prototype vehicle for the non-professional, weekend, competition

racer market [4]. The vehicle should have a very high performance in terms of acceleration,

braking, and handling and be sufficiently durable to be successful at the events described in the

formula SAE rules and held at the Formula SAE competition [5].

3.2 Design Objectives

Our primary objectives will be to fulfill the design requirements instituted by the SAE rules.

According to the SAE 2009 rules we must build a car with a fully operational suspension system

with shock absorbers, front and rear, with usable wheel travel of at least 50.8mm (2inches),

25.4mm (1inch) jounce and 25.4mm (1inch) rebound, with driver seated. The judges reserve the

right to disqualify cars which do not represent a serious attempt at an operational suspension

system or which demonstrate handling inappropriate for an autocross circuit [6]. Rules also state

that all suspension mounting points must be visible at Technical Inspection, either by direct view

or by removing any covers. Finally, the ground clearance must be sufficient to prevent any

portion of the car (other than tires) from touching the ground during track events, and with the

driver aboard there must be a minimum of 25.4mm (1inch) of static ground clearance under the

complete car at all times [7].

The car will be traveling on even terrain therefore when analyzing suspension we will

only be dealing with two major forces, cornering and braking. Lateral force is the forces exerted

on the suspension arms as the vehicle turns and the weight of the vehicle shifts towards one side.

The braking force is the force on the suspension arm created when the weight distribution of the

car shifts to the forward steering knuckle as the car breaks.

To calculate forces due to cornering, we must understand the forces created as the car

pushes against the asphalt, thus friction comes into play. In extreme turns we can assume that the

full weight of the vehicle will shift to one side of the car or even to one tire thus we must prepare

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the a-arm to withstand such force. When the full weight of the car is established we can run

calculations to find the normal force experience if the entire weight of the car were to shift to one

side or even one wheel.

For the braking forces we will perform similar calculations. As the vehicle brakes, the

brake caliper will force the brake pads into the rotor so as to stop its motion. Once the rotor is

locked the breaking force will be created by the friction as the weight of the car travels forward.

The braking force will then create a moment that will translate into the suspension arm through

the steering knuckle. Thus our design will have to sustain this moment.

3.2.1 Suspension Definitions

Shock absorbers, and travel

Shock absorbers and dampers are important elements of suspension and are the key

element to supporting and balancing the forces that the arm will be suffering. We will use

adjustable dampers so as to be able to control our jounce and bounce and also tune the

suspension for greater efficiency. Also, adjustable shocks will allow us to fine tune the

suspension to the different weight of different drivers. Shocks will be connected to the top A-arm

via a pull rod for the front suspension, thus mounting will be considered when analyzing stresses.

The rear suspension will use the more commonplace pushrod style where the link connects to the

lower A-arm. The connection to the A-arm will also determine the travel of the wheel assembly.

Ground Clearance

The lower suspension arm will also determine our ground clearance. SAE 2009 rules

specify a particular ground clearance as stated earlier. The tuning of shocks and the design of the

lower arm will all have to fit in order to achieve this clearance.

Wheelbase and Track Width

The minimum wheel base of the car is 60‖. The track widths may be different, but the

smaller track width cannot be less than 75% of the larger track width. The track width is

measured from the centerlines of the wheels.

The chosen track width for the front of the car is 48‖. This will provide a stability, but

it’s not so wide that it will hinder or cornering and maneuverability. The wheelbase is set at the

competition minimum of 60‖.

Kingpin Inclination and Scrub Radius

The first parameter that had to be determined besides track width was kingpin inclination.

This is the angle between vertical and the axis running through the upper and lower ball joints

(see figure 7). The kingpin inclination affects steering performance and return ability. This is

24

interrelated with the scrub radius and the spindle length, which were minimized for this design.

The spindle length is the distance from the kingpin axis to the centerline of the wheel at the

wheel axis. The scrub radius is the distance from the kingpin axis to the center of the wheel at

the ground. By minimizing the spindle length and scrub radius, the jacking effect when the

wheels are steered is minimized. That results in less steering effort on the driver’s part and less

sensitivity to braking inputs.

Figure 7 - Diagram of Kingpin Inclination and Scrub Radius [4]

Camber

Camber angle is the angle made by the wheel of an automobile; specifically, it is the

angle between the vertical axis of the wheel and the vertical axis of the vehicle when viewed

from the front or rear. If the top of the wheel is further out than the bottom (that is, away from

the axle), it is called positive camber; if the bottom of the wheel is further out than the top, it is

called negative camber [8].

Negative camber is useful to improve grip when cornering. A negative angle places the

tire at a more optimal angle to the road and thus transmits the forces through the tire rather than

across it. Negative camber also prevents the tire from rolling on itself and maximizes the contact

area of the wheel and tire during cornering.

