CH-54 Tarhe helicopters were a Vietnam-era approach to heavy transport helicopter design, which did not gain widespread acceptance. The CH-54 was a large helicopter, built on much the same airframe as the early CH-53 heavy helicopters. They differed, however, in that the CH-53 had a conventional cabin, while the CH-54 had only a crew compartment, sometimes with an additional flight control panel at the rear of that compartment. All cargo loads were carried externally.
Where the cabin would be present in a conventional helicopter, the CH-54 simply had a boom connecting the front part, containing the crew, engines, and main rotor, with the antitorque rotor and other steering equipment at the tail. Along the boom, however, was a heavy lifting crane, resulting in the informal name of "the Hook" for the aircraft.
In most applications, the savings of weight from a cabin, which could be empty in heavy lift applications, did not justify the somewhat greater lifting capability of the CH-54. The restriction became obvious when a modular cabin was made available, which could be attached to the boom, essentially making a cabin-less CH-54 into a CH-53.
Emphasis turned to increasing the engine power and rotor efficiency of the CH-53. There are a number of specializations of the CH-53, including the special operations MH-53 PAVE LOW, the general transport CH-53 series, a minesweeping RH-53 series, etc. An Israeli special operation to capture an Egyptian radar put their CH-53 at its limit in Operation Rooster 53, but the cabin was still needed to carry the raiding force.