Curtiss R-600 ChallengerThe Curtiss R-600 Challenger was a six-cylinder, double-row, air-cooled, radial engine for aircraft use built in the United States in the late 1920s. It developed.Design and developmentCurtiss started work on a small six-cylinder engine in May 1927. The engine was unusual in its design with aluminium cylinders mounted at 60°, so that it was in effect two staggered three cylinder engines. The engine was first run in December 1927, and was taken to market producing between at 1,800 rpm.Applications ANBO VI Consolidated XPT-5 Curtiss Robin Curtiss-Wright CW-14C Travel Air Hodkinson HT-1 Rearwin 2000