During World War II, the Douglas XCG-17 emerged as an assault glider in the United States.
This particular glider was created by converting a C-47 Skytrain twin-engine transport.
While the XCG-17 underwent successful testing, the demand for such a massive glider diminished.
As a result, no additional units of this type were constructed.
However, there was a single instance where another C-47 was temporarily transformed into a glider configuration for evaluation purposes in 1946.
Nevertheless, it was swiftly reverted back to its original powered configuration.
The United States Army Air Forces recognised that the Douglas C-54 Skymaster aircraft rendered conventional gliders obsolete due to its superior power and capacity.
Consequently, they identified the need for a larger assault glider and concluded that converting the already widely produced Douglas C-47 Skytrain would be the most suitable solution.
The C-47 could easily be transformed into a glider configuration with minimal modifications to its airframe while still fulfilling the desired capacity requirements.
Trials were conducted to assess the feasibility of a new approach using a conventional C-47 aircraft.
Initially, the trials involved performing regular dead stick landings with the powered C-47.
Subsequently, the aircraft was towed by another C-47 to further evaluate the concept.
The results of these trials indicated that the proposed scheme was indeed viable.
Based on these findings, a C-47-DL aircraft was selected for the conversion into a glider, which was designated as XCG-17.
This particular aircraft had previously served as a Northwest Airlines DC-3 before being requisitioned for military use at the onset of World War II.
The conversion process involved removing the engines from the aircraft while retaining the nacelles that housed the landing gear.
These nacelles were then covered with aerodynamically shaped hemispherical domes to enhance streamlining.
To compensate for the absence of the engine’s, fixed weights were added to the domes.
Furthermore, various other equipment that was no longer necessary for the unpowered configuration was eliminated to reduce weight.
This included the removal of the aircraft’s wiring and bulkheads, as well as the positions of the navigator and radio operator.
These modifications were implemented to optimise the glider’s performance and ensure its suitability for its intended purpose.
The conversion process, which took place at Clinton County Army Air Field, was successfully finalized on June 12, 1944, followed by the aircraft’s inaugural flight test shortly thereafter.
The flight testing of the XCG-17 demonstrated its commendable performance when compared to conventional gliders in active service.
Notably, this aircraft exhibited lower stalling speeds and higher towing speeds, along with the ability to glide at a significantly shallower angle.
Tow tests were conducted utilising various aircraft configurations, with the most frequently employed setup involving tandem towing by two C-47s.
In this arrangement, the towing aircraft were coupled one in front of the other, and the leading aircraft would detach after take-off.
However, this configuration posed risks for the “middle” C-47, prompting the determination that a single C-54 was the most optimal tug aircraft.
The cargo holds of the XCG-17 had a remarkable capacity of 15,000 pounds (6,800 kg), which was considerably larger than the typical capacity of conventional gliders.
Moreover, it had the ability to transport up to 40 fully equipped troops, further highlighting its superior capabilities.
Another impressive feature was its capacity to accommodate three Jeeps in a single load or, alternatively, two 105-millimetre (4.1-in) howitzers.
Notably, unlike other American assault gliders, the XCG-17 did not require any ballast to maintain its centre of gravity, making it truly unique in this regard.
Despite achieving satisfactory results during testing, the aircraft failed to meet the Army’s requirement of being able to land on unimproved fields.
Furthermore, by the time the evaluation of the XCG-17 was completed, the need for such a large assault glider had diminished.
Originally, the glider was intended to enhance the transportation of supplies to China over “The Hump,” but the war situation had improved, rendering the additional capacity provided by an oversized glider unnecessary.
As a result, no further examples of this type were manufactured.
Once the prototype had completed its trials, it was stored and eventually transported to Davis-Monthan Air Force Base for disposal in August 1946.
Specifications Crew Two Capacity 15,000 pounds (6,800 kg) cargo or 40 troops Length 63 ft 9 in (19.43 m) Wingspan 95 ft 6 in (29.11 m) Height 17 ft (5.2 m) Wing area 987 sq ft (91.7 m2) Empty weight 11,001 lb (4,990 kg) Gross weight 26,000 lb (11,793 kg) Performance Maximum speed 290 mph (470 km/h, 250 kn) max towing speed Cruise speed 190 mph (305 km/h, 165 kn) gliding speed Stall speed 35 mph (56 km/h, 30 kn) Maximum glide ratio
14:1 Wing loading 26.3 lb/sq ft (128 kg/m2)
Sources
The DC-3: 50 Years of Legendary Flight-Peter M Bowers.
Jane’s American Fighting Aircraft of the 20th Century-Michael J H Taylor.
United States military aircraft since 1909-Peter M Bowers.
