The JEMMA 7-cylinder radial engine was built by Bob Haagenson of California. The engine is 13”-long, 9”-wide, 10”-high, and weighs 11 lbs. 6 oz. (on base). Bob built about fifty model engines ranging from single cylinder (hit and miss) stationary engines to four, six, and eight-cylinder racing engines and eventually a Rolls Royce V12 Merlin aircraft engine. All were designed and built to burn gasoline on spark ignition, and several were built from his personal designs.

He fabricated the JEMMA from plans published in Strictly IC magazine. It measures about 8 inches in diameter, has a bore of .750 and stroke of .800, and burns a gas/oil mixture on electronic spark ignition. The upper end requires manual lubrication before operation.

Exhibit added: August 31, 2013 - Last modified: January 20, 2023

Presented by The Joe Martin Foundation for Exceptional Craftsmanship