Performance Improvement of Go Kart

Design, Fabrication and Performance Improvement Of Go Kart

Dept Of Mechanical Engineering [1] SNGCE, Kadayiruppu

CONTENTS

CHAPTER NO TITLE PAGE NO

LIST OF FIGURES……………………………………………... 3

LIST OF TABLES……………………………………………… 4

1 INTRODUCTION………………………………………………5

2 SCOPE OF THE PROJECT……………………………………..6

3 HISTORY OF GO KART……………………………………….7

4 PARTS OF GO KART…………………………………………..8

4.1 CHASSIS…………………………………………………...9

4.2 ENGINE…………………………………………………….12

4.3 STEERING SYSTEM……………………………………....14

4.4 TRANSMISSION SYSTEM………………………………. 17

4.4.1 CHAIN AND SPROCKET…………………………18

4.4.2 DRIVESHAFT……………………………………... 19

4.4.3 CENTRIFUGAL CLUTCH……………………….. 20

4.5 BRAKE…………………………………………………….. 21

4.6 TYRE………………………………………………………. 23

5 MATERIALS……………………………………………………25

5.1 1018 DOM…………………………………………………. 26

5.2 4018 CHROMOLLY………………………………………. 27

5.3 MARINE PLYWOOD…………………………………….. 28

6 TIG WELDING………………………………………………….29

7 REAR WING…………………………………………………… 31

8 ESTIMATION AND COSTING……………………………….. 34

9 IMPROVEMENTS………………………………………………35



9.1 DRAG REDUCTION SYSTEM…………………………...36

9.1.1 AEROFOIL………………………………………...39

9.1.2 COEFFICIENT OF DRAG………………………...40

9.2 F-DUCT……………………………………………………. 41

9.2.1 EFFECT OF ANGLE OF ATTACK………………. 44

9.2.2 STALL……………………………………………...46

10 CONCLUSION………………………………………………… 47

11 REFERENCE……………………………………………………48



LIST OF FIGURES

FIGURE NO DESCRIPTION PAGE NO

2.1 Go Kart 6

4.2.1 Engine of Go Kart 13

4.2.2 Performance Chart of Engine 13

4.3.1 Steering System 16

4.4.1 Chain 18

4.4.2 Sprocket 18

4.4.3 Driveshaft 19

4.4.4 Centrifugal Clutch 20

4.5.1 Brake 22

6.1 Tig Welding 30

7.1 Flow of air through wing 33

9.1.1 Variation of Drag and Downforce with Angle of Attack 36

9.1.2 Electronic Circuit for DRS System 38

9.1.3 Aerofoil 39

9.1.4 Coefficient of Drag for various shapes 40

9.2.1 Air Bleed through slit in wing 41

9.2.2 Air flow through F-DUCT in F-1 car 43

9.2.3 Relation between Coefficient of Lift and Angle of Attack 44

9.2.4 Variation of Lift of wing 46



LIST OF TABLES

TABLE NO DESCRIPTION PAGE NO

1 Composition of 1018 DOM 26

2 Properties of 1018 DOM 26

3 Composition of 4130 CHROMOLLY 27

4 Properties of 4130 CHROMOLLY 27

5 Properties of MARINE PLYWOOD 29

6 Cost and Estimation of various parts 34



CHAPTER 1

INTRODUCTION

There are many motor sports in the world. Bikes, Cars, Formula one are examples of them.

The drivers in these are very professionals and accurate. They can drive it very fast. But there

are also motor sports which do not need professional drivers and need no great speed. The

vehicles used are also very cheap. Such a motor sport is Go-Karting. They resemble to the

formula one car but it is not as faster as F1 and also cost is very less. The drivers in go-karting

are also not professionals. Even children can also drive it. Go-karts have 4 wheels and a small

engine. They are widely used in racing in US and also they are getting popular in India.

A go kart is a small four wheeled vehicle. Go karts come in all shapes and forms, from

motorless models to high powered racing machines.

This project deals with design, fabrication and modification of go kart, which can be used in

customized go kart racing championships. The main objective of the Final Year Project, at

Sree Narayana Gurukulam College of Engineering, is to build a high quality competitive go-

kart that can outperform the competition in acceleration, braking, and maneuverability; as well

as provide excellent driver ergonomics and vehicle aesthetics. The fundamental intent of this

project is to implement three years of theoretical engineering, specifically classroom material,

into real-life practical applications that can ultimately be used to develop real-world problem

solving skills.

Throughout the semester 7 and 8, the Go Karts team of eight worked diligently and

effectively, in a unified group, to come up with various design ideas and concepts. The

research material was presented as a group and discussed thoroughly. After a number of

revisions, the project was broken down into subsystems and each team member took

responsibility for one system. After subdividing the whole project, each member took on a

specific section that needed to be researched. Subsequently, each subsystem is evaluated and,

after rigorous calculations and drawings, the best system is selected.



CHAPTER 2

SCOPE OF THE PROJECT

Go-Karting is a big craze to the Americans and Europeans. It is initially created in United

States in 1950s and used as a way to pass spare time. Gradually it became a big hobby and

other countries followed it. In India go-karting is getting ready to make waves. A racing track

is ready in many cities for go-karting and in Kerala a racing track is also trying to establish in

Ernakulam. Indian companies are also producing go-karts in small scale. MRF and Indus

motors are the major bodies in karts and they are offering karts between 2 lakh and 7 lakh. But

to make go-karts popular, the price must come down. For that, many people are trying to build

one under 1 lakh. This is a dream come true. A go-kart just under Rs. 1, 00,000/-. So we are

sure that our project will have a high demand in the industry and also we are hoping to get

orders from the racing guns.

Fig 2.1 Go Kart



CHAPTER 3

HISTORY OF GO KART

Go-kart is a simple four-wheeled, small engine, single sealed racing car used mainly in United

States. They were initially created in the 1950s. The first Go kart was made by Art Ingles in

California; America in 1956.It has no suspension or differentials. Since there is no suspension,

the chassis must have flexibility and good stiffness. Post-war period for airmen as a way to

pass spare time. Art Ingles is generally accepted to be the father of karting. From them, it is

being popular all over America and also Europe.

The first kart manufacturer was an American company, Go Kart Manufacturing Co.

(1958). McCulloch was the first company, in 1959, to produce engines for karts. Its first

engine, the McCulloch MC-10, was an adapted chainsaw2-stroke engine. Later, in the

1960s, motorcycle engines were also adapted for kart use, before dedicated manufacturers,

especially in Italy (IAME), started to build engines for the sport.

A Go-kart, by definition, has no suspension and no differential. They are usually raced on

scaled down tracks, but are sometimes driven as entertainment or as a hobby by non-

professionals. Karting is commonly perceived as the stepping stone to the higher and more

expensive ranks of motor sports. Kart racing is generally accepted as the most economic form

of motor sport available. As a free-time activity, it can be performed by almost anybody and

permitting licensed racing for anyone from the age of 8 onwards. Kart racing is usually used

as a low-cost and relatively safe way to introduce drivers to motor racing. Many people

associate it with young drivers, but adults are also very active in karting.

Karting is considered as the first step in any serious racer’s career. It can prepare the driver for

high-speed wheel-to-wheel racing by helping develop guide reflexes, precision car control and

decision-making skills. In addition, it brings an awareness of the various parameters that can

be altered to try to improve the competitiveness of the kart that also exist in other forms of

motor racing. Their popularity has reached all over the world. There are kart tracks for every

skill level, from the extremely tame tracks located in family fun centers and amusement parks,

to high end speed grand prix karting tracks found in larger cities.

http://en.wikipedia.org/wiki/McCulloch_Motors_Corporation

http://en.wikipedia.org/wiki/Chainsaw

http://en.wikipedia.org/wiki/Chainsaw

http://en.wikipedia.org/wiki/Motorcycle

http://en.wikipedia.org/wiki/Italian_American_Motor_Engineering



CHAPTER 4

PARTS OF A GO KART

There are various parts and systems used in a Go kart. These are essential part of the vehicle

or the part by which the whole vehicle is being made of. Following is the list of Go kart parts

that is used for the project.

