USS United States (CVA-58)

The missing link between the wartime Essex class fleet aircraft carriers, the next-gen Midway, and the supercarriers of the 1960s was a near-forgotten ship class that was projected under the Truman administration and that would have easily dwarf any other warship on the planet for the decades to come, with a displacement of over 80,000 tonnes and lenght of 332 meters (1090 feets overall). The lead ship of this class was aptly named – USS United States. A fitting name for a 4 of july post…

Despite its relatively advanced design, the US class became significant in overall US carrier development. They were -despite obvious differences – progenitors of the Forestal class and their successor and their dimensions and tonnage was match by the USS Enteprise, laid down ten years afterwards. In between a quick review of both designs (especially the flight deck) revealed the enormous technological gap. The latter had nuclear propulsion, no armament whatsoever but its air group, a massive flight deck almost twice the width, three large overhanging lifts, and a brigde that would have been unrecoignisable for sailors in 1950. On the contrary, the United States could not offer more contrast: Heavily armed and armoured, narrow, with classic battleship style powerplant and no island… This alone says volumes about the staggering development speed of US carrier design after WW2. Not peacetime normal evolution, and for good reasons since 1947.

As a side note, the product of this was called CVA 58 (the only one ship ever called that way), which cries for explanations: To distinguish aircraft carrier (so “AC” for everybody but), from colliers (A standing for Auxiliaries) or “CA” reserved for armoured cruisers (Cruiser, Armoured). The navy decided to call aircaft carriers “CV” for “Carrier, Voler” (pardon my french – this means “flying”). Hence the CVE (E for escort), CVN (N for Nuclear) and ultimately CVA, the last for “Atomic”. Not for atomic propelled bombers, but in the sense of an atomic weapon delivery system. You’re welcome.

Genesis of the project

Despite some WW2-related aspects, the USS Unitesd States class was developed with a single, simple goal in mind: Projecting power at sea, but not a standard versatile air group, but carryong the newly developed strategic bombers of the USAAF. It was tailored for strategic operations to carry heavy four-engine B-29 or their successors, a bit like the Hornet with B-25s in 1942. Curtis LeMay’s SAC (Strategic Air Command) was founded on March 21, 1946, but as usual, the USAAF and Navy did not get along always well and the proposal was not overly enthusiastically received.

Of course the idea came from the Navy, not the USAAF: The chief proponent for this new new large carrier was Admiral Marc Mitscher. He wanted in 1946 a carrier able to handle the latest and most effective planes of the day. Early design discussions focused naturally around new jet aircraft, faster, larger, heavier and thus requiring an updated platform compared to the Midway-class generation. One of the advantage of the jet was its supposed longer range, allowing the carrier to operate farther away from the target. For the new aircraft carried it was agreed the deck would have to be longer and much reinforced to handle the weight of these jet aircraft landing. Catapults were to be also longer and more powerful, as the arresting systems and lifts. The project evolved in 1947-48 with several proposals and back-and-forth propositions betwen the admiralty and BuShip.

Preliminary design

Design

The strengthened deck (armoured) originally the hangar deck, was replaced higher to the the flight deck and it was chosen to in the end not to have no extra armor for it, for that would have created a greater tendency to roll in rough seas, with critically dangerous a metacentric height. Instead, armour was eliminated for good. It was believed that due to the nature of the payload (heavy strategic bombers) the new carriers would remain far away from any possible counterattack. In any case, at 33 knots and heavily armed, and keeping presumably a set of fighter jets used for an extensive CAP, plus radar warning, there were still layers of defense to pass.

Based on the new jet aircraft to carry, the design was made flush deck quickly, but due to large planes operations it became self-evident the island was a nuisance and it was felt safe to elimnated completely the control structure. Instead radar antennas, telemeters, FCS and the rest of what an island carrier was relegated to the two flight deck side sponsons, port and startboard. No island meant also no vertical funnel ducting and instead, they were truncated into two side funnels installed mid-ship under the flight deck, but far away from the hull with extensions to avoid smoke interference, notably in case of landing operations.

