Randall Wiseman was noodling around with engine designs some four years ago when he remembered the Spirograph that his nephew received one Christmas.

"I remembered playing with it, and that there was one gear relationship so that when you put the pen in a hole, it made an almost linear motion," Wiseman said. "I thought, that's no fun." Instead of a complicated design, all he got was a straight line.

That memory led Wiseman, a retired auto mechanic who lives in Bay St. Louis, Miss., to design a radical new crankshaft gear set, one that he claims can double engine efficiency and virtually eliminate piston wear.

"It should be very easy to make the transition to this technol-
ogy," Wiseman said. "But instead of eight cylinders, say, you'd only need four cylinders to produce the same power. And because the engine would be about half the weight, you'd get a fuel economy boost as well."

The design scraps the venerable connecting rod and rod bearing that translate the linear motion of the piston in the cylinder into rotational force on a crankshaft. That configuration dates back to some of the earliest steam engines, but the design has some inherent flaws.

For instance, the length of the piston stroke is limited by the length of the rod bearing that's attached to the crankshaft. If it's too long a stroke, the connecting rod will hit the side of the cylinder. In addition, the lateral swings of the connecting rod force the piston against the cylinder, creating friction.

Taking inspiration from a child's toy, a Mississippi mechanic designed a crankshaft that translates the linear motion of the piston into rotation through a set of planetary gears.

Wiseman abandons the rod bearing in favor of a planetary gear. That gear is configured in such a way that as the planetary gear makes one complete circuit inside the ring gear, a point on the edge of the planetary gear traces a straight-line path back and forth.

"I was never 100 percent convinced it was pure linear motion until we built the first prototype," Wiseman said. Attaching a piston rod at that point enables it to move in a straight line as it turns a crank, reducing wear in the cylinder and boosting efficiency.

"Because of the linear stroke coming out of the piston, we have the availability to have an unlimited stroke length," Wiseman said.

A piston that is two inches in diameter could have a six-inch stroke, since the connecting rod never has to swing out of alignment. The result, says Wiseman, is increased torque. "Ultimately, we could see an engine with a small bore and a long stroke," Wiseman said. "We'll have an engine that will produce usable power at lower rpm."

What's more, Wiseman noted, wear is so slight in a prototype engine (adapted from a handheld weed cutter) that the necessary lubrication came from gasoline.

The Wiseman engine has grabbed the attention of the Air Force Research Laboratory at Eglin Air Force Base in Florida. Researchers there are interested in boosting the efficiency of the small engines that power unmanned aerial vehicles—the drones that proved so effective during the war in Afghanistan.

In a side-by-side comparison for officials at Eglin, Wiseman tested an engine with his crankcase against an identical engine using the traditional combination crankshaft and connecting rod. The Wiseman engine ran twice as long on the same ration of fuel. Engineers at the U.S. Air Force Academy will soon examine a prototype Wiseman engine, officials at Eglin said.

Based on the demonstration, Eglin engineer Ben Plenge holds out hope that the technology could "significantly improve the operating performance of reciprocating internal combustion engines."

For Wiseman, however, the real sign of success will be breaking into the mainstream. He hopes that his crankshaft design will find its way into all manner of machines, from lawn mowers to Mack trucks.

"Maybe the Wiseman engine will some day be as famous as the Diesel engine or the Wankel engine," Wiseman said. "Who knows?"

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