Argus pulsejet's major components included the nacelle, fuel jets, flap valve grid, mixing chamber venturi, tail pipe, and spark plug. Compressed air rather than a fuel pump forced gasoline from the fuel tank through the fuel jets which consisted of three banks of three atomizers. These nine atomizing nozzles were in front of the air inlet valve system where it mixed with air before entering the chamber. A throttle valve, connected to altitude and ram pressure instruments, controlled fuel flow. Schmidt's spring-controlled flap valve system provided an efficient straight path for incoming air. The flaps momentarily closed after each explosion, the resultant gas compressed in the venturi chamber, and its tapered portion accelerated the exhaust gases creating thrust. The operation proceeded at a rate of 42 cycles per second. Beginning in January 1941, the V-1's pulsejet engine was also tested on a variety of craft, including automobiles and an experimental attack boat known as the Tornado. The unsuccessful prototype was a version of a , in which a boat loaded with explosives was steered towards a target ship and the pilot would leap out of the back at the last moment. The Tornado was assembled from surplus seaplane hulls connected in catamaran fashion with a small pilot cabin on the crossbeams. The Tornado prototype was a noisy underperformer and was abandoned in favour of more conventional piston-engine craft. The engine made its first flight aboard a Gotha Go 145 on 30 April 1941. Guidance system The V-1 guidance system used a simple autopilot developed by Askania in Berlin to regulate altitude and airspeed. A pair of gyroscopes controlled yaw and pitch, while azimuth was maintained by a magnetic compass. Altitude was maintained by a barometric device. Two spherical tanks contained compressed air at , that drove the gyros, operated the pneumatic servo-motors controlling the rudder and elevator, and pressurized the fuel system. The magnetic compass was located near the front of the V1, within a wooden sphere. Just before launch, the V1 was suspended inside the Compass Swinging Building (Richthaus). There the compass was corrected for magnetic variance and magnetic deviation. The RLM at first planned to use a radio control system with the V-1 for precision attacks, but the government decided instead to use the missile against London. Some flying bombs were equipped with a basic radio transmitter operating in the range of 340–450 kHz. Once over the channel,