Exam and Final Paper

In addition to finishing the build, you have two remaining assessments: an exam and a final paper.

1. The Final Paper.

Choose ANY relevant topic and get it approved by me. I will likely say it's fine, but will ask you tweak it. No matter what you write about, some history and technical issues will likely be addressed. The extent to which it focuses more on history or technical issues will be determined, but expect to deal with both on some level.

The paper will be as long as needed. If you find that you can write it in 2 pages, you probably haven't thought about it enough or done enough research - or it is a really trivial topic. On the other hand, 10 pages may not be realistic for the time period.

This paper will be due the week before the final week of the semester.

2. The Final Exam.

I would like you to take the final exam before winter break. It will be done in class. You are permitted to bring in a page of notes - that is, you can prepare for specific questions.

Your exam will consider of 4-5 questions, to be chosen from the following topics:

Write essays (2-3 paragraphs, as well as images, if needed) on 2 of the following topics:

2 stroke engine
Stirling cycle
4-stroke cycle
What happens when the key is turned in a car
(Topic TBA)

Write a paragraph or two (as well as images, if useful) on 2 of the following topics:

Carburetor
Brakes
Magneto
Octane
Efficiency and losses - why are engines not extremely efficient
(Topic TBA)

Brakes and Pascal's Principle

From Wikipedia: "Pascal's law, or the Principle of transmission of fluid-pressure, states that "Pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid, such that the pressure ratio remains the same."

For brakes or hydraulic lifts, the idea is simple. Apply a force (F1) through a small area (A1) and the pressure (P) is given by F1/A1.

The pressure is transmitted through the fluid equally. The pressure on the other side, onto another piston (area A2) will generate a force (F2). P = F2/A2

Since the pressures are constant:

F1/A1 = F2/A2

Some interesting pages to view:

http://www.mrwaynesclass.com/teacher/Fluids/hydraulics/home.html

http://physics.bu.edu/~duffy/semester1/c23_pressure_pascal.html

http://www.youtube.com/watch?v=VxLTDtaRCZk

http://www.yteach.co.uk/page.php/resources/view_all?id=p5_pressure_force_area_load_Pascal_compression_strength_t&from=search

for a more mathy approach

http://www.youtube.com/watch?v=A3ormYVZMXE&feature=related

Engines revisited - what happens when you turn the key?

Recall this video from class.

http://www.howstuffworks.com/engine.htm

See the cut-away engine animation:

http://auto.howstuffworks.com/engine1.htm

A first look at what happens when you turn a key.

1. Turn key

2. Current runs to starter (through solenoid) - this creates a magnetic field which engages the starter.

3. Starter motor turns engine and triggers a series of events.

4. Coil takes current from battery and increases voltage (it is essentially a transformer) - the voltage is applied to the distributor.

5. The distributor allocates voltage to each spark plug in the correct firing order.

(6. The alternator replenishes the battery.)

7. The electrical spark from the spark plug ignites the compressed fuel mixture (brought in during INTAKE STROKE), driving the piston downward (away from plug). This is the POWER (or combustion) STROKE.

8. Piston is driven upward - exhaust gases are expelled. EXHAUST STROKE

9. Fuel mixture is brought into cylinder, due to pressure differential and fuel mixture sent in through carburetor,. INTAKE STROKE

10. Piston is compressed again. COMPRESSION STROKE.

Piston motion is linear, but this is converted to rotary motion via crankshaft.


SEE VIDEO:

http://auto.howstuffworks.com/engine1.htm

http://auto.howstuffworks.com/engine2.htm


Furthermore:

Engines use water and air to dissipate the huge amount of heat generated. The pump moves water around the cylinder walls and valve jackets. Heat is transferred to water and water is pumped back to radiator. The hot water is cooled by air convection and cool water is pumped back to engine.

Oil is used to decrease friction caused by metal on metal. The oil pump circulates the oil to critical areas in the engine. An oil filter cleans the air, removing dirt and particles. The fuel pump pushes gas into the carburetor, which introduces air and creates a fuel-air mixture that travels into the cylinder chamber.

Adapted from Auto Repair by John Doyle, 1987.

Functions in the 4-stroke engine

4 Stroke Engine Parts

Reminder

Papers are due Friday, even though we have class tomorrow.

