Coaxial generator development

[Ernest Christley]

What d'ya think, veedubber?

Unit is from a Harley-Davidson.
9.5 lbs installed (including all mounting hardware).
$288.17 (including tax)
38 Amps
No belts or pulleys.

http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorFitting.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount2.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount3.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount4.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount5.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount6.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMount7.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMounted.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorMounted2.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorParts.jpg
http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorTest.jpg

[[email protected]]

On Aug 2, 3:38 pm, Ernest Christley > wrote:
> What d'ya think, veedubber?
>
> Unit is from a Harley-Davidson.
> 9.5 lbs installed (including all mounting hardware).
> $288.17 (including tax)
> 38 Amps
> No belts or pulleys.
>-------------------------------------------------------------------------------------------------------

Seems like the way to go, doesn't it?

The first one I did like this was about 1970, using the dynamo from a
Honda 250cc motorcycle. At prop speeds it managed to produce enough
power for my ignition and an 8-track tape :-)

The later versions (as you are using) uses rare earth magnets... the
early jobbies used Alnico and weighed a ton. But the rare earth
magnets don't deal with heat very well and since the unit is only
about 50% effective, for every amps-worth of electrical output you've
got to deal with an amps-worth of heat. Usually, at prop speeds that
isn't a problem but spin it any faster and you can see some serious
side-effects due to overheating.

I mention this because of the 'submerged' location on your
installation. I think I can see a couple of oil pipes here that tells
me the excess heat is going to appear in your oil. You should know
that the rare-earth magnets tend to spall or flake when overheated.

I've also had problems keeping the suckers aligned, which is why I use
the rim of the central hole and five fasteners to try and keep things
on the same plane. They get balanced as a complete assembly, by the
way.

We appear to be using the same stator & rotor but a different reg/rec
module. (I'm using the one sold by Great Plains) When properly set-up
I've got about 1mm of axial clearance between the poles of the stator
and the magnets. At prop speeds (ie, 2800 to 3000 rpm) it doesn't
take much skew to cause contact. Since my installations are not
submerged they're pretty easy to inspect and the bright line caused by
the momentary contact is always accompanied by a spew of abrasive
residue, ground off of the magnets.

Being magnetic -- and external to the engine -- the residue isn't much
of a hazard but it isn't something I'd care to have in my oil.

Since I run mine at prop-speeds the output is rather modest, only 8A.
to 10A, even through the momentary peak output is rated at something
like 40A. But with an electronic ignition system you only need about
5A to power the ignition system and maintain the charge on a small
battery. Truth is, I didn't want a system capable of producing the
maximum amperage since it would only get turned into heat at the
rectifier/regulator module. (Indeed, I would have been perfectly
happy with the old style 10 ampere unit and wish Steve still sold
them.) If you'll look closely at the photos in my blog you can see
how I solved the problem :-)

-R.S.Hoover

[Ernest Christley]

wrote:
> On Aug 2, 3:38 pm, Ernest Christley > wrote:
>> What d'ya think, veedubber?
>>
>> Unit is from a Harley-Davidson.
>> 9.5 lbs installed (including all mounting hardware).
>> $288.17 (including tax)
>> 38 Amps
>> No belts or pulleys.
>> -------------------------------------------------------------------------------------------------------
>
> Seems like the way to go, doesn't it?
>
> The first one I did like this was about 1970, using the dynamo from a
> Honda 250cc motorcycle. At prop speeds it managed to produce enough
> power for my ignition and an 8-track tape :-)
>
> The later versions (as you are using) uses rare earth magnets... the
> early jobbies used Alnico and weighed a ton. But the rare earth
> magnets don't deal with heat very well and since the unit is only
> about 50% effective, for every amps-worth of electrical output you've
> got to deal with an amps-worth of heat. Usually, at prop speeds that
> isn't a problem but spin it any faster and you can see some serious
> side-effects due to overheating.

I'm not liking the sound of that. I'll be running it at 6000RPM, or so.
The intake air will be flowing over it, so that should do a lot to
keep it cool.

>
> I mention this because of the 'submerged' location on your
> installation. I think I can see a couple of oil pipes here that tells
> me the excess heat is going to appear in your oil. You should know
> that the rare-earth magnets tend to spall or flake when overheated.

