Carrier: A Guided Tour of an Aircraft Carrier
The next day, the U.S. fleet found the Japanese carrier force and launched a counterstrike. Blasting through the surviving Japanese planes, they sank the carrier Hiyo and several vital fleet oilers, and damaged numerous other ships before returning to Task Force 58.12 The next day, the decisively beaten Japanese force withdrew to Japan. So great were the losses to Japanese air crews that their carriers would never again sortie as a credible force. When the U.S. 3rd Fleet invaded the Philippines in October of 1944, the four Japanese carriers that took part in the Battle of Leyte Gulf were used purely as decoys, and sunk by air attacks from Task Force 34.
The Revolt of the Admirals, the USS United States (CV-58), and the Korean War
When Japan surrendered in September of 1945, the United States had over a hundred carriers in commission or being built. Within months, the Navy had been slashed to a fraction of its wartime peak. Only the newest and most capable carriers and other warships were retained in the tiny Navy that remained. Part of this massive force reduction was a consequence of the simple fact that the war had ended and the naval threat from the Axis nations had been eliminated. But that was not the only rationale for cutting the fleet and other conventional forces.
The major reason for the cut was the development of the atomic bomb. Specifically, the leadership of the new United States Air Force (USAF) had convinced the Truman Administration that their force of heavy bombers armed with the new nuclear weapons could enforce the peace, protect the interests of the United States, and do it without large conventional ground and naval forces. This was a debatable point, which events were soon to prove hugely wrong. But the immediate result was a mass of hostility that broke out between the Navy and USAF in the last years of the 1940’s.
The hostility did not start then, however. It had its roots in the 1920’s in the battles over airpower between the Navy and Brigadier General Billy Mitchell. Mitchell, an airpower zealot and visionary, was not an easy man to like. He had already fought a losing battle to convince Army leaders of the virtues of airpower. Meanwhile, the small corps of Army aviators saw the developing strength of Naval aviation, which some of them saw as taking funds and support that should have been theirs. To set right this (perceived) imbalance, Mitchell and his fliers (against orders) sank the captured German battleship Ostfriesland, an act that did not sit well with the Navy. In 1925, fed up with Mitchell’s stings and barbs, his superiors brought him up before a court-martial, where Mitchell, ever unrepentant, stated that airpower made the navies of the world both obsolete and unnecessary. Not surprisingly, the Navy (and others) publicly defended themselves against these charges, and they did it so effectively that Mitchell’s professional career was finished. Mitchell’s supporters never forgot or forgave that. The result was a multi-decade blood feud.
The Navy/Air Force war reached its peak during the 1949 fight for new weapons appropriations. Then as now, new weapons systems were expensive. Then, as now, the Navy and the Air Force saw it as a zero-sum game: You win/I lose (or vice versa). Practically speaking, the fight was over whether the nation’s defense would be built around the new B-36 long-range bomber (armed with the H-bomb), or a new fleet of large aircraft carriers (called supercarriers) armed with a new series of naval aircraft that could carry atomic weapons. There was only enough money in the defense budget for one of these systems, and the Navy lost. The first supercarrier, the USS United States (CV-58), was canceled by Secretary of Defense Louis Johnson just days after her keel had been laid at Newport News, Virginia.
Outraged, the Navy’s leadership made their case for Naval aviation in a series of heated (some would say fiery) congressional hearings that called into question the capabilities of the B-36 and the handling of the matter by Secretary Johnson and the Air Force. Johnson did not accept this “Revolt of the Admirals” patiently; the Navy’s leadership suffered for their rebellion against him. Many top admirals were forcibly retired, and the Navy paid a high price in personnel and appropriations.13 However, it did manage to win some fiscal support for modernization of older fleet carriers and development of new jet aircraft.