1) CHASSIS

2) ENGINE

3) STEERING SYSTEM

4) TRANSMISSION SYSTEM

5) BRAKE

6) TYRE



4.1 FRAME

A frame is the main structure of the chassis of a motor vehicle. All other

components fasten to it; a term for this is design is body-on-frame construction. In 1920,

every motor vehicle other than a few cars based on motorcycles had a frame. Since then,

nearly all cars have shifted to unit-body construction, while nearly all trucks and buses still

use frames. The Go kart frame is made very flexible and stiff due to the absence of suspension

and differential. In selecting the frame material, metal with high elongation is considered to

absorb shocks. The frames are welded together by torsion bars .Maneuvering through tight

turns requires a well built and strong frames. The frame consists of three parts: primary,

support and secondary. The primary frame provides strength and stiffness; the secondary

frame is used to provide additional strength. This support frame houses the connection for

open system of Go kart.

CONSTRUCTION

There are three main designs for frame rails. Their cross-sections include: C-

shaped, Boxed and Hat.

C-shape

By far the most common, the C-rail has been used on nearly every type of vehicle at one time

or another. It is made by taking a flat piece of steel (usually ranging in thickness from 1/8" to

3/16") and rolling both sides over to form a c-shaped beam running the length of the vehicle.

Boxed

Originally, boxed frames were made by welding two matching c-rails together to form a

rectangular tube. Modern techniques, however, use a process similar to making c-rails in that

a piece of steel is bent into four sides and then welded where both ends meet.In the 1960s, the

boxed frames of conventional American cars were spot-welded here and there down the seam;

when turned into NASCAR "stock car" racers, the box was continuously welded from end to

end for extra strength (as was that of the Land-Rover from its first series).1956 Chevrolet 1/2-



ton frame. Notice hat-shaped cross member in the background, c-shape rails and cross

member in center, and a slight arch over the axle.

Hat

Hat frames resemble a "U" and may be either right-side-up or inverted with the open area

facing down. Not commonly used due to weakness and a propensity to rust, however they can

be found on 1936-1954 Chevrolet cars and some Studebakers. Abandoned for a while, the hat

frame gained popularity again when companies started welding it to the bottom of uni body

cars, in effect creating a boxed frame.

4.1.2 DESIGN FEATURES

While appearing at first glance as a simple hunk of metal, frames encounter great amounts of

stress and are built accordingly. The first issue addressed is beam height, or the height of the

vertical side of a frame. The taller the frame, the better it is able to resist vertical flex when

force is applied to the top of the frame. This is the reason semi-trucks have taller frame rails

than other vehicles instead of just being thicker. Another factor considered when engineering

a frame is torsional resistance, or the ability to resist twisting. This, and diamonding (one rail

moving backwards or forwards in relation to the other rail), are countered by cross members.

While hat-shaped cross members are the norm, these forces are best countered with "K" or

"X"-shaped cross members. As looks, ride quality, and handling became more of an issue with

consumers, new shapes were incorporated into frames. The most obvious of these are arches

and kick-ups. Instead of running straight over both axles, arched frames sit roughly level with

their axles and curve up over the axles and then back down on the other side for bumper

placement. Kick-ups do the same thing, but don't curve down on the other side, and are more

common on front ends. On perimeter frames, the areas where the rails connect from front to

center and center to rear are weak compared to regular frames, so that section is boxed in,

creating what's known as torque boxes. Another feature seen are tapered rails that narrow

vertically and/or horizontally in front of a vehicle's cabin. This is done mainly on trucks to

save weight and slightly increase room for the engine since the front of the vehicle doesn't

bear as much of a load as the back.2007 Toyota Tundra chassis showing an x-shaped cross

member at the back. The latest design element is frames that use more than one shape in the



same frame rail. For example, the new Toyota Tundra uses a boxed frame in front of the cab,

shorter, narrower rails underneath the cab for ride quality, and regular c-rails under the bed.

Ladder Frame: So named for its resemblance to a ladder, the ladder frame is the simplest and

oldest of all designs. It consists merely of two symmetrical rails, or beams, and cross members

connecting them. Originally seen on almost all vehicles, the ladder frame was gradually

phased out on cars around the 1940s in favor of perimeter frames and is now seen mainly on

trucks. This design offers good beam resistance because of its continuous rails from front to

rear, but poor resistance to torsion or warping if simple, perpendicular cross members are

used. Also, the vehicle's overall height will be higher due to the floor pan sitting above the

frame instead of inside it. Backbone chassis is a type of an automobile construction chassis

that is similar to the body-on-frame design. Instead of a two-dimensional ladder type

structure. Similar to a ladder frame, but the middle sections of the frame rails sit outboard of

the front and rear rails just behind the rocker panels/sill panels. This was done to allow for a

lower floor pan, and therefore lower overall vehicle in passenger cars. This was the prevalent

design for cars in the United States, but not in the rest of the world, until the uni-body gained

popularity and is still used on US full frame cars. It allowed for annual model changes

introduced in the 1950s to increase sales, but without costly structural changes. In addition to

a lowered roof, the perimeter frame allows for more comfortable lower seating positions and

offers better safety in the event of a side impact. However, the reason this design isn't used on

all vehicles is that it lacks stiffness, because the transition areas from front to center and center

to rear reduce beam and torsional resistance, hence the use of torque boxes, and soft

suspension settings. An Italian term (meaning "super-light") for sports-car construction using

a three-dimensional frame that consists of a cage of narrow tubes that, besides being under the

body, run up the fenders and over the radiator, cowl, and roof, and under the rear window; it

resembles a geodesic structure. The body, which is not stress-bearing, is attached to the

outside of the frame and is often made of aluminum.



4.2 ENGINE

The engine used in our Go kart is SUBARU-ROBIN EX 21. The Subaru EX21 Overhead

Cam Industrial Engines leads the industry in technology, offering more power, less noise and

easy, one-pull starting every time. Introduced as the first air-cooled engine line to use

advanced chain-driven Overhead Cam technology, the Subaru EX Series provides maximum

efficiency, performance and power with minimal noise and emissions. The engine design is

extremely compatible and easy to install, and simply exchanges with most existing slant

cylinder engines

The details of this engine are:

• Class: Air Cooled 4 Stroke OHC petrol Engine

• Max power 7HP at 4000 rpm

• Max Torque 13.9 Nm at 200 rpm

• Bore X Stroke 67mm X 60 mm

• Displacement 211 cubic centimeters

• Dry Weight 16 kg

• Fuel Capacity 3.6 liters

• Lube System Splash Lubrication System

• Lube Type SAE 10 W,20 W,30 W

• Emission Rating Grade 3 EPA/carb

• Governor System Mechanical Flywheel

• Fuel System Carbureted Float

• Length 311 mm

• Width 366 mm

• Height 335 mm



Fig 4.2.1 Sectional View of the Engine

Fig 4.2.2 The performance curve of the engine



4.3 STEERING SYSTEM

Steering serves the purpose of changing the direction of a vehicle which is in motion. Steering

of Go kart is very sensitive. Since there is only a solid rear axle and absence of differential,

one back wheel should skid over track surface. The steering system used in Go kart is Direct

Mechanical System. The Direct Steering includes Pittman arms, tie rods, steering wheels,

steering shaft and tie rod ends. The steering shaft is attached to the steering and Pittman arm

at other end. Steering wheel rotation rotates the steering shaft and causes the motion of

Pittman arm. The arm pushes the tie rod, which turns the wheel by pushing wheel spindle

arms.

