another poor man's car engine conversion

[jan olieslagers[_2_]]

Yesterday I was talking to a friend who plans to power his single-seat
slow flyer with an engine from a Citroen Visa. I suppose this engine (a
linear descendant from the famous Citroen 2CV) is not well known in the
US, it is an air-cooled 2-cylinder boxer, in this particular application
it would produce some 45 HP.

My friend absolotely wants it in the plane as it is in the car, i.e.
with the clutch side rearward (the plane is a traditional "puller"), and
wants to take power from the clutch side. His idea is to have a belt
reduction "behind" the engine, then a transmission axle above the engine
to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
things about transmission axles driving propellers, vibration not the
least. But he answers the axle needn't be long, as the engine is only a
2-cylinder.

Any thoughts / ideas / comments / experiences?
TIA,

[bildan]

On Feb 14, 6:38*am, jan olieslagers >
wrote:
> Yesterday I was talking to a friend who plans to power his single-seat
> slow flyer with an engine from a Citroen Visa. I suppose this engine (a
> linear descendant from the famous Citroen 2CV) is not well known in the
> US, it is an air-cooled 2-cylinder boxer, in this particular application
> it would produce some 45 HP.
>
> My friend absolotely wants it in the plane as it is in the car, i.e.
> with the clutch side rearward (the plane is a traditional "puller"), and
> wants to take power from the clutch side. His idea is to have a belt
> reduction "behind" the engine, then a transmission axle above the engine
> to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
> things about transmission axles driving propellers, vibration not the
> least. But he answers the axle needn't be long, as the engine is only a
> 2-cylinder.
>
> Any thoughts / ideas / comments / experiences?
> TIA,

Not a bad concept. I've spent some time thinking about the same
layout with larger engines. It has several advantages and a few
disadvantages.

Some advantages are that it moves the weight of the PSRU to the rear
of the engine and raises the propeller hub for better prop ground
clearance. It puts the radiator at the front of the engine with the
water pump mounted fan right behind it.

I think the key is that the shaft has to be thin and flexible to get
its resonance well below that of any other part of the drive train.
Going the other way to make a very stiff shaft raises its natural
resonance frequency so it's likely to match some other component
resulting in destructive resonance.

[Charles Vincent]

bildan wrote:
> On Feb 14, 6:38 am, jan olieslagers >
> wrote:
>> My friend absolotely wants it in the plane as it is in the car, i.e.
>> with the clutch side rearward (the plane is a traditional "puller"), and
>> wants to take power from the clutch side. His idea is to have a belt
>> reduction "behind" the engine, then a transmission axle above the engine
>> to drive the prop.

> I think the key is that the shaft has to be thin and flexible to get
> its resonance well below that of any other part of the drive train.
> Going the other way to make a very stiff shaft raises its natural
> resonance frequency so it's likely to match some other component
> resulting in destructive resonance.

You should model that sometime...

Charles

[bod43]

On 14 Feb, 14:26, bildan > wrote:
> On Feb 14, 6:38*am, jan olieslagers >
> wrote:
>
>
>
>
>
> > Yesterday I was talking to a friend who plans to power his single-seat
> > slow flyer with an engine from a Citroen Visa. I suppose this engine (a
> > linear descendant from the famous Citroen 2CV) is not well known in the
> > US, it is an air-cooled 2-cylinder boxer, in this particular application
> > it would produce some 45 HP.
>
> > My friend absolotely wants it in the plane as it is in the car, i.e.
> > with the clutch side rearward (the plane is a traditional "puller"), and
> > wants to take power from the clutch side. His idea is to have a belt
> > reduction "behind" the engine, then a transmission axle above the engine
> > to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
> > things about transmission axles driving propellers, vibration not the
> > least. But he answers the axle needn't be long, as the engine is only a
> > 2-cylinder.
>
> > Any thoughts / ideas / comments / experiences?
> > TIA,
>
> Not a bad concept. *I've spent some time thinking about the same
> layout with larger engines. *It has several advantages and a few
> disadvantages.
>
> Some advantages are that it moves the weight of the PSRU to the rear
> of the engine and raises the propeller hub for better prop ground
> clearance. *It puts the radiator at the front of the engine with the
> water pump mounted fan right behind it.
>
> I think the key is that the shaft has to be thin and flexible to get
> its resonance well below that of any other part of the drive train.
> Going the other way to make a very stiff shaft raises its natural
> resonance frequency so it's likely to match some other component
> resulting in destructive resonance.