When in straight-line acceleration, however, the greatest traction will be attained when

the camber angle is zero and the tread is flat on the ground. Therefore when considering camber

we must analyze both options and find a compromise between both because although it is

possible to make an adjustable camber suspension, it is of greater difficulty.

25

Figure 8- Camber [5]

Caster

Caster angle is the angular displacement from the vertical axis of the suspension of a

steered wheel in a car, bicycle or other vehicle, measured in the longitudinal direction. It is the

angle between the pivot line (in a car - an imaginary line that runs through the center of the upper

ball joint to the center of the lower ball joint) and vertical [9].

The caster angle is important to make the car easier to drive and improve stability.

Excessive caster angle will make the steering heavy and less responsive; however, in racing large

angles are used to improve camber gain in cornering. Once again, in our designs we will have to

compromise and see which will be more efficient for our increased performance vehicle.

26

Figure 9- Caster [6]

Toe

Toe is the angle made by the wheel with respect to the longitudinal axis of the vehicle.

Toe in, when the front of the tires are closer together than the rear of the tires, aids in straight line

stability, but can hinder steering performance. Toe out on the other hand will improve the

efficiency of the steering system.

Figure 10- Toe Angles [7]

27

3.3 Design Analysis

The front suspension is of the double wishbone type and has been designed to provide good

camber change in both bump and chassis roll. The kingpin inclination was kept small in order to

minimize the spindle length and scrub radius. It will activate its shock absorbers via a pull rod

and rocker link. By utilizing a pull rod, it allows a lower mounting of the shock absorbers,

aiding in lowering the Center of Gravity.

Figure 11- Example of Double Wishbone with Pull rods [8]

The rear suspension will consist of a design similar to the double wishbone setup, the Arning

four-link suspension. It has a regular A-arm for the upper arm, but the lower arm is a two piece

design. The lower ball joint is between frame and control arm, as opposed to between the

control arm and wheel upright. Between the wheel upright and the lower control arm is an

inclined axis that will induce toe in under jounce conditions and toe out under rebound

conditions. This positions the wheels ideally to allow the rear wheels to aid in steering under

normal chassis roll that occurs when the car is in a turn.

28

Figure 12- Plan View of Arning Four-Link [9]

The analysis will be done using Adams/Car. From there, we can get the loads that the

suspension arms will exert on the chassis. These loads can then be applied to the chassis in

Ansys in order to optimize our chassis.

Static Camber -1.5˚

Camber in Jounce -2.92°/1.5‖

Camber in Rebound -0.8˚/1.5"

Caster 4˚

Spindle Length 0.13"

Kingpin Inclination 3˚

Toe In 0˚

Ground Clearance 1.5"

Static Roll Center Height 1.25‖

Table 6 - Front Suspension Geometry

29

3.3.1 Braking Analysis

Braking is a huge aspect of the formula car. The formula car must be able to brake very

efficiently, as nearly every part of the competition involves braking. There is a test solely

devoted to the braking capabilities of the car. Also the endurance race involves heavy breaking.

We feel that the most efficient braking setup for this car will be to have brakes on both front

wheels and one brake on the rear sprocket. The braking system must be controlled by a single

control which will have two independent hydraulic circuits in case of a leak or failure. This

system will allow the car to maintain braking power in the case of a leak or failure.

Figure 13- Wilwood Brake Caliper from Side Mount Car

Figure 14– Upright from Side Mount Car

30

The components of the brake system will be taken from the 2005 side mount car. This braking

system includes a Wilwood combination (seen above) “remote” tandem master cylinder, which

meets the Formula SAE specifications [1], calipers with brake pads, rotors, brake lights, and steel

braided Teflon hoses.

As the side mount car has never been used, the braking system on it is brand new, which means

that we will not need to purchase anything apart from braking fluid for the car.

The brake rotors are made of hardened steel, which have been known to be very durable. As one

of the major aspects of competition is the auto-cross and endurance.

Wheels and Tires

We have decided to use 13” rims, which according to Formula SAE rules [1] is permissible. In

order to save money, we have decided to use the rims from the 2005 side mount car. These are

13” rims, with single bolt on. A picture of this rim can be seen below.

