A Simple Auto Engine Conversion

"Peter Dohm" wrote in message
. ..

The damper, which is indeed a relatively expensive part, is on the other
end of the engine and is intended to eliminate resonance within the
engine. A breif treatise, which probably started as an an internal
document at one of the big three auto makers, has been included on this
forum a number of times and is probably in an issue of Contact! Magazine
as well; but I can't find a copy on my current computer.

I could easily be incorrect about the purpose of the springs, but another
article from Contact! regarding the development of the BD-5 drive train
(which I also can not find) does provide some food for thought.


I have seen the BD-5 article, and agree totally with it, and the article
referenced above. My only doubt is Detroit's intent when originally
implementing these spring mechanisms.

Years ago during my auto racing days, a custom clutch builder related to me,
that the springs served only to reduce or eliminate chatter during
engagement, and assist the smooth engagement of the clutch. Although I
didn't understand exactly how, especially at that time, I now suspect his
has a lot to do with resonance.

If the mechanisms were implemented to dampen shock loads during aggressive
driving, why would so many high performance clutch assemblies omit them?
They all seem to prefer solid clutch disks because these mechanisms are
prone to failure, especially in activities like drag racing.

Has anyone published actual tested results on the amount of torque required
to flex these mechanisms? Whatever it is, I would guess they would offer
little resistance to a V-8 crankshaft and steel flywheel assembly spinning
5000 to 8000 RPM, when someone dumps a clutch. I always assumed that's why
most of them have springs with a flat profile wire. It looks to me like the
springs are designed to be bottomed out regularly.

Zebulon wrote:

Has anyone published actual tested results on the amount of torque required
to flex these mechanisms? Whatever it is, I would guess they would offer
little resistance to a V-8 crankshaft and steel flywheel assembly spinning
5000 to 8000 RPM, when someone dumps a clutch. I always assumed that's why
most of them have springs with a flat profile wire. It looks to me like the
springs are designed to be bottomed out regularly.



If you read the engineering texts you will find they are for reducing
shock loads and prevent gear chatter when idling or loafing around in
third gear on surface streets. Dan Horton who used to post hear did
measure them, though did not publish all of his data. They bottom out
well before the torque the engine is able to produce is reached, as you
would expect. In fact, I believe this is necessary to avoid a
longitudinal resonance during aggressive throttle changes.

Charles

wrote:
On Aug 31, 10:29 pm, "
wrote:
Sorry, but that quote does not say the specific technical reason(s) he
gave up, just the basic economic idea that i've already heard -- hence
the original post. I wanted to hear a really good reason to not use
an auto engine, give readily available magnetos. Someone eventually
said propellor loads on the auto crankshaft.

What? We didn't mention cooling issues, weight issues, PSRU issues,
cost issues or anything else? Aren't these good things to consider?

Dan


Guess you didn't know that the only thing holding back progress of the
auto engine in aviation was the availability of a hundred and twenty two
year old ignition design.

Charles

On Sep 3, 12:00*pm, Charles Vincent wrote:
wrote:
On Aug 31, 10:29 pm, "
wrote:
Sorry, but that quote does not say the specific technical reason(s) he
gave up, just the basic economic idea that i've already heard -- hence
the original post. *I wanted to hear a really good reason to not use
an auto engine, give readily available magnetos. *Someone eventually
said propellor loads on the auto crankshaft.

* What? We didn't mention cooling issues, weight issues, PSRU issues,
cost issues or anything else? Aren't these good things to consider?

* * * * Dan

Guess you didn't know that the only thing holding back progress of the
auto engine in aviation was the availability of a hundred and twenty two
year old ignition design.

Charles

Guess not. Now we can put a magneto on any old engine and go
flying! Considering that the magneto has a much higher failure rate
than the old battery point-and-condenser ignition, and therefore we
need two of them, I have no idea why, in this age of electronic
everything, the homebuilder market hasn't come up with a self-powered
electronic ignition module for conversions. It would look like a
magneto, and have the rotating magnet alternator to generate some
power, but wouldn't use the troublesome points or impulse couplings or
distributor and the alternator part would have many magnets, not just
one, so that the magneto dynamics that sometimes lead to drive failure
wouldn't be there. Dave Blanton found those dynamics in his
conversions and had to modify the mag drives to take it.

Dan

On Sep 3, 11:03*am, Charles Vincent wrote:
Zebulon wrote:

Has anyone published actual tested results on the amount of torque required
to flex these mechanisms? Whatever it is, I would guess they would offer
little resistance to a V-8 crankshaft and steel flywheel assembly spinning
5000 to 8000 RPM, when someone dumps a clutch. I always assumed that's why
most of them have springs with a flat profile wire. It looks to me like the
springs are designed to be bottomed out regularly.

If you read the engineering texts you will find they are for reducing
shock loads and prevent gear chatter when idling or loafing around in
third gear on surface streets. *Dan Horton who used to post hear did
measure them, though did not publish all of his data. *They bottom out
well before the torque the engine is able to produce is reached, as you
would expect. *In fact, I believe this is necessary to avoid a
longitudinal resonance during aggressive throttle changes.

Charles

The reciprocating engine has power pulses, which the flywheel
is expected to damp out. That flywheel can't damp it all out, of
course, and so those springs will allow a bit of flex to minimize the
pulsations being transmitted to the drive train. In racing, component
life and smoothness are not prime concerns; strength and minimal
failure points are, so they're left out.

