October 2018 web.pub

Fuel flowed from the crankcase through three large ports in the piston skirt, into the bypass and then the cylinder. This lightened and cooled the piston as well as providing a shorter flow path. The Dooling 60 also ran a needle roller big-end bearing. These innovations along with a short stroke allowed higher rpm than previous designs. By 1948 the engine was dominating tether boat and car racing as well as the new control line speed event. The Dooling brothers also were the leaders in the use of nitromethane in fuel, even before full size race cars used nitro. They started experiments in 1947 along with the developer of the glow plug, Ray Arden. It was found that methanol based fuels were better with glow ignition and nitromethane made even more power. Tests on the Dooling 61 gave 1.5 BHP @ 15,600 rpm on methanol /castor oil, while on Arden Formula B containing 37.5% nitro, 37.5% methanol and 25% castor oil it developed 1.98 BHP @ 17,100 rpm, a 32% increase. Nitrobenzene allowed even more power and the Dooling 61 began to suffer from crankcase failures. This resulted in the Bruce Underwood yellow jacket crankcase. After World War II control line flying became a very popular event. Control line speed engines were the next area of race engine development. The tether car 60 engines, now running glow fuel, were run in the larger control line speed classes. The Nitro Engine ( Continued from 15) Dick McCoy began designing car engines in 1941. He only managed to make 35 engines before World War II interrupted the model racing world. The McCoy 60 was very successful and quickly replaced the Hornet as the engine of choice in tether car racing. Despite serious competition from the Dooling 61, the Series 20 glow version stayed competitive well into the 1960s. Glow ignition versions developed 1.52 hp at 16,100 rpm. The engine was heaver and tougher than the Dooling. It didn’t suffer from crankcase failures, even on high nitro fuels. The next step was the Dooling 61 designed by the three Dooling Brothers, Russell, Harris and Tom. The brothers built their first tether car in 1937. By 1938 they were building production tether cars in their California facility. Their cars ran first model airplane then Hornet engines. After a successful run of military business during World War II, they designed an engine to go with their cars. It was the famous Dooling 61. Besides having a higher quality of construction than the standard model engine of the day, the Dooling 61 introduced the "bulge bypass". See pictures of the Dooling 29 below with a similar system. This system involves the provision of a large bulbous chamber in the normal bypass passage location. PROPWASH 16 October 2018 McCoy 60 McCoy 60 glow version Dooling 61 Yellow Jacket Dooling 61