Figure 15– Center Locking Wheel off of 2005 Side Mount Car

31

360 lb

Our tire selection is based on many different factors. Due to the fact that we are are reusing the

side mount cars rims, we are limited to 13” rims. This though is the preferred choice of many of

the teams competing, and therefore it is not of any disadvantage to us. 13” rims are optimum for

the performance of this car due to the overall weight. Another factor in tire selection is the width

of the tire. The width is a very important aspect for the handling of the car. The width we are

looking at, is something between 6.5” and 7.5”. Rims can usually take a certain range of tires

width. The 6.5” width is good because it reaches operating temperature quickly while weighing

only 9lbs. Lighter weight and quicker operating temperature compensate for better handling in

the 7.5” tire, which weighs 13lbs.

Tire selection is also based on weather. We must have tire compounds which can handle both

wet and dry conditions. Our tires will be bought from either Goodyear or Hoosier. Goodyear

offers this tire at a price of about $153, while Hoosier offers it at $133. Both companies offer

very similar tires made up of the same compounds and thus it is only a matter of which company

would sponsor us.

3.3.1.1 Braking Calculations

Calculations based on 2007 REV Car [10]

Brake Force Calculations

Brake Pedal:

Assume that the driver input force is 90 lb.

Moment output from pedal:

inlb

180)2()90(

Distance))(InputForce(Moment

The caliper:

The calipers have two pistons that actuate the brake pads so the force is multiplied by 2.

))((2 APF

Where:

4

2DA

P: the pressure from the master cylinder

4 in

32

D: the diameter of the caliper

FCaliper Force: the clamp load

A: area of the caliper

Rear Calipers:

lbF

inA

ceCaliperFor 64.67704.179.3252

04.14

)15.1( 22

The brake pads:

There are two brake pads so the force is multiplied by a factor of two.

)( Force)(Caliper 2 ForceRotor

Where:

= coefficient of friction = 0.45 (good assumption for most race cars)

Front:

lbF 26.48645.024.5402

Rear:

lbF 88.60645.064.6772

The rotor:

The torque applied on the rotor acts on both side so the torque is multiplied by 2.

))(Force(2)(Rotor Torque d

Where:

d: The distance between the center of the rotation and the force to act at a point midway across

the rotor face.

Front:

inlbT 2.4862522.4862

Rear:

inlbT 16.42485.388.6062

33

The wheels and tires:

r

TorqueF

Where:

F: Force generated between the tires and road

r: Rolling radius of tire

Front:

lbF 22.48610

2.4862

Rear:

lbF 82.42410

16.4248

Acceleration calculation:

W

FFa l )(2)(2 Rear WheelFront whee

Where:

a: Lateral deceleration

F: Force generated between the tires and the road for the front and rear tires. Force is multiplied

by a factor of 2 because there are 2 front and 2 rear tires.

W= Total estimated weight of the car, which includes car and driver.

ga 80.2650

)82.4242( )22.486(2

Stopping distance:

a

VD i

2

2

34

Where:

Si: the initial speed

a: Lateral deceleration

sftmile

ftX

s

hrX

hr

mileVi / 3.117

1

5280

3600

1 80

22

/ 99.89 1

s

ft32.14

X 80.2 sftg

ga

ftD 45.76)99.89(2

3.117 2

3.4 Detailed Drawings

Figure 16– Front Suspension Drawing

35

3.5 Budget Part Unit Price Quantity Total Manufacturer

Chromoly 4130 Tubing 5/8”OD x

.058”Wall

$26.50/8ft 2 $51 Onlinemetals.com

Spherical Rod Ends(sizes vary) $5-$10 32 $160-320 Aurora Bearing

Company

13” x 7.5” Aluminum wheels $215 4 $860 Keizer Aluminum

Hoosier 225/45/13 A6 Autocross Radials $181 4 $724 Tirerack.com

Tapered roller bearings(wheel bearings) $10-$20 8 $80-$160 Timken

Table 7– Initial Suspension Sub-Team Budget

3.6 Scheduling

3.6.1 Gantt Chart

Figure 17– Gantt Chart Suspension Sub-Team

36

3.7 Conclusions

This design should result in a sound suspension system for our formula car. Once the designs of

the front and rear are complete, the analysis using Adams will begin in order to optimize the

designs. It will provide optimum handling characteristics for weekend autocross racing.

Independent suspension all around will provide good traction to get the power to the ground and

help keep the driver in control of the vehicle at all times.

4.1 Drivetrain

4.1.1 Introduction

The drive train encompasses all the components that power the car. It is paramount that the

motor be reliable yet produces ample efficient power. The power produced from the motor must

be transferred to the differential in a simple compact manner. Then the differential must transfer

the power through the axles to the wheels. All these components must be carefully selected as to

not absorb excessive power from the motor yet be strong enough to endure rigorous race

conditions.

4.1.2 Purpose

The Drive Train team is responsible for creating and transferring the power obtained from the

engine, to the wheels with the highest efficiency possible. The ultimate purpose of team is to

design and build the drive train itself which encompasses the engine and its necessary

components, power transfer from the engine to the differential, power transfer from the

differential to the wheels, and ultimately power transfer to the ground.

