Aircraft Carriers May Get Advanced Hoist

Aircraft Carriers May Get Advanced Hoist

To streamline operations and improve performance, the U.S. Navy commissioned a new hoist to raise and lower the aircraft elevators.
The flight decks of U.S. Navy aircraft carriers are chaotic surfaces where aircraft launch and land. Every square inch is critically important, which is why when aircraft are not in use, they are stored just below the main flight deck in a giant hangar deck. Aircraft is transported from the hangar deck to and from the flight deck via massive and powerful aircraft elevators. 

Traditionally, such elevators are powered by a system of hydraulics. But to streamline operations and improve performance, an all-electric hoist has been developed to raise and lower the aircraft elevators.

“The all-electric elevator hoisting machinery is the muscle that is used to move the elevator platform up and down," said Noel Plamondon is the chief engineer for product development with Jered LLC in Brunswick, Ga. Jered, a PAR Systems company, developed and tested the all-electric hoisting machinery system for the Navy. “In theory this is a simple system, much like a personal elevator in a building. The actual system we provide is in no way simple due to the demands of the environment, available space aboard ship, and reliability requirements.”

All-electric aircraft elevators are more reliable than the systems they are intended to replace. Hydraulic systems are difficult to maintain, with many moving parts as well as seals and fluid associated with a fluid power system. In addition, the all-electric solution is significantly lighter in weight and occupies less space than the traditional hydraulic system.

Plamodon said the first obstacle for Jered’s design was to ensure the ability to operate in heavy seas with significant ship roll. Durability of design is often rated at its capacity to endure different sea states, which are a function of wave height and the expected degree of the ship’s roll or side-to-side motion. The ship motion combined with the wide range of cargo being located off center position on the platform require a speed control system that ensures the elevator speed is constant under all loading combinations.

It’s only been recently that electric elevator control systems have progressed to the point where they can produce constant speeds under such adverse conditions, Plamodon said. 

Another challenge was in the placement of the mechanical system for the hoisting machinery. Unlike commercial and residential buildings, which can place electric motors on their roofs, on an aircraft carrier, the hoisting machinery must be located next to and below the elevator itself.

“Hydraulic systems can do this with remote power units and runs of piping,” Plamodon said. “The Navy originally asked the question more than 15 years ago if it was even possible to meet the same space limitations with an electric system. This served as a challenge for us to tackle the request and find a solution.” 

The solution would need to be out of the box, so Jered turned the engineering challenge into a contest. 

“We split into teams within our own company, and each worked to develop a solution concept. A single team’s design was selected and presented to the Navy,” Plamodon said.

And finally, the last but most significant attribute of the system, according to Plamondon, is reliability. 

The 11 U.S. Navy aircraft carriers are powered by a nuclear reactor and can go 20 years without refueling, and the expectation is they will be at sea as often as possible. Availability is key: An aircraft carrier without an operational elevator is no use at all.

“The new system with many more parts, electronics, and software had to meet the same system reliability requirements of the legacy systems,” he explained. “The hydraulic engine system has been in use since WWII and has benefited from decades of testing and refinement. The all-electric elevator system has a designed system life of 50 years under conditions that cannot be fully tested prior to service. To ensure this system does not become obsolete we built in features monitor and record critical data from the system and allow upgrades as technology further develops.”

The Jered team worked in collaboration with a shipbuilder and the Navy’s Naval Sea Systems Command in the end-to-end design as well as the build, installation, and commissioning process. The Navy has yet to make the final decisions on whether it will adopt and implement this new type of power drive technology for aircraft elevators aboard carrier vessels. 

Jim Romeo is a technology writer in Chesapeake, Va.

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