USS United States model undergoing seakeeping tests at Carderock Navy test pool circa 1947. Note the fighters showed there was the mediocre Cutlass, but the jet bomber is completely unknown. Nothing resembled it in 1947 and it looks really advanced for the time, in its overall shape, almost a Rockwell B1. The model is also interesting for other points: The “gun-like” tubes which seem to protrude from masks were elevated funnels, which could be oriented to deflect smoke from the deck in any wind conditions. This was not kept for the final design. The deck looks also quite straight, with just forward catapults.

In these dicussions, it soon apparead that this radical no-island flush-deck design carried two major concerns: Smoke diversion from the flight deck remained a problem no early carrier (the 1920s generation) never really solved before raising it into large islands, and of course was the placement of early warning radar equipment, which needed some free room free from interference. If aerials were carried they needed to be small and placed low.
One solution proposed was to have the ship escorted by a specialized command ship, carrying the commander of the task force, and having the best and largest detection radars. This command ship would radio electronic information and orders from its command center, relegating the carrier as a simple “carrier” executant.

A second solution was to provide the carrier some specialized aircraft that be used as early warning radar warning in the air, detecting incoming aircraft over a large area. This was the germ for early warning carier-borne radar aircraft, such as the E-1 Tracer , but it would not be available before… 1956. In 1949, when the ship entered service, the only available, not-carrier operated, were the massive Lockheed WV and EC-121 Warning Star derived from the super constellation. Some hoped to adapt it to be carrier-operated as were future strategic bombers for this new aircraft carrier.

In the end, as for its core concept, the new CVA-58 class was to be design not to safely operate by itself, but in a larger task force, with traditional fleet carriers in complement. It was really reduced as a bomber carrier and could do little else, it was just an extended strategic arm within a larger force. In addition it was dependdent of what aircraft types would be in existence in the 1952-1960 era, the reasonable career expectancy for such concept. And we know how it went.

Colorization of the conway profile, rendition by the author with Vought Cutlasses for scale.

Final design general specs

As it appeared finalized and approved by president Truman on 29 July 1948, the new “supercarrier” (fist time the term was coined) was estimated to be around 66,434 tonnes standard, for 78,946 tonnes on trials, and up to 83,249 tonnes loaded for war operations, with its full air group. This was considerable compared to the Midway class (59,000) and remained above the following Forrestal and Kitty Hawk. The overall lenght was conditioned by the advent of a non-catapulted launch, with a few strategic bombers starting from the end of the aft landing deck and running about 300m with some extra help (rocket boosters). The ship measured 1088 ft (331.7 m) long overall and 1030 feets (314 m) at waterline level. At the time, having large air groups and their management on the flight deck made no sense: Strategic bombers needed to take all the space available, with possibly extra planes in the hangar, and fighters too.

The hull design however was made for speed, getting best advantage of a near-300,000 hp powerplant. It was 125 feets (38,1 m) wide at the waterline, for a near 1/10 ratio similar to cruisers and destroyers. Of course the flight deck was way larger, extended by using overhanging structures as much as possible and reached 190 feet (57.9 m) at its widest extension, at the level of the two side funnel tips port and starboard. The design was also peculiar in that it had no less than four hydraulic catapults installed: Two forward, in échelon to avoid intereferences when launching, and two mid-ships in extensions above the funnels, and oblique, port and starboard. They corresponded each to a pair of lifts: Two forward, including one starboard and one port midship, both overhanging. They served the two forward catapults. A third one was placed aft, just before the sponson starboard, and the fourth was a “classic” centerline, larger lift placed at the stern deck. The design gave dimensions hardly compatible with heavy strategic bombers, so we can assume the development of a carrier-borne wings-folding nuclear bomber was in the works at that time: It became ultimately the A5 Vigilante, which development started in the early 1950s.

