Chuck’s Patented Reduction Drive?

Chuck Slusarczyk in 1981 with patent #4,262,263 – his patent for a Powered Hang Glider With Reduction Drive.

Chuck’s Patented Reduction Drive?
Back when ultralights were new, most engine/prop combinations were direct drive. General aviation aircraft engines are direct drive. Of course, these run at slower revolutions so the prop speed isn’t excessive. On a high-revving 2-stroke engine, direct-drive props (commonly 36-inch diameters) are spinning so fast the prop tips create a lot of noise.
When I owned and flew a Flight Designs Jet Wing trike back in 1982, that direct-drive Kawasaki 440 engine and prop were so loud my neighbors complained and I had to cease flying except during certain hours.
To the rescue came Chuck Slusarczyk and his invention. The funny thing is, his patent is not for the reduction drive as many think and as this sidebar’s title suggests.
Even before he designed his groundbreaking Hawk, Chuck developed and was the first to use an “ultralight” reduction drive. His early experience was during the days of experimentation of powered hang gliders. The first such machines used the tiniest engines possible in the interest of saving weight.
Powered hang gliders had engines primarily to lift them aloft after which they would be shut down and soared. If they were noisy for a few minutes of climb, this was acceptable. When later developments needed more power without growing the engine, greater thrust was the solution.
Another branch of experimentation added landing gear and other components. As those aircraft got heavier, powerplants like the Mac 101 or the 15-horse Yamaha became insufficient. Consequently, designers fitted larger engines. This led to noisemakers like my Jet Wing, powerful but exceedingly noisy. Given the neighbor conflicts, something had to happen.
Chuck realized that he could dramatically increase usable thrust and offer quieter operations at the same time.
His innovation was a belt drive reduction system that allowed a small engine to spin a larger, higher thrust prop at speeds low enough to keep noise down. Since he was the first to do this on hang gliders (they weren’t yet called ultralights), he was able to patent the idea (patent #4,262,263).