· Chapter 6/7 of Shop Class as Soulcraft due Thursday (April 26th)
· No discussion Tuesday April 24thdue to guest speaker.
Updates
· Noelle and Alex: Worked on collecting hardware for mounting the handlebars.
· David and Alex K: Continued installing the clutch/transmission and the drive chain.
· Brendan and Jake: Worked on finding hardware to install nacelle
· Julianne and Charlie: Installed valve covers and finished the top end.
· Eric and Hannah: Worked on assembling the rear wheel and grinding the spokes to prevent puncturing the inner tube.
· Emily and Jordan: Continued to sand the bondo on the fenders.
· Ricky: Worked on the stater.
· Connor and Grace: Nearly finished the bottom end. Helped Emily and Jordan.
Reading
Chapter 5 recap of Shop Class as Soulcraft.
· Themes:
o The responsibility to devote time to repair motorcycles. Must balance between a speedy and affordable repairs versus spending the time to learn about different problems and aspects of the bike.
· Content:
o Discusses the beginning of the author’s introduction into motorcycle repair.
o Author received PhD in philosophy after finding an interest in ancient Greek philosophers. Attained employment at conservative Washington DC think tank, found it wasn’t satisfying and opened his own repair shop.
· Motorcycle/Technical terms:
o Café Racer: a lightweight, lightly powered motorcycle optimized for speed and handling rather than comfort and for quick rides over short distances.
o Pneumatic Tools: is a type of power tool, driven by compressed air.
· 3 more weeks of class (Final presentations will be given during Reading Period)
· Chapter 5 of Shop Class as Soulcraft due Thursday (April 19th)
· Will read one chapter per class until book completion (No discussion Tuesday April 24thdue to guest speaker. Both chapters for next week will be discussed Thursday April 26th)
Updates
· Ricky, Noelle, and Alex: Continued to work on mounting the battery box, will require fabrication to install due to modifications by previous owner.
· David and Alex K: Assembled the clutch/transmission
· Brendan and Jake: Worked on finding hardware to install nacelle
· Julianne and Charlie: Installed pushrods.
· Eric and Hannah: Continued to true the wheel. Almost finally completed. Sanded the rear hub to attach the sprocket.
· Emily and Jordan: Continued to sand and paint. Assisted by Glenn.
· Connor and Grace: Fixed hydraulic lift on motorcycle stand. Worked with David and Alex K. on clutch and transmission.
Reading
Chapter 4 recap of Shop Class as Soulcraft.
· Themes:
o Different people are inherently better at different jobs.
o Jobs also influence the worker.
o Failure teaches humility.
· Content:
o Discusses the beginning of the author’s shop experience. Got an apprenticeship at a Porsche dealership as a teenager. Didn’t learn much about car repair due to a subpar mentor.
o Father was a physicist and tried to impart wisdom using abstract advice that wasn’t easily received by the author.
o Talks about trying to figure out someone else’s design (i.e. his VW Beetle, God’s design of the human body, etc.) is a humbling process.
· Motorcycle/Technical terms:
o Turbocharger: a turbine-driven forced induction device that increases an internal combustion engine’s efficiency and power output by forcing extra air into the combustion chamber.
o “Matchporting”: matching up the exits of the intake manifold runners to the entrances of the head’s intake ports.
o Swing Axle: is a simple type of independent (rear wheel) suspension allowing wheels to react to irregularities of road surfaces independently, and enable the vehicle to maintain a strong road holding.
o Transaxle: an automotive mechanical component that combines the functionality of the transmission, axle, and differential into one integrated assembly.
Nitriding: a heat treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface.
Noell: attached new seat to blue motorcycle with new bracket, now working on assembling swing-arm and frame, found grease nipple, tapped frame with 1/4 26 thread
Julienne: spray painted cylinder, working on frame
Alex: Making a new manifold for carburetor because the last one was mistaken
David: About to put engine back together so we gathered parts, just missing the pawl retaining ring which we’ll take from the other motor if John says so
Jake: Smoothed out fork assembly/frame attachment ball bearings. Removed excess paint from joints
Brendan: Evaluated pieces from powder-coater, cleaned up fittings from fork tubes.