Depending on the driver, steering force and transmission of road forces back to the steering

wheel and the steering ratio of turns of the steering wheel to turns of the road wheels affect

control and awareness. Play — free rotation of the steering wheel before the wheels rotate is a

common problem, especially in older model and worn cars. Another is friction. Rack and

pinion steering is generally considered the best type of mechanism for control effectiveness.

The linkage also contributes play and friction. Caster offset of the steering axis from the

contact patch provides some of the self-centering tendency. Precision of the steering is

particularly important on ice or hard packed snow where the slip angle at the limit of adhesion

is smaller than on dry roads. The steering effort depends on the downward force on the

steering tires and on the radius of the contact patch. So for constant tire pressure, it goes like

the 1.5 power of the vehicle's weight. The driver's ability to exert torque on the wheel scales

similarly with his size. The wheels must be rotated farther on a longer car to turn with a given

radius. Power steering reduces the required force at the expense of feel. It is useful, mostly in

parking, when the weight of a front-heavy vehicle exceeds about ten or fifteen times the

driver's weight, for physically impaired drivers and when there is much friction in the steering

mechanism. Four-wheel steering has begun to be used on road cars (Some WW II

reconnaissance vehicles had it). It relieves the effect of angular inertia by starting the whole

car moving before it rotates toward the desired direction. It can also be used, in the other

direction, to reduce the turning radius. Some cars will do one or the other, depending on the

speed.



Steering geometry changes due to bumps in the road may cause the front wheels to steer in

different directions together or independent of each other. The steering linkage should be

designed to minimize this effect. The stability control of some cars may not be compatible

with some driving techniques, such as power induced over-steer. It is therefore, at least from a

sporting point of view, preferable that it can be disabled.

Static alignment of the wheels: Of course things should be the same, left and right, for road

cars. Camber affects steering because a tire generates a force towards the side that the top is

leaning towards. This is called camber thrust. Additional front negative camber is used to

improve the cornering ability of cars with insufficient camber gain.

Rigidity of the frame: The frame may flex with load, especially twisting on bumps. Rigidity is

considered to help handling. At least it simplifies the suspension engineers work. Some cars,

such as the Mercedes-Benz 300SL have had high doors to allow a stiffer frame. Driver

handling the car: Handling is a property of the car, but different characteristics will work well

with different drivers. Familiarity: A person learns to control a car much as he learns to

control his body, so the more he has driven a car or type of car the better it will handle for

them. One needs to take extra care for the first few months after buying a car, especially if it

differs in design from those they are used to. Other things that a driver must adjust to include

changes in tires, tire pressures and load. That is, handling is not just good or bad; it is also the

same or different. Position and support for the driver: Having to take up "g forces" in his/her

arms interferes with a driver's precise steering. In a similar manner, a lack of support for the

seating position of the driver may cause them to move around as the car undergoes rapid

acceleration (through cornering, taking off or braking). This interferes with precise control

inputs, making the car more difficult to control. Being able to reach the controls easily is also

an important consideration, especially if a car is being driven hard. In some circumstances,

good support may allow a driver to retain some control, even after a minor accident or after

the first stage of an accident.



Fig 4.3.1 Steering System



4.4 TRANSMISSION SYSTEM

Transmission means the whole of the mechanism that transmits the power from the engine

crankshaft to the rear wheels. In this vehicle, the power from the engine is transmitted to the

sprockets using chain, i.e. this is chain drive. We use chain drive because it is capable of

taking shock loads. Usually go-karts do not have a differential and so we eliminate differential

from our vehicle also. And also this go-kart has no clutch and gears because this is automatic

transmission.

The necessity of a transmission system in the vehicle is due to the following reasons:

• Variation of resistance to the vehicle motion at various speeds.

• Variation of tractive effort of the vehicle at various speeds.

So due to the above given reasons the transmission system of a vehicle must perform various

functions. The functions or use of transmission systems in a vehicle are due to the following

reasons:

• To connect the engine to driving shaft without shock.

• To vary the leverage between engine and drive shaft.

• To connect the engine from road wheels when desired

• To reduce the engine speed permanently in a fixed ratio.

The transmission system in the Go Kart varies from the conventional motor vehicle. In a Go

Kart there is absence of Gearbox and Differentials. For speed reduction instead of gearbox a

chain drive is being used. The absence of differential causes slipping at the corners. This

makes its driving more challenging.

The main parts of transmission system used in the Go Kart are:

1) CHAIN AND SPROCKET

2) JACKSHAFT

3) CENTRIFUGAL CLUTCH



4.4.1 CHAIN AND SPROCKET

Chain and sprocket arrangement is used for transmission of power from the engine to the

drive shaft. The power is conveyed by a roller chain, known as the drive chain or transmission

chain passing over a sprocket gear, with the teeth of the gear meshing with the holes in the

links of the chain. The gear is turned, and this pulls the chain putting mechanical force into the

system. Conventional roller chain drives suffer the potential for vibration, as the effective

radius of action in a chain and sprocket combination constantly changes during revolution. If

the chain moves at constant speed, then the shafts must accelerate and decelerate constantly. If

a drive sprocket rotates at constant RPM, then the chain (and probably the driven sprocket)

must accelerate and decelerate constantly.

The material used for making chain is 40MN/A3.

A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs or even sprockets

that mesh

with a chain track or other perforated or indented material. Sprockets typically do not have

a flange. There are two sprockets in the Go Kart. They are the Driver sprocket (sprocket in

engine side) and Driven sprocket (sprocket in drive shaft). In the Go Kart, there are 13 teeths

in driver sprocket and 63 teeths in driven sprocket. This creates an effective transfer of power

from the engine to the drive shaft. The main advantage of the chain and sprocket drive system

is its transmission efficiency at greater transmission distance. This system provides maximum

absorption of shock and minimum torque load.

The material used for making sprocket is alloy steel.

Fig 4.4.1 Chain Fig 4.4.2 Sprocket

http://en.wikipedia.org/wiki/Roller_chain

http://en.wikipedia.org/wiki/Sprocket

http://en.wikipedia.org/wiki/Wheel

http://en.wikipedia.org/wiki/Roller_chain

http://en.wikipedia.org/wiki/Caterpillar_track

http://en.wikipedia.org/wiki/Flange



4.4.2 DRIVE SHAFT

The drive shaft of a Go Kart is also known as the counter shaft or jackshaft. It is a common

mechanical design component used to transfer or synchronize rotational force in a machine. A

jackshaft is often just a short stub with supporting bearings on the ends and two pulleys, gears,

or cranks attached to it. The power from the engine is transmitted to the drive shaft for

enhancing the vehicle motion. Power from the engine is received through chain drive. The

drive shaft transmits the power from the engine horizontally. The jackshafts are the carriers of

torque hence they are subjected to torsion and shear stress. Since the jackshaft of a Go kart is

subjected to high stresses, it is necessary that the jackshaft material should be strong enough

to hold the stresses acting on the shaft. A Go kart does not have any differential system. So a

part of the forces acting on the kart during negotiating a turn is transmitted to the driveshaft.

Hence the driveshaft should be flexible to enhance the required change in dimensions.

The jackshaft material is made up of 4130 CHROMOLLY steel.

It is selected because it has high strength, durability and the percentage change in area is also

very high. It has a percentage elongation of about 30%; which is enough to withstand the

vibrations during racing.

Fig 4.4.3 Driveshaft



4.4.3 CENTRIFUGAL CLUTCH

The clutch system used in the Go kart is the centrifugal clutch. A centrifugal clutch is

a clutch that uses centrifugal force to connect two concentric shafts, with the driving shaft

nested inside the driven shaft. The input of the clutch is connected to the engine

crankshaft while the output may drive a shaft, chain, or belt. As engine revolutions per

minute increase, weighted arms in the clutch swing outward and force the clutch to engage.

