Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

Single mother in need of explanation

0 views
Skip to first unread message

Dumb_Blonde

unread,
Mar 13, 2007, 6:06:37 PM3/13/07
to
Thank you in advance for your time. I found a neat project to do with
my 14 year old son, but would like to know the science behind it so it
will be educational.

Here is the video link.

http://www.metacafe.com/watch/470767/firecracker_rocket_project_experiment/

It is a fire cracker experiment, and I know he will love it, but I am
clueless as to how this makes my car run.

**THE-RFI-EMI-GUY**

unread,
Mar 13, 2007, 6:39:33 PM3/13/07
to
I assume the can is open on one end like a soup can, not a coke can. I
think the water is there to provide an airtight, frictionless seal for
more effect. Keeping the firercracker dry is tricky. This looks like a
good use for the hundreds of firecrackers I have left over!

What he is simulating is the explosion that happens in one of your cars
engine cylinders. A car engine operates on a series of small controlled
explosions. In your car, the explosive force drives a piston down,
pushing a connecting rod which in turn rotates a crankshaft. A car
engine has 4 to 8 cylinders which fire sequentially and smoothly. The
links below illustrate this with a single cylinder like a lawnmower
engine. These are "internal combustion engines".

My sister did a similar science project years ago with a coffee can
fitted with a spark plug and filled with a very small amount of gasoline
or ether. A plastic lid was placed on top and an ignition coil made a
spark which blew the plastic lid off. Not as dramatic as a fire cracker.

http://www.keveney.com/otto.html
http://en.wikipedia.org/wiki/Four-stroke_cycle

Dumb_Blonde wrote:

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

Captain Midnight

unread,
Mar 13, 2007, 8:25:51 PM3/13/07
to
"**THE-RFI-EMI-GUY**" <rhyo...@nettally.com> wrote in message
news:45f72822$0$4929$4c36...@roadrunner.com...

Their is no explosion in a properly operating internal combustion engine.
The fuel merely heats the air. The expansion of the air pushes the piston.
An explosion called detonation or knock can put a hole in the piston. Some
engines require higher octane fuel to keep knock from occurring.


**THE-RFI-EMI-GUY**

unread,
Mar 13, 2007, 8:44:49 PM3/13/07
to
Its a matter of semantics. A arguably a hydrogen bomb simply heats up surrounding air (and matter).
-- 
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P

Arfa Daily

unread,
Mar 13, 2007, 9:34:14 PM3/13/07
to

"Captain Midnight" <Not...@twip.invalid> wrote in message
news:45f732f5$0$8973$4c36...@roadrunner.com...
That seems to me to be a misleading description of the principles of an
internal combustion engine. The fuel is mixed with the air in a very
carefully controlled ratio, highly compressed, and is then set light to,
either by a spark in the case of a gasoline engine, or by self ignition from
the rapid heating of the mixture during compression, in the case of a
diesel. It burns or combusts, and what comes out of the exhaust, after the
burning, is not air, but a fully reduced residue of the burning process. The
burning of the mixture under such intense pressure, in what is essentially a
fully contained space, takes place at such speed, it would usually be
considered to be representative of a controlled explosion. Detonation knock
is normally as a result of the timing of the ignition source not being ideal
for the engine in question. The detonation process should be started just
before the piston reaches top dead centre, so that by the time the burning
has spread fully from the initiating point - ie the spark plug - through the
entire mixture, and is thus at its fiercest, the piston has rolled over past
its point of being momentarily stationary, and is just beginning on its way
back down the cylinder. The rapidly burning ( exploding ? ) mixture will
then deliver maximum thrust to the piston, driving it down the cylinder
bore. If the mixture starts to burn too early, it will reach maximum energy
output before the piston has reached the top, so will oppose the upward
movement of the piston, which is still occuring, leading to the
pre-detonation knock.