This turned out to be a godsend, for the fiscal frugality of the Truman Administration came to a crashing halt with the outbreak of the Korean War in 1950, which caught the U.S. and the world with their military pants down. Except for some Air Force units in Japan and a few of the surviving aircraft carriers and their escorts, there was little to stop the North Korean forces from overwhelming the South. Built around the USS Valley Forge (CV-45) and the British light carrier Triumph, Task Force 77 was sent by the United Nations to interdict the flow of North Korean supplies and men. Eventually, Task Force 77 grew to four Essex-class carriers, and would become a permanent fixture not only during the Korean Conflict, but also throughout the Cold War.
For the next three years, carrier-based fighter-bombers rained destruction on the forces of North Korea and (after they entered the conflict) the People’s Republic of China. Korea was not a glamorous war. For the pilots and crews of the carriers and their escorts, it was a long, cold, drudgery-laden, never-ending fight in which victory always seemed distant. What glory there was went to the “jet-jocks” flying their USAF F-86 Saber jets up into “MiG Alley” to duel with the Korean, Chinese, and Russian pilots in their MiG- 15’s. But for the Navy and Marine pilots on the carriers, Korea meant blasting the same bridges and railroads they had hit last week, and would hit again next week. Still, Korea answered any question of America’s need for Naval aviation to protect its far-flung interests during the Cold War.
With the end of the Korean Conflict, and the inauguration of a new President, the answer took physical shape in the completion of the aircraft carrier development cycle. Within just a few years, the first of four new Forrestal-class (CV-59) supercarriers would be built, setting a model for every new American carrier built ever since. Despite improvements in every system imaginable (from nuclear power plants to radar-guided SAM systems), the Forrestals have defined the shape of U.S. carriers for almost forty years. Meanwhile, the development of aircraft like the F-4 Phantom II, E-1 Tracer, S-2 Tracker, and others, led to the present-day structure of American carrier air wings. And at the same time, the roles and missions of carriers and their battle groups—their moves as pieces on the Cold War chessboard—were fixed in the minds of the politicians that would use them. The model set by the Forrestal and her jet-powered air wing was an almost perfect mix for the Cold War. With some improvements in Naval architecture and aircraft design, it has stayed on and done a great job.
Critical Technologies: Getting On and Off the Boat
What things make carrier-based Naval aviation possible? Actually, a surprisingly few critical technologies set carrier and carrier-capable aircraft design apart from conventional ship and land-based aircraft designs. Most have to do with getting on and off of the ship, and being tough enough to do it over a period of decades.
The Need for Speed: Chasing the Wind
Other than being a lot of fun, speed is essential for aircraft carriers ... for two reasons:• High speed generates artificial wind over the flight deck to assist in the launching and landing of aircraft.
• High sustained speed allows carriers to rapidly transit from one part of the world to another.
Wind over the deck allows some influence over an aircraft’s “stall speed”—that is, the minimum speed at which an aircraft can still be controlled without falling out of the sky. The lower an aircraft’s stall speed, the easier it will be to launch and land (a consideration that’s especially important on the pitching deck of an aircraft carrier). You get wind over the deck, first of all, simply by steering the carrier into the wind. Every knot of wind over the bow acts as a knot of airspeed for an aircraft trying to take off or land, which is why carriers always come into the wind to conduct flight operations. You get even more wind over the deck by cranking up the speed of the carrier. Thus, if you have a fifteen-knot wind and steam into it at twenty-five knots, you can effectively launch and land a
ircraft at forty knots under their normal stall speed. Putting wind over the deck also maximizes aircraft payload and return weight and reduces stress on the flight deck. All of this means that carriers will be using their maximum speed more often than other ships.
