The Wright Model B engine was a fou

The Wright Model B engine was a four-cylinder gasoline-powered motor weighing 178 pounds, capable of developing up to 40 horsepower. The original 1903 engine weighed 160 pounds not including oil, water, or the magneto, and produced only 12 horsepower.4 In these early days, 1 horsepower was approximately equivalent to five propeller revolutions per minute at peak engine-operating efficiency. The less horsepower the fewer screw rotations, and thus less thrust for flying.5 As the narrow margin between flying speed and stall speed—the speed at which sufficient lift for flight is no longer generated—was often less than 10 miles per hour, every bit of power was absolutely essential.