The most common types have friction pads or shoes radially mounted that engage the inside

of the rim of housing. On the center shaft there are an assorted number of extension springs,

which connect to a clutch shoe. When the center shaft spins fast enough, the springs extend

causing the clutch shoes to engage the friction face. It can be compared to a drum brake in

reverse. When the engine reaches a certain speed, the clutch activates, working somewhat like

a continuously variable transmission. As the load increases, the speed drops, disengaging the

clutch, letting the speed rise again and reengaging the clutch. If tuned properly, the clutch will

tend to keep the speed at or near the torque peak of the engine. This results in a fair bit of

waste heat, but over a broad range of speeds it is much more useful than a direct drive in

many applications. The most common centrifugal clutches have friction pads (shoes) which

connect to the inside of the housing. The clutch shoe connects to a various amount of

extension springs on the center shaft. When the center shaft turns, the springs stretch out,

causing the friction pads to engage the friction face.

Fig 4.4.4 Centrifugal Clutch

http://en.wikipedia.org/wiki/Clutch

http://en.wikipedia.org/wiki/Centrifugal_force

http://en.wikipedia.org/wiki/Crankshaft

http://en.wikipedia.org/wiki/Revolutions_per_minute

http://en.wikipedia.org/wiki/Revolutions_per_minute

http://en.wikipedia.org/wiki/Drum_brake

http://en.wikipedia.org/wiki/Continuously_variable_transmission



4.5 BRAKE SYSTEM

A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The

rest of this article is dedicated to various types of vehicular brakes. Most commonly brakes

use friction to convert kinetic energy into heat, though other methods of energy conversion

may be employed. For example regenerative braking converts much of the energy to electrical

energy, which may be stored for later use. Other methods convert kinetic energy into potential

energy in such stored forms as pressurized air or pressurized oil. Friction brakes on

automobiles store braking heat in the drum brake or disc brake while braking then conduct it

to the air gradually. When traveling downhill some vehicles can use their engines to brake.

When the brake pedal of a modern vehicle with hydraulic brakes is pushed, ultimately a piston

pushes the brake pad against the brake disc which slows the wheel down. On the brake drum

it is similar as the cylinder pushes the brake shoes against the drum which also slows the

wheel down.

Go kart has single disc brake connected to the jackshaft. The brake is actuated by left leg

operated pedal. When pedal is pressed, a plunger is pushed in the master cylinder which

forces the brake fluid through the hose. It is important that fluid is free from bubbles because

air gap can cause sponginess to the pedal and severely reduce braking effect. The brake fluid

used is MOTUL dot 3 brake fluid.

The disc brake or disk brake is a wheel brake which slows rotation of the wheel by the friction

caused by pushing brake pads against a brake disc with a set of calipers. The brake disc (or

rotor in American English) is usually made of cast iron, but may in some cases be made of

composites such as reinforced carbon–carbon or ceramic matrix composites. This is connected

to the wheel and/or the axle. To stop the wheel, friction material in the form of brake pads,

mounted on a device called a brake caliper, is forced mechanically, hydraulically,

pneumatically or electromagnetically against both sides of the disc. Friction causes the disc

and attached wheel to slow or stop. Brakes convert motion to heat, and if the brakes get too

hot, they become less effective, a phenomenon known as brake fade. Disc-style brakes

development and use began in England in the 1890s. The first caliper-type automobile disc

brake was patented by Frederick William Lanchester in his Birmingham, UK factory in 1902

and used successfully on Lanchester cars. Compared to drum brakes, disc brakes offer better

stopping performance, because the disc is more readily cooled. As a consequence discs are

less prone to the "brake fade"; and disc brakes recover more quickly from immersion (wet

brakes are less effective). Most drum brake designs have at least one leading shoe, which

gives a servo-effect. By contrast, a disc brake has no self-servo effect and its braking force is

always proportional to the pressure placed on the brake pad by the braking system via any

brake servo, braking pedal or lever, this tends to give the driver better "feel" to avoid

impending lockup. Drums are also prone to "bell mouthing", and trap worn lining material

within the assembly, both causes of various braking problems.



Compared to drum brakes, disc brakes offer better stopping performance, because the disc is

more readily cooled. As a consequence discs are less prone to the "brake fade" caused when

brake components overheat; and disc brake recover more quickly from immersion (wet brakes

are less effective). Most drum brake designs have at least one leading shoe, which gives a

servo-effect; see leading/trailing drum brake. By contrast, a disc brake has no self-servo effect

and its braking force is always proportional to the pressure placed on the brake pad by the

braking system via any brake servo, braking pedal or lever, this tends to give the driver better

"feel" to avoid impending lockup. Drums are also prone to "bell mouthing", and trap worn

lining material within the assembly, both causes of various braking problems. Many early

implementations for automobiles located the brakes on the inboard side of the driveshaft, near

the differential, but most brakes today are located inside the road wheels. (An inboard location

reduces the unstrung weight and eliminates a source of heat transfer to the tires.)

Fig.4.5.1 Disc Brake



4.6 TYRES

Go kart tyres are specially designed for racing purpose. A tyre is a ring-shaped covering that

fits around a rim to protect it and enable better vehicle performance by providing a flexible

cushion that absorbs shock while keeping the wheel in close contact with the ground. The

fundamental materials of modern tires are synthetic rubber, natural rubber, fabric and wire,

along with other compound chemicals. They consist of a tread and a body. The tread

provides traction while the body ensures support. Before rubber was invented, the first

versions of tires were simply bands of metal that fitted around wooden wheels to prevent wear

and tear.

Generally two types of tyres are being used for go kart racing. They are:

• SLICK TYRE

• GOOVED TYRE

Slick Tyres are generally used in dry racing so as to give maximum grip in the road surface.

A slick tyre (also known as a "racing slick") is a type of tyre that has no tread, used mostly

in auto racing. By eliminating any grooves cut into the tread, such tyres provide the largest

possible contact patch to the road, and maximize traction for any given tyre dimension. Slick

tyres are not suitable for use on common road vehicles, which must be able to operate in all

weather conditions. They are used in auto racing where competitors can choose different tyres

based on the weather conditions and can often change tyres during a race. Slick tyres provide

far more traction than grooved tyres on dry roads due to their greater contact area but typically

have far less traction than grooved tyres under wet conditions.

Since there is no tread, slick tyre tread does not deform too much under load. The

reduced deformation allows the tyre to be constructed of softer compounds without excessive

overheating and blistering. The softer rubber gives greater adhesion to the road surface, but it

also has a lower tread-wear rating; i.e. it wears out much more quickly than the harder rubber

tyres used for driving on the streets. It is not uncommon for drivers in some auto sports to

wear out multiple sets of tyres during a single day's driving.

http://en.wikipedia.org/wiki/Rim_(wheel)

http://en.wikipedia.org/wiki/Synthetic_rubber

http://en.wikipedia.org/wiki/Natural_rubber

http://en.wikipedia.org/wiki/Traction_(engineering)

http://en.wikipedia.org/wiki/Tire

http://en.wikipedia.org/wiki/Tread

http://en.wikipedia.org/wiki/Auto_racing

http://en.wikipedia.org/wiki/Contact_patch

http://en.wikipedia.org/wiki/Traction_(engineering)

http://en.wikipedia.org/wiki/Deformation_(engineering)

http://en.wikipedia.org/wiki/Treadwear_rating



Grooved tyres are generally used in wet conditions. The grooves in the tyre reduce the slip in

the tyres during wet racing. The working of the groove sin the tyres are explained below.