Carriers need more than just a high maximum speed (for launching and recovering aircraft); they need to maintain a high transit speed so CVBGs can move quickly across the oceans. The whole point of forward presence is to have it available now. Building a high, sustained speed into a ship is not easy. While many ships may be capable of “dashing” for short times at high speeds, they are normally designed to cruise at more sane and economical rates. The twelve-knot cruising speed of your average merchant ship is fine for transporting cars or athletic shoes, but it just won’t do if you want to move a CVBG in a few days from the South China Sea (say) to the Persian Gulf. That means carrier power plants have to be durable enough to cruise at high speeds for days or weeks at a time, without having to put in for repairs or overhaul. This is one of the reasons why nuclear power plants and their highly reliable machinery have been the gold standard for carriers for going on three decades. Just how fast is fast enough? Most naval analysts believe that carriers require minimum battle/flank speeds of thirty-three knots/ sixty-one kph to operate aircraft in the widest possible wind and weather conditions, and sustained speeds of at least twenty knots/thirty-seven kph to allow for rapid transits to crisis areas.
A prototype F/A-18E Super Hornet prepares for a test launch from a catapult aboard the USS John Stennis (CVN-74). The plane handler is guiding the pilot to the catapult shuttle, which will launch the aircraft.
OFFICIAL U.S. NAVY PHOTO
Catapults and Wires: Getting On and Off the Boat
Though aircraft carriers are very big, there is still very little room on the flight deck to support takeoffs and landings. Since a carrier operates as many aircraft as a small regional airport on just a few acres of flat space (about 4.5 acres on a Nimitz-class (CVN-68) ship), it makes sense to take advantage of some mechanical muscle to assist the aircraft on and off the flight deck. To this end, carrier designers have for many years depended upon the tried-and-true technologies of catapults (to give aircraft the speed to take off) and arresting wires (to give the drag to land).
The current generation of carrier catapults are basically nothing but steam-powered pistons ... steam-powered pistons that can throw a Cadillac half a mile (one kilometer). That’s a lot of power! But when you’re trying to fling a fully loaded aircraft like an F-14 Tomcat or E-2C Hawkeye off a carrier deck, you need that much power. This is how it works. Simply described, the catapult is a pair of several-hundred-foot-long tubes built into the deck, with an open slot along the top (at deck level) that’s sealed by a pair of overlapping synthetic rubber flanges. A “shuttle” running above the deck is attached (through the flanges) to pistons at the rear of the tubes; and the nosewheel towbar of the aircraft is attached to the shuttle when it is launched. To accomplish the launch, high-pressure steam, drawn from the carrier’s propulsion plant pressurizes the tubes behind the pistons. When the proper pressure is reached, a lock is released, a small, disposable fastener called a “holdback” (it holds the nosewheel to the shuttle) breaks loose, and the pistons (and attached shuttle) fling the aircraft down the deck. At the end of the deck the towbar releases from the shuttle, and the aircraft is airborne. The piston and shuttle assemblies are then run aft (back to the rear of the tubes) in order to prepare for the next launch.
Catapults are high-maintenance, complex, high-risk pieces of equipment that have the ugly habit of failing or breaking if they are not treated with loving care. This is one of the reasons why some nations have chosen to forgo them in their carriers and employ instead vertical/short takeoff and landing (V/STOL) aircraft (like the Harrier/Sea Harrier jump jet), which do not require catapults to operate from ships. Though the technology behind a carrier catapult is relatively simple, the size of the tubes and the magnitude of the forces involved make designing and building them hugely difficult. Very few nations have either the technical or industrial skills to build them. Thus, the very proud and competitive French (who don’t like to admit to being second in anything military) are buying American catapult units for their new supercarrier, Charles de Gaulle. The Soviets, after a generation of trying, failed to devise a reliable catapult unit for their carrier, the Kuznetzov.
While taking off from a carrier is difficult, landing on one is almost appalling! Setting down a CTOL (Conventional Take Off and Landing) aircraft like an F/A-18 Hornet strike fighter, for example, has been compared to taking a swan dive out of a second-floor window and hitting a postage stamp on the ground with your tongue. During the Vietnam War, scientists made a study to find out when naval aviators were under their greatest stress during a mission. Their cardiac monitors told the scientists that getting shot at in a bomb run was not even close to the stress of a night carrier landing in heavy weather. In order to make carrier landings easier and less fearsome, the Navy has developed a series of automatic and assisted landing aides to help pilots get their aircraft onto the heaving, pitching deck. But once you’re there, how do you stop thirty or forty tons of aircraft that have just slammed down at something over a hundred knots?
