Transcendental Model 1-G: the first aircraft with rotary propellers (convertoplan)
In 1951, in the USA, the specialists of Transcendental Aircraft Corporation began to manufacture their first aircraft with turning screws, which the designers of the company began to develop in the 1945 year. Actually, the aircraft Transcendental Model 1-G was the first vehicle of such a scheme, the first convertiplane. The convertoplane weighing 655 kilograms was equipped with a six-cylinder Lycoming O-290-A engine, which developed the power of the 160 hp. The engine rotated two screws, the diameter of each was 5,18 meter. The screws were located at the ends of a small wing, whose span was 6,4 meters. To change the position of the screws were applied two electric motors, which developed the power of 120 W each. With their help, the screws were turned from the "helicopter" position to the "aircraft" and back.
The management of the screws of the convertoplane was carried out with the help of “spider” type swash machines, as well as a common pitch control system. The presence of two types of control - helicopter and aircraft - created a number of difficulties. So for transverse and longitudinal control in helicopter flight modes, a cyclic step knob and a step-gas lever located on the left side of the seat were used, and for foot-operated control - foot pedals. For transverse and longitudinal control on aircraft flight modes, the steering wheel was used. Helicopter control was associated with the aircraft, which allowed the pilot to maintain controllability when switching from one mode to another.
For the beginning of the 50-s of the last century, this aircraft was quite revolutionary, so the tiltrotor did not immediately rise into the air. Initially, Transcendental specialists tested their offspring for a long time on a purpose-built stand (transfer of screws from one position to another was being worked out). The total duration of the bench tests was 40 hours. During this time, the designers were able to make sure that all the components and assemblies of the convertoplane, a fairly complex transmission, the system of turning the screws and the controls work properly and without failures. The bench tests went surprisingly smoothly. 6 July 1954, the aircraft that received the registration number N2704A, performed its first free flight. Conducting long bench tests on the ground gave its result. The convertoplan was tested in the air for more than a year without any special problems and complaints, having completed more than 100 flights during this time and flying a total of 23 hours.
But 20 July 1955 of the year during the next test flight of the Transcendental Model 1-G crashed due to a control system failure. The pilot, piloting the device, got off with minor injuries, but the tiltrotor itself received significant damage. It was not enough to recover the device after a catastrophe, the information obtained during the tests was enough, and it was not possible to squeeze something larger from this model. Almost immediately, the designers of Transcenal, using the accumulated information, began work on a double convertible plane Model 2-G.
The design and layout of the Transcendental Model 1-G tiltrotor
According to the layout, the Transcendental Model 1-G tiltrotor was a high-wing monoplane, with two turning screws mounted on the ends of the wing. On helicopter flight modes, the aircraft was controlled, like a twin-screw transverse helicopter. The fuselage of the convertoplane truss structure, the trim was metallic. In the bow of the designers have placed a glazed cockpit.
The span of a highly rectangular wing in plan was 6,4 meters, the chord was 0,9 meters. The wing helped create the necessary lift in horizontal flight mode. For transverse control in aircraft flight mode, ailerons were located on the wing. The plumage is ordinary, the keel and the stabilizer have a truss structure with metal lining, whereas the trim on the steering wheels is linen. The chassis of the tiltrotor was three-support, the nose support was made non-retractable. All wheels were made self-oriented.
On the convertoplane were used three-blade screws with all-metal blades. Each of the blades was attached to the sleeve with the help of a combined horizontal and vertical hinge, the oscillations of the blade were limited to dampers. In a helicopter flight mode at maximum power, the screws rotated at a speed of 708 revolutions per minute, the peripheral speed of the blades was 192 m / s. With a cruising airspeed in airplane mode, the propellers rotated at a speed of 613 revolutions per minute (the peripheral speed of the blade tips was 176 m / s). In the helicopter flight mode of the tiltrotor, the propeller shafts were tilted slightly forward - by 6 degrees, and when moving to the horizontal flight mode (in an airplane mode), they, together with the gearboxes, were turned by 84 degrees using a worm gear and an electric motor. The process of moving screws from one position to another took about a minute 3-4. The transition between the flight modes was controlled by means of the button for turning on the electric motors for turning the propellers, which was located on the control wheel.
Flight performance of the Transcendental Model 1-G:
Overall dimensions: length - 7,92 m, height - 2,7 m, wingspan - 6,4 m, wing area - 5,9 m 2.
The diameter of the rotor - 2 x 5,18 m.
Empty weight - 658 kg.
Total weight - 794 kg.
Fuel supply - 53 l.
The power plant is an air cooled 6-cylinder engine Lycoming O-290-A, power is hp 160.
The maximum speed is 257 km / h (airplane mode), 190 km / h (helicopter mode).
The maximum flight duration is 1,5 hours.
Practical ceiling - 1524 m.
Crew - 1 man.
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