Powerplant

CVA 58 did not need something very innovating at that time. There were discussions about adapting nuclear power to provide electricity but it’s was still at experimental stage. The world’s first artificial nuclear reactor, Chicago Pile 1, was experimented on 2 December 1942, but it produced just some voltage measure. The first nuclear reactor to produce electricity experimentally was the small Experimental Breeder reactor (EBR-1) designed and operated by Argonne National Laboratory, Idaho, USA, started up in December 1951. Soon, benefiting from the 1953 President Eisenhower proposed “Atoms for Peace” program, budgets were allocated. But this was the Navy that pushed things forward with Admiral Hyman Rickover, pressing developement of the pressurised water reactor (PWR) for naval use. Its Mark 1 prototype started in March 1953 in Idaho, and later propelled the first nuclear-powered submarine, USS Nautilus, launched in 1954. In 1958, there was now a craze to adapt it to all USN major surface vessels as well. That was the start of the “New Navy” resting on nuclear and missile.

But not at a time USS United States was studied. In 1946-47, the only realistic plant could only be the one from the latest battleship planned (the montana class) or the Midway class, albeit buffed up. Eventually, engineers settled on using Eight 1,200 psi (8.3 MPa) Foster-Wheeler boilers, connected to four Westinghouse steam turbines totaling 280,000 hp (209 MW). They drove four 20.5 ft (6.2 m) diameter screws. By comparison, the Midways with the same Westinghouse Steam turbines used 212,000 shp (158,000 kW), so that was a substantial increase. The goal was of course to maintain a constant high speed for the task force, in order to strike and retire, staying out of harm. Top speed therefore was the same 33 knots (61 km/h) as for the previous CV. Compartimentation was the same as previous designs, made to delay and stop any ASW damage flooding, with extra buoyancy and void compartments.

Armament

That aspect was surely the most “WW2” aspect of the design. Of course it was not thought to be used for naval combat, the air group and task force ensures the right level of protection for this, but rather to provide at least a layer of closer AA protection. The hull was large enough to accomodate generous sponsons at the angles, and the admiralty was still anxious about heaving a carrier devoid of any self-defense. This will change only with USS Enterprise. Indeed, like CVA 58, the next class, Forrestal (CV-59) was given eight 5 in (127 mm)/54 caliber Mark 42 guns in sponsons, in the same way, as the CV-63 at initial phases of development, until the sea sparrow was planned instead.

USS United States therefore carried a generous armament still reminiscent of the Midway class, with eight 5 in (127 mm)/54 caliber guns in single mounts (four single in turrets port and starboard mounts), same models as for the USS Midway, and sixteen 76 mm/70 caliber guns in eight twin mounts. They were placed also on the same sponsons, one of each (so four), two aft (either side of the lift) and two forward (side by side on the bow deck), althought drafts shows there a single, but larger turret (possibly quadruple). It’s not clear at this point. Artist’s views and test models all shows a single standard turret, meaning seven turrets, not eight. Another aspect whis was also drived from the Midway and WW2 experimence was a battery of twenty Oerlikon 20 mm cannons, probably placed in deck-level side sponsons, perhaps as an afterthought. Ten could have easily took place along each side of the forward flight deck.

Artist impressions of the carriers are misleading (but that’s no surprise): For example, an early sketch navy shows shorter sonsons and only the 5-in guns, not bow turret, and 40 mm Bofors along the forward flight deck. The Carderock Navy test shows eight orientable funnels amidships, two 5-in in fwd side sponsons, six in aft sponsons, two at the bow, two aft. No details for lighter AA. The Popular Science 1949 cover shows four old style 5-in/38 turrets per side, and 20 mm guns forward plus a bow turret. To control the main guns, four telemeters were installed at the rear of each sponsons.

To control air operations, there were two towers on the right side, aft of the first sponson. It shows in succession a large two-storey cylindrical tower, a small one-stage tower, and a mast, reinforced to carry the stated electronics, an SPS-6 semi-circular radar and an SPS-8 dish array. The mast, as shown in the post’s main artist impression picture, by far the most precise and accurate, its a tripod, with an extension aft for the SPS-8 and carried a platform for both the SPS-6 and another unknown dish array, plus communication antennae and service rigging. The tower itself, assumed to be a substitute for a proper bridge, although tiny, coud be enough to carry basic navigation and observation equipments.