4.1.3 Goals

The design objectives for the drive train team are comprised of:

• Obtaining maximum power output from the engine with all the restrictions in

place.

• Make an engine that is as fuel efficient as can be without sacrificing power.

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• Build a flexible engine that can be tuned for different aspects of competition.

• Build a reliable and effective engine that can be easily repaired or replaced

• Design the most effective way to transfer power from the engine to the wheels.

• Obtain the best and most effective transmission.

• Design the least expensive way of mounting the differential to the chassis.

• Find the most efficient way of connecting the differential to the wheels.

4.1.4 Background

The engine and power train components are vital to the success of any Formula SAE team.

Evaluating the characteristics of the three most popular engines in past Formula SAE

competition that comply with rule 3.5.1.1 started the engine selection process. They were

evaluated on their power to weight ratio, complexity, availability, ease of modification and

tuning. The most popular is the fuel injected inline four cylinder 600cc found commonly in road

bikes. They‟re known for making the most power but are very complex to modify and tune. Next

is the fuel injected v-twin 550cc which is also commonly found in road bikes. It shares the same

characteristics listed above for the 600cc. Lastly a fairly new entry to SAE competition is the

naturally aspirated single cylinder 450cc that can be found in late model motocross bikes. It is

quickly gaining popularity due to its light powerful nature derived from its original purpose of

extreme off road racing. All the motors have an integrated transmission, although the 450cc

transmission has the closest gear ratios. This is ideal for the tight circuit the car will be

competing on. Thus the 450cc engine is the first choice for the FIT 2009 Formula SAE car.

4.2 Design Objectives

With the Max Power CRF523R ICE CUBE Big Bore/Stroker kit installed along with the other

proposed performance modifications, Max Power reports an average of 70rwhp. This is an

unrestricted power/weight ratio of 1.27 versus the 600cc at .92. Due to the 450cc being naturally

aspirated it will most likely have a higher power loss ratio than the 600cc. Although the above

power numbers are from well tuned motors which the team feels much more capable of tuning

the 450cc.

38

4.3 Design and Analysis

Power Train Components:

Tri-pod housing & Spline Shaft

Tri-pods

Tri-pod Boot

Tri-pod Axle Shafts (Axles)

Chain & Sprockets

CRF450R and Components

CRF523R ICE CUBE Big Bore/Stroker

Boyesen Hy-flo Water Pump

Pro Circuit Stainless Valves

Pro Circuits Camshaft

Pro Circuit Valve Springs

Hinson Clutch Basket

Torsen T-1 Differential

4.3.1 Drive train Analysis

Due to the success of its usage in most of the Formula SAE cars previously within other

universities, the 2009 team continues to use the ―university special‖ limited-slip differential

manufactured by Torsen Inc. The university special differential was derived from the center

differential used in the 1988 Audi Quattro. With the purchase of the differential set, we receive

the side gears, element gears and the planet gears which all make up the differential as well as

the sealed differential gear case that holds all these gears in place.

A key element in the selection of the Torsen T-1 differential selection is the Torque sensing

also known as the Torque Biasing system. The torque that comes from the engine is continuously

managed between the two axles and biased instantaneously according the variable road

conditions. Another key element is the weight. Compared to the 2004 Florida Tech FSAE car

which have used the Quaife Civic differential that is 13 lbs, the Torsen T-1 differential weighs

about 7 lbs.

39

Differential Candidate Quaife ATB Torsen T-1

Torque Bias yes yes

Limited Slip yes yes

Weight 13 lbs 7 lbs

Price $995.00 $495.00

Table 8 - Comparison of Quaife & Torsen T-1

Figure 18— Cutaway of differential (Torsen T-1) [11]

Some key specifications of the Torsen T-1 differential are as follows:

Table 9- Differential Specification [2]

Bias Ratio 3.0:1

Weight 7 lbs. 2 oz.

Lubrication 80W-90 GL5

Bolt Torque 35 ft-lbs

40

A depiction of the drive train system of the Florida Tech 2003 automobile is as follows:

Figure 19- Drive Train Prototype Florida Tech 2003 Car

4.3.2 Engine Choice

A rendered model of the Honda CRF 450 engine is as follows as it is designed on PRO-E:

Figure 20–(a)Pro E model of CRF450R Engine Model

41

Figure 21– Actual CRF450R[12]

Table 10- Engine Specifications

The decision to go with the 450cc engine as opposed to the standard 600cc engine that

has been used in the past was to lose some excess weight from the motor and still have decent

power output. The smaller 450cc engine can fit much more compactly in the chassis resulting in

a lower center of gravity and smaller wheelbase. Another benefit with the 450cc comes from the

tuning of the motor. It utilizes a carburetor induction system which simplifies the complex fuel

injection system of the 600cc motor. The simpler carburetor system will free up time for us to

put into other aspects of the car that may need much more attention. We feel this setup will be

competitive at competition when paired up with the design of our chassis.

