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THE POSTWAR CARRIER REVOLUTION

from AIRCRAFT CARRIER 100: The 100th Anniversary of the American Aircraft Carrier

from AIRCRAFT CARRIER 100: The 100th Anniversary of the American Aircraft Carrier, page 8

TOMORROW’S AIRCRAFT CARRIERS

BY NORMAN FRIEDMAN

The U.S. Navy’s newest supercarriers, the Gerald R. Ford class, are the latest beneficiaries of a revolution that, in effect, saved carrier aviation from obsolescence in the 1950s. It was proving increasingly difficult to handle jet aircraft that could compete with the new generations of jet fighters and bombers based ashore. Yet a carrier without high-performance jet bombers could not strike valuable targets ashore, hence would not be a valuable offensive weapon. Without effective fighters, she could not put up a viable defense against an enemy’s air arm. For the U.S. Navy, the critical issue was offensive. By the early 1950s, the U.S. Navy was arguing effectively that it deserved a place alongside the U.S. Air Force in the most important part of the U.S. arsenal: the nuclear force. Although carriers could not deliver nearly as many nuclear weapons as the Air Force, they could do so from many more directions. That alone would force the Soviets, the main target, to disperse their air defense. Thus, the presence of nuclear-armed carriers in places like the Mediterranean could contribute enormously to the success of Air Force bombers flying from Western Europe and over the North Pole. To some extent, the Air Force could offer similar flexibility using bases in places like North Africa – except that access to those bases was subject to political instability. When the Libyan king was deposed in a coup, the Air Force lost its base in North Africa – but the Sixth Fleet continued to operate in the Mediterranean.

A U.S. Navy Douglas A3D-1 Skywarrior of Heavy Attack Squadron VAH-1 launches from USS Shangri-La (CVA 38). This was the first A3D catapult shot. Without the steam catapult, the Navy would have been unable to develop a jet-powered nuclear bomber capability in the form of the Skywarrior.

This kind of consideration made it vital that the carriers be able to operate heavy jet aircraft. Yet that capability was by no means certain in the late 1940s. At that time, the key problem was to launch the bomber in the first place; recovering it back onto the carrier was considered secondary. At the time, carriers used hydraulic catapults. A system of wires and pulleys multiplied the stroke of a hydraulic ram. How much energy they could handle was limited by the tensile strength of the wires involved. Hydraulics was entirely adequate for World War II airplanes weighing much less than 20,000 pounds, which could fly off at speeds well below 100 knots. Jets were always a problem. A propeller creates a stream of fast air over a wing even when the airplane is not moving, so that the airplane feels lift from the outset. Even without a catapult, propeller aircraft could take off after rolling down part of a carrier’s deck. By way of contrast, a jet engine creates thrust (a force pushing the airplane forward) but not airflow over the wing; it takes forward motion to do that. The earliest jets could barely take off if they rolled the full length of the longest carrier decks. Catapults were not merely helpful, as with propeller airplanes, but essential. As jet weight and stall speed increased, the Navy ran into the limits set by the wires used in hydraulic catapults.

**A Grumman S2F-1 Tracker was the first aircraft to be catapulted by steam from the USS Hancock (CVA 19), the first aircraft carrier in the U.S. Navy to be fitted with the revolutionary steam catapult.**

In 1945, the Bureau of Aeronautics (BuAer) began work on a new generation of much more powerful catapults. Instead of being powered indirectly, as in a hydraulic catapult, they would use some source of power to drive a piston down a cylinder. The airplane would be hooked on to the piston.

After briefly considering alternative sources of power, the bureau fastened on explosives: The new catapult would be a kind of gun. Given the expectation that a new generation of catapults would soon be available, BuAer ordered a new generation of heavy nuclear bombers for the new carrier then planned (USS United States). A variety of exotic designs was offered, but in the end, the bureau chose a twin-engine jet, which became the very successful A3D (later A-3) Skywarrior. After a vicious interservice fight, the new carrier was cancelled, but the A3D survived because in theory, existing carriers could operate it – if they were fitted with the new catapults.

That was the rub. As the A3D reached the prototype stage, the “gun catapult” did not. Without it, the A3D could not operate from a carrier and the Navy could not take its desired (and valuable) place in the U.S. nuclear arsenal.

