Confusion Over Cargo Weight Of DC-4s. C-54s, and Carvairs

Shalom and greetings all my pals,

I am totally perplexed by pound weight of cargo load of DC-4s and Carvairs in both freeware CalClassics and payware Flight Replicas model bases.

According to real world Buffalo Airways website, their DC-4 can carry 20,000 pounds of cargo load.

In the payware model base, I tried to take off using both DC-4 and Carvair with 50 percent fuel load using full cargo load of 9,500 lbs as seen on this figure below which failed to climb after shaky take off and crashed on ground.

max_number_of_stations = 6
station_load.0 = 950, 10, 0, 1
station_load.1 = 2500, 2, 0, 1
station_load.2 = 2500, 1, 0, 1
station_load.3 = 2500, -2, 0, 1
station_load.4 = 1000, 5, 0, -1
station_load.5 = 1000, -10, 0, -1

I was forced to slash cargo load by half from 9500 lbs to 4750 lbs and reduce fuel load from 50 percent to 40 percent which barely got my payware plane into air, climbed very very slowly, and cruised at too slow speed 160 kt.

By contrast, for years years years I have NO problem flying CalClassics DC-4s and C-54s cruising at 200 kt using 8,200 lbs of cargo load and 50 percent fuel load as seen on the cargo load data beloe

My questions are: why are both freeware and payware DC-4s/C-54s as well as payware Carvairs have top cargo load of 9,500 lbs for payware addon and 8,200 lbs for freeware add on when the real world Buffalo Airways say their DC-4 can carry 20,000 lbs in full cargo load?? And why are DC-4s/C-54s/Carvairs in the payware model base cannot go above 160 kt in speed when in real life the maximum should be 220 kts and cruising should be 190 kt???

And why do CalClassics DC-4s have normal climb while the payware counterpart has painful slow climb??

Am I doing something wrong??

By the way, Carvairs in real life can carry 19,000 lbs of cargo load yet I could not climb with 9,000 lbs of cargo load which is set as maximum cargo load for payware add on!!

Regards,

Aharon