Engine Desing

Both pistions are on the same crankpin at a 45 degree angle, they share
the same camshaft and lobes. One one revelution both cylinders fire
and on the next revolution they are on the exhaust and intake stroke.
Bang Bang ...... Flup Flup. Listen to the engine next time you are
sitting next to a Harley at a stop light. It is very obvious.

Harley actually attempted to patten the sound against Japanese copies.

They called it: potato potato potato potato and said it was theirs and

theirs only. Think they lost that fight.

HuH? Harleys were built that way in the 19 naughts! This was done to
save weight. Unlike you the engineers back then knew that you could
provide two crankpins and have one cylinder fire every 360 degrees at
what ever angle they chose. The 45 degree angle is simply to get the
engine into a small space as possible in the frame.

It was the Japanese who copied Harley. Maybe Harley tried to sue them,
but most Japenese v twins use ofset crank pins for a smoother run.
Also the cylinders are more ofset to improve cooling.

On 12 May 2005 10:52:25 -0700, "Sport Pilot"
wrote:

HuH? Harleys were built that way in the 19 naughts! This was done to
save weight. Unlike you the engineers back then knew that you could
provide two crankpins and have one cylinder fire every 360 degrees at
what ever angle they chose. The 45 degree angle is simply to get the
engine into a small space as possible in the frame.

I should have known that, after all I just got finished putting
together my Ford V-6 which is a 90 degree bank angle V-6. It has
displaced crankpins to allow for even firing.

Corky Scott

Corky Scott wrote:
On Wed, 11 May 2005 23:19:25 GMT, "Cy Galley"
wrote:

I don't believe so. Since it is a FOUR cycle engine, Each cylinder
only
fires every other revolution. It is timed so that one cylinder
fires each
revolution. They alternate but since they are staggered, so is the
timing.

Cy, I think they really do go bang bang, flup flup because of the
angle of the V. They cannot be timed so that they can fire as
equally
opposite as a horizonatally opposed twin.

Harley actually attempted to patten the sound against Japanese
copies.
They called it: potato potato potato potato and said it was theirs
and
theirs only. Think they lost that fight.


IIRC they claimed trademark protection, not patent.

And they won.

My girlfriend says Harley's sound sexy. Now you know why.

--

FF

Earlier, wrote:

IIRC they claimed trademark protection, not patent.

And they won.

Trademark instad of patent, yes. But as for winning, Unka Cecil tells
it different:

http://www.straightdope.com/columns/000915.html

...The Japanese put it more diplomatically when
fighting Harley's trademark request, arguing
that all big motorcycles sound pretty much the
same. After six years of legal proceedings and
no resolution in sight, Harley caved, claiming
it had won in the court of public opinion,
etc...

This SF Chronicle article says that they dropped the trademark attempt
in 2000:

http://www.sfgate.com/cgi-bin/articl...618EDT0176.DTL

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com

On Mon, 09 May 2005 01:54:33 -0500, Chris W wrote:

As most of you probably know the opposing cylinders on most engines are
slightly offset to allow for the piston connecting rods to attach to the
crank at different spots. I know of a few model airplane engines, where
instead of having the cylinders offset and having the connecting rods on
different sections of the crank, the connecting rods interlock and are
on the same section of the crank. I have been told that the engines
that are built like this run very smooth with almost no vibration.
Obviously they have an odd firing pattern, but I guess having the 2
cylinders perfect in line makes it so well balanced. These are all 2
cylinder engines, on a 4 cylinder engine with a spark every 180 degrees,
it seems like it would be even smoother. My question is why don't they
make any engines for real airplanes like that? The 180 - 540 degree
firing sequence probably isn't as big a deal for the high rpm of model
airplanes as it would be for the low rpm of typical GA planes, so it
would probably only be suitable for engines with a multiple of 4
cylinders. It seems like it would be easier to make too, simpler crank
shaft, perfectly symmetrical crank case. The only more complicated part
would be the connecting rods. Just curious.

what you are trying to describe is called DESAXING after a french guy
with the surname desaxe.
the change in alignment is really not that much.
it does work.

I have heard of magic hot rod engine tuneups that just involved a
quiet shimming and refacing of the cylinder base to achieve a freer
and faster running engine by desaxing it.
Stealth Pilot

Stealth Pilot
:

On Mon, 09 May 2005 01:54:33 -0500, Chris W wrote:

As most of you probably know the opposing cylinders on most engines are
slightly offset to allow for the piston connecting rods to attach to the
crank at different spots. I know of a few model airplane engines, where
instead of having the cylinders offset and having the connecting rods on
different sections of the crank, the connecting rods interlock and are
on the same section of the crank. I have been told that the engines
that are built like this run very smooth with almost no vibration.
Obviously they have an odd firing pattern, but I guess having the 2
cylinders perfect in line makes it so well balanced. These are all 2
cylinder engines, on a 4 cylinder engine with a spark every 180 degrees,
it seems like it would be even smoother. My question is why don't they
make any engines for real airplanes like that? The 180 - 540 degree
firing sequence probably isn't as big a deal for the high rpm of model
airplanes as it would be for the low rpm of typical GA planes, so it
would probably only be suitable for engines with a multiple of 4
cylinders. It seems like it would be easier to make too, simpler crank
shaft, perfectly symmetrical crank case. The only more complicated part
would be the connecting rods. Just curious.

what you are trying to describe is called DESAXING after a french guy
with the surname desaxe.
the change in alignment is really not that much.
it does work.

