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Catapults launched U.S. naval aviation into the future.

The U.S. Navy began a year-long celebration of the Centennial of Naval Aviation (CoNA) in January commemorating 100 years of progress and achievements. Naval aviation marked its beginning with the purchase order of its first aircraft, a Curtiss A-1 Triad, on May 8, 1911. Propelled by pioneers who often risked their personal safety in the name of technology, the advent of the aircraft catapult arguably remains one of the most important advancements in naval aviation during the 20th century.




Catapults are used to launch aircraft from ships in the form of assisted take off. From Smithsonian Secretary Samuel Langley's use of a spring-operated catapults in 1903, to the Wright Brothers' weight and derrick-style catapult; followed by the experimental air-compressed catapult system used to make the first successful catapult launch; to hydraulic catapult systems, on to the current steam-driven catapult systems of today's aircraft carriers, the catapult has seen its share of technological advances. With technological advances in the field of electromagnetics leading to the development of an Electromagnetic Aircraft Launch System (EMALS) onboard Gerald R. Ford-class supercarriers, he catapult systems are yet again heading or change.

Prior to World War I, many countries, including the United States, worked feverishly to come up with a composite system o launch aircraft from ships. Individual visionaries in aviation saw, early on, how air superiority from the sea could change the course of fortunes for whichever country first perfected the use of aircraft catapults.

Mark Evans, a historian at the Naval History and Heritage Command, called the washington Navy Yard, "a breeding ground for aviation pioneers and a place of significance for the development of the modern-day catapult."


Evans said then-Lt. Holden Richardson compiled and drew up some of the first plans for catapults, and listed Capt. Washington Chambers as one of the first officers heavily involved with the design of the early catapult systems.

"Washington Navy Yard was the birthplace of the U.S. Navy's catapult launching, and also research and design. The design, the fabrication all occurred (sic) at the Yard," Evans explained. "[Chambers] drew up the plans for the early catapults based loosely on the design of the air cylinder used on ammunition hoists aboard ships, which was very innovative and cutting edge for the time."

Notable achievements coincided with the progression of catapult systems including those of then-Lt. Theodore "Spuds" Ellyson who, on Nov. 12, 1912, made history as the Navy's first successful catapult launch from an experimental catapult system on a stationary coal barge on the Santee Dock in Annapolis. Md. This came on the heels of an almost fatal attempt by Ellyson July 31, 1912. The amphibious seaplane Ellyson flew, a Glenn Curtiss A-1 Triad, left the ramp with its nose pointing upward and it caught a crosswind, which pushed the plane into the water. Ellyson was able to escape from the wreckage unhurt.

On Nov. 5, 1915, Lt. Cmdr. H. C. Mustin made the first catapult launch from a moving ship, the armored cruiser USS Carolina (ACR 12), in Pensacola Bay, according to Evans. This experimental work led to the use of catapults on battleships and cruisers through World War II, and to the steam catapults on present-day aircraft carriers.

On Nov. 18, 1922, Cmdr. Kenneth Whiting, piloting a PT Seaplane, made the first successful catapult launching from the Navy's first aircraft carrier, USS Langley (CV 1), at anchor in the York River. Naval aircraft had been launched from other shipboard platforms, but this one launching was of monumental importance to the modern U.S. Navy as it introduced an era of the Navy's aircraft carriers becoming the vanguard of its forces in the future.

"If it wasn't for research done at Washington Navy Yard up through World War I, we never would have been able to develop the catapult, and the technology that developed our first aircraft carrier ... of course today, carriers are at the forefront of the fleet," Evans said.

The Navy has used steam catapults for more than 50 years to launch aircraft from aircraft carriers. Compared to their comparatively crude, less efficient older siblings, the steam catapults have been a staple in naval aviation. Steam catapults, although long-tenured, are not without operational limitations especially for today's naval aircraft.

The size and manpower requirements of steam catapults place limits on their capabilities. According to research conducted by the Naval Air Warfare Center, Aircraft Division, Lakehurst, N.J., compared to steam catapults, EMALS weighs less, occupies less space, requires less maintenance and manpower, is more reliable, and uses less energy.

At the beginning of the 21st century, navies started experimenting with catapults powered by linear induction motors and electromagnets. The simplistic, linear approach of EMALS is another advantage over the more complex steam catapults, which have extensive mechanical, pneumatic, and hydraulic subsystems. EMALS uses no steam, which makes it suitable for the Navy's planned all-electric ships. The EMALS could be more easily incorporated into a ramp, which would reduce the aircraft's takeoff speed and consequently the launch energy required.

Experts are predicting the movement towards heavier, faster aircraft will soon result in launch energy requirements that exceed the capability of the steam catapult. An electromagnetic launch system offers higher launch energy capability, as well as substantial improvements in areas other than performance. These include reduced weight, volume and maintenance; and increased controllability, availability, reliability and efficiency.

While the steam catapult has many years of operation in the fleet, there are many drawbacks inherent in the system. The foremost deficiency is that the catapult operates without feedback control, which allows large transients, or momentary variations in current, voltage, or frequency, that can damage or reduce the life of the airframe. Extra force is often necessary because f the unpredictability of the steam system. This ends to needlessly overstress the airframe, most of which is top-side weight that adversely impacts the ship's stability and righting moment.

Another major disadvantage is the present operational energy limit of the steam catapult, according to a Naval Air Warfare Center study. he need for higher payload energies will push he steam catapult to be a bigger, bulkier and more complex system. Power electronics is the pivotal technology allowing EMALS to become reality aboard ship.

Although the current steam catapult system as served the Navy well since its inception, here is always room for improvement. The Navy is presently pursuing electromagnetic launch technology to replace the existing steam catapults on current and future aircraft carriers.

MALS will provide the capability for launching all current and future carrier air wing platforms from lightweight unmanned aerial vehicles to heavy strike fighters. Aircraft catapults ushered the Navy into an era of air superiority from the sea that has been essential in every conflict since World War II. With continued technological advances, they promise to be at the forefront for years to come.

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Publication:All Hands
Date:Jul 1, 2011
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