Sir Hiram Maxim was an American engineer who had moved to England. He built his own whirling arm rig and wind tunnel, and constructed a large machine with a wingspan of 105 feet (32 m), a length of 145 feet (44 m), fore and aft horizontal surfaces and a crew of three. Twin propellers were powered by two lightweight compound steam engines each delivering 180 hp (130 kW). Overall weight was 8,000 pounds (3,600 kg). It was intended as a test rig to investigate aerodynamic lift: lacking flight controls it ran on rails, with a second set of rails above the wheels to restrain it. Completed in 1894, on its third run it broke from the rail, became airborne for several hundred feet at two to three feet altitude  and was badly damaged upon falling back to the ground. It was subsequently repaired, but Maxim abandoned his experiments shortly afterwards.