You might like this.
http://ibis.experimentals.de/downloads/torsionalvibration.pdf

[Karl-Heinz Künzel]

jan olieslagers schrieb:
> Yesterday I was talking to a friend who plans to power his single-seat
> slow flyer with an engine from a Citroen Visa. I suppose this engine (a
> linear descendant from the famous Citroen 2CV) is not well known in the
> US, it is an air-cooled 2-cylinder boxer, in this particular application
> it would produce some 45 HP.

In Germany we have some microlights on this engine.

http://www.ulf-2.de/

Under "Bilder" on the left you will see details of the engine.

KH

[[email protected]]

On Feb 14, 6:38*am, jan olieslagers >
wrote:
.. But he answers the axle needn't be long, as the engine is only a
> 2-cylinder.
>
> Any thoughts / ideas / comments / experiences?
> TIA,

The "shortness" may not preclude harmonic vibration. Each situation
is unique.
I've never had any hands on with a @CV motor but from what I see here:

http://www.youtube.com/watch?v=7mvTWiF6KFM

It looks to me like it would be much easier to put the belt drive and
prop on the flywheel end. Far fewer things to move and/or
modify..........

For some other interesting insights into the Citroen motor for those
like me that don't have a physical one in front of them to examine,
take a look starting at 1:50.

http://www.youtube.com/watch?v=2QTTAzJbL3w

Are there sources for these motors, and/or parts, in the states?
===============================
Leon McAtee

[bildan]

On Feb 14, 8:41*am, Charles Vincent > wrote:
> bildan wrote:
> > On Feb 14, 6:38 am, jan olieslagers >
> > wrote:
> >> My friend absolotely wants it in the plane as it is in the car, i.e.
> >> with the clutch side rearward (the plane is a traditional "puller"), and
> >> wants to take power from the clutch side. His idea is to have a belt
> >> reduction "behind" the engine, then a transmission axle above the engine
> >> to drive the prop.
> > I think the key is that the shaft has to be thin and flexible to get
> > its resonance well below that of any other part of the drive train.
> > Going the other way to make a very stiff shaft raises its natural
> > resonance frequency so it's likely to match some other component
> > resulting in destructive resonance.
>
> You should model that sometime...
>
> Charles

It's been done many times - and examples built. If the propeller/
shaft resonance is well below the lowest fundamental frequency of the
engine/PSRU, you're probably OK. If it's above the lowest fundamental
frequency, you're probably not OK.

The neat thing is that the most successful solution is also likely to
be the lightest.

As an example, look at the ridiculously skinny half shafts on the rear
of a Honda CRV.

I ran the models several times on a V8 with a simple flex-plate PTO on
the flywheel housing driving an overhead shaft via a cog belt. It
didn't look as if there would be any problems at all if the propeller
shaft was thin enough.

The V8 sat low in the nose, water pump forward with the radiator in
front of that just like in a car. The prop shaft went forward over
the engine. It would fit perfectly in a 3/4 scale P-40 or a Piper
Pawnee glider tug.

[[email protected]]

On Feb 14, 9:07*am, Karl-Heinz Künzel >
wrote:

> Under "Bilder" on the left you will see details of the engine.
>
> KH
-----------------------------------------------------------------------------
Note the excellent method used for belt tensioning.

-R.S.Hoover

[Brian Whatcott]

jan olieslagers wrote:
> Yesterday I was talking to a friend who plans to power his single-seat
> slow flyer with an engine from a Citroen Visa. I suppose this engine (a
> linear descendant from the famous Citroen 2CV) is not well known in the
> US, it is an air-cooled 2-cylinder boxer, in this particular application
> it would produce some 45 HP.
>
> My friend absolotely wants it in the plane as it is in the car, i.e.
> with the clutch side rearward (the plane is a traditional "puller"), and
> wants to take power from the clutch side. His idea is to have a belt
> reduction "behind" the engine, then a transmission axle above the engine
> to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
> things about transmission axles driving propellers, vibration not the
> least. But he answers the axle needn't be long, as the engine is only a
> 2-cylinder.
>
> Any thoughts / ideas / comments / experiences?
> TIA,

A two cylinder air cooled 45HP engine implies heat rejection of some
portion of 70%/30% of 45HP/2, or a fraction of about 53 HP X 746 watts
from EACH cylinder.
39 kilowatts is serious heating, even if the biggest part departs via
the exhaust pipe. One reason why people pay attention to fins and ducts
- or even more, to water-cooling such engines.

