(Such a design having allegedly been tested at NAVAIR PSEF in 2003.) In 1911 the Macomber Rotary Engine Company of Los Angeles marketed one of the first axial internal-combustion engines, manufactured by the Avis Engine Company of Allston, Massachusetts. A four-stroke, air-cooled unit, it had seven cylinders and a variable compression ratio, altered by changing the wobble-plate angle and hence the length of piston stroke. It was called a "rotary engine", because the entire engine rotated apart from the end casings. Ignition was supplied by a Bosch magneto directly driven from the cam gears. The high voltage current was then taken to a fixed electrode on the front bearing case, from which the sparks would jump to the spark plugs in the cylinder heads as they passed within 1/16 inch (1.5 mm) from it. According to Macomber's literature, it was "guaranteed not to overheat". The engine was claimed to be able to run at 150 to 1,500 rpm. At the normal speed of 1,000 rpm, it reportedly developed 50 hp. It weighed and it was long by in diameter. Pioneer aviator Charles Francis Walsh flew an aircraft powered by a Macomber engine in May 1911, the "Walsh Silver Dart". In 1913 Statax-Motor of Zürich, Switzerland introduced a swashplate engine design. Only a single prototype was produced, which is currently held in the Science Museum, London. In 1914 the company moved to London to become the Statax Engine Company and planned on introducing a series of rotary engines; a 3-cylinder of 10 hp, a 5-cylinder of 40 hp, a 7-cylinder of 80 hp, and a 10-cylinder of 100 hp. It appears only the 40 hp design was ever produced, which was installed in a Caudron G.II for the British 1914 Aerial Derby but was withdrawn before the flight. Hansen introduced an all-aluminum version of this design in 1922, but it is not clear if they produced it in any quantity. Much improved versions were introduced by Statax's German division in 1929, producing 42 hp in a new sleeve valve version known as the "29B". Greenwood and Raymond of San Francisco acquired the patent rights for the US, Canada, and Japan, and planned a 5-cylinder of 100 hp and a 9-cylinder of 350 hp.