When a slick tyre is in contact with the wet surface in the road, the tyre surface makes a

contact with the water present in the road rather than the road surface. Due to then motion of

the vehicle, the tyre tends to spin in the water above the water surface. This results in the

reduced road contact and the tyre slips, which makes the vehicle slide. On the other hand,

when a Grooved tyre is used in wet condition, when the tyre makes a contact with the water

surface, the water escapes through the grooves and makes it possible to make contact with the

road surface. Thus an effective contact with road surface is made, which reduces the tyre slip.

Grooves also reduce heat. Heat escapes from the surfaces created by the grooves. One large

block of rubber will be hotter in equal service to two smaller blocks that sum to the same

amount of rubber. The smaller blocks have more total surface area to shed heat and the

distance to a surface is shorter. Grooves also create edges. More edges generally help on a

slick, non-abrasive track. Ironically, slick, non-abrasive tracks don’t tend to generate much

heat in a tire. On an abrasive track a racer may groove the tires to shed heat.

TYRE PRESSURE

Air pressure determines the majority of the spring rate within a tire. Too much air pressure

generally makes the car loose off the corner, while too little air pressure gives the car a tight

feeling on entry. Maintaining correct tire inflation pressure helps optimize tire performance.

Correct tire inflation pressure allows drivers to experience tire comfort, durability and

performance designed to match the needs of their vehicles. Proper tire inflation pressure also

stabilizes the tire's structure, blending the tire's responsiveness, traction and handling.

The tyre pressure required for slick and grooved tyres are given below:

• For Dry Racing appropriate tyre pressure is 14 – 16 psi.

• For Wet Racing appropriate tyre pressure is 15 – 20 psi



CHAPTER 5

MATERIALS

The materials used in go kart includes various varieties of steel. Materials to be selected for go

kart should be special. This is because; in a go kart there is no suspension. So it is the material

which bears all the shock that is generated during the ride.

For building a go kart, we must have a light and strong frame. So selecting a suitable material

is very important. To select a particular material for the vehicle we must consider various

properties of the materials like strength, durability, elongation, fatigue, wear resistance etc.

It is also important in selecting the cross section of the tubes used. This is because welding of

square tubes is easier. But considering the problems of bending the tubes into various shapes,

rounded tubes are advantageous. So we use a mixture of round and squared tubes in go kart.

If we are considering a stiff frame, even if it gives the necessary strength and durability to the

go kart, it will not be flexible and have a tendency to break easily. A frame made up of sturdy

and stiff frame is the key to maneuvering well in the track, especially in the turns. The most

important property of the go kart’s frame is to negotiate the turns effectively. This property is

directly linked to the material by which the frame is being made.

Generally, the go kart frame is made up of “4130 CHROMOLLY” steel. This is because it

has a very good strength with low weight. It is generally used for making airplane and formula

one racing car parts. The 4130 variant of the steel have extreme durability along with very

high flexibility. Go kart frames are generally made up of 4130 steels containing Vanadium.

This is because it gives extra strength and also work hardening effect also increase. But due

to the extreme cost and unavailability of the material we are considering “1018 DOM” steel

which compromises between the strength and cost.

The wing of the go kart is made up of MARINE PLYWOOD. Marine plywood is a plywood

grade which has comparatively high strength and machinability. Wing of the go kart should be

made with suitable material so that it has a minimal weight and strength. But due to the high

cost and due to difficulty in mounting, plywood/wood is selected. Compared to the wood,

plywood has high machinability; hence it is selected.



5.1 1018 DOM

The go kart frame is made up of 1018 DOM. Alloy 1018 is the most commonly

available of the cold-rolled steels. It is generally available in round rod, square bar,

And rectangle bar. It has a good combination of all of the typical traits of steel -

strength, some ductility, and Comparative ease of machining. Chemically, it is very

similar to A36 Hot Rolled steel, but the cold rolling process creates a better surface

finish and better properties.

ELEMENTS COMPOSITION (%)

Iron ( Fe) 98.91 to 99.26

Carbon ( C ) 0.018

Manganese ( Mn) 0.6 to 0.9

Phosphorous (Ph) 0.04 max

Sulphur ( S ) 0.06 max

Table 1 Composition of 1018 DOM

The go kart frame should be very strong, durable and should absorb shock during the

race. So the material used for making the frame should have desirable properties. The

general properties of the frame material are given below.

Density 7.87 g/cc

Tensile Strength 450 MPa

Elongation 18.3%

Hardness 132( Brinell Hardness Number)

Youngs Modulus 202 GPa

Table 2 Properties of 1018 DOM



5.2 4130 CHROMOLLY

The 4130 steel is a variety of steel having high durability, fatigue strength and high

elongation. It can bear very high loads despite being light in weight. Machining and welding

of this variety of steel is very easy. It is generally used in aircraft and racing applications.

The go kart jackshaft is made up of 4130 chromolly steel. This is because, jackshaft is

subjected to very high bending stress and torsion; so only a highly durable material can be

used for this purpose.

ELEMENTS COMPOSITION (%)

Iron ( Fe ) 98.17

Carbon ( C ) 0.33

Chromium ( Cr ) 1.9

Manganese ( Mn ) 0.9

Molybdenum ( Mo ) 0.25

Table 2 Composition of 4130 CHROMOLLY

The availability of this grade of steel is very difficult. The cost of this steel grade is too

high. This is due to its desirable mechanical properties and high manufacturing cost

involved. The general properties of the frame material are given below.

Density 8.09 g/cc


Elongation 29.8 %

Hardness 151 (Brinell Hardness Number)

Youngs Modulus 212 GPa

Table 4 Properties of 4130 CHROMOLLY



5.3 MARINE PLYWOOD

Plywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the

most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can

usually be locally manufactured. Plywood is used instead of plain wood because of its

resistance to cracking, shrinkage, splitting, and twisting/warping, and its general high degree

of strength.

Plywood layers (called veneers) are glued together with adjacent plies having their grain at

right angles to each other. Cross-graining has several important benefits: it reduces the

tendency of wood to split when nailed at the edges, it reduces expansion and shrinkage

equating to improved dimensional stability, and it makes the strength of the panel consistent

across both directions. There are usually an odd number of plies so that the sheet is

balanced—this reduces warping. Because of the way plywood is bonded (with grains running

against one another and with an odd number of composite parts) it is very hard to bend it

perpendicular to the grain direction.

A typical plywood panel has face veneers of a higher grade than the core veneers. The

principal function of the core layers is to increase the separation between the outer layers

where the bending stresses are highest, thus increasing the panel's resistance to bending.

Density 0.63g/cm³


Moisture Content 5 to 15 %

Youngs Modulus 7500 N/m²

Glue Shear Strength 1100 N

Nail Holding Strength 2696 N

Screw Holding Strength 1716 N

Table 5 Properties of Marine Plywood

http://en.wikipedia.org/wiki/Wood_veneer

http://en.wikipedia.org/wiki/Wood_grain

http://en.wikipedia.org/wiki/Bending



CHAPETR 6

TIG WELDING

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG)welding, is an arc

welding process that uses a non consumable tungsten electrode to produce the weld. The weld

area is protected from atmospheric contamination by ash shielding gas (usually an inert

gas such as argon), and a filler metal is normally used, though some welds, known as

autogenous welds, do not require it. A constant-current welding power supply produces

energy which is conducted across the arc through a column of highly ionized gas and metal

vapors known as a plasma.

GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals

such as aluminum, magnesium, and copper alloys. The process grants the operator greater

control over the weld than competing processes such as ash shielded metal arc

welding and gas metal arc welding, allowing for stronger, higher quality welds. However,

GTAW is comparatively more complex and difficult to master, and furthermore, it is

significantly slower than most other welding techniques. A related process, plasma arc

welding, uses a slightly different welding torch to create a more focused welding arc and as a

result is often automated.