Connor: found missing engine case bolts, working together with clutch+transmission to reassemble engine
Eric: Worked on wheels with Bill, day 5 of wheel lacing but it’s slow going. Spokes are OK, the nipples will go pretty deep into the spokes so they might be ground down.
Hannah: Eric said it all
Grace: Connor said it all
Alex K: sanded down powder-coated parts of the frame to make electrical contact. Every piece of the motorcycle needs to be the same electrical potential because tail-lights and other electrical parts only have one lede.
Charlie: worked on painting the cylinder with Julienne, finished top-end, started working on frame + cleaning out parts on the frame.
Ricky: removed greasy fabric from lots of the wires, cleaned wires and electrical pieces.
Bill’s presentation feedback: people loved it; drawings on tension and compression are especially useful and relates to Poisson’s ratio (which concerns things having a fixed volume in tension or compression)
Discussion on this week’s reading
Chapter 16: discussion lead by Brendan
No motorcycle references
Grading system concept: having no grades.
An interesting theoretical concept, especially in peoples’ responses.
Reminded people of this class with how we don’t have exact grades.
Not really practical reference because this is a fictional book and we don’t know how this would actually play out
Reality of wanting to get a degree vs. wanting to learn
“imitation is the real evil” before rhetoric teaching can begin – very true in things like writing seminar, where we’re trying to imitate while outsmarting.
Julienne disagrees: there are many disciplines, e.g. music, wherein you have to practice what is already written in order to develop creativity. So there is value to imitation. Prof. Littman agrees: picasso invented his own style after studying others. In Littman’s other course, you need to study others before you can be creative.
Defining rhetoric and dialectic:
Rhetoric is persuasive talk and writing, to convince others
Dialectic is a back and forth questioning for the search for truth
Chapter 17: discussion lead by Hannah
Concept of “quality”:
Phaedrus’ definition is that it can’t be defined
It probably can be defined because it’s a real thing that we interact with
It’s easier to define quality in terms of what it isn’t than what it is
Important theme of the book that he grapples with
The different elements of teaching writing, and why you need an outline:
An outline is usually a set of rules that you’re given without considering, similar to how the scientific method is something that is learned without necessarily learning its practical implications. But the reasons are there, and they are valid; they’re just often lost in the transmission.
Be careful about definitions, because definitions are a theory. When he was cross-examined, Prof. Littman was very careful in trying not to define things but to give examples.
Chapter 18: discussion lead by Eric
Esthetics
the study of quality, even though Phaedrus doesn’t want to define it
Conclusion is that quality can’t be defined. Implications?
questions if quality can’t be defined, then can you teach it? Points to example of when students were angry about his lack of an answer, they were upset because they thought that they were supposed to learn things that were already known.
When you remove quality from the world, what are you removing? In some sense, you lose some quality by taking away beauty from things, or taking away their individuality.
The consequence is that vulnerable populations suffer from a lack of basic opportunities without quality
Maybe not? baseline standard of living is constant without quality
Quality in terms of aesthetics, or quality in terms of function. (Important distinction!) Which one is sacrificed in a world without quality?
Architect vs. Structural Artist:
architecture is visually appealing, but doesn’t necessarily function well.
Structural artist has a visual appeal to it, but it really works.
Chris’ experience, based on the hike:
Chris should have swatted down his behavior a bit more as a gut reaction. Eric relates with a family member demonstrating similar behavior.
Must’ve been really tough for the father
No matter what you do, your actions have outcomes that you can’t necessarily predict.
Prof. Littman’s story about being a parent:
Sometimes it is important to stop bad behavior, but sometimes it’s important to not turn a bad situation into a worse one.
