Discussion in 'Hangar Flying' started by Hot Wings, Aug 26, 2014.
Its simple in a way, but then things like work, budget, etc gets in the way.
A thought about ignitions: aren't the ignitions on most industrial engines basically just a magnet whirling past a coil? Ie, no alternator per se, but as the magnet speeds past the coil, it creates a current by induction and the speed at which it grows and decreases determines the strength (voltage), in other words it's the same thing as when a set of points closes and the magnetic field in the coil collapses and creates a high voltage to the plug. It's just a magnet and a coil with a plug wire coming out of it - should be simple and lightweight if you don't need an electrical system, and you might be able to mount the magnet(s) on the prop hub...
Yes, but then you need to buy four coil units. And install them around an 8" flywheel plate (that could be lightened).
It will be fixed timing usually. At 20°.
With Slick mag, just one coil for all four cylinders and an impulse retards for start which allows full power at 28° timing.
I think the Aerovee uses four coils.
Well, yes and no. Yes, most modern industrial engines have electronic ignition systems that use a magnet and coil to both power the ignition system and trigger the spark. Yes, it is mechanically very simple, and as a result they tend to be very robust. But the electronics in the black box are usually pretty complicated, so overall it might not be the very simple system that you might imagine it is.
Edited to add: The black box usually has some capacity to vary the timing based on RPM using a pre-programmed lookup table.
Thanks, Bob K.
Right, I was mistaken in that the flywheel can only generate the current needed, there is no way that the speed of the flywheel can collapse the field fast enough to generate the voltage needed so they do use a black box, but I think it is relatively simple and just replaces the points with a transistor. There may be more to it, but it is solid state, small, light, relatively inexpensive.
And here is what I was thinking of; there is no room for an alternator in that flywheel, so it is just the magnet and ignition coil/box doing the work. I think you could arrange these components to work on a four cylinder it it were put at the prop hub; say two of these flywheels with a larger diameter phenolic disc sandwiched between them and the four coils mounted in twos, 180 degrees apart:
Now for the black box. Magnetron™ solid state ignition systems, in essence, replace the mechanical breaker points with a transistor. That is, we replace a mechanical switch with an electronic one. No moving parts, no arcing, no adjustments and solid state reliability.
The mechanics of a Magnetron ignition are almost identical to the workings of a breaker-point ignition: a complete circuit on the ignition coil grounds the electrical field it is generating so it stays on the circuit. But, whereas the breaker point system uses a mechanical set of breaker points and cams to push them down, the Magnetron coil uses a transistor to break and close the coil circuit.
Edward Heath is definitely the ancestor for cheap air racing. In fact he started his company well before the 1926 National Air Races, being founded in Chicago around 1911 (the exact date is hard to find). Starting as an airplane parts company, he soon began selling complete aircraft either flyable, as a set of parts or just the plans. After the war, he entered and one events in the 1923 NAR in St. Louis with the Heath Favorite. He later went on to introduce the Parasol and Super-Parasol, the best-selling planes of the period.
Heath continued racing and winning as a way to promote business for his company. Air races were covered in the national newspapers and reached a far wider audience than ads in aviation magazines.
You might be interested in an excellent book, The Heath Story by Chet Peek.
I've always liked the Heath Parasol LNB-4, somehow jauntier and cuter than the longer fuselage and smaller rudder of the Super Parasol.
If I put a couple of LM2500s into a 250 ton hull, I'd have a good chance of winning America's Cup. Without some restrictions, it's no fun.
With somewhat less snark, handicapping is a very important consideration in yacht racing, as without it, the largest boat would almost always win.
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