Well, you attach a hook to the tail of your aircraft (the famous “tailhook”) and “trap” it on one of a series of cables set across the deck. These cables are woven from high-tensile steel wire, which are stretched across the after portion of the ship. Usually four of these cables are laid out along the deck. The first is placed at the very rear of the carrier (called the “ramp” by naval aviators); the second a few hundred feet forward of that; and so on. The last goes just behind the angle that leads off the port (left) side of the ship. This creates a box into which the pilot must fly the aircraft and plant his tailhook onto the deck.
A prototype F/A-18E Super Hornet about to “trap” a landing wire during trials aboard the carrier John Stennis (CVN-74).
BOEING MILITARY AIRCRAFT
What happens if a pilot misses the wires? Well, that is another issue entirely. CTOL carrier landing decks are angled to port (left), about 14° off the centerline. This is so that if an aircraft fails to “trap” a wire, then it is not headed forward into a mass of parked aircraft. Instead, the aircraft is now headed forward to port. This is the reason why on every landing, as soon as they feel their wheels hit the deck, pilots slam the engine throttles to full power. Thus, if they do not feel the reassuring tug of the wire catching the hook (more of a forward slam actually), they can just fly off the forward deck (a “touch and go”) and get back into the pattern for another try. This is known as a “bolter,” and most naval aviators make a lot of these in their careers.
Generally, hitting the rearmost (or “number one”) wire is considered dangerous, since by doing that you’re risking coming in too low and possibly hitting the stem (fantail) of the carrier (which is known as a “ramp strike”). So too is catching the last one (“number four”). Because you don’t have much room to regain airspeed in the event of a “bolter,” you risk a stall and possible crash while trying to climb back into the pattern. Catching the number-two wire is acceptable. But catching the number-three wire (called an “OK Three” by the air crews) is optimum, for it allows maximum room from the fantail and maximum rolling distance to regain speed and energy in the event of a bolter. Catching the “number three” is evidence of great professionalism and skill. In fact, if there is not a shooting war around to test your abilities and courage, then a consistent string of “OK Three” traps is considered the best path to promotion and success for a carrier pilot.
So what comes next? You have hit an “OK Three” trap, your aircraft’s tailhook has successfully caught a wire, yet you are still hurtling forward at a breathtaking speed and may fly off the forward deck edge of the “angle” at any moment if all doesn’t go well. In other words, the excitement isn’t over. Each end of the arresting wire runs though a mechanism in the
deck down to a series of hydraulic ram buffers, which act to hold tension on the wire. When the aircraft’s tailhook hits the wire, the buffers dampen the energy from the aircraft, yanking it to a rapid halt. Once the aircraft stops, the pilot retracts the hook, and is rapidly taxied out of the landing zone guided by a plane handler. While this is happening, the wires are retracted to their “ready landing” position, so that another aircraft can be landed as quickly as possible. When it is done properly, modern carriers can land an aircraft every twenty to thirty seconds.
Aircraft Structures: Controlled Crashes
Any combat aircraft is subjected to extraordinary stresses and strains. However, compared with your average Boeing 737 running between, say, Baltimore and Pittsburgh, carrier-capable aircraft have the added stresses of catapult launches and wire-caught landings that are actually “controlled crashes.” That means your average carrier-capable fighter or support aircraft is going to lug around a bit more muscle in its airframes than, say, a USAF F-16 operating from a land base with a nice, long, wide, concrete runway. This added robustness of carrier aircraft (compared with their land-based counterparts) is a good thing when surface-to-air missiles and antiaircraft guns are pumping ordnance in their direction. But it also means that carrier aircraft, because of their greater structural weight, have always paid a penalty in performance, payload, and range compared with similar land-based aircraft.