Maybe it is just semantics, and some may disagree, but that has always been
my take on how an engine works, ever since I was first rebuilding them as a
kid, because I couldn't afford repair shop prices !!

Arfa


Arfa Daily

unread,
Mar 13, 2007, 9:42:21 PM3/13/07
to

"Arfa Daily" <arfa....@ntlworld.com> wrote in message
news:qiIJh.166$pP5...@newsfe3-gui.ntli.net...
Just as a matter of interest, I just looked up the word " explosion " at

http://dictionary.reference.com/browse/explosion

and interestingly, the first result, 5th definition, specifically mentions
the internal combustion engine. The third result, definition 1a also seems
to cover it neatly, as does the twelfth

Arfa


Arfa Daily

unread,
Mar 13, 2007, 9:52:55 PM3/13/07
to

"Arfa Daily" <arfa....@ntlworld.com> wrote in message
news:1qIJh.168$7l1...@newsfe4-gui.ntli.net...
Ah, it could be a question of semantics ! It's just occured to me what you
were saying. It is the pressure wave from the burning ( although I still
think " exploding " covers it also ) mixture that drives the piston down,
and not the actual burning mixture ( flame front is it called ? ), which
should not actually touch the top of the piston before it burns out, and can
cause damage, if it does. Yep ! that's it I reckon. We're both on the same
page now. Sorry ...

Arfa


**THE-RFI-EMI-GUY**

unread,
Mar 13, 2007, 10:33:23 PM3/13/07
to
I especially like this definition. In fact anyone who has watched a nitro fueled dragster can attest to the violent explosive manner of those engines exhaust. Those engine builders avoid "detonation" at all costs. 
  1. A release of mechanical, chemical, or nuclear energy in a sudden and often violent manner with the generation of high temperature and usually with the release of gases.
Most people don't think of the explosive process going on within an automobile engine because the  process is very refined, by mufflers, flywheels and engine timing.
-- 
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P

Homer J Simpson

unread,
Mar 13, 2007, 11:05:30 PM3/13/07
to

"Captain Midnight" <Not...@twip.invalid> wrote in message
news:45f732f5$0$8973$4c36...@roadrunner.com...

> Their is no explosion in a properly operating internal combustion engine.

Sure there is. But you want it at the correct time in the cycle. Knocking is
caused by misfiring.

clifto

unread,
Mar 14, 2007, 1:40:14 AM3/14/07
to
Arfa Daily wrote:
> That seems to me to be a misleading description of the principles of an
> internal combustion engine. The fuel is mixed with the air in a very
> carefully controlled ratio, highly compressed, and is then set light to,
> either by a spark in the case of a gasoline engine, or by self ignition from
> the rapid heating of the mixture during compression, in the case of a
> diesel. It burns or combusts, and what comes out of the exhaust, after the
> burning, is not air, but a fully reduced residue of the burning process.

To add to your excellent explanation, the byproducts of combustion, such
as carbon dioxide, together occupy more volume than the fuel-air mixture
did, and the heat generated by the rapid burn further increases the total
volume.

--
Martians drive SUVs! <http://oregonmag.com/MarsWarm307.html>

Captain Midnight

unread,
Mar 14, 2007, 3:49:26 AM3/14/07
to
"Homer J Simpson" <nob...@nowhere.com> wrote in message
news:_DJJh.41829$lY6.17214@edtnps90...

Detonation is all of the fuel burning at once(explosion). A proper flame
path will happen relatively slowly to push the piston(burn). The beginning
of the burn is timed to push the piston when the crank is in the proper
position. How long the burn lasts and it's timing is dependent on engine
design and application. If an explosion was acceptable there'd be no need
for high octane fuel. Apparently you've never seen a piston with a hole in
the crown. It's like the difference of flipping a light switch with your
finger or hitting it with a hammer.

