This curious plane, designed by United Aircraft concern, Chans-Vout, was first shown to the public in June 1946 of the year. Everyone who saw him at least once, without saying a word, gave him funny nicknames: “flying pan”, “skimmer” (“skimmer”), “pancake”, “unfinished pie”, “flying saucer” and so on. But, despite the really strange appearance, Chance-Vout XF5U-1 was a formidable car. History its that.
In 1933, a prominent American aerodynamic scientist, Charles Zimmerman, conducted a series of experiments with a small elongation wing. Theoretical studies have shown the effectiveness of this scheme. At the ends of the wing of ultra-low elongation, it was supposed to put the screws spinning in the direction opposite to the direction of rotation of the vortices descending from the wing. Then the inductive resistance of the wing-propeller system would fall, and the aerodynamic quality increased from 1 to 4, that is, it was possible to build an aircraft with a huge speed range. Low-turn screws of large diameter with sufficient power supply will allow you to hang like a helicopter transverse scheme, and to take a vertical take-off, and low drag will give the aircraft speed. In 1935, Zimmerman built a manned model with a 2 span. M. Equipped it with 2 × 25 hp. engines "Cleon" air cooling. The pilot was supposed to lie inside the fuselage - the wing. But the model is not off the ground because of the inability to synchronize the rotation of the screws. Then Zimmerman built a rubber model of a half-meter span. She successfully flew. After support at NASA, where Zimmerman’s inventions, as too modern, had been rejected, designers in the summer of 1937 were invited to work for Chance-Vout (CEO Eugene Wilson). Here, taking advantage of the great potential of the laboratories, Charles built a model - the V-162 electrolyte of a meter scale. He made a number of successful flights in the hangar.
At the end of April 1938, Zimmerman patented his aircraft, designed for two passengers and a pilot. His developments interested the military. At the beginning of 1939, as part of the competition for a fighter of an unconventional scheme, in which, besides Chance-Vout, the firms Curtiss and Northrop took part, Charles took up the development and construction of a light-engine analogue V-173. The work was funded by the US Navy. V-173 had a complex wooden structure, covered with cloth. Two synchronized Continental A-80 engines for 80 hp rotated through the gears huge three-blade screws with a diameter of 5,03 meter. Wingspan 7,11 m, its area 39,67 m2, the length of the machine 8,13 m. The chassis for simplicity made non-retractable, with rubber cushioning. The wing profile was chosen symmetrical, NASA - 0015. At the rate the aircraft was controlled by two keels with rudders, and by roll and pitch - with the help of whole-turn elevons. Due to the revolutionary concept of the V-173, it was decided to blow it in one of the largest wind tunnels in the world, at the Langley Field test complex, before the flight tests. Everything ended successfully in December 1941. Began flight tests.
After short runs and approaches at the airfield of the company in Stratford (Connecticut), the chief pilot of the company Boone Gayton 23 in November 1942 of the year lifted the V-173 into the air. The first 13-minute flight showed that the load on the handle, especially in the roll channel, is excessively large. This disadvantage was eliminated by installing weight compensators, adjusting the pitch of the screws depending on the mode of operation of the engines. The aircraft became obedient in control. Guyton stated that the handle without excessive efforts deviates in the channel of pitch by 45 degrees in both directions. Despite the secrecy of the program, the V-173 flew a great deal outside the Stratford airfield, becoming “their own” in the sky of Connecticut. With a flight weight 1400 kg horsepower 160 the car is clearly not enough. Several times as a result of engine failure, the V-173 made forced landings. Once, on a sandy beach, skipped, (small-diameter wheels burrowed into the ground). But every time a very low landing speed and strength of the structure saved him from serious damage.