Stock Power Output 53 Hp

Target Power Output 65 Hp

Weight 55lbs

Lubrication Honda HP4

42

4.3.3 Transmission Analysis

Our goal is to achieve a speed of 80mph. Looking at the speed calculations, we see that this car

is capable of reaching a speed of 120mph with a final drive of 4.4. This top speed is high and

therefore we can increase the ratio of the gear on the drive train in order to increase torque and

acceleration which would be more useful to us than a high top speed.

Below are the gear ratios of the CRF 450R:

Gear Ratios

1 - 0.800 (27/15)

2 - 1.470 (25/17)

3 - 1.235 (21/17)

4 - 1.050 (21/20)

5 - 0.909 (20/22)

Final Reduction 3.923 (51/13)

Final Drive #520 T-ring sealed chain

Below, we see that there are two tables plotted on the graph. The green plotted lines are the lines

that show the regular gear ratios and final drive of the car. After careful research we realized that

most teams set their final drive at 4.4:1. Final drive is the ratio between the sprocket attached to

the engine and the sprocket attached to the drive train. Using the regular final drive calculation,

our car would be able to hit speeds of up to 122mph. Although this is impressive, it is not the

most efficient setup to run the car at. This is so because during competition the car is predicted to

hit a top speed of about 70mph due to all the curves and the lack of straights.

Therefore after further investigation, we have decided to increase the final drive to 7.2:1, which

would give us a top speed of 82mph. This setup we feel is the best for the car, since in shortening

the gears, we can hit optimum power more often and thus get the most out of our horsepower and

torque. Looking at the dynamometer chart we found the optimum power to be between 7500rpm

and 9000rpm. Our chosen setup is shown on the graph with the red lines.

43

Table 11- Graph above shows regular and custom setup for the gear box of the car[13]

44

Figure 22- Dyno chart for the CRF450R

Looking at the Dyno Chart above, we see that the optimum horsepower for our Formula car is

between 7500rpm and 9000rpm. We can also see that the optimum torque for the car is between

7000rpm and 8000rpm. In order to get the most out of the engine we must set up the car so as to

spend most of our driving time at these rpm‟s. This can be done due to the fact that top speed is

not an issue. To do this we must shorten the gears and increase the final drive. Research has been

done on this and the final drive of 7.2:1 has been decided.

45

4.4 Detailed Drawings

Figure 23- Detailed Drawing of the Torsen T-1 Differential [12]

46

4.5 Budget Drive Train Budget:

PART QUANTITY COST

Tri-pod housing & Spline Shaft 4 $196.00 each

Tri-pods 4 $60.00 each

Tri-pod Boot 4 $36.00 each

Tri-pod Axle Shafts 2 $179.00 each

Plastic end pieces 2 $35.00 each

Torsen T-1 Differential 1 $490.00 each

Chain & Sprockets 3 sets $389.99

TOTAL $2495.99

Table 12 - Drive Train Budget

The parts associated with the drivetrain come from Taylor Race Engineering [14]. They carry a

variety of different parts that are dedicated towards Formula SAE cars.

Engine Budget:

PART QUANTITY COST

CRF450R and Components 1 $1000.00

CRF523R ICE CUBE Big Bore/Stroker 1 $2650.00

Boyesen Hy-flo Water Pump 1 $189.99

Pro Circuit Stainless Valves 1 set of 4 $350

Pro Circuits Camshaft 1 $457.99

Pro Circuit Valve Springs 1 set of 4 $239.99

Hinson Clutch Basket 1 $209.99

TOTAL $5097.96

Total Budget: $7113.95 Table 13 Engine Budget

47

Performance parts for the engine were sourced from Max Power Engines [15], which

have a great selection of replacement parts for our engine choice. The performance parts listed

above will increase the power output of the motor giving us a great advantage during

competition.

