another poor man's car engine conversion

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

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

KH
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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

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

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

You might like this.http://ibis.experimentals.de/downloa...lvibration.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.

bildan wrote:
You might like this.http://ibis.experimentals.de/downloa...lvibration.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

On Feb 15, 11:43*am, Charles Vincent wrote:
bildan wrote:
You might like this.http://ibis.experimentals.de/downloa...lvibration.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.

"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.

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

"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

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