The thin line on top pumps oil into the gearbox, and the 3/8" line along
the bottom allows it to flow back into the sump. They're not really
connected to the generator in any significant way.

> We appear to be using the same stator & rotor but a different reg/rec
> module. (I'm using the one sold by Great Plains) When properly set-up
> I've got about 1mm of axial clearance between the poles of the stator
> and the magnets. At prop speeds (ie, 2800 to 3000 rpm) it doesn't
> take much skew to cause contact. Since my installations are not
> submerged they're pretty easy to inspect and the bright line caused by
> the momentary contact is always accompanied by a spew of abrasive
> residue, ground off of the magnets.

I need to verify, but I'm fairly certain that the reg/rec I'm using is a
switching type. It turns off the line when the power isn't needed.
Saving the generator from producing heat in both the rotor/stator and
generator.

> Since I run mine at prop-speeds the output is rather modest, only 8A.
> to 10A, even through the momentary peak output is rated at something
> like 40A. But with an electronic ignition system you only need about
> 5A to power the ignition system and maintain the charge on a small
> battery. Truth is, I didn't want a system capable of producing the
> maximum amperage since it would only get turned into heat at the
> rectifier/regulator module.

I need to power ignition, injectors, pumps...and that's just to drive
the engine. There's radio's and lights that need a few electrons, too.

> them.) If you'll look closely at the photos in my blog you can see
> how I solved the problem :-)

And off I go to take a look.

[RST Engineering]

This may seem like a stupid idea, but good ideas sometimes come in stupid
clothes. In a normal air-cooled tractor engine, cold air comes in the
front, passes over and through the cylinders, and is exhausted through the
plenum chamber called the bottom of the cowl. Rapidly moving air, that
after it does it cooling job, is no longer of any use.

Remember back in dem halcyon days of the 50s and 60s we sometimes mounted
inefficient little generators on small pylons on the bottom of the airframe
and called them wind driven generators (the electrical equivalent of the
side-mounted venturi tube)?

I'm just wondering if anybody has used either this scrap dump air to run a
wind driven generator, or whether any one of a number of ways of generating
electricity from heat has been attempted to convert waste exhaust gas into
excited little electrons? SOrt of a turbogenerator, if you will.

Jim

--
"It is the mark of an educated mind to be able to entertain a thought
without accepting it."
--Aristotle


> wrote in message
...
> On Aug 2, 3:38 pm, Ernest Christley > wrote:
>> What d'ya think, veedubber?
>>
>>-------------------------------------------------------------------------------------------------------
>
> Seems like the way to go, doesn't it?
>

[Blueskies]

"RST Engineering" > wrote in message ...
> This may seem like a stupid idea, but good ideas sometimes come in stupid
> clothes. In a normal air-cooled tractor engine, cold air comes in the
> front, passes over and through the cylinders, and is exhausted through the
> plenum chamber called the bottom of the cowl. Rapidly moving air, that
> after it does it cooling job, is no longer of any use.
>
> Remember back in dem halcyon days of the 50s and 60s we sometimes mounted
> inefficient little generators on small pylons on the bottom of the airframe
> and called them wind driven generators (the electrical equivalent of the
> side-mounted venturi tube)?
>
> I'm just wondering if anybody has used either this scrap dump air to run a
> wind driven generator, or whether any one of a number of ways of generating
> electricity from heat has been attempted to convert waste exhaust gas into
> excited little electrons? SOrt of a turbogenerator, if you will.
>
> Jim
>
> --


Centrifugal blower run backwards...gotta watch out not to dam things up too much...

And...you could reverse drive it to pull air through the engine for cooling on the ground?

[Morgans[_2_]]

"RST Engineering" > wrote

> I'm just wondering if anybody has used either this scrap dump air to run a
> wind driven generator, or whether any one of a number of ways of
> generating electricity from heat has been attempted to convert waste
> exhaust gas into excited little electrons? SOrt of a turbogenerator, if
> you will.

Only problem I can see is that cooling runs on pressure differential, (as
you know) between the intake, and outlet.

Dam up the damn outlet, and it could have a drastic effect on the amount of
cooling air passing over the engine. People go to drastic measures to get
that outlet pressure low, like adding lips, ect, so I would not want to go
the other way with restricting the flow.

I would think that you would have to dam it up pretty good to get the 3-5 HP
you would probably need for a generator.

On the other hand, if you put a turbocharger hot section on the pipes, and
used that to drive a generator....?