OPERATION

Manual gas tungsten arc welding is often considered the most difficult of all the welding

processes commonly used in industry. Because the welder must maintain a short arc length,

great care and skill are required to prevent contact between the electrode and the

workpiece. To strike the welding arc, a high frequency generator (similar to a Tesla coil)

provides an electric spark; this spark is a conductive path for the welding current through the

shielding gas and allows the arc to be initiated while the electrode and the workpiece are

separated, typically about 1.5–3 mm (0.06–0.12 in) apart. Once the arc is struck, the welder

moves the torch in a small circle to create a welding pool, the size of which depends on the

size of the electrode and the amount of current. While maintaining a constant separation

between the electrode and the workpiece, the operator then moves the torch back slightly and

tilts it backward about 10–15 degrees from vertical. Filler metal is added manually to the front

end of the weld pool as it is needed.

http://en.wikipedia.org/wiki/Arc_welding

http://en.wikipedia.org/wiki/Arc_welding

http://en.wikipedia.org/wiki/Tungsten

http://en.wikipedia.org/wiki/Electrode

http://en.wikipedia.org/wiki/Welding

http://en.wikipedia.org/wiki/Shielding_gas

http://en.wikipedia.org/wiki/Inert_gas

http://en.wikipedia.org/wiki/Inert_gas

http://en.wikipedia.org/wiki/Argon

http://en.wikipedia.org/wiki/Filler_metal

http://en.wikipedia.org/wiki/Current_source

http://en.wikipedia.org/wiki/Welding_power_supply

http://en.wikipedia.org/wiki/Plasma_(physics)

http://en.wikipedia.org/wiki/Stainless_steel

http://en.wikipedia.org/wiki/Aluminum

http://en.wikipedia.org/wiki/Magnesium

http://en.wikipedia.org/wiki/Copper

http://en.wikipedia.org/wiki/Shielded_metal_arc_welding

http://en.wikipedia.org/wiki/Shielded_metal_arc_welding

http://en.wikipedia.org/wiki/Gas_metal_arc_welding

http://en.wikipedia.org/wiki/Plasma_arc_welding

http://en.wikipedia.org/wiki/Plasma_arc_welding

http://en.wikipedia.org/wiki/Tesla_coil

http://en.wikipedia.org/wiki/Electric_spark



EQUIPMENTS INVOLVED

The equipment required for the gas tungsten arc welding operation includes a welding torch

utilizing a non consumable tungsten electrode, a constant-current welding power supply, and a

shielding gas source.

APPLICATIONS

While the aerospace industry is one of the primary users of gas tungsten arc welding, the

process is used in a number of other areas. Many industries use GTAW for welding thin

workpieces, especially nonferrous metals. It is used extensively in the manufacture of space

vehicles, and is also frequently employed to weld small-diameter, thin-wall tubing such as

those used in the bicycle industry. GTAW is the welding procedure of choice for critical

welding operations like sealing nuclear fuel canisters before burial

Fig 6.1 TIG Welding Process

http://en.wikipedia.org/wiki/Spent_nuclear_fuel



CHAPETR 7

REAR WING

The wing in the go kart is attached to its rear part. In customized Go Karting Championship, a

rear wing is must. This is because, in customized Go Karting, the Karts moves at a very high

speeds which owes to its performance improvements; so it will be difficult for the driver to

control the Karts simply applying the brakes. Hence a rear wing is added to the existing Go

kart to improve its maneuverability.

The rear wings of a Go kart are generally made up of Aluminium alloys; due to its low weight

and high durability. But due to cost concerns the wing in our Kart is made up of marine

plywood. It is the customized part in the Go Kart. The DRS system of the go kart is attached

to the rear wing.

The rear wing of the kart consists of two flaps. The rear wings are used in the karts to increase

the downforce. According to the karting RULES, One flap should be fixed. Here, the lower

flap is being fixed. The angle of attack of the lower flap is adjusted at 340. The optimum angle

of attack is obtained from the analysis in FLUENT software.

Wing Aerodynamics

The basic principle of a Go Kart wing is exactly the same as with a common aircraft. The

greatest difference is the direction air is pressed and how that aerodynamic force is generated.

An aircraft wing works the opposite of a kart wing. Let us consider testing a single rear wing

in a wind tunnel. The main advantage of this theoretical example is that it leaves out some

natural factors. With a single wing, the turbulence generated by the engine is neglected. (The

engine cover mainly), neither the direction nor speed of outside wind be considered. It is

obvious that both these factors decrease the efficiency of an aerofoil.

The air flows onto the rear wing with a straight direction (which is often called clean air) at

the speed of the car. The flaps push the air up. Following Newton's law, an action causes a

reaction, so the aerofoil is being pushed towards the ground by the air. Having in mind that air

flowing onto the flaps is pushed upwards, and underflowing air keeps going its own way, a



low pressure area (nearing a vacuum at very high speeds) is created right behind the

horizontal aerofoils. This 'vacuum' causes a suck up of the air passing under that flap. The

underpassing air on the other hand again flows faster in an attempt to equalize pressure on

both sides of the aerofoil, and thereby increasing the total wing efficiency. Because of the

car's speed this is impossible, which is why the effect is maintained. The force that is created

by this type of wing, so that the car is pressed onto the ground, is called downforce.

Downforce

Downforce is a downwards thrust created by the aerodynamic characteristics of a car. The

purpose of downforce is to allow a car to travel faster through a corner by increasing the

vertical force on the tires, thus creating more grips.

The formulae for downforce is given by,

Where, D = Downforce in Newton

WS = Wing span in meters

H = Height in meters

AoA = Angle of attack in degrees

F = Drag coefficient

Ρ = Air density in kg/m3

V = Velocity in meter/sec

One of the main physical forces involved in downforce creation is the Bernoulli’s Effect. It

means that if a fluid flows around an object in different speeds, the slower moving fluid exerts

more force/pressure than the faster moving ones. In a rear wing of the kart, we must force

even more high speed/low pressure air below the flaps to create negative lift (downforce).

http://en.wikipedia.org/wiki/Aerodynamics

http://en.wikipedia.org/wiki/Car

http://en.wikipedia.org/wiki/Grip_(autoracing)



Fig 7.1 flow of air through a wing (assumed as an aerofoil). The arrow represents the effective

downforce created in wing



CHAPETR 8

ESTIMATION AND COSTING

Costing and estimation may be defined as systematic procedure for recording accurately every

item of expenditure, incurred on the manufacture of a product by different departments of any

manufacturing concern.

SL No DESCRIPTION QUANTITY AMOUNT

1. Engine 1 23000.00

2. Jackshaft 1 2500.00

3. Wheel and Hub assembly (front) 1 1560.00

4. Wheel and Hub assembly (back) 1 2080.00

5. Steering wheel, Steering shaft with Pittman

arm

1 2664.00

6. Tyre 4 14000.00

7. Centrifugal clutch 1 1456.00

8. sprocket 1 890.00

9. Female tie rod end 1 510.00

10. Male tie rod end 1 590.00

11. Precision ball bearing 3 450.00

12. Seat 1 850.00

13. Brake assembly 1 1200.00

14. Brake disc and pads 1 1800.00

Table 6 Cost and Estimation of Various Parts



CHAPETR 9

IMPROVEMENTS IN EXISTING KART

This corresponds to the modification brought up by us in the existing go kart.

We got this innovative idea from the formula one racing championships. These ideas are not

adopted for Go kart racing in India. The improvements brought about in the Go kart increases

the speed, cornering abilities and maneuvering ability of the kart. These can be proved by the

road test analysis of the kart after the modification of the kart. From the road test data’s we

obtain excellent improvements from the existing kart.

