XCG-16 – The Experimental Glider
Although conceived during the Second World War, the XCG-16 glider originated from a design philosophy from 1930 and became one of the most unusual and innovative glider ideas to be tested.
The glider was intended to transport heavy equipment and supplies, ranging from vehicles and military personnel. Later, it became part of experiments in carrying fuel to supply to long-range bombers in flight.
The XCG-16 was created to be a critical part of the war effort, with its ability to transport heavy equipment and supplies without the need for an engine. Although not ultimately selected for production and having a troubled test history, the XCG-16’s design remains distinctive.
The origins of the XCG-16 can be traced back to the pre-war years in May 1930, when American aero engineer Vincent Burnelli experimented with different lifting theories and flying wing concepts. The United States Army Air Force (USAAF) issued a specification calling for a new concept design which used Burnelli’s patented concept of a lifting fuselage design.
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To determine the most suitable concept design for the job of army and air force use, a competition between different aircraft manufacturers was arranged to be held at Wright Field.
Designers Hawley Bowlus and Albert Criz took Burnelli’s concept and used it as a basis to create their own glider for the competition.
Bowlus’ previous experience had not been in designing military aircraft and hardware but in creating leisure aircraft and recreational vehicles for the civilian market. His most notable design had been the Bowlus Road Chief: the trailer and caravan upon which Airstream had based their famous design. He had also worked as one of the consultants on the Spirit of St Louis, the aircraft piloted by Charles Lindberg who completed the first non-stop transatlantic flight between New York and Paris.
Despite not having experience in producing designs for combat and army purposes, Bowlus pressed ahead with his concept, working closely with Criz and the employers at his business Bowlus Sailplanes.
Work on the new glider prototype began in February 1942. With the Second World War underway and battles raging between the Allies and Axis forces in key theatres of the conflict.
As gliders had not been included in the Treaty of Versailles to limit what weaponry or aircraft Germany could produce, the Nazi regime had a strategic advantage thanks to investing time and money more into glider research during the interwar years.
Gliders themselves had not been considered an effective weapon by either side, but following the outbreak of the war, the Nazis found them to be effective in certain combat situations when invading neighbouring countries.
During the Nazi invasion of Belgium in 1940, German military forces were able to quickly overcome Belgian forces using gliders to land troops into areas considered impenetrable behind Belgian lines. Gliders were used effectively to capture strategic sites, such as the battle of Fort Eben Emael in May 1940 where a team of glider-borne Nazi soldiers quickly overran the fort and caught Belgian troops by surprise.
Although the United States had been neutral during the early stages of the war, battles like Fort Eben Emael caught the attention of the USAAC who began to take gliders into more serious consideration.
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The USAAC put out a request to various manufacturers for a glider capable of transporting troops, heavy equipment and supplies that could be tugged behind engine-driven bombers and transport planes and released to glide safely down into combat zones.
In their response to the USAAC’s specification, Bowlus and Criz opted not to use the traditional single fuselage design which had been the standard for most American glider designs. Instead, both men decided to attempt a flying wing concept by studying Burnelli’s philosophy closely and applying their ideas on top of it.
A half-size prototype model was created in late 1942 by Bowlus Sailplanes, with Bowlus and his team considering the initial test results to be good.
Bowlus then established the General Airborne Transport Company in addition to his existing business to anticipate mass production his glider design. He also persistently lobbied the American government to secure a contract and financial backing for the project.
The first full-size glider prototype named the MC-1 glider was produced by General Airborne Transport. It closely followed the design of the half-size model and initial factory tests were again concluded as showing potential for the new design.
Bowlus went back to the USAAF and tried to secure manufacturing rights to build training and transport versions of the new glider.
The full MC-1 design was conceived as being larger than other gliders being produced at the time. It was drawn up as a high-wing glider with a wooden frame and fabric covering but continued to incorporate Burnelli’s philosophy.
It had a total wingspan of 110 feet and a length of 67 feet. Bowlus also intended for the glider to have a cargo capacity of up to 15,000 lbs. The cargo and troops would be loaded through two large cargo doors positioned at the front of the glider to allow for easy access and a quick exit during a battle situation.
