Mi 26 Halo the worlds biggest? Check out proposals for the US Marines "new" CH 53.
Defense Science Board Task Force on Mobility
Scroll down to page 55/56, "Future Capabilities"
Future Capabilities
Proposals have been made to extend the capabilities of the CH-
53E. The current design has a 79-foot diameter rotor and can
transport a 9,500-pound load 110 nautical miles. The services are
pursuing designs designated as the CH-53X and the CH-53X+. They
promise capabilities not achievable with the CH-53E:
�� The CH-53X would retain the 79-foot diameter of the CH-
53E but would operate with a disc loading of 16.3 lbft-2 in
contrast to the disc loading of 14.23 lbft-2 used in the CH-
53E. It would obviously require a higher-performance
engine than the one used in the CH-53E. The proposed CH-
53X design should allow the transport of a 27,000-pound
load over a distance of up to 110 nautical miles.
�� The CH-53X+ is designed to carry a 40,000-pound payload
to a range of 250 nautical miles. It would require making
major aerodynamic and structural changes to the CH-53E.
Maintaining current disc loading would require a 116- to
120-foot-diameter rotor. This modification would in turn
require a redesigned fuselage and an extended tail rotor
boom.