Electricity Demonstration:
Solenoid with an iron pipe: powering the sole creates a magnetic field which magnetizes the iron bar and draws it into the solenoid. Pull is regardless of current.
Make and break circuit: coil of wire with lots of little wires in it. Also demonstrated step-up transformer by coils with different numbers of loops.
(Diagram of transformers and make or break circuits attached below)
(Diagram of transformers and make or break circuits attached below)
Today’s agenda: Lecture with Bill Becker on Wheels
Bill Becker biography:
Retired architect, architecture undergraduate at Case Western and Masters from Penn
Retired as a motorcycle designer and builder
Favorite thing about motorcycles: amazing and functional pieces of design, where aesthetics and engineering work together flawlessly
Likes working with vintage machine and upgrading them to a higher standard than when they were new
Lecture:
Why can’t bicycles or motorcycles stand by themselves? “Because they’re too (two) tired!”
Wheel from a French moped: has a hub and brake in the middle, essentially analogous to motorcycle wheel
History of wheels:
The wheel is a form, as long as it is circular with a pivot it is consistent
Spokes: an innovation to make wheels lighter and springier
First motorcycle has two different wheels
front wheel: spoked, moves freely through space, only pressure is force of gravity
back wheel: solid wheel, applying pressure from drive chain onto the ground to move the bike
Three subjects: physics, engineering, and material science
Physics
Mass: defines how a matter in one object relates to matter in another object (on earth, define by weight: relation of mass of earth to mass of object)
Objects are subject to gravity and motion – inertia or acceleration
“weight is not a friend of the wheel”
on a railroad car, heavy wheels are OK
but on a racecourse/motorcycle, you want wheels to be light so that less work is required to accelerate them ––> spokes; thin rim; aluminum hub
Vectors: ways to describe the direction and magnitude of forces we are talking about
Material science
Athletes look for certain things in different classes, e.g.
Wrestlers want a high strength to weight ratio
Gymnasts want flexibility, strength, and small mass
Basketball players want strength, flexibility, and height
Materials of a motorcycle also look for different qualities for different needs:
Aluminum: strong, flexible, low weight, corrosion resistant, machinable, malleable, inexpensive; it can be cast into unusual shapes (like in engine case)
Cast iron: strong, porous (can absorb oil), reduces friction, dissipates heat well but brittle
Steel: can be hard, soft, corrosion resistant (hardened steel: ball bearings; woodrift keys) (softened steel: fender, needs to be bent into shape)
Rubber: flexible, not very compressible but high tensile strength, corrosion-resistant, lightweight
More: polyester, brass, chromium, asbestos, plastic, air
Material scientists will select from these to do different jobs in the wheel
Engineering
Terms:
Deadload – the weight of the thing itself, i.e. motorcycle with fluids in it
Liveload – weight of it with a rider on it
Static loading: object is stationary, just applying gravitation forces
Dynamic loading: object is moving through space, loading due to contours of the road, turning, impact, acceleration/deceleration
Forces acting on a materials:
Compression – some materials (e.g. brick) are very good in compression, others (e.g. rubber/sand) are very compressible
Tension – another structural force that is just “pulling” on things – aluminum, steel are good; glass is bad
Bending – just a combination of compression and tension
Shear – forces are opposed off-axis to create a “tearing” effect
Thomas Young: physician, material scientist
relationship between stress and strain
Force on an object in compression: expect straining (i.e. getting fatter/shorter)
Force on an object in tension: expect stretching
Young’s models:
Increasing strain increases stress, up to plastic deformation
Linear relationship btw. stress and strain during elastic deformation
concave-down parabolic relationship between stress and strain during plastic deformation
Fractures at the end of plastic deformation phase
Wheels:
Patterns of four spokes at a time (36 spokes in total on most bikes; 40 on British)
Spokes evenly spaced around the rim
On a motorcycle wheel, spokes are not arranged to intersect the axis of the wheel because of a differential between forces on the hub and forces on the wheel
Spokes are off-angle to make a rigid geometry by translating forces between hub and rim
Triangulation both in the plane of the wheel and laterally (i.e. coming out of the plane of the wheel)
Spokes are in pairs of four to resist opposing and proposing rotation; out of plane bending
Loading of the wheel and tension of the spokes:
Spokes are great in tension and bad in compression because of their slender shape and size + how they are connected to the rim
Static loading of gravity of the rider – top spokes are doing the work to hold the hub up
Impact loading – all the spokes that are opposite to the point of impact go into tension
Acceleration – half of the spokes (the ones that point in the direction of acceleration along the hub) go into tension
Turning – rigidity out of the plane of the wheel go into tension
Nowadays, many wheels are cast instead of spoked because of the cost of labour; 88 parts in our spoked wheel but only 1 in a cast wheel. There is some debate as to which is more aerodynamic.
