[6] A decision to use a twin-engine design instead of a four-engines was considered viable if sufficiently powerful engines were available, allowing for lower operating costs and a less complex structure.

[7] Engineering work involved a three-year commitment from the company and incorporated an extensive amount of wind tunnel testing at the California Institute of Technology (Caltech).

[8] The design of a 24–34 passenger airliner proceeded to the prototype stage as the CW-20 at the St. Louis, Missouri facility with the initial configuration featuring twin vertical tail surfaces.

Powered by two 1,700 hp (1,300 kW) R-2600-C14-BA2 Wright Twin Cyclones, the prototype, registered NX-19436 flew for the first time on 26 March 1940 with test pilot Edmund T. "Eddie" Allen at the controls.

[5][11][12] The design was then modified to the C-46A, receiving enlarged cargo doors, a strengthened load floor and a convertible cabin that speeded changes in carrying freight and troops.

[5][13] An important change was made: more powerful 2,000 hp (1,500 kW)c Pratt & Whitney R-2800 Double Wasp engines replaced the Twin Cyclones.

[14] Although a one-off XC-46B experimented with a stepped windscreen and more powerful engines, a small run of 17 C-46Es had many of the same features as the XC-46B, along with three-bladed Hamilton-Standard propellers replacing the standard Curtiss-Electric four-bladed units.

[12] Most famous for its operations in the China-Burma-India theater (CBI) and the Far East, the Commando was a workhorse in flying over "The Hump" (as the Himalaya Mountains were nicknamed by Allied airmen), transporting desperately needed supplies to troops in China from bases in India.

Unpredictably violent weather, heavy cargo loads, high mountain terrain, and poorly equipped and frequently flooded airfields proved a considerable challenge to the transport aircraft then in service, along with a host of engineering and maintenance nightmares due to a shortage of trained air and ground personnel.

After the troublesome Curtiss-Electric electrically controlled pitch mechanism on the propellers had been removed, the C-46 continued to be employed in the CBI and over wide areas of southern China throughout the war years.

In particular, the U.S. Marines found the aircraft (known as the R5C) useful in their amphibious Pacific operations, flying supplies in and wounded personnel out of numerous and hastily built island landing strips.

It augmented USAAF Troop Carrier Command in time to drop paratroopers in an offensive to cross the Rhine River in Germany (Operation Varsity).

So many C-46s were lost in the paratroop drop during Varsity that Army General Matthew Ridgway issued an edict forbidding the aircraft's use in airborne operations.

The operation's paratroop drop phase was flown in daylight at low speeds at very low altitudes by an unarmed cargo aircraft without self-sealing fuel tanks, over heavy concentrations of German 20 mm, 37 mm and larger caliber anti-aircraft (AA) cannon firing explosive, incendiary and armor-piercing incendiary ammunition.

Although Curtiss-Wright reported the accumulation by November 1943 of the astounding total of 721 required changes in production models, the plane continued to be what maintenance crews around the world aptly described as a "plumber's nightmare".

Still others were listed merely as "missing in flight", and it is a safe assumption that many of these exploded, went down in flames, or crashed as the result of vapor lock, carburetor icing, or other defects.

The cause of the explosions was eventually traced to pooled gasoline from small leaks in the tanks and fuel system, combined with a spark, usually originating from open-contact electrical components.

The C-46 became a common sight in South America and was widely used in Bolivia, Peru, Brazil, Argentina and Chile, especially in mountainous areas (where a good climb rate and high service ceiling were required) or to overfly deep jungle terrain where ground transport was impracticable.

A dozen surplus C-46's were purchased in the United States covertly for use in Israel's 1948 war for independence and flown to Czechoslovakia in a circuitous route along South America and then across to Africa.

The type's long range proved invaluable in flying cargo, including desperately needed dismantled S-199 fighters from Czechoslovakia as well as other weapons and military supplies.

On the return flight the C-46's would dump bombs out the cargo door on various targets at night, including Gaza, El Arish, Majdal, and Faluja (Egypt and Israel also used C-47s as bombers and transports locally).

[citation needed] C-46's served in Korea and Vietnam for various U.S. Air Force operations, including supply missions, paratroop drops and clandestine agent transportation.

[24] According to First Nations Transport, as of Jan 2016, the latter aircraft (C-GIBX) was claimed to be airworthy with two new engines and available for sale with the fire bottles and props needing updates.