Douglas XCG-17

The Douglas XCG-17 was an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 assault glider, developed by the conversion of a C-47 Skytrain
C-47 Skytrain
The Douglas C-47 Skytrain or Dakota is a military transport aircraft that was developed from the Douglas DC-3 airliner. It was used extensively by the Allies during World War II and remained in front line operations through the 1950s with a few remaining in operation to this day.-Design and...

 twin-engine transport during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Although the XCG-17 was successful in testing, the requirement for such a large glider had passed, and no further examples of the type were built; one additional C-47, however, was converted in the field to glider configuration briefly during 1946 for evaluation, but was quickly reconverted to powered configuration.

Design and development

With the introduction of the Douglas C-54 Skymaster four-engined transport aircraft
Military transport aircraft
Military transport aircraft are typically fixed and rotary wing cargo aircraft which are used to deliver troops, weapons and other military equipment by a variety of methods to any area of military operations around the surface of the planet, usually outside of the commercial flight routes in...

, the United States Army Air Forces
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....

, observing that conventional gliders then in service would be an inefficient use of the C-54's power and capacity, determined that a requirement existed for a new, much larger assault glider. It was determined that the best solution to the requirement was the conversion of the Douglas C-47 Skytrain, already in large-scale production, to meet the requirement. The C-47 could be converted to a glider configuration with minimal alteration to the airframe, and would provide the required capacity.

Trials conducted using a conventional, powered C-47, first conducting ordinary deadstick landing
Deadstick landing
A deadstick landing, also called a dead-stick landing is a type of forced landing when an aircraft loses all of its propulsive power and is forced to land. The term is often misunderstood, as the flight controls in the majority of aircraft are either fully or partially functional, even with no...

s, then being towed by another C-47, indicated that the scheme was feasible. Therefore a C-47-DL was taken in hand for conversion into a glider, which was given the designation XCG-17. The aircraft, formerly a Northwest Airlines
Northwest Airlines
Northwest Airlines, Inc. was a major United States airline founded in 1926 and absorbed into Delta Air Lines by a merger approved on October 29, 2008, making Delta the largest airline in the world...

Douglas DC-3
The Douglas DC-3 is an American fixed-wing propeller-driven aircraft whose speed and range revolutionized air transport in the 1930s and 1940s. Its lasting impact on the airline industry and World War II makes it one of the most significant transport aircraft ever made...

 that had been impressed into military service at the start of World War II, was modified by the removal of the aircraft's engines; the nacelles, containing the landing gear, remained in place, covered with aerodynamically profiled hemispherical domes for streamlining, containing fixed weight to compensate for the removal of the engines. Other equipment, no longer necessary with the conversion to an unpowered configuration, was also removed to save weight; items removed included the aircraft's wiring and bulkheads, along with the navigator's and radio operator's positions.

Operational history

The conversion, carried out at Clinton County Army Air Field, was completed on June 12, 1944, with the aircraft undergoing its initial flight test shortly thereafter. The flight testing of the XCG-17 proved that the aircraft was satisfactory; compared to conventional gliders in service, the aircraft possessed lower stalling and higher towing speeds than conventional gliders, as well as gliding at a significantly shallower angle. Tow tests were conducted using a variety of aircraft; the most commonly used configuration was a tandem tow by two C-47s, with the towing aircraft coupled in tandem and the leading aircraft detaching following takeoff. This configuration was dangerous for the "middle" C-47, however, and it was determined that a single C-54 was the optimal tug aircraft.

The XCG-17's cargo hold had a capacity of 15000 pounds (6,803.9 kg); alternatively, up to 40 fully equipped troops could be transported, these figures being significantly larger than conventional gliders' capacity. The XCG-17 was also capable of carrying three jeeps
Willys MB
The Willys MB US Army Jeep and the Ford GPW, were manufactured from 1941 to 1945. These small four-wheel drive utility vehicles are considered the iconic World War II Jeep, and inspired many similar light utility vehicles. Over the years, the World War II Jeep later evolved into the "CJ" civilian...

 in a single load, or alternatively two 105 millimetres (4.1 in) howitzer
A howitzer is a type of artillery piece characterized by a relatively short barrel and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent...

s. Regardless of the aircraft's load, no ballast
-Objects:* Ballast tank, a device used on ships and submarines and other submersibles to control buoyancy and stability* Ballast weights, metallic plates used to bring auto racing vehicles up to the minimum mandated weight...

 was required to maintain the aircraft's center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity...