Fortunately, another navy was also attacking the catapult problem: the Royal Navy. British priorities were very different from those of the U.S. Navy; the Royal Navy was concerned more with protecting convoys around Europe from Soviet naval air attack. This was largely the legacy of experience fighting convoys through to Murmansk in the face of German torpedo bombers. Too, the Royal Air Force successfully barred the Royal Navy from any strategic nuclear role. Much more importantly, partly because its carriers were significantly smaller than those of the U.S. Navy, the Royal Navy needed a new-generation catapult if it was to operate the jet fighters it saw as its own hope for the future. The British had taken a different approach to the catapult problem. A British engineer, C.C. Mitchell, had been impressed by the way in which the Germans used steam to propel the catapult that launched their wartime V-1 missile. He designed a carrier catapult that was fed by steam from the ship’s boilers. The U.S. Navy’s Bureau of Aeronautics had considered and rejected steam as a power source. As the gun-catapult project stalled, the U.S. Navy’s Deputy Chief of Naval Operations for Aviation ordered the Navy to test the British catapult. The Royal Navy made its prototype, on board the maintenance carrier HMS Perseus, available.

The steam catapult solved the A3D problem and propelled the U.S. Navy into the jet age. In effect, 200 feet of steam catapult was equivalent to thousands of feet of runway ashore; the Navy could operate fighters and medium bombers every bit as powerful as those flying from land bases. Conversely, without the steam catapult, the U.S. Navy and other modern navies would have been crippled. Much later, very high-powered fighters were able to take off from ski-jumps aboard carriers, prominent examples being the Russian Kuznetzov and the Chinese Liaoning. Other carriers with ski-jumps operate STOVL fighters. In both cases, payload is limited by the absence of a steam catapult.

With the Gerald R. Ford, the U.S. Navy is employing an alternative electromagnetic catapult – the Electromagnetic Aircraft Launch System, or EMALS. It says a great deal for Mitchell that no other highpowered catapult has been perfected in the more than 60 years since the U.S. Navy met his steam catapult. The Bureau of Aeronautics’ gun catapult was never completed, nor was a proposed alternative internal-combustion version.

The steam catapult made it possible to launch an airplane from a carrier, but the same airplane still had to land back on. In the 1940s, the U.S. Navy (Bureau of Aeronautics) view was that the problem was simply to provide arrester gear capable of absorbing more energy. However, landing a jet airplane on a carrier was a more difficult proposition. Before jets, a pilot approaching the carrier watched a landing signal officer (LSO) signal whether his approach was good. Once he was “in the slot,” the LSO could signal him to cut his engine, and thus to stall into the deck. For jets, this procedure was dangerous for two different reasons. One was that a jet engine responded far more sluggishly to commands. The engine worked using the heat it generated, and cutting the throttle did not suddenly cool the engine or cut the stream of hot air and gas emerging from it. A second was that streamlined jets approached a carrier far faster than their piston predecessors. A pilot and LSO set up a cycle of observation and response, and in the case of a piston engine airplane, there was just enough time for the pilot to respond effectively.

An F2H-2 Banshee making a carrier landing aboard USS Oriskany (CVA 34) in 1955 illustrates the dangers of operating jets aboard straight deck aircraft carriers. The only safety feature should the Banshee fail to trap is the barrier rigged across the deck, but if the Banshee bounces above the barrier, or the barrier fails, it will crash into the aircraft arrayed in the deck park forward. The naval aviator of that era faced an all-or-nothing commitment to landing.

Again, the British seem to have had more interest in the problem. Their carriers were smaller, and for various reasons, they had less experience with LSOs (before World War II, their pilots landed without them). They became interested in reviving pilot-controlled landing for jets. To do that, the pilot needed some direct indication of whether he was on the glide path. At Farnborough, Nick Goodhart realized that a combination of a mirror and indicating lights could do just that. By 1952, Farnborough was experimenting with pilot-controlled carrier landing. At the time, the U.S. Navy was not particularly interested.