The size of a spoke is determined by its material strength, trying to be maximally aerodynamic while still supporting the weight of the bike. Bicycle spokes are very thin because they are lightweight and very little torque is transmitted by the rider.
This singular spoke brought to demo can hold about 800 lbs! All the spokes in tension at any moment can hold up to 8,000lbs.
Julianne: worked on cutting valves for cylinder head. Measured distances for holes for bolts.
o Used lathe to make 45 degree angles
o Used steel blue to see what material was removed
o Exhaust is the smaller valve. Intake is larger to take in more air.
Noelle: cleaned carburetor. Took it apart and put back together. Started putting it back onto red motorcycle.
Charlie: cut valves. Working on finding x and y coordinates of all the holes in the engine cover.
o Mapping holes: put engine cover on bed of mill. Found drill bits that fit holes. One hole is origin and you mark the subsequent holes off that. Put x-y coordinates into CREO and take that to the “laser” cutter.
Connor: cleaned bottom end of engine. Disassembled and collected parts. Painted it and let it dry. Cleaned it out with air hose to get rid of sand.
Emily: worked on fenders by polishing them with dye grinder. Changed to sand blasting the rust off. Filled the extra holes on fender with bond-o.
Hannah: Problems locating part. Setting things up to get chromed. Putting rear wheel together today. Cleaned sprocket threads.
Eric: Rethread old hub so they weren’t sandblasted. Assembling rear hub.
David: waiting for new parts to come in for transmission. Took demo transmission apart and put it back together a couple times. Works well now.
Jake: figured out speedometer gear box ratio for our bike. Cleaned polished parts. Tried diagnosing vibration of red bikes front forks
Today we started in the shop and finished our class with a visit from Professor Gideon Rosen to discuss our ZAMM reading.
This discussion was focused on themes within the chapters of ZAMM but not necessarily direct relation to the narrator and Phaedrus.
-What is philosophy?
– The love of wisdom. The attempt to say how things in the broadest possible sense of the term hang together. Aims to give a comprehensive picture of the world at a fundamental level. The description of philosophy sounds like the description of physics.
-Hume and Kant.
– When you look at the world you see a constantly changing barrage of colored shapes. The melting ice cube at first you see a cubical solid and over time you see a change of shape. What starts off as cold is no longer cold. From moment to moment there is nothing constant about the melting ice cube, but something has remained the same. It has just changed form. Appearances are constantly changing but there is a single persistent constant.
o How do you know?
o Where do you get the idea that there might be something consistent despite the changing?
Modern day philosophers are reacting against Descartes idea. Descartes says things are innate ideas from god. You can reason without experience based on these innate ideas. Example: Geometry. Because god wouldn’t lie you’re accessing this knowledge that was given to you by a benevolent god.
Even if you originally learned about the Pythagorean theorem from your 6thgrade teacher, when it comes to math you can run through the proof yourself. Teacher is a short cut according to Descartes.