I will also accept some other form of descriptive device: poster, movie, etc.

The important thing is that you explain your system or piece of technology. At least one image should be included.

Good luck!

Better magneto images

The Magneto

The magneto is an alternating-current generator that contains a permanent magnet. A magneto requires no source of direct current for its operation. The most common use of magnetos is in the ignition system of some internal-combustion engines. Magneto ignitions are used in lawn mowers, snow blowers and other 2-stroke engines; they may be used in vehicles—including certain tractors, snowmobiles, motorboats, motorcycles, and small airplanes—that do not require storage batteries to operate auxiliary equipment. Like the storage battery in an automobile, the magneto provides the electric voltage that causes the spark plugs in the engine to spark.

The two main parts of a magneto are a permanent magnet and an armature. The armature is a piece of metal around which is wound the primary, a coil of a few turns of heavy wire.

In most magnetos today, the armature is stationary and the permanent magnet rotates; in others, the permanent magnet is stationary and the armature rotates within the magnetic field produced by the magnet. The relative motion of the magnet and armature generates an alternating current in the primary.

In the typical magneto used in an internal-combustion engine, the magnet is turned by the crankshaft of the engine. The voltage generated by the magnet in the primary coil is not sufficient to cause a spark in the spark plugs. The secondary, which consists of many thousands of turns of fine wire, is wound around the primary. The two coils act like a step-up transformer. The breaker points are electrical contacts in the circuit containing the primary. They are used to interrupt the current in the primary, causing an extremely short, high-voltage burst of current in the secondary. This current is directed to the spark plugs.

Magneto ignition was developed in 1878 by Nikolaus August Otto. It was widely used on early automobiles.

http://science.howstuffworks.com/magneto-info.htm

Carburetor

Carburetor Theory

The carburetor has one main function: to regulate engine speed. It accomplishes this by adjusting the amount of air and fuel that reaches the engine chamber, which then sustains combustion.

For a low-speed idle you have a small amount of air and fuel entering the engine. This lowers the chemical mixture entering the combustion chamber, and thus lessens engine power and subsequently lowers the RPM (revolutions per minute). As we open the throttle, the carb allows more air and fuel into the combustion chamber, thus increasing engine power and RPM's.

The Venturi Effect

What allows the carb to pull fuel from the fuel tank is the Venturi effect, a phenomena related to the Bernoulli principle. This states the velocity of a fluid entering a tube increases as it passes through a smaller diameter region.

Fluids are generally incompressible, so the same amount of fluid (volume) is going to try to get through a volumetric cross-section of tube - if you make the diameter smaller, the fluid has to move faster to get through.

In a carburetor, this increase in air speed allows more fuel to be drawn from the float chamber (a fuel reservoir) through the jet, where it is somewhat atomized.

This low pressure region is precisely where fuel enters the carburetor throat. This is what allows the engine to "suck" fuel from the gas tank.

Moped repair manual

For the Puch and pocket-bike groups - you may find some good repair ideas here:


http://blizzard.rwic.und.edu/~nordlie/moped/repair.html

2-stroke cycle with more details, and some 4-stroke engine stuff

First, a blast (literally) from the past: the steam engine:

http://science.howstuffworks.com/transport/engines-equipment/steam1.htm'

Scroll down and run the animation.

>

The familiar 2-stroke engine:

http://science.howstuffworks.com/transport/engines-equipment/two-stroke1.htm

With animation:

http://science.howstuffworks.com/transport/engines-equipment/two-stroke2.htm

>

Watch this video; the engine he shows in cut-away is a 2-stroke single-cylinder engine:

http://auto.howstuffworks.com/engine.htm

>

Here is a single-cylinder 4-stroke engine, if you're thinking ahead a little:

http://auto.howstuffworks.com/engine1.htm

(Note the FOUR strokes: intake, compression, combustion, exhaust)

This one is more like a lawn mower engine.

