[ausev] MYT Swing piston engine

[Dan Jacobson]

Gil and others, the pixs of the MYT engine look like a swing piston engine. The Germans experimented with these during WW2, (Lutz swing piston gas generator). This was first thought of as a gas generator for turbine use, then as a possible aircraft engine. The war ended before they got them to work. The British took over the work after the war. Basically, the engine has two sets of three pistons. Each set (of pistons) is arranged 120 degrees apart on a hub or "spider". The two spider connected piston sets are placed into a torus (doughnut) shaped cylinder and are free to turn and/or swing back and forth. (Thus the name.) As the sets of pistons swing and turn they can uncover intake and exhaust ports in the torus wall, and pass a spark plug for ignition. Problems include sealing the piston and wall (piston rings), and the spider to piston connection. This is usually a slot in the inner torus wall. 
  The problem that defeated the Germans and the British is some what more subtle. In a regular reciprocating piston engine, maximum pressure occurs near "top dead center". At this position the piston and connecting rod have only a little "leverage" on the crank arm. Remember, the crank arm is almost vertical at top dead center. As the piston moves down, the pressure drops and the piston gains in leverage as the crank arm becomes more horizontal. In the swing piston engine, as the fuel air mixture fires, the piston always has full leverage on the spider arm. (No top dead center condition.) In testing, the spider arms failed within minutes of running on fuel. The other issue that was not solved was the connections (and gearing) needed to get power out of the swing arm spider to a shaft for a propeller. Again, remember, the pistons need to swing back and forth as well as rotate around the torus. (The book does not say, but I would guess some sort of ratchet system.) If you can get this all to work, more power can be obtained by stacking more torus cylinders on the shaft. The Germans expected 445 bhp for a weight of 309 pounds. I think this would be a 30 inch diameter engine, one stack. A multi stack engine of about 3450 bhp would have been 6.5 feet long. The pistons were about 6.5 inches diameter, each on a spider arm about 7.7 inches long. Most of this information is from German Jet Engine and Gas Turbine Development, 1930-1945. Antony L. Kay, 2002, Airlife Publishing, England. I hope this helps. Dan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.austinev.org/pipermail/ausev/attachments/20090101/c7bbde04/attachment.html