– With Hume and Kant god plays no role.
o Hume is a radical empiricist. Thinks all ideas come from experience. No innate idea. Hume is confused about where we get the idea of the thing that remains constant. He says we have no such idea. You can say the water was there at the beginning and at the end but you’re just “feigning or pretending” that there was something there. Verbal fiction.
o Kant thinks its obvious you do not just see an array of colored shapes unless you’re “tripping.” You see things undergoing change. Kant says there’s a raw matter of experience. The mind imposes structure on it. The mind constructs a world of persisting things that interact with physical laws. The world we experience is constituted by the mind. Kant’s Copernican revolution.
Think of your idea of what a motorcycle is. You conjure up a fuzzy picture of a motorcycle from a certain angle. But it’d be a mystery to match up a motorcycle from head on as opposed to sideways. Thoughts aren’t a stream of pictures. Concepts are not pictures, more like descriptions. Not matching experience with a picture, but if it satisfies some description. It would even be abstract.
-Eastern vs Western Philosophy
– There is eastern thought. Chinese word for philosophy had to be invented when translating western philosophy. Not from the basis of authority. Indian philosophy is more similar to western philosophy than Chinese or Japanese for cultural reasons.
– Eastern and romantic link is from western romanticism from rational strands. People took for granted the aim of philosophy. They disagreed about what the fundamental bits of philosophy were
-Electrons trajectory.
– Kant built his philosophy off the idea of innate ideas. Quickly was proven false.
– Empirical measurement based on result. Polarized sunglasses at 45 degrees experiment shows how measurement changes the environment.
-Socrates and universities as churches
– Church that is now a bar considered sacrilegious. Equated to university threatened to losing accreditation. The rebuttal being i t’s not about accreditation, its about the search for truth.
– Saying what a university is. You could be describing what all universities have in common or you could be saying what you think a university should be.
– What is worth preserving in universities?
o Creation of new knowledge and education for leadership.
– Mission should be to produce more educated people.
Professor Littman will bring the parts to the chromer in Philadelphia
What everyone did:
o Sarah: Washed parts on Tuesday
o Hannah: made nut to cover threads on the front hub, began to assemble back hub
o Noelle: Gathered frame parts, found missing parts, there is one pin that is missing, the carburetor worked on the ’58 motorcycle
o Eric: assembled rear hub
o Charlie: Cleaned and sanded parts; going to clean out the valves today
o Connor: continued cleaning the bottom engine and reassembled the engine using old covers
o Jake: Need to determine if the speedometer gearbox is working
o Brendan: getting stuff ready to go to the powder coater; tack welded the lower nacelle, welded two pieces of medal together
o Alex: dismantled the carburetor, which was not working well
o David: went over the small parts of the clutch and transmission; ordered missing parts
o Alex K.: helped bottom end team sand blast engine case; putting together demo transmission
o Jordan: cleaned parts for wheel group, polished exhaust; professor Littman got some useful tools
o Grace: worked with Connor to clean bottom engine and tape it up
o Julianne: exhaust valve had stuff on the inside that needed to be chiseled out
o Ricky: sandblasted battery casing; started taking horn apart
Review of Professor Martinelli:
o Two strokes vs. four strokes; fins; carburation (lowering pressure—Bernoulli’s equation); thermodynamic relationships
o One student’s reaction: our motorcycle had not been designed with the principles in mind, especially with respect to form
Tuesday’s reading: next three chapters in Zen—11, 12, 13; we will go directly to the shop, then we will transition from 3-4—meet directly in the shop on Tuesday!
