captinjohn

I was wondering why not much is being done to develop a lite-weight mag and be done with batteries & Glow on say 20cc & bigger RC engines. I drew up a sketch that popped into my mind and you can "kinda see" what I am posting about. I wish more of the good talent out there would help us all (working together) to develop such a lite weight mag. I think the main rotor could be made from about 1/8 inch plate aluminum attached to a hub or machined from much thicker piece of aluminum. A real lite coil must be found & magnets that could be attached to the rotor. With the pic-up coil facing back-side of rotor a more narrow set-up would be good. The pick-up surface would be flat instead of curved to match new flat surface. Please add any ideas and data to this thread. Here is sketch below! Capt,n

av8tor1977

My Feedback: (6)

I see what you are getting at, and it seems quite feasible. Another way would be to have the rotor magnets on a small diameter rotor instead of on a big flywheel. The only reason they are made on a big flywheel is so that the mag can double as a cooling fan for the engine in their original intended applications. I have had motocross motorcycles that have a small diameter rotor instead of a large mag flywheel, and they allow the engine to rev quicker due to the lower rotating weight, and due to the weight being close to the crank centerline.

Some of the Fuji and Zenoah airplane engines are made this way; I wonder if the pieces could be adapted to our conversion engines?

AV8TOR

hewismayer

Good idea and with super strong earth magnets very possible. Instead of 1 ½ lbs for ignition it would be 8oz. I still like the gas on glow too simple to be true. Other than mixing fuels and cleaning out the engine it a great idea.

captinjohn

AV8TOR, I liked you idea too, but I just went and weighed 4 flywheels I had off engines. The lightest was a small dia one off a Zenoah that weighed 208 Grams. It felt heavy for its size...I think bcause the material is not much aluminum but heavy metal magnets. The next was a Torro (IKEDA-uko841) 3 3/8 dia and weighed 237 grams...not that much more. Next was a Phelon at 303 grams (metal pins removed) and last was another Pheoln at 273 grams (4039 with pins removed) with 3 3/8 dia. I think because of hi cost of some small dia flywheels & the little weight saving that we need to improve a mag only system that is not a "blower" or a "heavy flywheel". Capt,n[X(] EDIT Added photo

av8tor1977

My Feedback: (6)

Here is something similar to your idea Captain, and maybe a start? It doesn't create high tension voltage, but could run a battery powered ignition system without a battery. One would possibly have to buffer the circuit and use a voltage regulator if you wanted to run without a battery I imagine...

http://www.sullivanproducts.com/GenesysMainFrame.htm

AV8TOR

av8tor1977

My Feedback: (6)

I was just reading more about that Genesis system. They can provide it adjusted to put out 12 volts. One could hook that right up to a point triggered or Hall Effect triggered Kettering style ignition system and go fly. All you would need to come up with would be the ignition coil. One might need a 12 volt battery to power the ignition until the engine started and the charging system started putting out.

Now, one of you needs to buy the Genesis system, reverse engineer it, and figure out how to do it on the cheap!!

AV8TOR

captinjohn

AV8TOR, I looked around on the web-site and it looks like some of the technology is right there. The rotor and magnet system could be modified. I would like see a mag made using just the same components they use now ,but made for ignition only. No extra flywheel weight or cooling fins and smaller air gap type coils used. We got a way to go, but with several people putting good ideas together it can happen. Capt,n

Ram Jet

I agree. I think it's doable. Now, convince someone that there is enough market out there to recover tooling and R&D expense and maybe do somthing unAmerican like make a profit and someone will do it. There is no form of ignition more reliable. Oh, sure, CD ignition. Gods own fire! Until a solid state component goes south. My Honda 500 single motorcycle has CDI ignition. Great until I have to replace a "magic box" to the tune of $150.00 plus. I had CDI ignition on an old Kawasaki 500 years ago - great until it needed repair. Try to fix that problem on the road to nowhere on Sunday afternoon 100 miles from the nearest dealer. Magnetos are simple, powerful and aside from a set of points and condensor (which can be inexpensively purchased and carried with you) there is the very occasional remagnetizing of the rotor.

KISS, I'll take a mag any day on any kind of engine.

Bill

captinjohn

I think I will draw up a better sketch of what may work and send it to Sullivan. It sure looks like they have good technicians to work on similar parts that would be needed. If they did not produce one, maybe a person could buy some parts they already make and use them in building a workable light-weight mag. If we do nothing, it will never happen. Maybe bigboat here on RCU can help also. Finding a lite coil & magnet for rotor would help. Capt,n

Patxipt

I had the chance of poking at a Genesys system a year or so ago at the local hobby shop - I reckon they still have it - and that's nothing more than a flat style brushless motor/induction generator.