4.6 Scheduling

4.6.1 Gantt Chart

Figure 24– Gantt Chart for Drivetrain Sub-Team

4.6.2 Milestones and Deadlines

Decided on Torsen Differential October15, 2008

Final drive ratio 3.25 October 20, 2008

Intake system Design October 29, 2008

Differential Prototype November 5,2008

Order Radiator and Fan November 25,2008

Intake system for 2009 car December 1, 2008

Final Power Train Design Completion December 10, 2008

48

4.7 Conclusions

The team feels confident in our drive train component selection. Due to the sheer simplicity and

availability of the 450cc along with performance parts, we feel it will be a very competitive

motor. By choosing a lighter motor, the overall handling of the car should benefit from the lower

center of gravity. The chain drive will provide variable light weight power transmission to the

well proven Torsen differential. This drive train is very light weight and simple, yielding better

performance and more time available for testing.

49

5.1 Driver Interface

5.1.1 Introduction and Purpose

The main purpose of this sub team is to provide safety to the driver and also to provide the car

with an efficient steering system which is crucial for one of the competition‟s disciplines. The

steering system is a vital component of a car as well as the driver‟s interface. The purpose of this

sub team is also to provide the best interface possible between the driver and the car.

5.1.2 Goals

Our goal is to make a car that can turn with the smallest curvature angle possible. Indeed, during

the competition, one of the disciplines is a short circuit that the car should achieve in which the

turns are very short and the wideness of the path is small. The driver should have the best driving

position possible and be able to kill the engine easily. The wheel also needs to be taken off with

no effort in case of emergency and the driver needs to get off the car. Thanks to all the parts we

can get from previous cars, we also want to keep the expenses in our sub team as low as possible.

5.2 Design Objectives

Our main objective is to give the driver comfort and simplicity of controlling the vehicle.

However, as we want to save money and be sure to finish the car in time, we do not plan to make

the seat and pedal adjustable. We want to keep our design simple and to give the driver as much

control as possible at a low cost. We want to do all of this without over viewing the driver‟s

safety.

5.3 Driver Interface Design and Analysis

5.3.1 Accelerator and Clutch Pedals

5.3.1.1 Engineering Specifications The main design objective of design the acceleration and clutch pedals to work within the limits

of the throttle body of the carburettor and the clutch. Also for the comfort of the driver, the

pedals cannot interfere with the movement and placement of the driver‟s foot. While the pedals

50

need to fit within the dimensions of the vehicle, they also need to be mounted such that the travel

distance of the pedals will work within the vehicle‟s cockpit.

5.3.1.2 Design History In designing the pedals and mounts, it was realized that the designs of both pedals would be

easier if everything was kept as simple as possible. With the motor and transmission that the

team decided upon, the accelerator and clutch are both cable driven.

As designed on the side-mount car, the pedals could be mounted to the chassis with the cables

mounted directly to the pedal assembly. This design was previously used on the side-mount

project of the previous team. The previous team designed this pedal assembly with a spring to

retract the pedal. An example of this can be seen in figure 23 as the accelerator pedal mounted on

the side-mount project. Note as the previous team took a different route with the clutch pedal

whereas the FSAE car will use this design for both the accelerator and clutch pedals.

Figure 25. Side-mount car pedal setup

5.3.1.3 Engineering Analysis With the pedal mounted on the chassis as shown above, the pedal will be easy to engineer and

mount. Final tuning of the carburettor will determine how much pedal travel is needed to achieve

the best results. Ideally, the pedals should not travel very far. The goal of the overall design is to

have a pedal that rotates between 45 and 60 degrees from the pivot point to minimize the linear

distance of pedal travel but to give the driver more control and half throttle and half clutch.

Pedals are useless without control up to their fully extended positions. Spring forces to return the

pedal to its original position should be high enough to return the pedal quickly but at the same

time not interfere with the amount of force the driver needs to exert to use the pedal. In addition

51

to these decisions, the pedal area can be altered allowing the driver to move between pedals

effortlessly and not have to worry about hitting the wrong pedal.

5.3.1.4 Material Study The materials chosen for this design should accompany the simplicity of the engineering. The

materials must be readily available and easy to manufacture. The material which would suit the

need is aluminium. Aluminium is light weighted, strong, easy to machine and inexpensive. Nuts

and bolts to mount the pedal assembly will be made of steel and can easily be found at the local

hardware store for a very low price.

5.3.2 Brake Pedal

5.3.2.1 Engineering Specifications The engineering specifications of the brake pedal are very similar to the accelerator and clutch

pedals. For the comfort of the driver, the pedal cannot interfere with the movement and

placement of the driver‟s foot. The pedal will also need to fit within the dimensions of the

vehicle and needs to be mounted such that the travel of the pedal will not interfere with anything.

5.3.2.2 Design History As designed on the side-mount car, the pedal assembly will be mounted to the floor plate of the

chassis with a hydraulic reservoir. A brake pedal similar to the accelerator and clutch pedals

could not be utilized because the team chose a hydraulic system over a cable system. The brake

pedal assembly can be seen in figure 23 between the accelerator and clutch pedals.

