Wright Brothers 1903 Engine

[Don1966]

Yes that is what I was looking to see. So matching that with the NASA description the dynamo/generator is normally open circuit and feeding the coils wound around the magnet. When a cylinder is due to fire the breaker in that cylinder closes so a current builds up in the coils of the coils and the dynamo. At the firing point the breaker opens and the current tries to continue to flow resulting in a spark.

With modern magnets you could probably build a suitably scaled dynamo to achieve 10V 4A (40W), but I doubt if the stored energy would be sufficient so an additional inductor (spark coil) would be required. The breakers in the cylinder with a 1" bore would also be a challenge 

I believe your missing the point Roger if you do build the same Dynamo there is no reason it doesn't work like it did for the Wright brothers.

Don

[10KPete]

Been studying that drawing with a magnifying glass on my 'puter screen. Very near the top of the view it says that 3 permanent magnets
are required.

Looking at the drawing of the label that is on the 'magneto', near the bottom of the view, I see what looks like 2600 RPM and 10 volts
output.

The wire coils that go around the magnets are called out as, I think, 126 turns of #18 wire. One coil wound RH and one LH.

I would sure like to see the rest of the electrical info on this system. It has me completely intrigued and I believe that it can be scaled perfectly. Correct me if I'm wrong, but I gather the model would be 1/4 of the full size?? And 1" bore?

Sorry to butt in like this,
Pete

[Roger B]

Hi Don, I may well be thinking in the wrong way but this was my logic:

A certain amount of energy is required to ignite the mixture (keeping the energy below this level is the principle used for intrinsically safe electrical equipment for use in explosive/flammable areas). In a conventional ignition systems this energy is stored in the magnetic field in the coil until it is released by breaking the circuit. In a CDI system it is stored in the electric field of a capacitor charged up to a suitable voltage. Reducing the size of the dynamo will reduce the inductance (less iron/steel) and hence the amount of energy stored. 1/4 scale may be ok, it may be to small  If it is too small adding additional inductance (spark coil) should solve the problem.

I have attached a page from Gas, Gasoline and Oil Engines by Gardner D Hiscox showing a system where a spark coil is required when starting/running with batteries but the inductance of the Magneto/Dynamo is sufficient when running on that.

[Don1966]

Roger I spent 50 yrs working with Electronic and Electrical I know how things work. If you build a 10V 4A magneto it would work the same as it did back then. Your producing the same energy..........


Don

[GailinNM]

This is another fine and challenging project for you Bill.
I don't think that this link has been posted but I could have missed it. It is to the Smithsonian publication on the design of the Wright brothers early engines.

http://freepages.rootsweb.ancestry.com/~wakefield/history/38739-h/38739-h.htm

Of particular interest is the cutaway drawing of their first engine. It shows the generator used for the ignition system. Here is the J PG of that drawing contained in the above publication.

http://freepages.rootsweb.ancestry.com/~wakefield/history/38739-h/images/img009.jpg

this is a fairly large and detailed JPEG image and you might have to go to the link to see all the detail.

A few notes on the ignition system. As described in several accounts, "a separate coil and dry battery were used for starting the engine and were not carried aloft". So, you could have an external ignition module with a dummy generator and still be true to scale. Particularly if you're an old man like me and "forgot" to disconnect it once the engine was running.

for those interested in building a working magneto/generator I suspect that the original configuration was a series wound DC generator. The horseshoe-shaped parts would have just been a fairly soft "magnetically" material such as mild steel or cast iron and the coils around them were for generating the magnetic field for the generator. This is very common for that period of time because permanent magnet material technology was not well-developed then so electromagnets were the common source of the field. Alnico magnet technology did not come around until the mid-1930s. Other indications that this is just a DC generator are the brushes for the Armature shown in the illustrations. Also we know that this was not a timed magneto such as was used later on hit and miss engines because it is a friction drive from the flywheel so the generator probably turns about 4 to 5 times the engine RPM.

This is pure conjecture on my part, but if it was a series wound generator, there would have been only minimal output from the residual magnetism of the field core until the igniter points closed. The full current would then be dumped into the field coils until the points opened. Then the magnetic field of the field coils would collapse generating a much higher voltage for the igniter with the return path being through the brushes and Armature.

