The DC3 and C47 range payload issue is complicated by the fact that as engine power grew so does Maxium Takeoff weight: this means more cargo can be lifted without sacrificing fuel.
In additon C47B carried more than the 3046Litres and some variants had an extended wing span. Moreover the C-47 had access to 100/130 octane which increased takeoff power
enormously and therefore payload. The fuel issue (B4/87 octane for the Ju 52 and 100/130 octane for the C-47 explains some of the differences in performance)
DC-3/C-47 was just flat out more efficient. As well it should be considering it was much newer. The fuel issue is a non-issue. Some R-1830s were able to give 1200hp for take-off on 100 octane (not 100/130 and there is a difference) and some managed it on 95 octane and a few even did it on 91 octane. C-47 used 28 cylinders to get 2400hp. Ju-52 used 27 cylinders to get 2175-2490hp depending on version.
The Ju-52 used high drag engine installations, the corrugated skinning was high drag and the fixed landing gear was high drag. Needing to use more power to get the same speed explains a lot of the performance difference.
My understanding is that range calculations are given at full internal normal fuel load with maximum cargo permissable at that MTOW at cruise speed.
Greater range is possible at reduced load or reduced speed. Reduced speed gets you nowhere in a head wind and irritates passengers as well as wasting aircraft time.
For transport planes the range calculations were a bit more complicated. For economy of manufacture transport planes were often fitted with a standard fuel tank set up. It was up to the user airline (or military) depending on route flown (or stage in route) or mission to adjust the fuel capacity and passenger/cargo load to suite up to the max capacity of the tanks or a maximum allowable cargo or passenger load. Some aircraft due to fuselage floor or other limits could only carry xxx amount of cargo no matter how much fuel was left out. DC-3 was original designed as a "sleeper" aircraft. Fuselage was designed to hold 12-14 passengers in bunks on over night flights. When changed to a "day" aircraft the passenger load went to 21.
In the C-47's case an overload was possible: this I suspect required 100/130 fuel, a long sealed runway, no obstacles at the end of the runway and probably accepted increased risk of a crash landing if there was an engine failure immeidatly after takeoff. The Ju 52/3m range figures are clearly given at Max Fuel with Max Payload at that Max Takeoff Weight
at maximum cruise. The Ju 52/3mge3 could econ cruise at 117L/100km which would give a range of 2400km at a mind numbing slow speed with little cargo.
The figures I have given for the DC-3/C-47 are at normal operating weights, over load was certainly possible.
Roughly it looks like the basic 1940 DC3 with 20% more fuel than the Ju 52/3m (circa 3000L instead of 2500L) carried the same cargo as the Ju 52/3mge3 some 66% further ie 1000 miles instead of 600 miles.
Assuming a 15% reserve one could argue that a DC3 could supply 2.5 tons of cargo to a base 425 miles away while the Ju 52/3m only 260 miles. This is a huge difference as it
gets the takeoff point well away from enemy fighter attack. The C-47B and better fuel improved these figures. The Ju 52 proably had better short field performance.
There is no reason to suppose the Ju 52 had enough better short field performance to make any real difference. Take off run for the DC-3 at 24,800 lbs is about 1000ft and one source give 1050ft for the JU-52. Stalling speed for the Ju-52 seems to be 63-65mph while the DC-3 seems to be 67-69mph (unless overloaded). Technically the Ju-52 may be better but since the difference seems to be 10% or less I don't think there is much practical difference.
Its worth looking at the Ju 252 parameters:
Why?
It is a given fact that at given level of technology a bigger airplane will carry more cargo, more economically than a smaller airplane. It is why airplanes kept getting bigger.
A 50,000lb 4050hp transport should be faster and show better economy than a 26,000lb 2400hp transport.
A better match would be the C-46.
But back to the point of the thread. Neither aircraft introduced the idea of troop movement or supply by air. The C-47 did a better job of it and was able to do it in places the Ju-52 could not (over water or over mountains, large areas of jungle)