That is the way that the Great Plains electronic ignition works. They package it in something that fits inside the distributor hole, but I know one person that just put the magnets by the prop hub and mounted the sensors near it. You could do the same with the ring gear. I believe that you can buy all the components from Great Plains without the distributor housing. The sensor is all a small module that does not need a separate relay.
Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On Behalf Of Serge VIDAL Sent: Tuesday, December 27, 2005 6:56 AM To: KRnet Subject: Réf. : Re: KR> Corvair ignition Colin, Indeed, my KR2 has got a very special electronic ignition, which I call "solid state". And believe me, this has absolutely nothing to do with standard electronic ignition as you know it. Let me try and explain. It is a very simple set of components that "reads" the ignition timing with a magnetic sensor, and triggers the ignition coils with a relay. Period. So, it has got absolutely no software in it, in any form whatsoever. It is only a handful of plain and simple electronic components that react to a magnetic impulse. How does it work? There is a tiny steel mass clamped to the crankshaft. Around the crankshaft, you have small magnetic sensors (roughly half the size of a matchbox) that react when that steel mass passes by (for one of my two ignition systems, the steel mass is a 4mm grubscrew that protrudes by about 3mm... so we are talking very small mass, here!). As for the exact operation principle, I believe the magnetic pick-ups create a very small magnetic field, and react when that field is disturbed, although I am not too sure about that. Then, the magnetic pick-up triggers a relay, which in turn triggers an ignition coil, which in turn fires two spark plugs (the coil has got two output wires). Now, the idea is that each of these magnetic pick-ups takes care of two cylinders. I mean, it triggers two cylinders at the same time each time the magnetic mass passes by, and therefore, once per revolution f the crankshaft. These would be the two cylinders that are at opposite times of the 4-stroke cycle, and therefore, offset by one full revolution of the crankshaft. So, for a given cylinder, one turn out of two, the system will fire the cylinder at the correct timing. The next turn, the cylinder will be fired at the wrong timing, but that will be during the exhaust phase, so this will have no effect whatsoever. If your engine is a two cylinders, a single pick-up will do. If your engine is a four cylinder, then you will need two pick-ups, offset by 180°. A six cylinders will take three pick-ups, offset by 120°. And so on... It doesn't get more reliable and more simple than that. So, what's the beauty of the system? Well, I see many. - It runs on the crankshaft, not the camshaft, so you don't have to worry about gears, or build mechanical interfaces - It runs from the outside of the engine, so no ports - It has no mechanical contact whatsoever, so no friction, no breakage, no slippage, no nothing; - It is set once and for all. Bolted in place, zero maintenance except for checking the condition of the electrical contacts. - It has an extremely low parts count, and very few failure modes. - It costs peanuts, because it comes straight out motorcycle junkyards And here comes the one-and-only drawback: - It needs electricity to run, so you have to make sure you dont' lose both your alternator and your battery. The only sophistication in the system is the advance-retard mechanism. This system will give you less advance at engine start, and a constant advance thereafter. How does it work? Very simple again. The steel mass can move for a certain angle ( it has a mechanical angular travel), and is held in the "start" position (low advance) by a spring. As soon as the engine turns, the strength of the spring is overcome by the centrifugal force of the rotating crankshaft, and the steel mass moves towards its normal position (ful advance) and stays there for as long as the engine runs. Let me add that I did not design that system. It came with the engine when I bought the plane. But I was so happy with it that when I upgraded the engine (you see, I became power hungry), I replicated it, and introduced more redundancy (two spark plugs per cylinder). As far as I am concerned, the track record is 400 fligh hours on the previous engine without a glitch, and about 3 flight hours with the new engine, still without a glitch. So, I'm a believer. Serge Vidal KR2 "Kilimanjaro Cloud" Paris, France "AVLEC" <av...@telkomsa.net> Envoyé par : krnet-boun...@mylist.net 26/12/2005 16:48 Veuillez répondre à KRnet Remis le : 26/12/2005 20:07 Pour : <brokerpilot9...@earthlink.net>, "KRnet" <kr...@mylist.net> cc : (ccc : Serge VIDAL/DNSA/SAGEM) Objet : Re: KR> Corvair ignition Colin, if you had the oppertunity to see the system in Serg's plane, you would see how simple it really is. You literally just remove it from the donor motorcycle and install it on the motor of your choice( any motor, any number of cylinders. By just seperating the power supply to the seperate ignitions, you end up with a totally seperate ignition system for every two cylinders (for odd number of cylinders just leave off one of the plug leads). In the case of a VW I doubt that you would be able to stay in the air with two cylinders but with the corvair 3100 that I should be getting soon, if one of the three independant ignitions should fail I would be left with the equivalent of an out of tune type IV VW to take me home! That system in Serg's plane has done probably in the region of 600 hrs + without as much as a hickup. It also needs zero maintenance except to check the electrical connections now and then.Thats reliability in my book! It even has centrifugal advance!! It doesn't get much simpler than that. Regards Dene Collett KR2SRT builder South africa Whisper assembler See: www.whisperaircraft.com mailto: av...@telkomsa.net ----- Original Message ----- From: "Colin Rainey" <brokerpilot9...@earthlink.net> To: <kr...@mylist.net> Sent: Sunday, December 25, 2005 02:42 Subject: KR> Corvair ignition > Dene > If you are going to go to that much trouble with the ignition system, when there is very little faults with the original system, and a Petronics electronic update from either Summit Racing or Clark's Corvairs will eliminate any other normal failure. Modern electronic ignition systems do not just "quit" as in days gone past, if it is a quality system. > > You can use an external GM crank sensor, or cam sensor, and install a 3 tiered trigger system, then have 3 GM late model capacitive coils which is what they use on the Aerovee VW engine, and trigger each one individually, hooked up to the 2 companion cylinders so that one is firing on the exhaust stroke while the other is firing on compression stroke. The only problem with that type of simple system is it is fixed timing, unless you figure out how to incorporate an ignition module. Since caps, rotors, and normal use distributor shafts don't fail in use suddenly, but rather deteriorate slowly over time, a pilot will notice they are wearing out before failure. Therefore, that is ALOT of engineering to go through for very little pay off, and will definitely hurt peak performance. > > Most sudden failures of ignition systems today are actually systems that have been ignored, and driven with for some time, until the vehicle will not operate any more. From my observation here, KR pilots are ALOT more conscientious and will abort takeoffs and determine the problem, instead of flying anyway, and "worry about it later" attitude. > > If it makes a difference I will be flying behind a single ignition system, of electronic type, and vacuum advance distributor, and expect with regular maintenance and attention to have the same reliability as I have in my driveway... > > Merry Christmas from our family to yours, including our "new baby boy" Zeus, a 2 pound miniature Doberman/rat terrier mix. > > Colin Rainey > brokerpilot9...@earthlink.net > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