Following are the modifications that are brought in the existing go kart

1) DRS (Drag Reduction System)

2) F- DUCT



9.1 DRAG REDUCTION SYSTEM

Drag Reduction System is a system aimed at improving the aerodynamic drag of the vehicle.

Driver adjustable bodywork, commonly known as drag reduction system (or DRS), is a

motorsport technology aimed at reducing aerodynamic drag in order to promote overtaking in

racing. DRS were introduced in the 2011 Formula one season. I consist of an adjustable flap

on the rear wing of the car, which opens and closes in correspondence with a driver's

commands.

The device opens an adjustable flap on the rear wing of the car (which when closed creates

more downforce for greater cornering) to reduce downforce, thus giving a pursuing car more

speed and a greater chance of overtaking a car in front.

The horizontal elements of the rear wing consist of the main plane and the flap. The DRS

allows the flap to lift a maximum of 50 mm from the fixed main plane. This reduces

opposition (drag) to airflow against the wing and results in less downforce. A large amount of

downforce is generated by the change in angle of the flaps in the wing.

Fig 9.1.1 the variation of drag and downforce with change in Angle of Attack

http://en.wikipedia.org/wiki/Formula_One

http://en.wikipedia.org/wiki/2011_Formula_One_season



Principle of Working of DRS system

According to fluid mechanics of an aerofoil, downforce is created on the aerofoil on account

of the pressure difference between the fluids flowing above and below the aerofoil.

Downforce is the force acting downward in an aerofoil, i.e. opposite to the lift on an aerofoil.

The magnitude of the downforce is proportional to the pressure difference in the aerofoil.

When a wing (assumed to be aerofoil) is placed in the fluid flow, the velocity of fluid below

the aerofoil is greater than that above. Hence a pressure difference is created. The magnitude

of the force is proportional to the pressure difference. So when the velocity of flow below the

aerofoil increases or the pressure of fluid flowing increases the downforce increases. When

the downforce increases, the kart sticks to the road. So when a kart is negotiating a turn, if the

downforce increases, the kart sticks to the road, decreasing the tendency to slip.

So the DRS system can be made in such a way that it permits maximum downforce during

cornering and a minimum downforce at straight lines.

Working of DRS system

The DRS system controls an adjustable flap in the rear end of the car. The DRS system is

actuated using the switch in the steering wheel.

When the switch is made ON, the adjustable wing turns to an angle of 660. When the flap

turns the aerodynamic drag on the vehicle increases and the kart sticks to the road surface in

the corners. During the straight run the flap is made horizontal to the surface, which decreases

the drag and allowing the vehicle to accelerate more.

The angle of turn of the adjustable wing is found using the FLUENT software. It is calculated

by finding the optimum angle from a list of angle which permits the flow of fluid under the

wing with maximum velocity.

The flap is turned at the given angle with the help of a stepper motor attached to the side of

the wing. The stepper motor receives power from the battery placed in the base of the frame.

An electronic control unit is attached to the stepper motor to turn to the fixed angle. It also

controls the speed of the stepper motor turning.



ELECTRONIC CIRCUIT

The following diagram shows the electronic circuit used in the DRS system this circuit is

connected to a 12V battery placed in the base of the frame.

The system uses a stepper motor to turn the wings. The speed of turn, angle of turn etc are

pre-set in the microcontroller. The microcontroller used is 89c51.

Fig 9.1.2 Electronic Circuit for DRS System



9.1.1 AEROFOIL

An aerofoil is the shape of a wing or blade or sail as seen in cross-section. An airfoil-shaped

body moved through a fluid produces an aerodynamic. The component of this

force perpendicular to the direction of motion is called lift. The component parallel to the

direction of motion is called drag.

Fig 9.1.3 Aerofoil

In the figure, there is a difference in the curvatures of the upper and lower surfaces of the

airfoil (the curvature is called camber). The camber of the upper surface is more pronounced

than that of the lower surface, which is somewhat flat in most instances. In figure, note that

the two extremities of the airfoil profile also differ in appearance. The end which faces

forward in flight is called the leading edge, and is rounded; while the other end, the trailing

edge, is quite narrow and tapered. A reference line often used in discussing the airfoil is the

chord line, a straight line drawn through the profile connecting the extremities of the leading

and trailing edges. The distance from this chord line to the upper and lower surfaces of the

wing denotes the magnitude of the upper and lower chamber at any point.

As the airstream strikes the relatively flat lower surface of the wing when inclined at a small

angle to its direction of motion, the air is forced to rebound downward and therefore causes an

upward reaction in positive lift, while at the same time airstream striking the upper curved

section of the leading edge of the wing is deflected upward. In other words, a wing shaped to

cause an action on the air, and forcing it downward, will provide an equal reaction from the

air, forcing the wing upward. If a wing is constructed in such form that it will cause a lift force

greater than aerofoil, it will fly.

http://en.wikipedia.org/wiki/Wing

http://en.wikipedia.org/wiki/Sail

http://en.wikipedia.org/wiki/Multiview_orthographic_projection#Section

http://en.wikipedia.org/wiki/Fluid

http://en.wikipedia.org/wiki/Perpendicular

http://en.wikipedia.org/wiki/Lift_(force)



9.1.2 COEFFICIENT OF DRAG

In fluid dynamics, the drag coefficient (commonly denoted as: cd, cx or cw) is a dimensionless

quantity that is used to quantify the drag or resistance of an object in a fluid environment such

as air or water. It is used in the drag equation, where a lower drag coefficient indicates the

object will have less aerodynamic or hydrodynamic drag. The drag coefficient is always

associated with a particular surface area.

The drag coefficient of any object comprises the effects of the two basic contributors to fluid

dynamic drag: skin friction and form drag. The drag coefficient of a

lifting airfoil or hydrofoil also includes the effects of lift-induced drag.

Fig 9.1.4 The Coefficient of Drag of various shapes

The drag coefficient is given by the formula:

Where, Fd =Drag Force, in Newton

ρ = Mass Density of Fluid, kg/m3

v = Velocity, in m/sec

A = Reference area, in m2

http://en.wikipedia.org/wiki/Fluid_dynamics

http://en.wikipedia.org/wiki/Dimensionless_quantity

http://en.wikipedia.org/wiki/Dimensionless_quantity

http://en.wikipedia.org/wiki/Drag_(physics)

http://en.wikipedia.org/wiki/Drag_equation


http://en.wikipedia.org/wiki/Hydrodynamics



http://en.wikipedia.org/wiki/Skin_friction

http://en.wikipedia.org/wiki/Form_drag

http://en.wikipedia.org/wiki/Airfoil

http://en.wikipedia.org/wiki/Hydrofoil

http://en.wikipedia.org/wiki/Lift-induced_drag



9.2 F- DUCT

The principle of F-DUCT was introduced to formula one by McLaren Mercedes team. It was

technically called as RW-80.

To concept of F-Duct technique could be understood by considering simple aerodynamic

concept. It has been evolved from the analysis of fluid flow through the wing. At the simplest

level a wing generates downforce due to its profile- accelerating airflow on its lower surface

in relation to the flow over the top surface. If flow is accelerated, the pressure drops. Hence

there will be a net downward force on account of the difference in the pressure between the

two surfaces. Pressure drop can be build up in the wing by increasing the angle of attack of

the wing. This is because when AoA increases, the velocity of air below the wing increases.

But if the angle of attack of a wing is increased it can ultimately ‘stall’ due to flow separation

along the trailing edge, with a resultant loss in downforce and consequently aerodynamic grip.

To get around this problem, dual element or slot-gap wings are used, these allow for some of

the high pressure flow from the top surface of the wing to bleed to the lower surface of the

wing. This increases the speed of the flow under the wing, increasing downforce and reducing

the boundary flow separation.

