Americans may have invented it, but the British made naval aviation work. Jet-powered flight introduced a new set of challenges for aircraft carriers nearly 40 years after Eugene Ely's famous plunge off the foredeck of the USS Birmingham in November 1910.
Adapting the aircraft carrier's floating runway for the jet age meant reconsidering almost everything about carrier-deck design and operations that was known and proven during the crucible of the Second World War.
Making that transition would occupy the US Navy and the Royal Navy most of the decade following Japan's surrender, but many key ideas came from the British side of the Atlantic. "If you want to balance it out it's not a fair trade," says Bob Dunn, a retired US Navy vice admiral and aviator. "We took more from them than they got from us." The model for the modern aircraft carrier was set over nine months in 1955 when first the HMS Ark Royal and then the USS Forrestal entered service. Each represented that service's first aircraft carrier designed from the keel up to support jet-powered fighters, bombers and patrollers.
© US Navy
Catapults, angled decks and mirror landing aids eased the transition from propeller-driven aircraft to heavier, jet-powered types
While the Forrestal was a US-flagged ship, its most innovative design features all resembled the Ark Royal's in almost every detail. Both ships were the brainchild of a small group of thinkers embedded in the Royal Aircraft Establishment (RAE) at Farnborough.
In the winter of 1944-45, with the Battle of the Bulge still raging, the Royal Navy had already decided the future of naval aviation belonged to jets. "These officers took a look and said, 'We've got to figure out how to put jets on the carrier'," says Thomas Hone, a professor at the US Naval Warfare College and co-author of American and British Aircraft Carrier Development, 1919-1941.
Led by senior engineer Lewis Boddington, the RAE embarked on a series of experiments, starting inauspiciously with a short-lived concept for recovery fighter jets on carrier decks. That was the unlikely concept of the undercarriage-less aircraft and the rubber mattress deck. To increase the fuel-thirsty jet's range, aircraft designers removed the landing gear. Instead of landing on wheels, the concept required the jets to land by flaring to a stall slightly above the carrier deck and crashing on to a rubber mat. The results were predictable.
"That didn't work for a number of reasons," Hone says. The rubber-mat approach seemed feasible when a master pilot such as the RAE's legendary Eric "Winkle" Brown flew the manoeuvre, but concerns persisted about the ability of more average pilots to pull it off. More generally, the rubber-mat solution was fine for the first wave of lightweight jet designs that emerged immediately after the Second World War. The USN quickly adopted a long-range strike strategy for its carrier-based fleets, which required ever-larger and heavier aircraft. The rubber mat was not so scalable. Ultimately, the companion idea of extending the range of jets by eliminating retractable landing gear faded for similarly practical reasons. It was never clear how crews would manhandle the wheel-less aircraft around the deck.
A long-term solution to the problem of landing jets on aircraft carriers lingered through the middle of 1951. The problem was not just about stopping aircraft with higher landing speeds, the goal was also to maintain the efficiency of flight operations at sea despite the transition to jets. Before the Second World War, US carriers, which emphasised the strike role of naval aviation, had found the answer in the "deck park", Hone says. This involved erecting large net barriers across the carrier's straight deck, allowing aircraft to continue landing in front of the barrier while other fighters were being re-armed and refuelled behind the barrier. It was a simple and efficient solution but only worked as long as propeller-driven aircraft required no more than half a typical carrier deck to take off or land.
With the transition to jets, the aircraft would need the entire length of existing straight-decks to come to a stop. The Americans' approach to this problem was typical of the nation's industrial spirit at the time, and new carriers sported ever-longer straight decks as the 1950s approached. The British, however, had a different idea. In August, Boddington for the first time heard a proposal from a British carrier pilot, then-Royal Navy Capt Dennis Cambell. "Together, they came up with this idea of angling the deck," Hone says. In one stroke, the problem was solved. Aircraft could be recovered in one section of the deck and not interfere with take-off and landing operations in another. It was a major, far-reaching innovation that changed the history of naval aviation forever. "In the past, they built the ship and then accommodated the ship to the airplanes," Hone says. The key idea of the angled deck was finally to design the ship from the start with the goal of making them suitable for handling take-off and landing operations for fast jets. The appeal of the angled deck was immediately recognised by the USN, which took the concept farther than the RAE's engineers had considered. While the British concept called for canting the deck by 4-5°, the USN adopted a more radical design with a deck angled by 8-10°, Hone says.
© US Navy
USS Forrestal's design features resembled the Ark Royal's
After experimenting with the USS Midway, the navy modified the USS Antietam with a slightly angled deck to conduct a full-scale demonstration. Both navies then took the next step and designed the Ark Royal and Forrestal from scratch as angled-deck carriers. Once the problem of deck layout was solved, the RAE focused its efforts on other needs demanded by the transition to jets. With aircraft designs introduced after the Second World War, carriers needed to provide more of a boost aligning the bow with the direction of the wind.
The steam catapult originated in the 1930s with both navies, but the idea was not developed further until after the war was over.
The British again revived the concept, generating steam pressure of 24.2bar (350lb/in2) off the boilers feeding the carrier's engines, Hone says. Americans initially worried about whether the concept could be scaled up to on larger US carriers, with boilers that produced steam at 41.4bar, but "it worked fine", Hone says.
Angled decks and catapults, however, were not enough to complete the transition from light, propeller-driven aircraft to heavier and mostly jet-powered types.
Guiding aircraft to a stop on the carrier deck became more of a challenge as aircraft landing speeds got faster. The previous system relying on landing system officers using flags to signal the glideslope to the pilot proved inadequate.
Royal Navy Rear Adm Nicholas Goodhart is credited with inventing the solution to this problem. It was called the mirror landing aid, and it uses a system of lights that are only visible to the pilot on a correct glideslope.
"This is way to coach the pilot onto the carrier," Hone says. "Jets came in fast, so they change position fast. It was better to have lights reflected in the mirror. The pilot has to react to it."
Source: Flight International