Noah. Too big of a gear box would be needed to turn the high RPM of the
turbo down to prop RPM's for the generator.
--
Jim in NC

[[email protected]]

On Aug 3, 9:03 am, "Blueskies" > wrote:
>
> And...you could reverse drive it to pull air through the engine for cooling on the ground?
--------------------------------------------------------------------------------

Hahahahahaah,,, :-)

Don't be so silly :-) You're about two orders of magnitude out.

Minimum cool-down is going to take a pressure differential of about
3"H2O. With either suck-through or blow-through, for something like
an O-200 that's going to take about 3hp... about 2100 watts. You'd
need a couple of hundred pounds of batteries and a blower to match.

-R.S.Hoover

[Ernest Christley]

RST Engineering wrote:

> I'm just wondering if anybody has used either this scrap dump air to run a
> wind driven generator, or whether any one of a number of ways of generating
> electricity from heat has been attempted to convert waste exhaust gas into
> excited little electrons? SOrt of a turbogenerator, if you will.
>
> Jim
>

I remember one company making such a contraption as a drop down
emergency back-up generator. As I recall, the problem with using them
full-time is their horrible overall efficiency.

I'd be careful with anything that pulled energy from the cooling
airstream. Like Blueskies said, you gotta watch that you're not damming
things up. If you have engine cooling air leaving the airplane still
cool, the first thing you'd want to do is close up and streamline the
cooling intakes to reduce drag.

There have been some interesting developments with materials utilizing
the Seebeck (sp?) Effect recently. The new materials are driving the
efficiency up. I think the ultimate generator would be a
cylinder-head/peltier-cooler-in-reverse combination.

[Ernest Christley]

RST Engineering wrote:
or whether any one of a number of ways of generating
> electricity from heat has been attempted to convert waste exhaust gas into
> excited little electrons?

Lots of wind to cool around an exhaust pipe, and the rotary's exhaust is
noted for being exceptionally hot. Dang-it, Jim! Now you've got me
thinking again. Everytime I start doing that, by build time increases
by another three months.

Read this:

http://www.fieldlines.com/story/2005/11/2/31928/0770

[[email protected]]

On Aug 2, 11:17 pm, Ernest Christley > wrote:

>
> I need to verify, but I'm fairly certain that the reg/rec I'm using is a
> switching type. It turns off the line when the power isn't needed.
> Saving the generator from producing heat in both the rotor/stator and
> generator.
>
>-----------------------------------------------------------------------------------------

Dear Ernest,

I'm afraid that only addresses the power OUTPUT, not generation. So
long as the magnetic field is present and is being cut by the winding
of the coil, a voltage WILL appear across the coil, as will some
residual heating effects. The regulator can isolate this from the
battery but that only addresses the output-side of the equation.

That's a guess of course -- we're using different components. But in
a permanent-magnet type dynamo the Field is always 'on' so to speak --
there is no 'control' as is found in the typical generator-type dynamo
since there is no Field winding. In either case, I think your method
of installation calls for a bit more head-work.

-R.S.Hoover

[Bill Daniels]

> wrote in message
...
> On Aug 2, 11:17 pm, Ernest Christley > wrote:
>
>>
>> I need to verify, but I'm fairly certain that the reg/rec I'm using is a
>> switching type. It turns off the line when the power isn't needed.
>> Saving the generator from producing heat in both the rotor/stator and
>> generator.
>>
>>-----------------------------------------------------------------------------------------
>
> Dear Ernest,
>
> I'm afraid that only addresses the power OUTPUT, not generation. So
> long as the magnetic field is present and is being cut by the winding
> of the coil, a voltage WILL appear across the coil, as will some
> residual heating effects. The regulator can isolate this from the
> battery but that only addresses the output-side of the equation.
>
> That's a guess of course -- we're using different components. But in
> a permanent-magnet type dynamo the Field is always 'on' so to speak --
> there is no 'control' as is found in the typical generator-type dynamo
> since there is no Field winding. In either case, I think your method
> of installation calls for a bit more head-work.
>
> -R.S.Hoover

Fun, goofy thread.

Actually, there is something called an electrically augmented turbocharger.
It's a turbocharger with an electric motor on the shaft connecting the
turbine and compressor ends. The idea is for the electric motor to help the
engine exhaust spin up the turbocharger reducing turbo lag. It's also used
on 2-stroke piston ported diesels to provide enough manifold pressure to
start them and idle.