BrianW

[Brian Whatcott]

bod43 wrote:

> You might like this.
> http://ibis.experimentals.de/downloads/torsionalvibration.pdf
>
That URL would do well to be presented to any engine developer.
Moreover, it's not only engines with jack shafts or quill shafts
that are affected. I read a comparable piece that was - perhaps
still is - available on the net about the historical development
of some Pratt & Whitney engines.
The P&W work also mentioned pendulum crankshaft dampers, one
of the methods not mentioned in bod43's reference.

The automobile clutch friction plate torsion springs mentioned
in the URL aboveremind me of a feature of the first motorbike
I owned; a 1936 BSA 250 CC side valve model with girder forks
and unsprung rear end.
The drive side of the crank was splined. Over the splines,
a chainwheel was free to rotate, but outboard of its hub
was a wavy edged cylinder. On this a splined drive hub with a
complementary wavy cylinder was fitted, and a stiff spring
pressed the driven hub to the chain wheel via those wavy edges.
If the crank wished to move, while the chainwheel stayed fixed,
the driven hub would slide outwards against spring force.
This provided a soft drive characteristic always useful in a
single cylinder engine.

Brian W

[Brian Whatcott]

wrote:
> On Feb 14, 9:07 am, Karl-Heinz Künzel >
> wrote:
>
>> Under "Bilder" on the left you will see details of the engine.
>>
>> KH
> -----------------------------------------------------------------------------
> Note the excellent method used for belt tensioning.
>
> -R.S.Hoover

I looked for it but didn't see it. Was it an eccentric shaft mount on
the driven wheel? Those planes looked like Fournier RF4s at fist
glance. Yummy!

BrianW

[[email protected]]

Found a whole series of rebuild videos. Shade tree mechanicn' isn't
just a US thing. All I can say is that these must be durable little
motors.............

http://www.youtube.com/watch?v=0olqe-jgDiI
======================
Leon McAtee

[[email protected]]

On Feb 14, 2:00*pm, Brian Whatcott > wrote:

> I looked for it but didn't see it. Was it an eccentric shaft mount on
> the driven wheel? * Those planes looked like Fournier RF4s at fist
> glance. Yummy!
>
----------------------------------------------------------------------------------------------

Yes. You can see it in one of the engine photos. The eccentricity
appears to be machined into the shaft. That is, a diameter of about
2" from which the shaft stub projects off-center. This method is
probably the most common, dating back to the Stewart PSRU. But the
problem has always been adequate CLAMPING of the eccentric, which this
PSRU appears to have resolved through the use of TWO clamping plates,
as shown in one of the photos. There's some very good Practical
Engineering here.

-R.S.Hoover

[bildan]

> You might like this.http://ibis.experimentals.de/downloads/torsionalvibration.pdf

I've read this several times in the past. What strikes me is the
absence of test equipment like wireless load cell torque sensors on
the shafts. If used, any torsion oscillations could be seen on an
oscilloscope long before they became destructive.

High speed shafting is as old as the industrial revolution. Solutions
to torsion oscillations are just as old. Yes, there are potential
problems but there are also well tested solutions. The trick is
knowing what they are and how to use test instrumentation.

The other thing that jumps out about the Bede saga is that fact that
they were trying to put an experimental engine/prop drive into an
experimental airplane before it was de-bugged and they were doing it
under a deadline.

That's snakebite country. Even things that work everywhere else are
almost certainly going to bite you under those conditions.

It's vital to work one problem at a time. If it's an experimental
engine and prop drive, work on that until it's been running sweetly
for a long time. Then, maybe, think about designing an airframe
around it.

[Charles Vincent]

bildan wrote:
>> You might like this.http://ibis.experimentals.de/downloads/torsionalvibration.pdf
>
> I've read this several times in the past. What strikes me is the
> absence of test equipment like wireless load cell torque sensors on
> the shafts. If used, any torsion oscillations could be seen on an
> oscilloscope long before they became destructive.

You must have missed the fact that this all took place in the early
sixties and seventies. Even if they had practical wireless sensors for
this, they didn't have the compute power available economically to
process it. Having said that, you still have to account for the effects
of the sensor. For that matter I think that wireless sensors and
attendant equipment are still not practical for the average modern
homebuilder.
>
> High speed shafting is as old as the industrial revolution. Solutions
> to torsion oscillations are just as old. Yes, there are potential
> problems but there are also well tested solutions. The trick is
> knowing what they are and how to use test instrumentation.
>
> The other thing that jumps out about the Bede saga is that fact that
> they were trying to put an experimental engine/prop drive into an
> experimental airplane before it was de-bugged and they were doing it
> under a deadline.
>
> That's snakebite country. Even things that work everywhere else are
> almost certainly going to bite you under those conditions.
>
> It's vital to work one problem at a time. If it's an experimental
> engine and prop drive, work on that until it's been running sweetly
> for a long time. Then, maybe, think about designing an airframe
> around it.