Dan

On Wed, 3 Sep 2008 11:12:15 -0700 (PDT),
wrote:


Guess not. Now we can put a magneto on any old engine and go
flying! Considering that the magneto has a much higher failure rate
than the old battery point-and-condenser ignition, and therefore we
need two of them, I have no idea why, in this age of electronic
everything, the homebuilder market hasn't come up with a self-powered
electronic ignition module for conversions. It would look like a
magneto, and have the rotating magnet alternator to generate some
power, but wouldn't use the troublesome points or impulse couplings or
distributor and the alternator part would have many magnets, not just
one, so that the magneto dynamics that sometimes lead to drive failure
wouldn't be there. Dave Blanton found those dynamics in his
conversions and had to modify the mag drives to take it.

Dan

http://www.emagair.com/Index.htm

I have these on my lycoming and I think that it would be possible to
machine some kind of mount to fit it to an auto engine.

On Sep 3, 3:14*pm, (Drew Dalgleish)
wrote:
On Wed, 3 Sep 2008 11:12:15 -0700 (PDT),
wrote:

* * * * Guess not. Now we can put a magneto on any old engine and go
flying! Considering that the magneto has a much higher failure rate
than the old battery point-and-condenser ignition, and therefore we
need two of them, I have no idea why, in this age of electronic
everything, the homebuilder market hasn't come up with a self-powered
electronic ignition module for conversions. It would look like a
magneto, and have the rotating magnet alternator to generate some
power, but wouldn't use the troublesome points or impulse couplings or
distributor and the alternator part would have many magnets, not just
one, so that the magneto dynamics that sometimes lead to drive failure
wouldn't be there. Dave Blanton found those dynamics in his
conversions and had to modify the mag drives to take it.

* * * * Dan

http://www.emagair.com/Index.htm

I have these on my lycoming and *I think that it would be possible to
machine some kind of mount to fit it to an auto engine.

Well. There it is! I wonder when they'll get certification?
I'd like to try a pair on one of our 172s to see if fuel economy and
performance are better. Should be, with variable timing.
The one drawback I can see: They use battery power, with a
built-in alternator in case the aircraft's electrics die. Without an
impulse coupleing, they wouldn't generate enough power for hand-
propping, so my old A-65 non-electric systemed Jodel is out of luck.
Dan

"Peter Dohm" wrote

The damper, which is indeed a relatively expensive part, is on the other
end of the engine and is intended to eliminate resonance within the
engine. A breif treatise, which probably started as an an internal
document at one of the big three auto makers, has been included on this
forum a number of times and is probably in an issue of Contact! Magazine
as well; but I can't find a copy on my current computer.

I could easily be incorrect about the purpose of the springs, but another
article from Contact! regarding the development of the BD-5 drive train
(which I also can not find) does provide some food for thought.

You are thinking of two different things.

The thing on the accessory end of the engine is the harmonic balancer, and
it does indeed dampen resonance in the crankshaft.

Dampeners also exist that go between the engine and the load, usually found
in industrial applications, or in marine applications.
--
Jim in NC

Drew Dalgleish wrote:
On Wed, 3 Sep 2008 11:12:15 -0700 (PDT),
wrote:


Guess not. Now we can put a magneto on any old engine and go
flying! Considering that the magneto has a much higher failure rate
than the old battery point-and-condenser ignition, and therefore we
need two of them, I have no idea why, in this age of electronic
everything, the homebuilder market hasn't come up with a self-powered
electronic ignition module for conversions. It would look like a
magneto, and have the rotating magnet alternator to generate some
power, but wouldn't use the troublesome points or impulse couplings or
distributor and the alternator part would have many magnets, not just
one, so that the magneto dynamics that sometimes lead to drive failure
wouldn't be there. Dave Blanton found those dynamics in his
conversions and had to modify the mag drives to take it.

Dan

http://www.emagair.com/Index.htm

I have these on my lycoming and I think that it would be possible to
machine some kind of mount to fit it to an auto engine.

Hot damn, now with an electronic ignition available, I can finally rip
that heavy water soaked v8 auto engine out of my truck and replace it
with a smooth running lycoming. After all, how hard could it be to
design a clutch and transmission adapter and effective cooling baffles
for idle to 60mph.

Charles

wrote


Well. There it is! I wonder when they'll get certification?
I'd like to try a pair on one of our 172s to see if fuel economy and
performance are better. Should be, with variable timing.

The one drawback I can see: They use battery power, with a
built-in alternator in case the aircraft's electrics die. Without an
impulse coupleing, they wouldn't generate enough power for hand-
propping, so my old A-65 non-electric systemed Jodel is out of luck.

One of the models use a backup internal alternator, that should
power the units indefinitely, according to their information. It does need
800 RPM, though, but could be a "get-around" for that.

If you had a small gel cell 12 volt battery onboard, that would supply power
for starting and taxi operations, then switch off the battery, and it will
go to internal power.

With two self powered units onboard, the chances of both of them failing
would be less than both mags failing, I would think.

It would require a check on shut down, and start up, to verify both are
generating their own power.

With the battery shut off and 800 or more RPMs, turn off the starting power
battery, then cycle one unit then the other. If one of the units has
failed, you would know it.
--
Jim in NC

Anyone see a problem with that?