B, was produced in larger numbers by the Wright brothers and was used by the army "for training pilots and conducting aerial experiments" including tests of "a bombsight and bomb-dropping device". The issue of patent control was correctly seen as critical by the Wrights, and they acquired a wide American patent, intended to give them ownership of basic aerodynamic control. This was fought in both American and European courts. European designers were little affected by the litigation and continued their own development. The legal fight in the U.S. had a crushing effect on the nascent American aircraft industry, and even by the time of America's entry into World War I, in 1917, the U.S. had "only six [American made] airplanes, and fourteen trained pilots". The numbers increased substantially over the subsequent years but during the war, all of the fighter aircraft flown by Americans were designed and built in Europe. Stability The Wright Flyer was conceived as a control-canard, as the Wrights were more concerned with control than stability. It was found to be unstable and barely controllable. During flight tests near Dayton the Wrights added ballast to the nose of the aircraft to move the center of gravity forward and reduce pitch instability. The Wright Brothers did not understand the basics of pitch stability of the canard configuration. F.E.C. Culick stated, "The backward state of the general theory and understanding of flight mechanics hindered them... Indeed, the most serious gap in their knowledge was probably the basic reason for their unwitting mistake in selecting their canard configuration." According to aviation author Harry Combs, "Wright designs incorporated a 'balanced' forward elevator...the movable surface extending an equal distance on both sides of its hinge or pivot axis, as opposed to an 'in-trail' configuration...which would have enhanced controllability in flight." Orville wrote of the elevator, which the brothers called a "front rudder", "I found the control of the front rudder quite difficult on account of its being balanced too near the center and thus had a tendency to turn itself when started so that the rudder was turned too far on one side and then too far on the other." Thus, these early flights suffered from overcontrol. After Kitty Hawk The Wright Brothers returned home to Dayton for Christmas after the flights of the Kitty Hawk Flyer. While they had abandoned their other gliders, they realized the historical significance of the Flyer.