Umm, don't thnk that's what he's talking about. A few early radials used
desaxe cyliners, but that's a cylinder that's been offset form the
centerline of the crank to take advantage of a straighter conrod during the
power stroke. prolly worked OK, bu ti think they only use it in two strokes
nowadays if at all.
What th ewirter seems to be describing is an arrangement where two opposing
pistons share a crankpin. I've seen twins like this and they vibrate like
hell. A boxer (whihc most all flat opposed engines are) is a much smoother
arrangement.


Bertie

On 16 May 2005 00:28:47 GMT, Bertie the Bunyip
wrote:

Stealth Pilot
m:

On Mon, 09 May 2005 01:54:33 -0500, Chris W wrote:

As most of you probably know the opposing cylinders on most engines are
slightly offset to allow for the piston connecting rods to attach to the
crank at different spots. I know of a few model airplane engines, where
instead of having the cylinders offset and having the connecting rods on
different sections of the crank, the connecting rods interlock and are
on the same section of the crank. I have been told that the engines
that are built like this run very smooth with almost no vibration.
Obviously they have an odd firing pattern, but I guess having the 2
cylinders perfect in line makes it so well balanced. These are all 2
cylinder engines, on a 4 cylinder engine with a spark every 180 degrees,
it seems like it would be even smoother. My question is why don't they
make any engines for real airplanes like that? The 180 - 540 degree
firing sequence probably isn't as big a deal for the high rpm of model
airplanes as it would be for the low rpm of typical GA planes, so it
would probably only be suitable for engines with a multiple of 4
cylinders. It seems like it would be easier to make too, simpler crank
shaft, perfectly symmetrical crank case. The only more complicated part
would be the connecting rods. Just curious.

what you are trying to describe is called DESAXING after a french guy
with the surname desaxe.
the change in alignment is really not that much.
it does work.

Umm, don't thnk that's what he's talking about. A few early radials used
desaxe cyliners, but that's a cylinder that's been offset form the
centerline of the crank to take advantage of a straighter conrod during the
power stroke. prolly worked OK, bu ti think they only use it in two strokes
nowadays if at all.
What th ewirter seems to be describing is an arrangement where two opposing
pistons share a crankpin. I've seen twins like this and they vibrate like
hell. A boxer (whihc most all flat opposed engines are) is a much smoother
arrangement.


Bertie

you know I think you are right bertie.
I misread the post. I agree totally with your analysis as well.

shapers use a scotch link as well. they can get quite a vibration up
even at low rpm.
Stealth Pilot

Stealth Pilot
:

On 16 May 2005 00:28:47 GMT, Bertie the Bunyip
wrote:

Stealth Pilot
om:

On Mon, 09 May 2005 01:54:33 -0500, Chris W wrote:

As most of you probably know the opposing cylinders on most engines
are slightly offset to allow for the piston connecting rods to
attach to the crank at different spots. I know of a few model
airplane engines, where instead of having the cylinders offset and
having the connecting rods on different sections of the crank, the
connecting rods interlock and are on the same section of the crank.
I have been told that the engines that are built like this run very
smooth with almost no vibration. Obviously they have an odd firing
pattern, but I guess having the 2 cylinders perfect in line makes it
so well balanced. These are all 2 cylinder engines, on a 4 cylinder
engine with a spark every 180 degrees, it seems like it would be
even smoother. My question is why don't they make any engines for
real airplanes like that? The 180 - 540 degree firing sequence
probably isn't as big a deal for the high rpm of model airplanes as
it would be for the low rpm of typical GA planes, so it would
probably only be suitable for engines with a multiple of 4
cylinders. It seems like it would be easier to make too, simpler
crank shaft, perfectly symmetrical crank case. The only more
complicated part would be the connecting rods. Just curious.

what you are trying to describe is called DESAXING after a french
guy with the surname desaxe.
the change in alignment is really not that much.
it does work.

Umm, don't thnk that's what he's talking about. A few early radials
used desaxe cyliners, but that's a cylinder that's been offset form
the centerline of the crank to take advantage of a straighter conrod
during the power stroke. prolly worked OK, bu ti think they only use
it in two strokes nowadays if at all.
What th ewirter seems to be describing is an arrangement where two
opposing pistons share a crankpin. I've seen twins like this and they
vibrate like hell. A boxer (whihc most all flat opposed engines are)
is a much smoother arrangement.


Bertie

you know I think you are right bertie.
I misread the post. I agree totally with your analysis as well.

shapers use a scotch link as well. they can get quite a vibration up
even at low rpm.
Stealth Pilot

Scotch link? Is that where one big end is forked to go round the other rod?
On that subject, I seem to remember one of the Flying and Glider manuals
from the thirites has insturctions on how to turn one of those diabolical
contraptions into a boxer engine. It meant a new crank and bending the con
rods!
And I thought Moslers were crap...


Bertie

Bertie the Bunyip wrote:
...
What th ewirter seems to be describing is an arrangement where two
opposing
pistons share a crankpin. I've seen twins like this and they vibrate
like
hell. A boxer (whihc most all flat opposed engines are) is a much
smoother
arrangement.


What is the distinguishing characteristic of a boxer, that opposing
cylinders fire simultaneously?

--

FF