Sometimes an experimental airframe demands an experimental engine.
Engineering is seldom one dimensional, which is why I was poking at the
use of a long flexible shaft as a guaranteed solution. As far as
deadlines go, thats may not be a factor for a homebuilder, as many
projects get completed post mortem, but it is a factor form commercial
endeavors (Moller notwithstanding)

Charles

[bildan]

On Feb 15, 11:43*am, Charles Vincent > wrote:
> bildan wrote:
> >> You might like this.http://ibis.experimentals.de/downloads/torsionalvibration.pdf
>
> > I've read this several times in the past. *What strikes me is the
> > absence of test equipment like wireless load cell torque sensors on
> > the shafts. *If used, any torsion oscillations could be seen on an
> > oscilloscope long before they became destructive.
>
> You must have missed the fact that this all took place in the early
> sixties and seventies. * Even if they had practical wireless sensors for
> this, they didn't have the compute power available economically to
> process it. *Having said that, you still have to account for the effects
> of the sensor. *For that matter I think that wireless sensors and
> attendant equipment are still not practical for the average modern
> homebuilder.

I didn't miss it. I did tests like this in the early 1960's. Load
cells are just Wheatstone Bridges and the wireless tech WAS available
then - it just used discrete components instead of IC's. It needs no
computer power whatsoever since it's an analog signal. If you don't
like wireless tech, slip rings are available.

The sensors are very light and have little or no effect on the shaft
under test - if they did, no one would use them. In any event, you
can put an accelerometer on a shaft bearing housing and see if it's
output changes when you remove the torque sensor.

The only reason they didn't use instrumentation must have been that
Bede was cheap and in a hurry. It was definitely available and not
expensive.

Torsional resonance instrumentation is absolutely practical for home
builders and it doesn't cost all that much. The oscilloscope is
probably the most expensive thing and you could probably borrow one.

If I were going to do the auto engine shaft drive thing, I'd buy a
cheap running engine from a junk yard. If it ran rough, so much the
better. I'd build up the firewall forward drive system on a trailer
with a club prop. Then I'd run it to find and eliminate resonances.
Only then would I build an exact replica of the flight article using
new components and run that on the test stand.

[Peter Dohm]

"bildan" > wrote in message
...
> I didn't miss it. I did tests like this in the early 1960's. Load
> cells are just Wheatstone Bridges and the wireless tech WAS available
> then - it just used discrete components instead of IC's. It needs no
> computer power whatsoever since it's an analog signal. If you don't
> like wireless tech, slip rings are available.
>
>The sensors are very light and have little or no effect on the shaft
> under test - if they did, no one would use them. In any event, you
> can put an accelerometer on a shaft bearing housing and see if it's
> output changes when you remove the torque sensor.
>
> The only reason they didn't use instrumentation must have been that
> Bede was cheap and in a hurry. It was definitely available and not
> expensive.
>
> Torsional resonance instrumentation is absolutely practical for home
> builders and it doesn't cost all that much. The oscilloscope is
> probably the most expensive thing and you could probably borrow one.
>
> If I were going to do the auto engine shaft drive thing, I'd buy a
> cheap running engine from a junk yard. If it ran rough, so much the
> better. I'd build up the firewall forward drive system on a trailer
> with a club prop. Then I'd run it to find and eliminate resonances.
> Only then would I build an exact replica of the flight article using
> new components and run that on the test stand.
>
>
While it is very likely that Jim Bede was cheap, or broke, and in a hurry; I
have also heard that they, meaning the senior staff on the project, simply
did not believe it--and also had great difficulty accepting the idea that a
softer, and intuitively a weaker, drive system could solve a torsional
resonance problem.

Also, my persoanl recollection is that there was once additional information
posted somewhere regarding the BD-5 development project--but I have no idea
where to find it on the free Internet. A very similar, if not the same,
article is also available in a back issue of Contact! and used to be readily
available--possibly on PrimeMover--and I could swear that there were more
pictures and possibly longer text.

In any case, you are absolutely correct that all sorts of strain guages, and
connections for them, were readily available and inexpensive by the middle
sixties and the frequency range was perfect for the cheapest oscilloscopes
commonly used in high school electronics classes at that time.