Pinging is hot spots in the combustion chamber causing self ignition at the
wrong time. The extra heat from this can cause detonation though.


mark krawczuk

unread,
Mar 19, 2007, 9:55:36 AM3/19/07
to
Detonation is all of the fuel burning at once(explosion). A proper flame
> path will happen relatively slowly to push the piston(burn).
tell me what is the change over point at which a "slow burn" turns to a
explosion.
u want the fuel to burn slow , so teh engine runs slower ?

you are incorrect , dentonation is the IGNITING of fuel at the wrong time
.

hmmm of course its a explosion, i`ll put u in a petrol vapour filled room
with a sparkplug connected up to a engine , via a long plug lead, then i`ll
crank the engine over KABOOM !!!!of course its gonna explode.

"Captain Midnight" <Not...@twip.invalid> wrote in message

news:45f79c1e$0$27030$4c36...@roadrunner.com...

Captain Midnight

unread,
Mar 20, 2007, 3:57:40 AM3/20/07
to
"mark krawczuk" <krawc...@dodo.com.au> wrote in message
news:45fe9728$0$98624$c30e...@lon-reader.news.telstra.net...

Seems you are also incapable of understanding the difference between burning
and an explosion too.


Ancient_Hacker

unread,
Mar 20, 2007, 12:05:20 PM3/20/07
to
On Mar 19, 8:55 am, "mark krawczuk" <krawczu...@dodo.com.au> wrote:
> Detonation is all of the fuel burning at once(explosion). A proper flame> path will happen relatively slowly to push

The technical term is "High order reaction". The two options are:

(1) A flame front moves across the gas, taking milliseconds. That
what happen when you light a match, or a spark plug fires in a
properly operating innternal combustion engine.

(2) High order: The reaction starts instantly at many places throught
the materinal, as it's heated to its iginition point throughout.
Takes place in nano to microseconds. That's what most explosives do.

Captain Midnight

unread,
Mar 21, 2007, 4:10:07 AM3/21/07
to
"Ancient_Hacker" <gr...@comcast.net> wrote in message
news:1174406720.3...@n76g2000hsh.googlegroups.com...

Bingo! And it produces a shock wave that combustion does not.


Michael A. Terrell

unread,
Mar 21, 2007, 4:34:26 PM3/21/07
to

Captain Midnight, huh? Tell me, what is the name of the street where
the abandoned C-band uplink earth station that you used to jam HBO with
?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Captain Midnight

unread,
Mar 22, 2007, 6:03:13 AM3/22/07
to

"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
news:460196D5...@earthlink.net...

> >
> Captain Midnight, huh? Tell me, what is the name of the street where
> the abandoned C-band uplink earth station that you used to jam HBO with
> ?
>

http://www.macdougallelectronics.com/bio.html


Michael A. Terrell

unread,
Mar 23, 2007, 12:09:24 AM3/23/07
to


I already know that, but where is the location of the earth station
used to Jam HBO, or even the name of the company that built the
equipment?

mark krawczuk

unread,
Mar 24, 2007, 10:20:44 PM3/24/07
to
hi, read this "
There are three rates of combustion; ordinary combustion, explosion (Rapid
Combustion), and detonation..


look around onthe net , hmmmmm rapid combustion , err COMBUSTION !!!!! OR
EXPLOSION,.... i am right.

"Captain Midnight" <Not...@twip.invalid> wrote in message

news:4600dbb0$0$18842$4c36...@roadrunner.com...

mark krawczuk

unread,
Mar 28, 2007, 5:46:17 PM3/28/07
to
no one challenging me .........
]

"mark krawczuk" <krawc...@dodo.com.au> wrote in message

news:4605dc4f$0$98632$c30e...@lon-reader.news.telstra.net...

Captain Midnight

unread,
Mar 29, 2007, 1:24:47 AM3/29/07
to
What? You haven't received your Net Wit award yet?

"mark krawczuk" <krawc...@dodo.com.au> wrote in message

news:460ae1ef$0$24861$c30e...@pit-reader.telstra.net...

0 new messages