5.3.2.3 Material Study The brake pedal assembly from the side-mount car is a Wilwood Engineering brake pedal with

optional dual master cylinders. As shown in figure 24, the Wilwood brake pedal is adjustable and

has an brake bias adjuster to fine tune braking between the front and rear wheels. The figure also

shows the dual master cylinders mounted behind the pedal to reduce the overall room the

assembly.

52

Figure 26 Wilwood Dual Cylinder brake assembly [2]

5.3.3 Steering Wheel

5.3.3.1 Engineering Specifications The steering wheel for this vehicle needs to meet two specifications. The steering wheel design

needs to be easily removable so that the driver can exit the vehicle quickly in case of emergency.

Also, the steering wheel needs to be able to turn a full rotation easily without interfering with the

driver. The driver needs to be able to turn the steering wheel one full rotation easily or the

performance of the car will be limited.

5.3.3.2 Design History The steering wheel went through a few transformations in its design. Originally, a racing steering

wheel was going to be purchased along with a quick release hub. To keep costs down, a standard

round wheel would have been used with a very simple hub. The decision to reuse the steering

wheel on the side-mount project became a possibility as well. This decision was thrown away

when the steering wheel was determined cheap and poorly constructed. Figure 25 shows the

steering wheel of the side-mount project.

53

Figure 27Steering wheel of the side-mount

The final decision was to engineer one about 12 inches in diameter. A Formula style steering

wheel will be constructed with rounded edges for easy driver manoeuvrability and non-rounded

portions on the top and bottom to give the driver more room in the cockpit.

5.3.3.3 Material Study The material selected for the steering wheel is aluminium; the use of rubber grips has not been

decided yet. Aluminium was selected for the steering wheel because it needs to be light weight

and durable. The steering wheel will need to be removed often and a heavy steering wheel will

be detrimental and unnecessary. A light weight aluminium wheel will also be easy to

manufacture and ease the steering of the car.

A pin will be used to keep the steering wheel attached to the shaft. The pin will be machined out

of steel because it‟s strong and readily available. Other ideas for the pin include a ring that is

easy to grasp so the driver can remove the pin quickly in case of emergency.

5.3.4 Steering Rack

5.3.4.1Engineering Specifications The design objective of the steering rack is to steer the car with minimal effort. For the

ergonomics of the driver, the steering rack needs to have a ratio high enough to quickly steer the

wheels but low enough that the driver has control of the car at all times. Also, the steering rack

needs to be able to be small and light enough to mount within the car and cannot be detrimental

to the overall performance.

54

5.3.4.2 Design History Steering racks are difficult to manufacture and the purchase a pre-made rack was decided from

the beginning. However, we also had the option of reusing the steering rack from the side-mount

project, which had been mounted to the car vehicle but never used. This steering rack, as

pictured on the side-mount car in figure 26, has the gearing ideal for the competition and

although it needs to be well lubricated, suits our needs.

Figure 28-Steering Rack of the side-mount

5.3.5 Driver’s Seat

5.3.5.1 Engineering Specifications A driver seat has to accommodate for the driver comfort and ergonomics. The weight of the seat

also should not weigh down the car.

5.3.5.2 Design History The design for the actual seat had been up in the air for awhile. The original plan was to reuse

the seat from the side-mount project, the plans changed, however, when it was realized that

someone had already reused the seat. Another idea was to make a seat out of fabric, but this was

deemed unsafe and impractical. The final decision was to purchase a light weight seat.

5.3.5.3 Material Study There are many seats on the market for the type of vehicle our team is building. Generally, all of

the seats are made of either some form of plastic or fibreglass. These two materials are light

weight and somewhat flexible for comfort. The Tillet T8 seat shown in figure 27 is a good

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example of what we are looking for. Racing seats such as the T8 generally range from 150 to 300

dollars.

Figure 29Tillet T8 Racing Seat [1]

5.3.6 Instrumentation

5.3.6.1 Engineering Specifications Instruments to measure parameters of race cars come in all shapes and sizes with different

sensitivities. Finding instruments to monitor the performance of our vehicle generally comes

down to compact, accurate gauges that are inexpensive.

5.3.6.2 Design History We will not be able to manufacture our own instruments, however, we will be able to purchase

them and wire them into a cluster. The gauges needed for this vehicle will probably consist of a

tachometer, coolant temperature, oil temperature, battery voltage, and speedometer. Summit

Racing manufactures compact and accurate gauges which were featured on the side-mount

project. Figure 28 shows the condition of the gauges. Notice the gauges are new and never

mounted. Overall, instrumentation will cost a few hundred dollars.

