I entered the airlift challenge and for it I give you the largest military cargo plane: the Lockheed C-5 Galaxy.

Controlls:

Basics controls
AG1=open cargo bay
VTOL=Flaps

Wikipedia:

The Lockheed C-5 Galaxy is a large military transport aircraft designed and built by Lockheed, and now maintained and upgraded by its successor, Lockheed Martin. It provides the United States Air Force (USAF) with a heavy intercontinental-range strategic airlift capability, one that can carry outsized and oversized loads, including all air-certifiable cargo. The Galaxy has many similarities to the smaller Lockheed C-141 Starlifter and the later Boeing C-17 Globemaster III. The C-5 is among the largest military aircraft in the world.

The payload:

It’s just 2 of the stock gator 2 helicopters, with disabled control. Before you comment, I know the gear pops into the cargo bay, but I don’t care. Also I know the door clips through the cockpit briefly and is shaky during flight, I am too lazy to fix these.
It has decently accurate flight performance and weight. It also has realistic max payload weight(250,000 pounds)

Gallery: