GarryB wrote:At about 60 tons payload, the new models carry 1/3rd more anyway....
I'm not an engineer or aviation expert, so is an aircraft's carrying capacity based on the power of its engines? With a payload of 60 tons, the new Il-76MD-90A now has a bigger payload capacity than the Chinese Y-20
Both the structure and the airframe pay a role.
The chineses built the Y20 with the aim to be a heavy transport plane able to carry more than 60 tons (I believe I read somewhere 66tons mentioned). However till now it cannot fully fulfill its requirements because the available engines are not powerful enough (and even the new Chinese engine developed for this aircraft is still not enough).
The il-476 has instead engines potentially more powerful (and if I am not mistaken they are derated to 14.5 tons of takeoff thrust, against the 16 tons of the Tu204 version and 17.6 tons of the Il96-400 version) but probably is limited by the internal space (lenght, width (and height)) of the cargo hold).
As an example the Y20 has a cargo hold width of 4m against 3.2m of the Il-76.
That means that the Il-76MD-90A can carry a maximum heavier payload, but some payloads could be too wide to fit, while they could fit on the Y20.
Of course it is not only a matter of internal space. The airframe needs to be able to carry an increased load, and I believe several structures were reinforced when going from the baseline il76 to the il-76MD-90A (AKA il-476).
We discussed this quite a lot in the an124 and on the transport fleet threads.