[Stealth Pilot[_2_]]

On Sat, 14 Feb 2009 13:38:56 +0000, jan olieslagers
> wrote:

>Yesterday I was talking to a friend who plans to power his single-seat
>slow flyer with an engine from a Citroen Visa. I suppose this engine (a
>linear descendant from the famous Citroen 2CV) is not well known in the
>US, it is an air-cooled 2-cylinder boxer, in this particular application
>it would produce some 45 HP.
>
>My friend absolotely wants it in the plane as it is in the car, i.e.
>with the clutch side rearward (the plane is a traditional "puller"), and
>wants to take power from the clutch side. His idea is to have a belt
>reduction "behind" the engine, then a transmission axle above the engine
>to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
>things about transmission axles driving propellers, vibration not the
>least. But he answers the axle needn't be long, as the engine is only a
>2-cylinder.
>
>Any thoughts / ideas / comments / experiences?
>TIA,

if you hunt out the cd on the micro imp (there is a web site) you will
see pictures of molt taylor's effort to use one of these engines to
power the prototype micro imp. he gave up on it after extensive
tinkering failed to achieve anything like the published power figures.
( where have we heard that before :-) :-) )

if this is a much improved version of the motor you may have
success.(you may not)
molt taylor solved the vibration problem using his flexidyne drive
unit. you could make one of these from the drawing details on the cd.
all of his notes and photos of the project right up to his death are
on the cd. it's an interesting browse. almost all the details of his
engineered drive shaft are there in the drawings as well. from memory
some of his calculations are absent.

Stealth Pilot

[Peter Dohm]

"Stealth Pilot" > wrote in message
...
> On Sat, 14 Feb 2009 13:38:56 +0000, jan olieslagers
> > wrote:
>
>>Yesterday I was talking to a friend who plans to power his single-seat
>>slow flyer with an engine from a Citroen Visa. I suppose this engine (a
>>linear descendant from the famous Citroen 2CV) is not well known in the
>>US, it is an air-cooled 2-cylinder boxer, in this particular application
>>it would produce some 45 HP.
>>
>>My friend absolotely wants it in the plane as it is in the car, i.e.
>>with the clutch side rearward (the plane is a traditional "puller"), and
>>wants to take power from the clutch side. His idea is to have a belt
>>reduction "behind" the engine, then a transmission axle above the engine
>>to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
>>things about transmission axles driving propellers, vibration not the
>>least. But he answers the axle needn't be long, as the engine is only a
>>2-cylinder.
>>
>>Any thoughts / ideas / comments / experiences?
>>TIA,
>
> if you hunt out the cd on the micro imp (there is a web site) you will
> see pictures of molt taylor's effort to use one of these engines to
> power the prototype micro imp. he gave up on it after extensive
> tinkering failed to achieve anything like the published power figures.
> ( where have we heard that before :-) :-) )
>
> if this is a much improved version of the motor you may have
> success.(you may not)
> molt taylor solved the vibration problem using his flexidyne drive
> unit. you could make one of these from the drawing details on the cd.
> all of his notes and photos of the project right up to his death are
> on the cd. it's an interesting browse. almost all the details of his
> engineered drive shaft are there in the drawings as well. from memory
> some of his calculations are absent.
>
> Stealth Pilot

If you are talking about the Flexidyne coupling, those were and still are
made by Dodge (now Baldor Dodge) which has a web site at:
http://www.dodge-pt.com

The Flexidyne coupling is a soft start device that acts as a centrifugal
clutch, rather than a dampener or soft drive system component; but is
reputed to solve some very low frequency (resonance on starting) problems
and appears to have a wealth of accessories and mounting methods available.
I have no personal experience whatsoever, but I do recall that the units
were a feature of more than one of Molt Taylor's designs--including both the
IMP series and the power pack system that merged a pair on engines to a
single propeller.

Peter

[Bear Bottoms[_4_]]

On Sat, 14 Feb 2009 13:38:56 +0000, jan olieslagers wrote:

> Yesterday I was talking to a friend who plans to power his single-seat
> slow flyer with an engine from a Citroen Visa. I suppose this engine (a
> linear descendant from the famous Citroen 2CV) is not well known in the
> US, it is an air-cooled 2-cylinder boxer, in this particular application
> it would produce some 45 HP.
>
> My friend absolotely wants it in the plane as it is in the car, i.e.
> with the clutch side rearward (the plane is a traditional "puller"), and
> wants to take power from the clutch side. His idea is to have a belt
> reduction "behind" the engine, then a transmission axle above the engine
> to drive the prop. Now I'm sceptical 'cause I heard all kind of bad
> things about transmission axles driving propellers, vibration not the
> least. But he answers the axle needn't be long, as the engine is only a
> 2-cylinder.
>
> Any thoughts / ideas / comments / experiences?
> TIA,

He's a ****ing idiot on his way to die.
--
Bear Bottoms
Private Attorney General