“SKIMMER ZIMMERMAN”

The lead engineer on this project was appointed E. Greenwood. Full-size wooden mock-up of the fighter, designated F5U, team Greenwood finished in late may of 1943 and June 7, presented his naval Commission.

 

Fighter differed from its predecessor flying the V-173. The first thing that caught my eye — two powerful engine Pratt & Whitney R-2000-7 with a capacity of 1350 HP For efficient cooling in the wings were provided with two large circular air intake is located they the fan blows air into the motor compartments. The exhaust air coming out through adjustable louvers on the top and bottom surfaces of the wing.

 

The placement of the pilot in the cockpit F5U was more rational than in the V-173 is now he was located in the forward compartment acting cylindrical section, which is closed by the large teardrop-shaped lantern. To improve visibility down to the floor of the cabin provided for the glazing.

 

Propellers fighter had a smaller diameter than the V-173, which allowed to reduce the Parking angle of the aircraft by nearly five degrees. Since the plane was designed for deployment on the deck of an aircraft carrier, it was equipped with the brake hook for hooking over the cable arresting gear. Mandatory requirement for carrier aircraft was built-in steps or ladder for boarding of the pilot in the cockpit — the use of ladders, step ladders, as it was on /-173 on the pitching deck of a ship is strictly forbidden. F5U for the design of such devices proved to be quite challenging because its cabin is at a height of over three metres above the ground. However, Zimmerman is, as always, found a very original solution. To sit in the cockpit F5U, the pilot had to move the car back and the back of the plane, setting foot in special ledges, climb into the cockpit.

 

Normal calculated takeoff weight of the aircraft reached 7200 kg, making it one of the heaviest carrier-based fighters in the United States (F4U — 5700 kg, F6F — 6900 kg, and twin-engine 000 kg).

 

Basic controls — gorizontalnyj all-moving stabilizer and two keel with rudders. In the rear of the unit was the two automatic flap to fight the ground effect during landing. The latter’s work was already tested on the V-173. Military recommended to check and all-moving stabilizers that were made by Zimmerman in October 1943. The stabilizers of the V-173 was converted by type F5U, and upgraded the car made a successful flight on 22 October 1943.

 

 

XF5U-1 with screws from Corsair fighter PA gazovojj site

 

Special attention during the design applied to the air screws. The model shown to the military, were equipped with temporary props that have nothing to do with the real — they just had yet to develop. Therefore, project approval was delayed until after the development of the whole power plant.

 

The developers of the screws had to deal with several serious problems. The first problem lay in the mechanism of transmission of torque from the engines to the screws and the synchronization of their rotation — it was decided though simple, but not effectively enough — with the help of the installation gear and the long shaft of square section. Experienced large loss of capacity, and the reliability of this scheme was low as the failure of at least one of the gears leads to the complete loss of control.

 

The second problem was. what blades experienced more stress caused by the asymmetric flow around the propeller at high angles of attack. At least this could lead to strong vibration, and even to the destruction of the screw. When this task himself, Zimmerman could not find an acceptable solution, while in November 1943, he was not up with the bright idea to make the screw of the two pairs of blades with variable cyclic pitch of each pair. New screw called balanced propeller. Thanks to swash the pilot could tilt the disc of the rotating propeller in any direction at an angle of 10 degrees, thus reducing the load on the blade and deflecting the thrust vector of the propeller. Interestingly, a similar system was previously used only on helicopters. For F5U, already promising to be a maneuverable fighter, the use of a swashplate can make it highly maneuverable and virtually invincible in battle. The final draft of the F5U in that form — with balanced propellers, were approved.

 

 

 

 

 

Ejection seat JD-1 Martin-Baker

 

In March 1944, it began the construction of two prototypes: one of them was intended for static tests, the second —for flight. 15 July 1944 to facilitate the financing of the program of flight tests of the V-173 and XF5U construction combined.

 

The first instance of the XF5U-1 was rolled out of Assembly plant August 20, 1945. The test aircraft was planned to take place in late 1945 at the airbase Muroc. For this experimental car was loaded onto the ship and through the Panama canal to deliver on the West coast. However, these plans were not realized. After the defeat of Germany started a review of all military programs of the United States with a view to their reduction. Not paid attention and company Vought. 24 may 1945, the firm was financial audits. The financiers of the fleet noted that the program “Skimmers Zimmerman” has already cost taxpayers $ 250 million, but the achievements were more modest.

 

The audit resulted in a substantial reduction of funding for the program, and free up funds were aimed at the development of aircraft jet engines. Lack of funds led to a delay in the supply unloaded screws with cyclic pitch control, which is made firm Hamilton Standard Hydromatics.

 

In February 1947, the copy of the flight had to temporarily put the screws from istrebitelya F4U Corsair. To spend at least ground testing of power gearboxes installation and trial run, the blades of the left propeller mounted in reverse position. This is clearly seen in photos of the aircraft with the logos of the company Hamilton on the blades of screws: on the left they are on the back sides of the blades, and on the right — front.

 

Ground testing gazovka and taxiing of aircraft, conducted test pilot B. Guyton, have been quite successful. After delivery of standard screws and mounting the aircraft is prepared for loading onto the ship for transport to the base Muroc. However, on March 17, 1947 programme for the creation of the fighter F5U closed. The Navy lost interest in piston fighters, because the sailors has already had more promising jet fighter — FH1 Phantom, the F6U Pirate and FJ1 Fury. Aircraft XF5U-1 was decided to utilize.