Reading discussion:
o INTRODUCTION
o Starts off more intellectually than Zen; values shop class
o In terms of motorcycles, he enjoys their simplicity
o Alex thinks that his approach is self-indulgent—how the job is self-gratifying. He has the Marxist, worker attitude
o Mentions dipstick, carpenter’s level
o CHAPTER 1
o P. 24 motorcycle reference—solvents used to clean different parts of the motorcycle; the author’s wife can use different; ignition backfire p. 35 “often this sense making entails not so much problem solving as problem solving” are good questions better than good answers?
o White collar jobs vs. blue collar jobs (more meaningful?). he believes in learning by doing
o Economic pressure—can’t outsource the trades
o Washing machine reference: a washing machine exists to serve you, but when it is broken you have to ask what it needs—a change of perspective.
o He likes objective measures—how do you know when you are doing a good job? He HATES management consultants!
o We must get outside of out head and looking for something; we are all problem solvers. If you notice dripping oil, it might be nice
o Page 32: “my purpose of this book is to elaborate the potential for human flourishing in the manual trades—their rich cogitative challenges and psychic nourishment—rather than stake out policy positions or make factual claims about the economy”
o Blinder (outsourced) vs. MIT economist (rule based)
Assignment for Tuesday: Think of questions for Professor Martinelli
Assignment for Thursday: Introduction and chapter 1 of Shop Class as Soulcraft
Announcements:
Get stuff to be powder-coated or chromed together
We might be missing frame parts
Make sure we have anything that will be painted ready to be powder-coated
Example: battery box
Next Tuesday: Professor Martinelli
Come up with a set of questions for him
Week four scribe: take notes next week
Housekeeping:
Ricky: Found a taillight at the bunker and got that working; checked the spark plug on the red motorcycle
Noelle: With Alex, assembled carburetor; flooded the carburetor and it leaked; lathed out the top plate because it was warped; reattached it and it no longer leaked
Eric: Determined which front and back hub to use; began plugging it up for powder coating
David: With Alex, found that half of a split-ring washer is missing (but there was one at the bunker)
Connor: With Grace, cleaned the engine plates and put them back together; going to sandblast it today
Charlie: Tried to disassemble the headlight; put it in a new chromed case
Brendan: Cleaned the light; organized parts for powder coating
Alex: Worked with Charlie
Grace: Worked with Connor
Jordan: With Emily, put together the jacks for the wheels
Julianne: With Charlie and Ricky, went to the bunker; finished cleaning top end parts
Sarah: With Ricky, attached the light and tested it; watch the dem for the spark plug
Jake: Searched on ebay
Hannah was out
Tiger Cub Engine Calculations Reading:
Octane is C8H18
Air is 20% O2
Nitrogen goes in and out of engine
While it is a spectator, it still starts to react to form NOx
A problem with engines
Sulfur present – emissions
Carbon dioxide and water vapor are also products
Energy release is 44,400 J per gram octane
Air to fuel ratio is about 15:1 by weight
14.7:1 grams in industry
What limits the amount of power output is the amount of oxygen
Could make the engine larger
Compress the air
Super/turbocharging
Use pure oxygen or
Nitrous oxide
Nitromethane
⅕ liter -> .257 g of air and .0171 g fuel yields 759 J
37,950 Watts out of the engine (100% efficiency)
50.9 horsepower (if the engine was fully efficient)
Engine has about 20% efficiency in actuality
Demo:
Two cylinders (pipettes) with a platinum wire
They are bubbling with the top open
When the top is closed, the bubbles cannot escape
The gas inside the left cylinder is going down more quickly than the right
This cylinder holds the hydrogen (H2O -> two moles hydrogen for only one mole oxygen)
When the hydrogen got to the bottom, a spark was lit and the ping pong ball moved upwards about a foot and a half
The product is water
The pressure increases because of heat (PV=nRT)
Thus, the ball is launched
On the second launch, the ball went up about three feet
On the third launch, the ball went up about two and a half feet
Brake dynamometer:
A device that allows you to figure out the torque and power of a motor
A rope is wrapped around the shaft of the motor (called a rope brake)
This motor is an electric motor
The ropes are pulled tighter and the differences of the tensions in the ropes will allow you to find the torque as a function of speed for this motor at a certain voltage
The speed of the motor will also be recorded
As the rope is pulled tighter, the engine slows down
For an electric motor, torque vs speed is linear
The torque is greatest at stall
Power = Force (Torque) * Velocity
To get a power vs speed graph, multiply the two axes together and graph with respect to speed
The graph is a parabola (opening downwards)
The greatest power to the motor will be at the center of the parabola, which is half of the possible velocity
Homan force vs velocity is called the Hill Curve
Concave and with a downward slope
The power vs velocity graph for a human on a bike also has a peak, where it will be easiest to get up a hill
Efficiency of an electric motor would be the power curve divided by the force (torque) curve
Graphed with respect to velocity, it is a straight line with a positive slope
The most efficient is using the least amount of energy
Questions for Professor Martinelli:
Where does air flow play a role in our motorcycle?