However, once the engine is running and the exhaust pressure takes over from
the electric motor, there's no reason why the motor can't swich to being a
dynamo/generator. There's plenty of excess energy in the exhaust of an
engine producing 60 - 75% power to generate ample electric power. I once
pitched this idea to the DeltaHawk folks as a way to dump the heavy roots
blower and alternator and get a quick response turbocharger.

Of course, if your engine doesn't need a turbocharger in the first place,
just replace the compressor end with a high RPM alternator.

Fun thinking about this stuff.

Bill D

[cavelamb himself[_4_]]

RST Engineering wrote:

> This may seem like a stupid idea, but good ideas sometimes come in stupid
> clothes. In a normal air-cooled tractor engine, cold air comes in the
> front, passes over and through the cylinders, and is exhausted through the
> plenum chamber called the bottom of the cowl. Rapidly moving air, that
> after it does it cooling job, is no longer of any use.
>
> Remember back in dem halcyon days of the 50s and 60s we sometimes mounted
> inefficient little generators on small pylons on the bottom of the airframe
> and called them wind driven generators (the electrical equivalent of the
> side-mounted venturi tube)?
>
> I'm just wondering if anybody has used either this scrap dump air to run a
> wind driven generator, or whether any one of a number of ways of generating
> electricity from heat has been attempted to convert waste exhaust gas into
> excited little electrons? SOrt of a turbogenerator, if you will.
>
> Jim
>

The reason the air comes out the bottome of the cowling is because there
is a low pressure area there to pull it out.

Putting something in the way to hinder that flow might be counter
productive. :)


--

Richard

(remove the X to email)

[Ernest Christley]

wrote:
> On Aug 2, 11:17 pm, Ernest Christley > wrote:
>
>> I need to verify, but I'm fairly certain that the reg/rec I'm using is a
>> switching type. It turns off the line when the power isn't needed.
>> Saving the generator from producing heat in both the rotor/stator and
>> generator.
>>
>> -----------------------------------------------------------------------------------------
>
> Dear Ernest,
>
> I'm afraid that only addresses the power OUTPUT, not generation. So
> long as the magnetic field is present and is being cut by the winding
> of the coil, a voltage WILL appear across the coil, as will some
> residual heating effects. The regulator can isolate this from the
> battery but that only addresses the output-side of the equation.
>

Yes, it does keep producing a voltage, and possibly an extremely high
one at that; but heat comes from work, and a voltage is only half of
that equation. You need to move some AMPS with that voltage to heat
things up. The magnets will push the electrons as hard as they can be
pushed, but the switching regulator has opened the circuit. The
electrons bang into a wall, all jumbled together at the end of the wire.
Once the magnet passes, the little guys will relax and spread out a
bit until the next magnet comes along to push them all up against the
wall again. Thus, there is some current flow, but it is AC and in the
milliamp range.

It's easy enough to test. Run one with no load for a while. That
includes taking the regulator out of the circuit. Those older style
regulators worked by acting like a fat resistor to dump excess power,
making sure that the generator ran at full load all the time. Dollars
to donuts (yeah, I know, not a great deal anymore) that the generator
will be cooler than most of the other engine parts.

Now, put a headlamp on as a load, and run it again. You'll need the
regulator this time. You could even run it with just your regulator
(but, that's hard on the regulator). I bet another dollar that the
generator heats right up. Probably warm enough to cook that donut.

> That's a guess of course -- we're using different components. But in
> a permanent-magnet type dynamo the Field is always 'on' so to speak --
> there is no 'control' as is found in the typical generator-type dynamo
> since there is no Field winding. In either case, I think your method
> of installation calls for a bit more head-work.
>
> -R.S.Hoover

A critical piece that doesn't really come across in the pictures is that
there is a very strong air stream passing over and around the generator.
In fact, the final goal is for it to be on the inside of a centrifugal
blower. The one thing I do have left to do is to add a splash guard that
will keep debris from filling up the rotor over time, but that will be
simple enough to do.

I went out to take this picture. Used the Gimp to highlight the air
intake areas that will provide cooling air. The pattern continues all
the way around the gearbox.

http://ernest.isa-geek.org/Delta/Pictures/EngineGeneratorAirIntakeAndCooling.jpg