I too long for a small magneto igniton for my small glow engines, without having to worry about CDI batteries and all that. Nothing beats flipping the prop and away it goes - one reason I like model diesels.

carlosponti

My Feedback: (1)

remember this guy
http://www.rcuniverse.com/forum/m_40...tm.htm#4031310

what ever happened with that?

captinjohn

I copied one of the last postings. Looks like that flywheel developed cracks in spokes!!!....



Gryohead








Posts: 82
Joined: 3/8/2005
From: Rayland, OH, USA
Status: offline Stratosman, Darin

had to modify my lite wheel, he turned another 1/8" off the inside where it goes onto the taper of the shaft. I installed it and ran my engine up to 7100 rpm, shut it down to check the wheel and to my surprise I found three of the four spokes had cracks and the wheel was oval {not round anymore}. Makes for a good paper weight.

Gryohead
TLC priceless!!!!!!!!!!!!! [X(]


So that was the end of that one. My Idea was to make the wheel (rotor) part from flat aluminum plate and attach magnets in cut-outs. Opposing side of rotor would be a counter balance, perhaps held there with rivets. Capt,n

TFM70

Years ago when I was a kid, I had a motor bike and the magnets had become demagnitized and I had no spark. I found a bare wire on the magneto coil going to ground and I disconnected it from ground and connected a 1.5 volt battery between the wire and ground. I could turn the engine over very slowly and when the points opened I got a fat spark at the spark plug. The engine ran good with the battery.
On these weedeater engines they claim to have CDI or solid state which I suppose takes the place of the points maybe. Would it be possible to connect a battery for starting purposes?

captinjohn

TFM70 I have never tried adding a battery to a mag to allow it to produce a better spark. It makes good sense for sure and may be needed in this lite-weight ignition we would like to create. I have heard of jump start systems that indeed do work good I read. I have no idea how they work. Did you leave the 1.5 volt battery in circut all the time or just for starting? It is good to see new people sharing ideas...welcome aboard and Merry Christmas. Capt,n

TFM70

Captain
I did this about 60 years ago, so my recollection is vague,but I believe I left it in to run cause the magnets were shot and it didn't produce any spark without the aux battery. With the old style magnetos it makes sense that the current provided by the battery and interruped by the points is the same ? as current generated by the magnets passing the coil.
I don't have any hardware to look at but I envision something like a booster battery for starting only. You would probably have to wire it thru a diode to protect the electronics.
If you have one of the modern style solid state, CDI, etc systems laying around look and see if it has some common lead from the coil that a battery could be connected to.
Of course I may be all wrong about this.

Bigboat

OK, first of all you have to create an rotating magneticfeeld and a coil to generate the Voltage you need.
It's not necessary the magnet and the coil fit on the engine, you can also use a dynamo.
A small brusless (flight) motor can be use like a dynamo, you only have to mounth it near the axis.
With a bridge, some condensors and a Voltageregulator you can create your own powersupply.

av8tor1977

My Feedback: (6)

Care to scratch out a schematic for using a brushless hobby motor as a generator?

Thanks,
AV8TOR

Bigboat

Something like this will doit.

av8tor1977

My Feedback: (6)

Thanks! Type of transistor? Suggested values of capacitors?


AV8TOR

Bigboat

At the right isn't a transistor, but a Voltage regulator (78xx)
Use a 7805 to stabelize on 5 Volt, 7812 on 12 Volt.
The values of the capacitors depent on the current you wil make.
Same for the diode-bridge.

tkg

My Feedback: (1)

The used to be a gentleman in England who made a product called a MiniMag. He was trying to sell the company but I don't know what happened.
These were very small magnetos for converting glow engines.

av8tor1977

My Feedback: (6)

Ah, that's the regulator. I wondered why a transistor and why not the schematic sign for a transistor. Makes sense now, as do the capacitors. Don't remember the number at the moment, but there is an adjustable voltage regulator that I would use. May have to throw something like this together just for fun.

I'm a real amateur at electronics. Question... Would one expect to get the same current out of a motor used as a alternator that it is rated for used as a motor? Seems very unlikely a small 300 watt motor could sustain for example a 25 amp at 12 volt output.

Thanks again,
AV8TOR

captinjohn

OK....I kinda see what you did now. I had a very old John Deere tractor and the mag just did not cut it. I added power to it from a battery and did about the same thing! Capt,n

captinjohn

I am looked at the schematic and it looks like 6 diodes to convert AC to DC and 2 capacitors...one being a variable one?? Also 1 voltage regulator chip 7805. How is this tied in with coil or coils? Thanks Capt,n

captinjohn

More reading...kinda interesting...check it out http://walbro.com/brochurefiles/3368...%206-26-03.pdf Capt,n