Today

Folks,

I'm out again today.  Please begin work on your historical paper.  If you have doubts as to whether or not I'll approve the paper, email me.

I expect to be back by Friday's class, and we'll do some work then.  I believe all go-cart parts are in, and the Geely scooter stuff, too.

Thank you.

Sean

Sean out today

Folks - I'm out today.  Here's what you should be doing:

Revisit the sites below (particularly the 4-stroke engine ones).  Watch the animation and be sure to read the howstuffworks pages.

Also, come to class on Wednesday with a potential historical topic for your final paper.  Plan on this being a 5-7 page paper on a topic of automotive historical significance.

I hope to be back by Wednesday.  Sorry to be out.

Engines vs. Motors

http://www.youtube.com/watch?v=FfTX88Sv4I8

http://www.youtube.com/watch?v=XVdZj2EDmhM
with labels

http://www.youtube.com/watch?v=aATDsYVVcRM&feature=fvwrel

http://www.animatedengines.com/otto.html
Otto Cycle

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

Alternate pages for the animation:

http://www.poetv.com/video.php?vid=8037

http://videosift.com/video/Animation-of-car-engine-assembly-and-operation

More info than you need:

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

Motors:

http://www.animations.physics.unsw.edu.au/jw/electricmotors.html

FYI

http://www.mopedcentral.com/forsale.html

For those of you looking to buy something - this guy buys and sells project mopeds.

Fun, from class

http://www.youtube.com/watch?v=dJfSS0ZXYdo

http://www.youtube.com/watch?v=QQh56geU0X8

Pascal's Principle - the secret of brakes

In general, most fluids are incompressible (or very slightly compressible).  As a result, pressure applied to a fluid is transferred equally everywhere in the fluid.  Recall the definition of pressure:

P = F / A

Pressure = force / area

The units could be psi (pounds per square inch), or (in SI units), newtons per square meter (also called a pascal, Pa).

Force (F1) is applied to the small piston (A1), yielding a certain pressure (P).  This is transmitted to the secondary piston (A2).  To keep the ratio (P) constant, the resulting force (F2) on the other piston must be proportionally larger.  This can be used to lift large objects (auto lifts) or stop fast cars with the application of your feet.

FYI:

http://hyperphysics.phy-astr.gsu.edu/hbase/pasc.html

Related:  Pascal's law



The change in pressure equals the density times g (9.8 m/s/s) times the change in vertical height - this is useful for determining the pressure difference between two very different altitudes.


Now about those brakes....

Imagine pushing on brakes.

Fluid is transferred through brake lines to either drums or discs:

http://hogantire.com/tcbrakes.htm

http://auto.howstuffworks.com/auto-parts/brakes/brake-types/brake.htm

More from today's class

The Bernoulli Principle:

The pressure in a "moving stream" of fluid is LESS than that of the surrounding fluid.  Recall the demonstrations:

- blowing between the 2 soda cans
- the beach ball suspended by the air from the shop vac
- imagine putting your thumb over the nozzle from a garden hose

The last example relates to the "equation of continuity" -

A1 v1 = A2 v2

Meaning:  As the area (of the tube) gets smaller, the speed of the fluid gets greater.

Videos for the carburetor:

http://www.youtube.com/watch?v=4MnOgR4_jaE

http://www.fz1-forum.com/forum/gen-i-garage-tech-help/13659-how-carburetor-works-short-animation.html

Carb image

Carburetor

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.

http://static.howstuffworks.com/mpeg/chainsaw3.mpg

http://auto.howstuffworks.com/question377.htm

Engine stuff.

Engines galore!

Steam Engines:

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

http://www.animatedengines.com/locomotive.html

Stirling Engines:

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

http://www.animatedengines.com/vstirling.html

http://www.animatedengines.com/stirling.html

http://www.animatedengines.com/ross.html

2-stroke Engines:

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

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

4-cycle Engines:

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

(single cylinder)

Intake, Compression, Combustion, Exhaust

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

(more typical, and more complex)

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

What goes wrong typically?

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

car review / field trip

FOLKS:

Car review will be due on Tuesday.  Feel free to turn it in early. This is such a crazy week for many people - it seemed safer to extend the deadline by a class.  Remember - it should resemble a pro review that you might see in places like this:

http://www.edmunds.com/car-reviews/

http://www.caranddriver.com/

http://www.consumerreports.org/cro/cars/index.htm

We're doing the field trip next Thursday (Oct 4) to DC.  My astro class will hit the air/space museum while you'll hit the American history museum.  Let me know if this presents problems.

moped parts, etc.

It's a place called Treatland - treatland.tv

For next class, I anticipate having a go-cart frame and engine.

Hopefully also handlebars for the bike.

I should have ordered a moped (Puch) throttle cable by then.

Enjoy the weekend!

Go-ped folks -- decide what is next.  Two Go-peds are basically running.  They could definitely stand tune-ups, etc.  The third one (with the seat) needs work.  Think about that one.

Josh and Chris - keep up your spirits!

Check out the Stirling stuff on the previous post.

Other info:

The bike engine kit is on order.  I hope it's here by the end of next week.

Still looking for a go-cart.

It looks as though I'm going to have some donor bicycle(s).

Stirling Engines

Have a look.  Have a read.

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

http://www.animatedengines.com/vstirling.html

http://www.animatedengines.com/stirling.html

http://www.animatedengines.com/ross.html

http://www.animatedengines.com/ltdstirling.html

Also, if you have time - look on youtube for some Stirling engines.

Have a gander at these sites and read what you can:

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

http://www.animatedengines.com/locomotive.html

If you have time, look into steam engines and Hero's engine.

Enjoy!