Fig 9.2.1 Air bleeding through slit in the wing



However if the flow over the lower section of the wing can be stalled, the lift/drag ratio

worsens, but the overall result is a massive drop in the coefficient of lift, resulting in a net

reduction in drag, hence the benefits in relation to top speed. It should however be noted that

it is only stalling the trailing edge flow that is beneficial as opposed to stalling the entire wing.

This concept can be overcome by considering a flexible wing with slots. But in case the wing

fails, the whole wing arrangement fails and results in a greater drag. So it is not advisable to

use a full flexible wing.

McLaren team found out a solution for this problem. They redirect the airflow over the rear

wing and consequently allowing the flap to stall. Whilst they have been very tight lipped

about the system, it is most likely that the conduit from the front to rear of the car has a vent

in the cockpit that can be blocked by the drivers left leg, which is not in use on long straights.

Blocking the vent could direct enough airflow through the conduit to disrupt the flow over the

rear flap and induce a stall. The F-Duct system allows the car to go faster on the straights by

channeling air flow, controlled at the discretion of the driver, to the rear wing. This reduces

down-force and drag, making the car gain approximately 3 miles per hour on the straights, if

used timely.

The F-Duct in the kart provides an air scoop attached to the upper chassis, which extends

towards the rear wing. Initially, at slower speeds where the car needs maximum down-force in

corners, the port-hole of the F-Duct system into the cockpit is left uncovered. So the air forces

into the duct, which eventually falls in the rear wing. Thus the downforce created in the wings

increases and the kart gets maximum maneuverability at the corners. When the kart is moving

through a straight line, the downforce required by the kart is nil. So the driver puts his left foot

in the duct system, which blocks the flow of air through the duct. So the air falling in the rear

wing decreases and a minimum downforce is obtained. This enables the driver to accelerate

more.



Disadvantage

The main and only disadvantage of the F-Duct system is that, the control of Go kart is

reduced. This is because; the driver should shut the F-Duct in straight run. But when he is

negotiating a turn just after the straight line, he has a chance of losing the control. Also when

the competition becomes tighter, the driver may not have time to concentrate on the F-Duct

system. The primary job of the racer; i.e. to drive carefully during a competition is reduced by

adopting these techniques.

No matter that these system i.e. F-Duct and DRS helps in improving the lap time, it is only

valid when used properly. A little carelessness of the driver may result in greater reduction in

speed.

So these systems should be used with utter care during a race.

Fig 9.2.2 Air flow through F-DUCT in a F1 car



9.2.1 EFFECT OF ANGLE OF ATTACK

In fluid dynamics, angle of attack (AOA, or (Greek letter alpha)) is the angle between a

reference line on a body (often the chord line of an airfoil) and the vector representing the

relative motion between the body and the fluid through which it is moving. Angle of attack is

the angle between the body's reference line and the oncoming flow. This article focuses on the

most common application, the angle of attack of a wing or airfoil moving through air.

In aerodynamics, angle of attack specifies the angle between the chord line of the wing of

a fixed-wing aircraft and the vector representing the relative motion between the aircraft and

the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be

definable, so an alternate reference line is simply defined. Often, the chord line of the root of

the wing is chosen as the reference line. Another alternative is to use a horizontal line on the

fuselage as the reference line (and also as the longitudinal axis).

Fig 9.2.3 Relation between Coefficient of Lift and Angle of Attack


http://en.wikipedia.org/wiki/Greek_alphabet

http://en.wikipedia.org/wiki/Alpha_(letter)

http://en.wikipedia.org/wiki/Angle

http://en.wikipedia.org/wiki/Chord_(aircraft)


http://en.wikipedia.org/wiki/Vector_(geometry)


http://en.wikipedia.org/wiki/Fixed-wing_aircraft

http://en.wikipedia.org/wiki/Wing_root

http://en.wikipedia.org/wiki/Wing_root



Critical Angle of Attack

The critical angle of attack is the angle of attack which produces maximum lift coefficient.

This is also called the "stall angle of attack". Below the critical angle of attack, as the angle of

attack increases, the coefficient of lift (Cl) increases. At the same time, below the critical

angle of attack, as angle of attack increases, the air begins to flow less smoothly over the

upper surface of the airfoil and begins to separate from the upper surface.




9.2.2 STALL

A stall is a condition in aerodynamics and aviation wherein the angle of attack increases

beyond a certain point such that the lift begins to decrease. The angle at which this occurs is

called the critical angle of attack. This critical angle is dependent upon the profile of the wing,

its profile form, its aspect ratio, and other factors, but is typically in the range of 8 to 20

degrees relative to the incoming wind for most subsonic airfoils. The critical angle of attack is

the angle of attack on the lift coefficient versus angle-of-attack curve at which the maximum

lift coefficient occurs.

Stall of an aerofoil depends upon the critical angle of attack. It is the AoA at which maximum

lift occurs. Above this critical angle of attack, the aerofoil is said to be in a stall. An aerofoil

shaped object like a wing by definition is stalled at or above the critical angle of attack rather

than at or below a particular airspeed. The airspeed at which the aircraft stalls varies with the

weight of the wing, the load factor, bank angle, the center of gravity of the aerofoil and other

factors. However the wing always stalls at the same critical angle of attack. The critical or

stalling angle of attack is typically around 15° for many airfoils.

Fig 9.2.4 the figure showing the variation of lift of the wing (regarded as an aerofoil) under

various angles of attacks. The figure also shows the formation of separated flow as the angle

of attack increases.


http://en.wikipedia.org/wiki/Aviation

http://en.wikipedia.org/wiki/Angle_of_attack

http://en.wikipedia.org/wiki/Angle_of_attack#Critical_angle_of_attack

http://en.wikipedia.org/wiki/Profile_(engineering)

http://en.wikipedia.org/wiki/Planform

http://en.wikipedia.org/wiki/Aspect_ratio

http://en.wikipedia.org/wiki/Lift_coefficient

http://en.wikipedia.org/wiki/Stall_(flight)

http://en.wikipedia.org/wiki/Airspeed

http://en.wikipedia.org/wiki/Load_factor_(aeronautics)



CHAPTER 10

CONCLUSION

This Final Year Project report due at the end of the eighth semester (March 2012) mainly

consists of the completed designs for all the sub-systems of the racing go kart. The 2011cc, 2

stroke, 4 wheeled racing car, Go-Kart, we finally made one under 25K which is a big truth.

Big companies will design one go-kart at a minimum of 2 years. But we made this from six

months.

The project report is prepared in such a manner that every layman can understand the details

pertaining to the project. The report is prepared in simple language and described well. The

report give adequate idea and design guide line for making suitable report is expected to prove

valuable to the successor students of mechanical engineering to know the essentials of a

project and project report.



CHAPTER 11

REFERENCE

• Automobile Engineering Volume 1 & 2 by Kirpal Singh

• Automotive Technology by Joseph Heistner

• Racecarengineering magazine

• Manufacturing Technology of O.P Khanna

• http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=m4130r

• http://scarbsf1.wordpress.com/2010/05/29/turkey-red-bull-f-duct-revealed/

• http://www.insideracingtechnology.com/tech103anglattack.htm

• http://blog.kartbuilding.net/category/chassis-design/

• http://www.pbr.com.au/technical/documents/hydraulicbrakesystemsguide.pdf

http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=m4130r

http://scarbsf1.wordpress.com/2010/05/29/turkey-red-bull-f-duct-revealed/

http://www.insideracingtechnology.com/tech103anglattack.htm

http://blog.kartbuilding.net/category/chassis-design/

http://www.pbr.com.au/technical/documents/hydraulicbrakesystemsguide.pdf

Documents

Performance Improvement of Go Kart