Aviation of World War II

The worldwide commercial success of Douglas DC-3 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.

* - the base crew of 4 people, two pilots, a navigator and a radio operator were supplemented by two replacement pilots, who had places to rest in the aircraft cabin.

C-54 Variants

• C-54 was the original powerplant with four Pratt-Whitney R-2000-3 radial engines rated at 1350 hp. (24 aircraft built).
• C-54A is a militarized modification capable of carrying 50 military personnel, or 14742 kg (cargo, powered by four R-2000-7 radial engines with a capacity of 1350 hp (252 aircraft were built) ). 77 were built in Santa Monica and 117 at a new plant in Orange Place, Chicago. This modification appeared in January 1943 and had 33 bucket-shaped canvas seats, a large cargo hatch, reinforced floor, a lifting boom, and enlarged wing fuel tanks. The latter brought the full supply of fuel to 14134 liters and the total weight to 30844 kg, making it possible to carry a payload of 4082 kg at a distance of 4828 km.
• C-54B - variant of C-54A, in which two additional fuel tanks in the fuselage were replaced by wing tanks of 1889 liters in each wing; the first aircraft were equipped with R-2000-3 engines, and later - R-2000-7 engines. The need to develop such an aircraft was dictated by the need to carry large loads over short distances. The takeoff weight increased again and amounted to 33112 kg. The plane could take up to 49 military personnel or 36 wounded on a stretcher. The C-54B variant was produced in 89 cars in Santa Monica and 100 in Chicago.
• VC-54C - the only C-54A aircraft - personal aircraft of President Franklin D. Roosevelt and nicknamed Sacred Cow - Sacred Cow. It had an electric lift for lifting a wheelchair into the fuselage. Due to the additional tanks, it had a flight range of 8850 km. The salon housed an office and three meeting rooms.
• C-54D - the main production version of the Skymaster aircraft, basically similar to the C-54B, but equipped with four 1350 hp R-2000-11 radial engines. (380 aircraft built in Chicago).
• C-54E - a version of the C-54D aircraft with a convertible cabin, in which two fuel tanks located in the cockpit were finally replaced with soft-walled tanks located inside the wing (125 aircraft were built , of which 105 in January-July 1945 in Santa Monica). The total fuel supply in the wing tanks was 13627 liters.
• C-54G - a transport and landing variant based on the C-54E aircraft and equipped with R-2000-9 radial engines with a capacity of 1450 hp each. (1081 kW) (162 cars built in Santa Monica).
• C-54M - designation of 38 C-54E aircraft used as coal carriers on the Berlin Air Bridge; the payload has been increased by 1134 kg.

The US Navy, which carried out some of the airlift in the Pacific, received 183 aircraft from US Air Force orders between 1943 and 1945. These included 19 R5D-1 (C-54A), 11 R5D-2 (C-54B) and 20 R5D-4 (C-54E) built in Santa Monica, and 38 R5D-1, 19 R5D-2 and 76 R5D-3 (C-54D) built in Chicago. Squadrons of the Air Transport Service of the Navy were equipped with aircraft until it was disbanded in 1948; some units later became part of the joint military air transport service.

Skymaster for Great Britain

Britain received 24 aircraft under Lend-Lease at the end of the war. The RAF received the designation Skymaster C.Mk.I.

The first to receive in June 1941 was the only C-54B, which was handed over for personal use to British Prime Minister Winston Churchill. For this, a special 10-seater VIP cabin was equipped at Armstrong Whitworth Ercraft, and the aircraft was transferred to the Northolt base for operation in the 24th squadron. He later flew VIP flights with Squadron 246 and was returned to the United States in November 1945.

The next 10 Skymasters arrived from February to July 1945, and the remaining 13 were not delivered.

They were built as a C-54D according to the specification of the US Armed Forces, the aircraft from the C-54B differing only in the type of installed engines and various small details, training was carried out mainly in the 1332th retraining unit, and the aircraft were mainly operated in the 246th squadron Group 47, then were transferred to 232 Squadron in Palam, from where this unit carried out regular flights between Ceylon and Australia.

All 10 aircraft were returned to the United States in July 1946, and they entered the US Navy under the designation R5D-3.

Ten copies of the Douglas Skymaster were received by the RAF Transport Command for flights to the Far East. These flights were performed by the 232nd and 236th squadrons. In the photo, the first Skymaster delivered to the United Kingdom was adapted in a VIP version for use by British Prime Minister Winston Churchill.

Bibliography

• Encyclopedia of military engineering /Aerospace Publising/
• American warplanes of World War II/under cor. David Donald/
• British military aircraft of World War II / ed. Daniel J. March /

	Drawing C-54 Skymaster
	Douglas DC-4E
	Airplane-tanker Douglas C-54G-15DO "Sfcymaster" (N2742G, s / n 36089, s / n Do483, tanker # 15) from Aero Union. (Miguel Snoep). "Sfcymaster" is not a mistake ...

In the USA, land aircraft are mainly used for fire extinguishing, and instead of water they prefer various extinguishing and fire-retarding solutions and suspensions (intensive experiments in this area have been conducted since the 50s).
This is due to the fact that the main tracts of forests of industrial importance are located in the western United States in the Rocky Mountains, where water bodies suitable for landing seaplanes are extremely rare.
In addition, according to American experts, water is far from an ideal extinguishing agent, and often after wetting forest combustible materials, combustion is restored and continues with the same force.

Airplane-tanker Douglas C-54G-15DO "Douglas DC-4". Douglas Commercial - in this case, it performs functions that are very far from the transportation of passengers.

Stacking the landing gear forward has another clear advantage. In the event of a hydraulic system failure, it is sufficient only to open the chassis retracted position locks, for example, with a lever with cable wiring, and the struts themselves, under the influence of their weight and the incoming air flow, will be released, which is an undoubted advantage over the rest of the chassis retraction and release schemes.

Drawing DC-6. The visual difference is the rectangular windows of the passenger cabin.

During the Second World War, more than 1000 four-engine DC-4 Skymaster were built, they crossed the Pacific and Atlantic oceans 88000 times, while only three aircraft were lost - an impressive indicator of the aircraft's reliability.
US AAF, using the DC-4 and C-54, funded Douglas' development of a larger-capacity, pressurized version of the model. The project received the designation XC-112A, the prototype performed its first flight on February 15, 1946. Potentially a nearly finished passenger liner, Douglas continued to develop this version under the designation DC-6.
The prototype retained the same wing span as the DC-4, but the fuselage was redesigned for the operation of the high-altitude system, increasing its length by 2.06 m. The round windows DC-4 were replaced with rectangular ones - an obvious distinction of the DC family -6. The power plant of four Pratt Whitney R-2800-34 PDs had a total power of 8400 hp. In the standard version, from 48 to 52 passenger seats were installed, in the sealed version, 86 seats were allowed.

It is unlikely that replacing round windows with rectangular ones in a pressurized fuselage was the right decision. The crashes of two de Havilland Comet a / c BOAC in 1954 showed that the appearance of fatigue cracks in the metal in the corners of the windows led to the destruction of the fuselage by explosive decompression.
Note that all windows on modern aircraft have rounded corners.