A Grumman F9F-8 Cougar from Fighter Squadron 91 (VF-91) Red Lightnings engages the crash barrier aboard the U.S. Navy aircraft carrier USS Kearsarge (CVA 33), in 1956. The barriers that had been so successful in arresting errant propeller-driven aircraft had to be modified to safely catch the smooth, pointed, propellerless shapes of the new jets.

During this period, the British, who had built the first Western jet aircraft, were interested in exotic jet configurations. For example, unlike a propeller airplane, a jet could land on its belly, saving the weight of landing gear. Inspired by the German Me 163 rocket fighter, which did exactly that, Farnborough investigated the possibility of covering a carrier flight deck with a flexible rubber mat. Through the mid-1950s, work on such flexible decks continued, and for a time, the U.S. Navy was also interested. Ultimately, the flexible deck was a dead end – but before it died, it led to something vitally important: the angled deck. At a 1951 conference on the configuration of HMS Ark Royal, then nearing completion, her prospective commanding officer, Capt. D.F. Campbell (at that time Director of Naval Aircraft Development and Production), asked whether the proposed flexible deck could be angled to one side. In that case, an airplane landing on it could quickly be taken off so that another could quickly land. His next step was to ask whether a conventional carrier landing deck could (or should) be angled to one side. Campbell was aware of Farnborough work on pilot-controlled landing, and he asked whether it should be introduced in connection with the angled deck. Campbell later wrote that he had conceived the angled deck even before the crucial meeting. He was concerned that it might be difficult to recover the new Scimitar fighter-bomber on short British carriers, which did not have enough flight deck length for it to decelerate properly.

At this time, standard procedure in both the U.S. Navy and the Royal Navy was to park airplanes at the bow after they landed. They were protected from further airplanes landing on board by a wire (later nylon) barrier. In practice, landing airplanes sometimes jumped (bolted) the barrier to crash into the airplanes parked forward, often with disastrous results. It seemed likely that the faster the landing airplanes, the greater the possibility of bolters and crashes. Angling the landing deck would end this problem, because the landing airplane would never be headed into the airplanes parked forward. If he had to, a pilot could simply apply more power and keep flying, turning around for another attempt. As an incidental benefit, the angled deck ended the question of whether the pilot could or should cut power during an approach: He should not, because he might have to go around again.

The shape of a second chance. A Douglas F4D-1 Skyray of Fighter Squadron (VF-13) Night Cappers approaches the U.S. Navy aircraft carrier USS Essex (CVA 9) in 1959. The angled deck allows the aircraft to add power and “bolter,” or go around for another landing attempt, if the hook fails to engage a wire, all while on a trajectory that avoids the deck park of aircraft forward.

U.S. Navy adoption of the British steam catapult in the teeth of opposition by the Bureau of Aeronautics made for interest in other British innovations. Thus, U.S. officers attended British discussions of the angled deck well before the British could apply their idea to their own new carriers (they did paint an angled deck on the trials carrier Illustrious to see whether pilots could land at an angle to the ship’s course). The angled deck was considered so promising that it was almost immediately tested on board the U.S. carrier Antietam.

A U.S. Navy Grumman S2F Tracker comes in to land aboard the training carrier USS Antietam (CVS 36) in the Gulf of Mexico, guided in by the optical landing system at the edge of the flight deck. Initially, the system used an actual mirror before being replaced with a Fresnel lens in more modern systems.

For the U.S. Navy, the angled deck could solve another problem. When it contemplated very large jet aircraft, the U.S. Navy decided to make the open part of the flight deck as wide as possible. The huge abortive carrier United States was to have had a flush flight deck and a retractable island. There would be only limited space for radars, so plans called for a separate ship (sometimes called a “pilot fish”) to accommodate both long-range radar and fighter control in a carrier task force. The prototype was the converted cruiser Northampton. After the Korean War broke out and funding became available, the Navy ordered another large carrier, a slightly scaled-down United States, called USS Forrestal. She too would have had a flush deck, and she too was paralleled by a pilot fish, in this case a projected conversion of the incomplete large cruiser Hawaii. A major irony of both the United States and Forrestal designs was that both featured massive sponsons projecting from their straight flight decks. These sponsons could easily have been parts of angled decks, but that was not the intent. Rather, the idea was that they could support additional catapults. Using them, the carrier could launch bombers and fighters simultaneously.

