Staff Writer (Updated: 5/1/2015):
The CW-20T prototype later evolved into the CW-20A that featured a revised tail in the form of the more recognizable single rudder assembly. Later development focused in on the requirements as put forth by the United States Army Air Corps which put the CW-20A under trials with the designation of C-55, which consequently ordered a production version of the model now designated as the CW-20B.
The CW-20B was redesignated to the more familiar C-46 identification. Final trial models were provisioned to fit up to 45 combat-ready troops and fitted with two Pratt & Whitney-brand R-2800-51 radial engines. The C-46 entered service with the plain designation of simply "C-46" in the Pacific Theater - and used almost exclusively there up until about March of 1945, to which the Commando would be seen across the European Theater as well. From its initial acceptance into service with the USAAF, the C-46 system would become the heaviest aircraft in that branch of service and make a name for itself as a true warrior workhorse, transplanting troops and cargo alike, across battlefields and beyond.
Variants abound with the C-46 Commando. The United States Navy utilized a designation of R5C for their own Commando version with 160 models of the R5C-1 going to the United States Marine Corps. Specialized utility and troop models would be produced from the hundreds to the thousands. The C-46A Commando itself could carry up to 50 infantrymen and load/unload cargo through a large cargo door on the port side of the aircraft.
The C-46 was officially retired from service in 1968, replaced by the equally effective C-130 series of transports.