Diego Aeroplane Manufacturing Company incorporated on August 25, 1909, capitalized at $200,000. The company was located in room 432 of the Keating Building on the corner of Fifth and F Streets in downtown San Diego. Walsh was vice president and general manager. He built his airplane in the old Rogers carriage shop on Third Street (between E and F Streets) near the company headquarters. This location is now a parking garage for the Westfield Horton Plaza. By late November, Walsh had essentially completed his airplane. Built from seasoned spruce and piano wire it measured 40 feet long with a 50-foot wingspan. It was reported to be the largest monoplane in the world at the time. Like the Wright Brothers design, a motor drove twin pusher propellers through a bicycle chain. The propellers were seven feet long and made of Oregon pine with hickory hubs. Like Curtiss, he used a tricycle type landing gear and ailerons vice the Wright's wing warping method for lateral control of his Bleriot-type monoplane. His wings tapered from curved in the middle to flat ends. The reason given for this is that the newspaper picture he used as his template for the design had the ends of the wings cutoff, so that is how he thought they looked. Attached to these was his specially designed device to automatically provide lateral stability to his airplane. This consisted of a fifteen-pound weight suspended from a five-foot rod which was connected to both wingtips. As air flow acted on the wings, the weight would act as to raise on wingtip and lower the other, maintaining lateral stability without pilot input. For control, Walsh designed a dual lever system, closely resembling that of the Wright Brothers. One controlled the engine and one controlled the pitch. It was powered by a 30 H. P. Cameron automobile engine. Walsh tested his airplane at the Coronado Island Country Club racetrack during the last week of December. He was one of three local San Diego aviators, including Waldo Waterman, attempting to enter an airplane in the 1910 Los Angeles International Air Meet at Dominguez Field. The airplane was damaged during ground runs at Coronado on December 29. His wife Alice sold her jewelry so that he could attend the event as a spectator. While there, he made the most of the opportunity to learn about airplane design from the most legendary pioneers in aviation.