56

Figure 30Summit Racing gauges

5.3.7 Safety Equipment

5.3.7.1 Engineering Specifications For safety requirements, the driver must comply with the safety guidelines of the Formula SAE

rules as stated in Article 17. The driver is required to have a helmet, fire suit, gloves, goggles or

face shields, and shoes. Specifications are as follows:

Helmet

- Snell M2000, SA2000, M2005, K2005, SA2005

- SFI 31.2A, SFI 31.1/2005

- FIA 8860-2204

- British Standards Institution BS 6658-85 types A or A/FR rating

Fire Suit

- SFI 3-2A/1 (or higher)

- FIA Standard 1986

- FIA Standard 8856-2000

Fire resistant gloves and shoes with no holes

Goggles or face shields made of impact resistant materials

A harness of 5 points or more made of Nylon or Dacron polyester.

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5.3.7.2 Material Study

5.4 Engineering Drawings

Figure 31- Wilwood Pedal [2]

5.5 Budget As we want to keep the price low in this sub team, we are going to use a lot of parts that

come from the previous cars. More specifically, the wheel, the seat, the pedals, the driver’s suit,

and the steering system can be reused. But certain parts or materials have to be bought, like the

firewall material to protect the driver from the fuel container and the engine. The mirrors will

also have to be bought for driver visibility. A new belt should also be bought for better safety.

However, the head restraint does not have to be pursued as we can only buy the material and

build it ourselves. Some shield component, like steel or aluminum must be used to protect the

driver from any sharp components, like the suspensions but more importantly the steering

system.

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BUDGET

GLOVES Pro Series Glove $114.95

PosiGripTM Driving Gloves $69.95

FormulaGrip Driving Gloves $89.95

SHOES Heatshield Speedway Driving Shoes $154.95

Cool Max Socks $16.00

K Mid Sparco $109.00

RESTRAINTS Formula Car 6-Way $199.95

55 in Seat Belt Roll Bar V Harness All Bolt

In $179.95

55 in Floor Mount Seat Belt Pull Down Y

Harness $179.95

HELMET Helmet Skirt $49.95

Drag Bike Super Bandit - Nylon Liner -

Black $440.00

Street Bandit - Nylon Liner - White $399.00

SUIT R.J.S. Single-Layer Driving Suits $89.99

Simpson Single-Layer One Piece Driving

Suit $169.95

FIRE

EXTINGUISHER

H3R Perfromance Halguard Fire

Extinguisher $119.95

SEAT Tillet T8 Standard Clear $189.95

Tillet T8 Standard Clear With Full Black

Cover $229.00

Pedals Billet Pedal Set $229.00

Pedal Grips $19.95

Materials Aluminum ~ $120

Firewall ~ $150

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Table 14- Parts Availabilities or Prices.

5.6 Gantt Chart

Figure 32– Gantt Chart Driver Interface Sub-Team

5.7 Conclusion

In conclusion, the driver‟s interface is crucial for the well-behavior of the car. Even though the

cockpit will be modest, the driver will be comfortable with a good visibility and the car will have

a good steering. Everything will be studied, from the steering ratio to the position of the upper

body and the legs. The SAE rules govern many aspects, but we will optimize the steering and

driver position for the competition.

lowest total $1,402.79

highest total $1,743.65

Unexpected expenses (~ +20%) ~350

TOTAL $1750 - $2100

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6.1 References

[1] 2009 Formula SAE Competition Rules and Regulations

[2] www.asnt.org/ndt/primer3.htm

[3] www.matweb.com

[4] http://us1.webpublications.com.au/static/images/articles/i28/2895_15lo.jpg

[5] http://www.desertrides.com/reference/images/terms/camber.gif

[6] http://www.autowarrantybroker.com/_images/GlossaryImages/art_Caster.gif

[7] http://driftjapan.com/blog/wp-content/uploads/2007/11/toe-in-vs-toe-out.jpg

[8]

http://documents.wolfram.com/applications/mechsystems/Examples/3DExamples/HTMLImages/Mech.

Example.FrontSuspension.en/Mech.Example.FrontSuspension.en_a_1.gif

[9] US Patent # 3189118

[10]http://www.my.fit.edu/rev

[11]http://www.torsen.com

[12]http://www.honda.com

[13]http://www.fatboyraceworks.com

[14]http://www.taylor-race.com

[15] http://www.maxpower-engines.com

[16]

http://www.crutchfieldracing.com/agoracart/agora.cgi?cart_id=6685105.18890*N_6MG2&xm

=on&product=Chassis

[17] https://www.safetysupplyamerica.com/c-750-fr-nomex.aspx

[18] http://store.summitracing.com/

[19] http://www.pittsperformance.com