It was also envisaged that the the XCG-16 would be towed into the air by a C-47 or C-54 air force transport plane, which would then release the glider to continue on its own.
At the back, the glider featured a twin boom design for the tail.
The XCG-16’s design also intended for it to be equipped with spoilers which would be deployed to reduce lift and increase drag. This would allow the glider to descend quickly and land in a short distance on most kinds of terrain. The glider was also equipped with retractable landing gear, which could be deployed for landing on rough ground.
The maiden flight test of the MC-1 began on the 19th of July 1943 at March Field, California. The first test run proved to be a success and was commended by military and business observers.
A second test flight was scheduled at March Field on the 11th of September 1943, but this run ended in disaster. Among the glider’s crew and passengers were renowned aviator and businessman Richard Chichester du Pont and military glider specialist Colonel Ernest Gabel who would pilot the MC-1 for its run.
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The glider was towed behind a Lockheed C-60 for the demonstration. After takeoff, the glider accidentally flew into the airstream of the C-60’s prop wash causing it to violently shift from side to side. The weight ballast inside the glider had not been properly secured and came loose. The ballast began to shift as the XCG-16 continued to rapidly tilt, worsening the effect.
The C-60’s pilot tried releasing the glider to save the situation, but by this point, the MC-1 was already losing control despite Gabel’s best efforts to correct and stabilize the aircraft. As soon as the two rope was severed, the glider began to enter an uncontrollable spin towards the ground.
The order was given to jump, even though the glider was beneath the safe recommended altitude to safely parachute. Knowing that a crash landing was impossible at this stage, three of the passengers including Du Pont attempted the jump as the glider continued plummeting towards the ground. Although two of the passengers made it down safely, Du Pont died when his chute did not open in time.
Gabel remained on the glider and was killed when it crashed into the ground.
Despite the tragic setback at March Field, Bowlus continued with the design and the US military awarded a contract to the General Airborne Transport Company in in November 1943 after negotiations.
The contract approved the construction of three MC-1 units; two flyable and one for static tests were awarded by the USAAF. The completed full-sized MC-1 gliders were also given the military designation XCG-16 and the name stuck.
In the end, only one completed XCG-16 unit was produced and sent for USAAC testing.
Test pilots and engineers reported that the XC-16 demonstrated strong abilities in the air, including excellent stability and manoeuvrability. However, military observers also concluded that the glider did not meet expectations in terms of its cargo and loading abilities, and would not be suitable when used in a combat situation.
As a result, no further units were produced.
There was some talk of using the glider for new air force experiments. In 1944, the American military began exploring the idea of extending the existing range of transport and bomber aircraft by having a trailing glider carry fuel for the aircraft.
The XCG-16 airframe was given to the Cornelius Aircraft Company which had experience in building gliders to modify it and try testing the forward swept wing design in a way to exploit the XCG-16’s stronger capabilities.
The Cornelius Company made several alterations to the existing glider and it was named the XFG-1 and prepared it for a test flight. However, the first XFG-1 model crashed in October 1944 during a demonstration. A second model was produced by Cornelius based on the Bowlus format but by this point, the US military had lost interest in the project.
At this point, the Waco CG-13 was in development and completing maiden flights. The CG-13 demonstrated the ability to carry a significant payload and found use as a troop carrier in the Pacific and as a non-combat transporter glider in Europe.
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All remaining contracts between General Airborne Transport and the military were cancelled in November 1944 and no production models of any variant of the XCG-16 saw frontline service.
- Crew: Two pilots
- Capacity: 42 troops or 10,050 lb (4,570 kg) of cargo
- Length: 48 ft 4 in (14.72 m)
- Wingspan: 91 ft 10 in (27.98 m)
- Height: 18 ft 4 in (5.58 m)
- Empty weight: 9,480 lb (4,310 kg)
- Gross weight: 19,540 lb (8,880 kg)
- Maximum speed: 220 mph (354 km/h, 190 kn)