The main disadvantage of the V-173, Guyton and the famous pilots Richard "Rick" Burové and Charles Lindberg who joined him during the tests, recognized the poor view from the cab ahead during taxiing and takeoff. The reason for this is a very large parking corner, 2215. Then they raised the pilot's seat, made the window for a review down and forward. But that didn't help much either. The takeoff of the aircraft amounted to only 60 meters. With a headwind of 46 km / h, it rose vertically into the air. The ceiling of the car is 1524 m, the maximum speed is 222 km / h. In parallel with the design and testing of the V-173, Chance-Vout began to design the fighter. The contract for its development from the Navy 16 September 1941 of the year, a day after giving consent to purging V-173 in the pipe Langley Field. This project was branded with VS-315. After successfully completing the V-173 purge (January 19 1942), the US Navy Aeronautics Bureau asked the company for a technical proposal to build two prototypes and a full-size purge model in the 1 / 3.
By May 1942, the work on the technical proposal was completed. Young talented engineer Eugene "Pike" Greenwood joined the Zimmerman team. He was responsible for designing the design of the new aircraft. In June, the technical proposal was transferred to the Aeronautics Bureau, the future aircraft received the name of the system adopted in the Navy: XF5U-1. Its main feature was the ratio between maximum and landing speed - around 11, in the usual way - 5. Estimated speed range from 32 to 740 km / h. To achieve these characteristics, many problems had to be solved. For example, at low flight speeds, the angle of attack greatly increased. Due to the asymmetry of the flow around on the V-173, very strong vibrations were noted that threatened the structural strength. To get rid of this mode, the company Chance-Vout, which collaborated with the Hamilton Standard company (it produced propellers), developed a propulsion device called the “unloaded propeller”. Wooden blades of a very complex shape, with a wide butt, were fastened to steel eyes connected with a swashplate. With it, you can change the cyclic pitch of the blades.
The Pratt-Whitney company also took part in the creation of the propeller motor group. She designed and manufactured a synchronizer for R-2000-7 engines, five-time gearboxes, clutches that allowed either of the two motors to shut down in case of damage or overheating. The specialists also helped design a fundamentally new fuel system that allowed the engines to be powered during a long flight at high angles — attacks (up to 90╟ while hovering in a helicopter mode). Externally, the XF5U-1 almost repeated the V-173. The same remained and control system. The pilot's gondola and the wing - the fuselage of a semi-monocoque structure were made of metalite (a two-layer panel of balsa and aluminum sheet) of a very durable and fairly lightweight. Engines, recessed in the wing - the fuselage, had good access. It was planned to install 6 machine guns "Colt-Browning" caliber 12,7 mm with a supply of cartridges for 200 pcs. on the barrel, four of which on production machines wanted to replace the Ford-Pontiac M-20А with 39-mm guns, which were still under development by that time. The wooden layout of the XF5U-1 fell on the mockup commission of the 7 Navy June 1943. He had three-bladed screws. After the alterations caused by the commission’s remarks, the contract for the production of prototypes again submitted for consideration for inexplicable reasons was signed only on July 15 of the year 1944. It was decided to equip the first prototype with Pratt-Whitney R-2000-7 engines (1100 hp - maximum power, 1350 hp - at the injection pump with water injection), the second - XR-2000-2, with Wright turbine generators. Armament on the first prototype was not installed. The first prototype of the XF5U-1 was rolled out of the 25 June 1945 hangar. By this time, the firm received permission to conduct flight tests at the well-equipped Murok Dry Lake (California) test site. Previously, 24 March, she appealed to the Navy with a request to continue funding the project, since the loan allocated to XF5U-1, was already squandered. To save money, the flight test program was cut, in particular, its flight part and static tests.
