October 2018 web.pub

(Continued on Page 16) The Nitro Engine By Lohring Miller NAMBA Safety Chairman This will be a multi part series on the development and manufacture of the high performance nitro engine. Until very recently, the glow ignition model engine was the standard power plant in all powered models. We are interested in racing, so this first part is a quick history of model racing engines. Later parts will describe the details necessary to build a high power nitro engine. The first really successful model internal combustion engine was the Brown Jr. It was a simple two stroke, spark ignition, gasoline engine first built around 1934. It powered many of the free flight models of the day. However, speed couldn’t be measured in the airplanes of the time. The speed formats involved running in circles around a central post. The first of the circle racers were tether boats. In England, many builders were trying to make IC engines to compete with flash steam engines in British tether boat racing. In 1925 the first two strokes began to appear and IC engines started to be more popular. They were still custom built. After World War II the tether boats began to run US engines that were developed for tether cars. In the US, tether car racing was the dominant speed venue. At first builders ran various model airplane engines. However, in 1938 Walt Cave and Charlie Anderson developed an engine strictly for tether car racing that was the basis for racing engines for two decades. It became the Hornet 60. It had rotary disc- valve induction, cross-flow loop scavenging, a ringed aluminum piston, a twin ball-race crankshaft and was the first production racing engine. The early versions claimed a power of 0.55 BHP @ 15,500 rpm. PROPWASH October 2018 15 Hornet 60 Hornet 60 Brown Jr