Hiram Maxim made a fortune from his invention of the Maxim machine gun, and he used a good bit of that fortune to explore heavier-than-air flight. Maxim began his aerial experiments at Baldwyns Park, England, in the late 1880's, leading to the construction in 1893 of his enormous biplane Test-Rig, which weighed about 7,000 pounds. The machine's two steam engines each produced 180 h.p., and turned two propellers each 17-1/2 feet in diameter. Since the device was intended to be a test vehicle, it was held to a track, preventing it from rising from more than a couple of feet.
On the Maxim Biplane Test-Rig's third test run, on July 31, 1894, with Maxim and a crew of three aboard, it lifted with such force that it broke the reinforced restraining track and careened for some 200 yards, at times reaching an altitude of 2 or 3 feet above the damaged track. It was believed that a lifting force of some 10,000 pounds had likely been generated. The Test-Rig was subsequently used on a number of occasions to raise funds for charities, rather than raising itself. Within a year or so the Maxim Test-Rig was dismantled.