C-54 ✪ Skymaster
Long-range Transport Aircraft
The worldwide commercial success of forced to look for ways to improve the project. The first experimental four-engine DC-4E (Experimental) was built to specifications originally developed by United Airlines. United quickly reached an agreement with American Airlines, Eastern Airlines, Pan American Airways and TWA to distribute supplies. The joint development was dictated primarily by the high cost of the project, each of the parties contributed $ 100,000. The DC-4E made its maiden flight on June 7, 1938.
However, the great complexity of the project, engine problems and the growing awareness that the plane is too large for this payload, led to a drop in the interest of some of the sponsoring airlines. An airplane with four engines, both in production and in operation, was a very costly affair. The only prototype DC-4E was sold to Japan, where it received the designation LXD1 and was used by Nakajima in the development of the G5N heavy bomber.
The first serial Douglas C-54 Skymaster made its maiden flight in early 1942, the prototype was not built, except for the DC-4E prototype, in fact a completely different aircraft.
A total of 1242 vehicles were built. By the end of World War II, 839 airliners were in the service of the Air Transport Command. It was the ideal long-range heavy military transport aircraft for its time, with a payload of ten tons.
On the basis of the DC-4, various specialized variants were created: 21 aircraft with V-shaped Rolls-Royce Merlin engines with a capacity of 1725 hp each. from. (1286 kW), developed by the Montreal "Canadair" specifically for the Canadian Air Force (called "North Star"); DC-4M was developed for civil operators; another version of the DC-4 was the Aviation Traders Carvair. The capacity of various modifications was also different: the basic version was designed for a crew of 4 people and 44 passengers, with a rather large step between the seats, but some airlines performed a denser layout of the passenger compartment - for 86 seats. The DC-4M variant was designed to carry 62 passengers in the economy class cabin.
This aircraft made a great contribution to the operation to establish the so-called Berlin Air Bridge in 1948-1949. Moreover, the airliner also turned out to be a long-liver, and a small number of such aircraft continued to fly even at the beginning of the new millennium.
Construction . An all-metal cantilever low-wing aircraft of a classic design with four piston engines and a retractable tricycle landing gear.
Wing - all-metal cantilever split, trapezoidal in plan with transverse V 7 °. Consisted of a center section and removable consoles. The three-spar center section is rigidly connected to the fuselage, the single-spar consoles. Aileron single-spar with a metal frame and linen sheathing. The wing had NACA single-slot flaps. Despite the high specific load on the wing, its good mechanization provided sufficient lift to ensure a short take-off run, which was absolutely necessary in wartime conditions.
Chassis - retractable three-pillar, with a front steerable pillar. There is a spring-loaded crutch at the rear of the fuselage. There were two wheels on the main landing gear, respectively, the cleaning scheme changed, now the racks were retracted forward into the nacelles of the internal engines. The brakes are hydraulic.
Controls and Systems - pneumatic de-icing system on the leading edges of the wing and stabilizer. Hydraulic control system for flaps, landing gear retraction, front pillar rotation, wiper. The main electrical system is 24 volts DC. Four engine-driven DC starter-generators and four batteries.
Equipment - radio station, radio semi-compass, radio altimeter, Sperry autopilot, altimeter, speed indicator, artificial horizon, direction indicator, magnetic compass, etc. The autopilot had a gyroscope as a vertical gyroscope with three degrees of freedom with power supply from the AC power supply 400 Hz. The quality of the autopilot, the possibility of fine tuning, allowed the aircraft in 1947 to take off, climb, fly at level and land with control from the autopilot.
On the prototype, to power the starter-generators when starting the engines, an APU was provided - an auxiliary power unit driven by a starter-generator, which was removed in the serial version.
Powerplant - four piston engines installed in aerodynamic nacelles in the middle of the wing. Closed with three-piece NACA hoods. The following types of engines were used:
- Pratt & Whitney R-2000-3 - 1100 HP (820 kW), 14-cylinder double-row star-shaped air-cooled carburetor engine (C-54, C-54B);
- Pratt & Whitney R-2000-7 - 1333 hp (994 kW), 14-cylinder double-row star-shaped air-cooled carburetor engine (C-54A, C-54B);
- Pratt & Whitney R-2000-9 - 1450 HP (1081 kW), 14-cylinder double-row star-shaped air-cooled carburetor engine (C-54A, C-54B);
- Pratt & Whitney R-2000-11 - 1350 HP (1006 kW), 14-cylinder double-row star-shaped air-cooled carburetor engine (C-54D);
- Pratt & Whitney R-2000 - 1450 HP (1081 kW), 14-cylinder double-row star-shaped air-cooled carburetor engine (DC-4-1009);
Hamilton Standard Hydromatic three-blade variable pitch propeller with a diameter of 4 meters.