Gail in NM

[10KPete]

Wow, thanks Gail! This is a most fascinating engine.

Pete

[b.lindsey]

Gail, thanks for posting this. I had seen it in some earlier research but had never posted this particular cutaway view of the engine. Another interesting feature is that the connecting rods are hollow to save weight while both the pistons and rings were cast iron. The revolutionary use of aluminum at the time was limited to the crankcase casting.

Bill

[fumopuc]

Hi Gail, thanks for posting the link and the drawing also. A very interesting engine.

[BillTodd]

With regard to the ignition.

I'm not an historical expert but this looks to me to be simple LT (low tension) type as described above .

The internal contact points are normally open , the generator is  idling  producing a few tens of volts , as it is unloaded

At TDC or just before (adjusted here by a sliding shaft)  one cylinder's contact points will close (all 4 are connected together) ,the generator will now be loaded fully , producing somewhere near the rated 10v (which will be lost in the winding resistance)  and 4 amps (which will flow through the winding creating a magnetic field of stored energy)

shortly after, the contacts will open, causind the current to stop and the magnetic field to collapse rapidly. As the field collapses, a much higher voltage is generated causing an arc at the contact point (which ignites the fuel air mixture)

You can replace the generator with a battery , but it will need an inductor (i.e a coil of wire on a soft iron former)  to limit the current and store energy for the high voltage arc.

[Myrickman]

I found the fuel mixer and hot shoe vaporizer interesting, albeit crude. This was a detail I previously was unaware of. Commercially-made carburetors of this period were lacking in fuel metering ability so this was a common way of compensating. Thanks for posting. Paul

[Don1966]

With regard to the ignition.

I'm not an historical expert but this looks to me to be simple LT (low tension) type as described above .

The internal contact points are normally open , the generator is  idling  producing a few tens of volts , as it is unloaded

At TDC or just before (adjusted here by a sliding shaft)  one cylinder's contact points will close (all 4 are connected together) ,the generator will now be loaded fully , producing somewhere near the rated 10v (which will be lost in the winding resistance)  and 4 amps (which will flow through the winding creating a magnetic field of stored energy)

shortly after, the contacts will open, causind the current to stop and the magnetic field to collapse rapidly. As the field collapses, a much higher voltage is generated causing an arc at the contact point (which ignites the fuel air mixture)

You can replace the generator with a battery , but it will need an inductor (i.e a coil of wire on a soft iron former)  to limit the current and store energy for the high voltage arc.

I have a problem with that, when the generator is idling as you say and the contacts open, it is a full voltage and the fields will draw little current to support the generator. A yes when the contacts close the voltage is lost, but in the armature resistance not the field because the armature is the source not the fields. The full load amps will be flowing in the armature and small resistance of the contact circuit when closed, the fields current will be next to nothing. When the contacts close is when the field will discharge itself not when the contacts open. I believe the 4 amps is the key to making it work because we are using contacts to create the arc. The arc will accure when the contacts close just like a welding machine does when you strike an arc. Everyone has it in there mine that you need high voltage to produce an arc that's not so. The only reason you would need high voltage is if we have to jump a gap like a spark plug and when you have high voltage the current is very low. You should be able to use a battery to create the same effect as the magneto. When you put the two battery wires together they produce an arc because of the high inrush current of zero resistance. That is may take on the subject enuf said.

Don

[BillTodd]

its series wound Don, the same current is flowing through both armature and field windings,  Contact closure current is relatively small due to reluctance of both windings , it will rise linearly limited by series resistance. (likely to be higher than the rated 4amps )


Welders strike an arc as they disconnect (that's why you scratch start a tig for instance) .

The sparks you get when shorting a battery are molten metal burning after being heated by their resistance (that's why they are yellow not blue - and not really hot enough to ignite petrol)

The high-ish voltage is necessary to start an arc proper , once the plasma is formed current flow will maintain the temperature tto sustain it.

[Don1966]

The drawing Bill showed is not series connected it's parallel connected like a shunt motor. A series generator only puts out when loaded agree.

Don

[Don1966]

I need to correct what I said about the contact closing to produce the arc. It's the closing and sudden opening that creates the arc. This is a make break system.

Don

[b.lindsey]

Thanks Don, that is what I was thinking from what I have read, but I am easily confused on this stuff as you know 

Bill