, a trait unique among American assault gliders.

Despite the satisfactory results in testing, however, the aircraft failed the Army's requirement that it be capable of landing on unimproved fields; in addition, by the time the evaluation of the XCG-17 was completed the need for such a large assault glider had passed. The primary role for the glider had been intended to increase the amount of supplies that could be carried to China over "The Hump
The Hump
The Hump was the name given by Allied pilots in the Second World War to the eastern end of the Himalayan Mountains over which they flew military transport aircraft from India to China to resupply the Chinese war effort of Chiang Kai-shek and the units of the United States Army Air Forces based in...

"; the war situation had, however, become more favorable and the added capacity an oversized glider would provide was no longer required. No further examples of the type were produced; the prototype, its trials complete, was placed in storage, being ferried to Davis-Monthan Air Force Base
Davis-Monthan Air Force Base
Davis–Monthan Air Force Base is a United States Air Force base located within the city limits, and approximately south-southeast of downtown, Tucson, Arizona....

 for disposal in August 1946.

In August 1949, the aircraft was sold to Advance Industries, its engines being reinstalled to return the aircraft to powered status in DC-3C configuration. Some sources, however, indicate that the XCG-17 was re-converted to C-47 configuration in 1946. Following its restoration to powered status, the aircraft was transferred to Mexico, where it remained in civilian service until 1980.

Field conversion

Although the XCG-17 failed to lead to any production of a C-47 derived glider type, a single C-47 was converted in the field to a glider configuration by the Fifth Air Service Area Command, located at Nichols Field
Nichols Field
Nichols Field was a U.S. military airfield located south of Manila in Pasay City and Parañaque City, Metro Manila, Luzon, the Philippines. During the World War II era, it was the location of the Far East Air Force's U.S. 20th Air Base Group. Also, based here was Troop F of the U.S. 26th Cavalry...

 on Luzon
Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon...

 in the Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

, during January 1946. Carried out in much the same manner as the XCG-17, the conversion included octagonally shaped fairings over the engine mountings, with an auxiliary power unit
Auxiliary power unit
An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...

 from a B-24 Liberator
B-24 Liberator
The Consolidated B-24 Liberator was an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and a small number of early models were sold under the name LB-30, for Land Bomber...

 bomber being installed.

Referred to as "XCG-47" as well as "XCG-17", and named "Nez Perce", the aircraft undertook its initial flight following conversion on June 17, 1946, towed by a C-54. The flight tests of the field-converted aircraft proved favourable, and an ambitious flight, towing the aircraft from Luzon to Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

 in Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, was planned. This flight was intended to prove the suitability of large gliders to act as an "aerial freight train
Freight train
A freight train or goods train is a group of freight cars or goods wagons hauled by one or more locomotives on a railway, ultimately transporting cargo between two points as part of the logistics chain...

" for regular transport.

The flight, conducted in late June 1946, took 11 hours of flight time and included an overnight stay on Okinawa; covering 1800 miles (2,896.8 km), it concluded at Tachikawa Airfield
Tachikawa Airfield
is an airfield in the city of Tachikawa, the western part of Tokyo, Japan. Currently under the administration of the Ministry of Defense, it has also served as the civil aviation with Japan's first scheduled air service.-Operations:...

 near Tokyo. Despite the success of the flight, the "aerial freight train" concept did not catch on; the aircraft had its engines re-fitted in August 1946 and was returned to service as a normal C-47.

Military (as C-47, then XCG-17)

 United States
  • United States Army Air Forces
    United States Army Air Forces
    The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....

Specifications (41-18496)

See also

External links

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