US Navy (1939-1942) Aircraft Carrier Preliminary Design

These "Spring-styles" were preliminary first drafts and lacked the cross-sectional displacement, and detailed hull and decks stress load analysis that US shipwrights would calculate as a preliminary to the first detail drawings to check for volume and area fits for engines, work-spaces and what were called even then, "ship-hotel" function items such as food and water storage, berthing, and mechanicals.



The flight deck cruiser was a perennial gun clubber favorite as the surface warfare officers as far back as 1930 looked for ways to combine a light cruiser's and aircraft carrier's roles into one ship. Despite the impracticality of take-off and land-on of aircraft on a warship that packed a centerline main battery right in the glide paths of the flight deck circuit, this idea was revisited every couple of years. The Americans thought they found a solution at last;



Notice the slight angle of the flight deck and the attempt to ensure the take-off run is to the port of the forecastle?



It was a direct order from FDR. There is some confusion about this order. The original myth is that FDR ordered the conversions after the slaughter of the USN fleet carriers at Coral Sea and Midway, except the USN to that moment had lost two aircraft carriers to the IJN's FIVE. The USS Wasp and USS Hornet had not been squandered yet and the Americans did not think they were in CV crisis mode until after the Battle of the Santa Cruz Islands. I have never seen in print a good explanation for the Roosevelt order, except that maybe he thought the RN idea of the HMS Unicorns might have some merit, or maybe he thought about fleet air defense vessels, aircraft carriers that carried fighters to protect the fleet while large aircraft carriers performed the strike role.



The Battle of the Rennell Islands showed how inadequate the idea of large CVEs as substitute "fleet carriers" was. The CVEs were tactically too slow to pace the surface ships they were supposed to protect. Hence, the Clevelands / Independences were rushed to conversion. USS Saipan was more a direct descendant of that botched Independence class CVL, which was unstable, a poor weather boat and a one bomb or torpedo funeral express for the unfortunate crew which served aboard those junk heaps.



The US aircraft carriers, Lexington and Saratoga, did not have armored flight decks. In construction, they were very similar to HMS Ark Royal which also did not have an armored flight deck. What they had was a steel frame superstructure deck to which light steel cladding overlaid with wooden planking was topped. The hull sides had ribs and frames which plated up to meet that flight deck. The later "armored box hanger British carriers had the strength deck made the flightdeck. Armor sides came down the length of the hanger to the hanger deck which was a load bearing deck, but nowhere near as armored defensively as the "overhead". The ends of that box were sealed off with armored shutters. This was the "armor" scheme. If a bomb got into it, well the confined explosions would wipe out anyone in one of the fire-curtain divided compartments. The automated seawater sprayers would eventually put out the fires, but nobody would survive in the burning compartment too well. And one might as well write off the hull post war, since that box was integral to the central hull. A hanger fire ruined frame and plate around and adjacent to it.

The Americans wanted none of that. They saw what happened to HMS Illustrious. What they liked was an armored overhead to protect from bombs. What they wanted to keep was the armored hanger deck as the strength deck and stand an armored flight deck as a cantilever bridge frame structure over it. The hanger void space and the truss support framing would act as a thermal barrier / path limiter to prevent the hull and framing below the armored hanger deck from losing temper. And open hanger sides would allow overpressure venting if the bomb got through the flight deck. The British must have agreed, because their designs for the Maltas followed the same structural logic. The armored box hanger was a dead idea and a rotten one.



An improved Cimmaron class. The WWII versions were too slow.



Interesting in the Springstyles is the various cruiser designs. One suspects that the Americans could have gotten away with an Atlanta with more directors and fewer guns, as a sort of heavy fleet escort. The heavy cruisers were a complete waste of steel. More light cruisers were wanted as a lessons-learned in the surface battles with the Japanese. One had to smother the Japanese cruisers and destroyers under a hail of shells before the Japanese obtained a torpedo solution on one, while one's own destroyers charged under that covering fire to deliver their own torpedo attack. That rapid fire gun drill was one thing the USN did get right. Six inch guns could do it, but 8 inch guns were too few and too slow in cycle to rain continuous fire down on a dodging enemy.