Carberation
Cooling
Windage in the engine
Exhaust
Aerodynamic drag
Streamlining shapes
On the wheels
Fluid in the engine
Lubrication
27 February 2018
Notes by Eric: Professor Littman was not here today. In his absence, we were joined by a guest: Professor Luigi Martinelli
Broad overview of the role of fluid mechanics, and more generally whatever happens when you try to move against air or water
Whenever you are doing mundane tasks, you are dealing with fluid flows. Either they are opposing your motion or helping you.
o Two regimes—organized (laminar) and chaotic (turbulent)
Chaotic flow will offer more resistance to the motorcycle
Cost of turbulent flow vs. closing the wake is a tradeoff constantly considered.
Distance between back of ride and wake seeks to be minimized.
Some helmets are designed to minimize the gap between the rider and the air flow
Often propulsion requires a working fluid
o The flow rate—the amount of fluid that can go in or out—is determined by the shape of the valve.
o The sizing of the fin is determined by the property of the flow of the engine head; therefore, the extent of the fin design of an air cool engine
Sometimes the two combine
o In a sail boat, the systems are integrated—balance, steering, and other properties of the sail
o Other, seemingly more complex systems, such as a rocket, are actually simpler.
Two vs. four stroke. Two-stroke—as you draw in fresh mixture, you exhaust from the previous combustion; the two-stroke exhaust may let out unburned fuel. If you solve the environmental problem, you would have a lighter engine because you do not need a valve. In a four-stroke engine, one stroke pulls in and compresses fuel then ignites it (power stroke), then the next stroke pushes out the exhaust.
o The Tiger Cub has two valves to have a desirable mass flow rate. The cam controls how quickly the valves open and close
Engine cooling—require heat exchange between the engine and the outside air
Overview of aerodynamic forces on ground vehicles
CARBURATION
Venturi effect: for an incompressible flow, a reduction of area causes an increase in local flow velocity and a consequent decrease in pressure.
o Always have high velocity, low pressure
The carburetor then fulfills 3 primary functions:
o Control engine power by adjusting the air intake flow
o Meter the fuel flow in the air flow aspirated maintaining the ratio air/fuel to optimal values throughout the engine operating range
o Homogenize the mixture of air and fuel to enable the subsequent combustion
It is possible to obtain optimal thickness, spacing of the fins by mathematical computations
There are two approaches to improving design: evolutionary and computational
External aerodynamics
Even with seemingly benign topics, it is hard to optimize,
Hybrid between electric bike and moped is most efficient
The speed at which the oil moves around is quite low; our motorcycle has a dry sump reduces the complexity of the system; if we had a
Next week: learning about aerodynamics and drag on Tuesday
Housekeeping:
Emily: With Jordan, cleaned up and polished the engine covers using a sandblaster, sandpaper, and a die grinder
A die grinder uses compressed air to make a fan blow with very high speed (and low torque) – great for polishing
Noelle: With Alex, disassembled the Amal carburetor and found and labeled all parts for it
David: Cleaned the pieces of the transmission with Alex
Jake: Made a tool to compress the shocks; took the shocks apart and cleaned them
Brendan: Had to bore a hole to take apart the shocks; sandblasted them
Connor: General disassembly; removed oil pump; missing ball bearing for the oil pump