>

And if you're really thinking ahead, here is a 4-cylinder 4-stroke engine:

http://auto.howstuffworks.com/engine2.htm

>

And if you're super-curious, here is how the pistons translate all that up-and-down pumping into rotational motion (via the crankshaft):

http://auto.howstuffworks.com/engine4.htm

>

For casual reading: what can go wrong....

http://auto.howstuffworks.com/engine3.htm

The Carnot / Stirling Cycle

http://www.bpreid.com/carnot.php

http://galileo.phys.virginia.edu/classes/109N/more_stuff/flashlets/carnot.htm

http://library.thinkquest.org/C006011/english/sites/thermo3.php3?v=2

The 2-stroke engine

Some useful reading here:

http://www.southernskies.net/page_info/runningtwostrokeengine.html

http://www.theultralightplace.com/2%20stroke%20principle.htm

http://science.howstuffworks.com/transport/engines-equipment/two-stroke2.htm

http://en.wikipedia.org/wiki/Two-stroke_engine

Stuff

http://blizzard.rwic.und.edu/~nordlie/moped/repair.html

Syllabus

Automotive Physics
Fall 2011
Sean Lally

Course description

Students will learn what makes the ubiquitous automobile run - fuel,
engine, transmission, braking, steering and more. We will look at the
standard automotive systems in the first few weeks, and then design
and build our own gasoline-powered go-cart. Different groups of
students will work on the myriad elements of car design and
construction. Text materials will be online, and students will need
to provide their own eye and ear protection, as well as work clothing
(once construction begins). Grades will come from short research
papers and the extent to which the systems in the car actually
function. Want to know how a car works, how to change a tire or try
your hand at welding? We have a class for you.


Welcome to Automotive Physics! I’m so glad to have you hear. Let’s
get down to business. What do you want out of this class? We need to
decide that right away. I have an agenda, but I’m not married to it.
I need you learn about the parts of automobiles: engine, steering,
brakes, transmission and so forth. And then I’d like you to apply
these ideas (more or less) to build your own vehicle(s). That’s about
it. That said, the general path of project construction will be
determined by the groups in the class. I anticipate there being 3-4
ongoing group projects – and we’ll need to figure this out SOON.

General philosophy

I am neither a gearhead, nor a mechanics. I’m certainly not an
expert. I just like cars. I have offered this course because I think
it will be fun and informative for all of us. Don’t get too
frustrated with me if I can’t easily answer your questions – honestly,
this will probably happen a lot!

Grading

At present, I expect to determine grades from the following:

Half of the grade:

Proposal of project
Car review – examine automotive reviews and generate one of your own
History paper – pick a car or innovation with real historical importance
Technical paper – explain the science behind a particular automotive innovation
Test of some sort


The other half of the grade:

Your construction work, alone and with your team
Team evaluation
Self-evaluation/reflection

Topic sequence:

Introduction

What do YOU want out of the class?
What do YOU want to build?
What is it about cars that attracted you to the class?

Some physics

Gas laws (PV = nRT)
1st and 2nd laws of Thermodynamics
Conservation of energy
Pistons and compression
Carburetor

The engine

Carnot cycle
Stirling cycle
Introduction to the engine
Engines vs. motors
2-stroke
4-stroke
Otto cycle
Diesel cycle
Wankel cycle (?)

The systems

Transmission
Steering and differential
Braking (and Pascal’s principle)
Lubrication
Cooling
Electrical
Ignition
Power train

Building!
Useful web resources:

http://animatedengines.com/
http://auto.howstuffworks.com/car.htm
http://www.howitworks.net/how-automobiles-work.html
http://www.howstuffworks.com/engine.htm
http://www.goped.com/
http://www.dune-buggy.com/buggylinks/Commercial/Plans/
http://www.spidercarts.com/
http://www.kartbuilding.net/
http://gokartplans.com/
http://www.diygokarts.com/kart-plans/kart-plans-main.html


Potentially Useful iPad / iPhone apps:

Repair pal
Pocket dyno
Dynolicious
Speedometer v. 1.1
g-meter
g-tac
Dev-toaster’s Rev

Print resources:

Auto Repair Illustrated - Doyle. My favorite book so far on all things auto. I found a copy at Ukazoo,
How Cars Work - Tom Newton
Auto Repairs for Dummies – Deanna Sclar
Automotive Science and Mathematics – Bonnick, Allan
Kinetic Contraptions - Curt Gabrielson
The Way Science Works - Macmillan
How to Keep Your VW Alive - John Muir
The Two-Can Stirling Engine – William Gurstelle
Build your own off-road buggy – Ron Champion

Local resources:

http://www.crazyraysautoparts.com/
Chris' Moped Repair: 443.414.1291
Parkville small Engine Repair


In preparation for our time together, here are some things I'd like
you to assemble:

clothes that can get dirty or greasy
eye protection
ear protection
hair ties (if you have long hair)

Course materials will be online, on this blog or presented on a flash
drive. There is no text for this class.
Finally, think about what you want to accomplish in this class. I have
an agenda, of course - I would like each student to learn the basics
of what makes automobiles run. I'd like to spend around 2-3 weeks
covering the basics: engine, transmission, brakes, etc. During this
time, you (and your team) will begin design on some component of a car
(go-cart, actually).