Temporarily equipped with 4-blade propellers similar to those used on the F4U-4 Corsair fighter (Hamilton model Hydromatic), the XF5U-1 successfully steered. The second instance was used for static tests. After installing “unloaded propellers” on the first prototype, Bun Gaitan finally lifted the plane into the air in mid-January 1947. Skimmer, as they called the car at the company, passed the flight test program with flying colors, reaching a record speed of 811 km / h for that time. This unofficial record belonged to Richard Burovs. He reached speeds at an altitude of 8808 m in afterburner mode. The possibilities of vertical take-off from a special trapeze “in helicopter”, with screws up, and hovering also in “helicopter” were demonstrated. The Skimmer was prepared for shipping by sea through the Panama Canal to California, but the program was suddenly closed. There were two main reasons: financial difficulties at the company, and the rejection of Skimmer was the easiest way to save money, and the fact that rearmament was already underway fleet US jet technology. In the spring of 1948, according to the instructions of the Navy, all valuable equipment was removed from the aircraft, and the hulls were turned into scrap metal by bulldozers. At about the same time, V-173 was transferred to the museum at the Smithsonian Institution, where it is stored to this day.
The XF5U-1 fighter was a two-powered integral-configuration monoplane with an elliptical wing of the NACA 0015 symmetric profile throughout its span.
Structurally, the aircraft consisted of three main parts: the front, middle and rear. In the front there was a pilot's cabin, air intakes with fans of forced cooling of engines and compartments with small arms. The middle part of the fuselage was formed by two power frames-spars, between which were located the engines, the main and consumable tanks, shafts and gear drives of the screws. In its lower part, the main landing gear was fastened to the front power frame. In the rear were the main controls of the aircraft, the tail wheel and the brake hook.
The power set of the structure was made of aluminum alloys, and the lining of the new composite material was metalite, patented by Vought and representing a sandwich glued and formed in a large autoclave from two thin aluminum sheets separated by a layer of ultra-light wood - balsa. The strength and rigidity of the material obtained made it possible to radically reduce the number of frames and ribs reinforcing the aircraft's casing, making the structure almost monocoque.
Cockpit airtight, closed drop-shaped sliding light. The drive of the moving part of the lantern is electric. Pilot's seat - ejection, such as JD-1, produced by the British company Martin-Baker. On the front panel of the instrument panel were the main flight-navigation instruments, instruments for monitoring the systems of the aircraft and the power plant. On the left panel were located knobs engine controls, the cyclic pitch of the screws, trim tabs, chassis and brake hook. The right panel was occupied by a gas station and a radio station control panel.
The power plant consisted of two Pratt & Whitney R-14-2000 (D) Twin Wasp 2 X-cylinder twin-row X-cylinder engines. On the front of the crankcase of each engine was fixed gearbox with bevel gears, which transmitted torque to a single transverse shaft drive screws. In addition, an engine cooling fan was connected to the gearbox. Exhaust hot air exited through adjustable flaps on the lower and upper surfaces of the fuselage. Exhaust gases through the manifold and the U-shaped exhaust pipe were removed under the fuselage. In case of failure of one of the engines, the pilot could disconnect him from the gearbox, using the appropriate clutch. Aircraft propellers - with variable common and cyclic pitch. Blades of the screw - wooden.
Aircraft landing gear tricycle with tail wheel. All racks are two-wheeled. Hydraulic cleaning system. The large parking angle of the aircraft forced the designers to fix the brake hook on the upper surface of the fuselage. The mechanism of release and cleaning of the hook is hydraulic, pyramidal type.
The control system of the aircraft is mechanical, rigid. By roll and pitch, the machine was controlled using differential deflectable all-round stabilizers. Stabilizers are equipped with trimmers and external weight compensators. Stabilization of the aircraft in the direction is provided by two trapezoidal keels with rudders of a large area. In the tail of the aircraft were installed automatic flaps, used when landing for parrying.
The fighter’s radio equipment consisted of a short-wave radio station and a radio compass. The antennas of these devices were under the fuselage. On prototypes XF5U-1 weaponry was not installed. Serial machines were supposed to arm six Browning 12,7-mm machine guns with 400 ammunition for ammunition or four X-NUMX-mm M-20 cannons. Under the fuselage two pylons could be installed for hanging bombs with a total weight of up to 39 kg or fuel tanks with a capacity of 454 l. The use of unguided rockets or dive-bombing was completely ruled out due to the large diameter of the propellers.