Note to quartermasters: make sure to order new ball bearing
Eric: With Hannah, sandblasted different parts of the wheel; going to assemble motorcycle stands today in shop
Alex: With Noelle, worked on disassembling the carburetor and cataloged parts; began to clean the carburetor
Alex: Finishing disassembling bottom half of engine; took of main sprocket
Grace: Worked with Connor and Alex to disassemble the engine; will check to make sure everything is working; will go through the gasket packet to figure out if replacements are needed
Jordan: Worked on polishing with the polishing wheel and by hand
Sarah: With Ricky tested connections with a voltmeter and with a light; today, will generate sparks with old motorcycle
Julianne: Continued to clean top end parts; need a piston and rings
Ricky: With Sarah, checked electrical connections
Charlie: Sandblasted the two top end pieces
Hannah is not here
Discussion of Chapters 9 and 10:
Chapter 9:
Motorcycle References
Engine misfire:
Spark fires but no fuel is ignited
Misfire can cause a bang or backfire
Happens if the unexploded gas goes into the exhaust line
Content
Scientific Method
Helpful to diagnose complicated problems
Ends up driving Phaedrus crazy
Six elements:
Statement of problem
Hypotheses
Experiments for each hypothesis
Predicted results of the experiment
Observed results
Conclusions
Hypotheses sometimes sound dumb but are important because assumptions shouldn’t be made
132: Experiment only fails if it cannot provide data either way
Inductive vs. Deductive reasoning
Inductive: making a hypothesis out of data
Deductive reasoning: inferring what is happening based on observations
Underlying Form
Classic vs. Romantic approach
Chapter 10:
Content
Characterizing Phaedrus: how did he lose his mind? Comparing Phaedrus and Einstein
Both study science for the stake of science – to learn – pursuit of knowledge
Page 111: The difference between experience and nature
Does nature provide the data?
Phaedrus is more interested in inquiry
The philosopher’s approach
Where knowledge comes from
Phaedrus thinks that there are infinite hypotheses and thus thinks that they can never be solved
Exponential growth of data and information but not of knowledge
Top Speed of the Motorcycle: 62 mph
K’Nex model of a Model T engine: Four stroke cycle
2:1 gear ratio
Crack turns the connecting rod, which makes the pistons move up and down
The spark plug goes off when the piston is at the top
As the piston move up, the exhaust is blown out
Intake valve opens when the piston is at the bottom: air and fuel mixture enters
RPM: revolutions per minute of the crank
What is the maximum RPM of our motorcycle?
“Triumph-10001.pdf” – workshop instruction manual
We have the T20 model
Technical data is located at the bottom of the manual:
63 mm bore (diameter of piston)
64 mm stroke
Power output: 10 (brake) horsepower at 6000 RPM
6000 rpm = 100 revolutions per second
Gear ratios
Engine sprocket: 19 (teeth)
Clutch sprocket: 48 (teeth)
Gearbox sprocket: 17 (teeth)
Rear wheel sprocket: 46 (teeth)
Clutch is going at 2375 RPM
Crack to clutch: 19/46 * 6000 = 2375 RPM
Rear wheel is going at 877 RPM (in the fourth gear)
Clutch to rear wheel in top gear: 17/46 * 2375 = 877 RPM = 14.6 revolutions per second
14.6 revolutions per second * 6.28 ft = 91.7 feet per second
91.7/66 = 1.04 * 60 mph = 62 mph
48/19 * 46/17 = 6.84 (which was given as the top gear ratio)
Ratio of how fast the crank is turning to how fast the wheel is turning
Gear ratios increase as the gear goes down
Tiger Cub Bible
Page 173: Gearboxes for all of the Tiger Cub motorcycles
Standard, wide, close, extra-close, and ultra-close gearboxes