Seven aerial photographs showing the major different modernizations of the U.S. Navy Essex-class aircaft carriers (left to right): USS Franklin (CV 13), as delivered, Feb. 21, 1944. Franklin received no or little modernization. USS Wasp (CV 18), after her SCB-27A conversion in late 1951: new hydraulic catapults, new island, removal of the deck guns, new bow. USS Hancock (CV 19) after her SCB-27C modernization, circa 1955: like SCB-27A but new steam catapults and relocation of the aft elevator to the deck edge. USS Antietam (CV 36) after the installation of an experimental angled deck, circa 1954. USS Bennington (CV 20) after SCB-125: enclosed hurricane bow, angled deck, starboard deck edge elevator. USS Hancock (CV 19) after SCB-125 in April 1957. USS Oriskany (CV 34) received SCB-125A, here on May 30, 1974.

Once the Antietam tests succeeded, the Forrestal was rapidly redesigned. An angled landing deck would carry even a large approaching bomber well clear of the usual island position on the starboard side of the ship. Given a conventional island, the ship could accommodate the radars needed to control her fighters. The elaborate and expensive pilot fish was no longer needed. The Hawaii conversion was cancelled.

All later U.S. carriers have angled decks. The main change from the Forrestal is that the island has been moved aft, farthest so in the Gerald R. Ford class. The further aft the island, the more space is available alongside the angled deck for parking larger and larger aircraft and, as importantly, for servicing them between flights.

The USS George Washington in 2002 as seen from an F-14 Tomcat fighter aircraft assigned to the Jolly Rogers of Fighter Squadron 103 (VF- 103), during final approach for an arrested landing on the ship’s flight deck. Note the optical landing system along the port deck edge ahead of the parked aircraft, and the two waist catapults on the large area of angled deck. Today’s supercarriers could not exist without the three major postwar aircraft carrier breakthrough developments.

As Campbell suspected, the angled deck made it almost mandatory to operate jets at full power when landing, and that further complicated the task of an LSO. Although Goodhart’s mirror landing sight was conceived independently of Campbell’s angled deck, the two innovations fit together extremely well. A U.S. Navy receptive to British ideas quickly adopted the mirror landing sight. The main difference since has been to replace the mirror with a Fresnel lens. The landing sight is mounted alongside the landing path, stabilized so that the approaching pilot clearly sees whether he is on the appropriate approach path.

An F-4S Phantom II aircraft of Fighter Squadron 161 (VF-161) Chargers thumps onto the deck of USS Midway (CV 41). The angled deck, steam catapult, and optical landing system made it possible for the U.S. Navy to operate the big Phantom II, which had such superlative performance that it was also adopted by the U.S. Air Force.

The steam catapult made it possible to operate high-performance jets from carriers. The proof that carrier aircraft were fully competitive with those ashore was the F-4 Phantom II: the U.S. Air Force felt compelled to adopt it as the best fighter of its time. Without the steam catapult, there could not have been a Phantom II. Without the angled deck and the mirror (later Fresnel lens) landing sight, it could not have been operated on board carriers, because it would have suffered an unacceptable accident rate.

A U.S. Navy F-14A Tomcat from Fighter Squadron VF-51 Screaming Eagles intercepts a Russian Tupolev TU-95 Bear. The big, heavy interceptor with the long-range missiles and powerful radar needed to defend the carrier battle group during the Cold War would not have been able to operate from U.S. Navy aircraft carriers without postwar aircraft carrier innovations.

These innovations have provided carriers with the flexibility that has made them worthwhile. In the 1950s, the U.S. Navy was interested mainly in maintaining its ability to deliver nuclear strikes despite improving Soviet air defenses. It retained a carrier nuclear strike role even after strategic missile submarines took over much of the strategic nuclear mission. It turned out, moreover, that the efforts made to accommodate heavy nuclear bombers on board carriers made it possible for the same carriers to operate heavy fighters and conventional bombers like the Grumman A-6 Intruder and the LTV A-7 Corsair II. Without the big fighters and bombers, carriers would have been unable to participate in the Vietnam War air attacks on North Vietnam.

This article is from:

AIRCRAFT CARRIER 100: The 100th Anniversary of the American Aircraft Carrier

by Faircount Media Group