I expect that we will have 2-3 teams. Each will need to appoint
members to work on: frame, brakes, engine mounting, pedals, steering.

You will also need to decide whether or not this will be a closed
go-cart (with roll cage).

Mind you, I'm not married to most things in this class. If you decided
to build a motorcycle instead, I'd be happy with that - though I know
virtually nothing about it. If you wanted to build a helicopter
(rotorcycle), more power to you. My main job will be to keep you
focused and realistic, help you find resources and teach you some
basics. I'm not overly knowledgeable about cars, but I love the
process and I'm excited to learn with you.

Grades

Expect grades to come from the following:

2 papers - one on an auto system (ie., brakes) and one on an auto or
innovation of historical significance
the work that you and your team accomplish
team member evaluation
self-evaluation
test (yes, I said "test")

Where we are now.

Greetings, fellow car fanatics!

Here's where we left off, in terms of groups:

2-wheeler (motorcycle, etc.) -

Mark

Alex M?

Yi

Tess

Elliot

Claire

Hannah

Motorized bike -

Amy P

Nick

Kid car -

Amy L

Daniel

Julia

Maya

Go-kart -

Tal

Wayne

Dan

Emily

Anna Rose

Isabella

This last group needs to decide whether it will be 1 group or 2 - there is some disagreement as to what project people really want to undertake.

Also, Alex Marion needs to pick a group.

Here are a couple of things worth viewing (for certain groups):

For the motorized bike group:

http://bikemotorkit.com/

This and a bike will be nearly everything you need. Let me know if you're ready to commit and I'll order it.

For the 2-wheeler group:

http://baltimore.craigslist.org/mcy/2570164545.html

If we act fast, we can get this (and restore it). Let me know.

For the go-kart group(s):

http://www.dune-buggy.com/buggylinks/Commercial/Plans/
http://www.spidercarts.com/
http://www.kartbuilding.net/
http://gokartplans.com/
http://www.diygokarts.com/kart-plans/kart-plans-main.html

We could also consider buying a frame, etc. - Craigslist is a good place to start.

Let's figure stuff out by Wednesday, if at all possible.

Thanks - Sean

Friends - welcome to the maiden voyage of Park School's "Automotive Physics" class. I'm thrilled that you're here.

In preparation for our time together, here are some things I'd like you to assemble:

clothes that can get dirty or greasy
eye protection
ear protection
hair ties (if you have long hair)

Course materials will be online, on this blog or presented on a flash drive. There is no text for this class, though I do recommend these books:

The Way Science Works - Macmillan
The Way Things Work - Macaulay
How to keep your VW alive - Muir

Finally, think about what you want to accomplish in this class. I have an agenda, of course - I would like each student to learn the basics of what makes automobiles run. I'd like to spend around 2-3 weeks covering the basics: engine, transmission, brakes, etc. During this time, you (and your team) will begin design on some component of a car (go-cart, actually).

I expect that we will have 2-3 teams. Each will need to appoint members to work on: frame, brakes, engine mounting, pedals, steering.

You will also need to decide whether or not this will be a closed go-cart (with roll cage).

Mind you, I'm not married to most things in this class. If you decided to build a motorcycle instead, I'd be happy with that - though I know virtually nothing about it. If you wanted to build a helicopter (rotorcycle), more power to you. My main job will be to keep you focused and realistic, help you find resources and teach you some basics. I'm not overly knowledgeable about cars, but I love the process and I'm excited to learn with you.

Grades

Expect grades to come from the following:

2 papers - one on an auto system (ie., brakes) and one on an auto or innovation of historical significance

the work that you and your team accomplish

team member evaluation

self-evaluation

test (yes, I said "test")