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Monthly Archives: April 2019

THE COMMANDO

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My dad told me a number of stories about flying in an aircraft during World War II, in which the aircrews could transport their gear by driving a jeep up a ramp into the plane.  That plane, the Curtiss C-46 Commando, played a pivotal role in World War II, as well as Korea and Viet Nam.  During the course of this blog, we’ll follow the service of the Commando in a number of tasks for which it was uniquely suited.

Development of the C-46 began in 1937 by Curtiss-Wright as the CW-20 airliner.  The CW-20 was initially developed through private funding for the purpose of competing with the four-engine Douglas DC-4 and the Boeing Stratoliner by offering a pressurized cabin.  However, the CW-20 cabin provided an edge in pressurization over the previous two aircraft due to a figure-eight or double-bubble fuselage, which enabled it to better withstand the pressure differential at high altitudes.  This was accomplished by having the sides of the fuselage creased at the level of the floor, not only separating the two sections, but sharing the stress of each, rather than merely supporting itself.  This concept allowed the main spar of the wing to pass through the bottom section, which was designed for cargo without disturbing the upper passenger compartment.  The emphasis in the design of the CW-20 was one of simplicity coupled with economy, which dictated a twin-engine concept as opposed to a four-engine one.

After an intensive series of wind tunnel tests, the CW-20 in its final form had a streamlined fuselage with the cockpit area blended as a glazed dome.  In spite of its aerodynamic appearance, the aircraft had a large capacity for its day and could comfortably seat thirty-four passengers.  The engines featured a unique nacelle tunnel cowl, in which air was ducted in and expelled through the bottom of the cowl, reducing turbulent airflow and induced drag across the upper wing surface.  Though Curtiss-Wright approached a number of airlines to sign contracts for the CW-20, only 25 letters of intent were received.  However, CW management decided there was enough potential to begin production.  The initial configuration of the CW-20 included twin vertical tail surfaces with the aircraft powered by two 1,700 hp. Wright Cyclone engines.  After a successful test flight in March 1940, the aircraft was fitted with a large single tail to improve performance at low speeds.  As a result of tests later that year, General Henry “Hap” Arnold became interested in the potential of the twenty as a military transport and ordered 46 CW-20As  in September 1940. This order was later increased to 200 planes.  Now designated the C-46, the aircraft received enlarged cargo doors, a more durable load floor and a convertible cabin, which allowed ease of change in carrying freight and troops.  Perhaps the most important modification was the upgrade to the 2,000 hp. Pratt & Whitney R-2800 Double Wasp engines, giving the C-46 the ability to fly on a single engine for extended periods.

By December 7, 1941 only two of the proposed two-hundred aircraft of the 1940 order had been delivered to the USAAF.  The Commando was well suited to operations in the Pacific Theater, due to its heavier payload, longer range, faster cruising speed and higher altitude over the Douglas C-47 Skytrain.  The surface area of the Commando’s wing was also greater than either the Boeing B-17 Flying Fortress or the Consolidated B-24 Liberator, the largest USAAF bombers in service at the time. With a service ceiling of nearly 28,000 ft., the C-46 was the prime mover in flying cargo over the Himalaya Mountains to troops and bases in China in desperate need.  This effort gained importance during the early phases of B-29 operations from China launched against the Japanese home islands.  While other transports had been employed in the area, the C-46 proved the most versatile and durable aircraft, in overcoming adverse weather conditions, heavy cargo loads, mountain terrain and poorly equipped runways, which remained a constant challenge.  During the course of its service in the China, Burma, India and Pacific areas, the Commando experienced a number of mechanical problems, primarily with the Curtiss-Electric pitch control mechanism on the propellers.  However, once the pitch control mechanism had been removed the incidence of mechanical problems began to decrease.  The US Marines found the C-46 (R5C) useful in both flying supplies to island bases and evacuating wounded personnel from unimproved runways.

Though the Commando played a vital role in the CBI and Pacific areas, it was not deployed in significant numbers to Europe until March 1945, when it complemented existing C-47 Skytrain transports during Operation Varsity, the airborne effort in support of Allied forces crossing the Rhine.  Though the C-46s sustained a twenty-five per cent loss rate, this was largely due to delayed upgrades of self-sealing fuel tanks with the aircraft particularly vulnerable during low altitude air drops.  While the plane overall had been successful during World War II, after undergoing a number of modifications, its airline service after the war became limited due to both higher fuel and maintenance costs over the C-47/DC-3.  However, a number of surplus C-46s were used by small airlines, such as the Flying Tigers and World Airways to carry both cargo and passengers over mountainous and jungle areas of South America, where vehicle transport would be impractical.  C-46s were flown in support of Israel’s war for independence in 1948, flying both cargo and bombing missions.  Commandos flew resupply missions for Chiang Kai-Shek’s forces in the civil war against Mao’s Communist forces in China.  In the early 1950s, C-46s flew clandestine missions in both Korea and French Indo-China, dropping both agents and supplies behind enemy lines. The CIA formed its own airline for these operations, Civil Air Transport, later renamed Air America.  The C-46 also flew supplies in support of the Bay Of Pigs invasion in 1961, as well as counterinsurgency operations in Viet Nam until being replaced in that role by the C-130 in 1968.

While the Commando experienced a number of mechanical problems during its service, such as fuel system and fluid leaks, these were primarily solved by maintenance in the field.  Though the C-46 required about 50% more maintenance hours over the C-47, the Commando was both a larger and a more capable aircraft, performing a variety of missions for our nation at a critical time.

 

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