By keith gentile
You've provided a compelling argument in your refutation to Slade's (et al) claim that armored flight decks were not very useful or even counterproductive. When features are carried into the future, this usually means they have merit.
However, you may have overstepped in claiming that the armored carriers could hold nearly as many planes ton-for-ton by parking them on the flight deck and do so without compromising stability and by suggesting that the Illustrious Class carriers had multiple superior defense systems to the Yorktowns. For the sake of not wanting to muddy the waters with "this carrier class could do this but the next generation could do that" ushering in a never ending discussion amongst bouncing balls, I'll stick to your original comparison of Illustrious vs Yorktown Classes.
Aircraft Complements
Even in restricting the discussion to two classes of carriers, in order to make a true "apples to apples" comparison two adjustments need to be made. It is a mistake to compare Illustrious Class carriers to Yorktown Class carriers by assuming they were both designed under the same restrictions imposed by treaty. I believe the treaties limited total tonnage to a category of ship, not the weight of any given ship in the class. At any rate, Illustrious Class carriers displaced 23,000 tons standard load while the Yorktown Class displaced only 19,800 tons. And as you mentioned, a thousand tons is quite a considerable weight to play around with.
Also, you suggested that Illustrious Class ships didn't require as much space as American carriers since the Unicorn Class carrier was available for repairing damaged planes, providing spares and maintenance facilities but then didn't add that additional tonnage (even if it were carried by a separate ship) required to achieve armored flight decks. So by the time one takes into account the 3,200-ton weight difference between the classes and adds to it the additional 5,000-plus tons of the Unicorn (16,000 tons divided by three ships), what would the 8,500 extra tons on a 19,800-ton Yorktown Class allowed it to achieve in total armor and/or aircraft complement?
The utility of adding an additional ship that was more lightly armored and was significantly slower with a maximum speed of 24 knots compared to 30 knots on the Illustrious Class has to be brought into question. The Unicorn's full flight deck would have offered as compelling a target for enemy attack aircraft as any other carrier. By placing all eggs in one basket, what happens if this most vulnerable ship of the four with its unique capabilities gets sunk? Also, the Unicorn Class was meant to service three Illustrious Class ships; this meant these three Illustrious carriers would have been forced to steam together to utilize its services, and its significantly slower speed would have put a damper on the capabilities of all three.
Speed is not merely nice to have on an aircraft carrier. Even a slightly slower speed becomes an issue with heavier planes taking off against light head winds. And as potent as an aircraft carrier is, should it fall under the guns of a surface fleet, it becomes a sitting duck. The US Navy believed speed was so important that it added 10,000 tons to the Iowa Class fast battleships' design for practically no other reason than to increase their speed by 6 knots allowing them to keep up with the carriers. If speed were so optional to a carrier, why not just design carriers for slower speeds and make life easier on the designers of the rest of the fleet? If a carrier group is tasked with a hit-and-run operation, it's best if they're running as fast as possible before a counterstrike can be organized, not to mention dodging bombs and out-maneuvering torpedoes. In theory a different, heavier design might have partially solved the speed and armor weaknesses, but this would have further increased the resources needed to achieve armored flight decks and still without solving the all-eggs-in-one-basket problem.
Finally, it was never clear how many and of what type of aircraft the Illustrious Class could hold. Here, numbers are so hap-hazardously applied in source material that they become almost meaningless. We know how many planes the Yorktowns could hold because they served with a fairly standard complement of larger, modern, heavier aircraft. But when it's suggested that the Illustrious Class could hold 36 aircraft, specifically what kind was it referring to? And when they sailed into the Pacific later in the war with planes parked on deck, did they hold older planes, newer, or a balanced number of types between smaller and lighter fighters and the larger, heavier bombers? Since they had been tasked with the strictly defensive roll of protecting the fleet from incoming enemy aircraft from Formosa, were they mostly made up of comparatively smaller, lighter weight fighters? Without more information, an apples-to-apples argument can't be applied.
Stability
As for stability and as it relates to both handling and torpedo damage, that is still very much in question. Your defense of the handling was that you could not find anything to show that stability problems existed. And herein lies a big problem when researching such things--lack of information. Without having a nautical engineer go over various carrier designs specifically contrasting one to the other or at least having sufficient open-source material to draw upon, we're forced to guess. A lot of the answers I'm sure are sitting somewhere in Her Majesty's Royal Archive under the title "Top Secret" and long since forgotten about. But forced to guess, it stands to reason that by raising the heavy protective steel plating higher, stability will become an issue. Moreover, how can it then be that this big engineering headache you mentioned was successfully accomplished on armored deck carriers while nearly doubling the number of even heavier planes than they were initially designed to hold and then parking those additional planes on top of the deck, no less? Add to that the large increase in antiaircraft batteries from its initial design you mentioned, again on--or very close to--the apex of the hull. Yipes!
As evidence of their stability you mentioned that the typhoon that took off the bow end of an Essex carrier had no effect on the British carriers. Well, that may be true (although that in and of itself doesn't prove stability). But I couldn't find anything that placed the British fleet anywhere near the eye of the storm (where Halsey so boldly drove his fleet). As was mentioned British ships were being used to protect the fleet at Okinawa against attacks coming up from Formosa placing them south of the eye of the storm. When that British captain replied to the American inquiry after the storm about how his ships had fared, he may not have been joking when he replied, "What storm?" At any rate it is doubtful they chose to retreat from the storm in the wrong direction (as Halsey did) thus having to endure sailing smack through the middle.
Glass Jaws
Bombs
Time and again you supported your argument about the dangers of neglecting to armor the flight deck by using the examples of what a single bomb hit can incur on a ship with an unarmored flight deck. And this is true but only when coupled with a carrier that has been caught unawares of an incoming strike and happens to be in the middle of flight ops with fuel hoses lying about, ordinance everywhere, and so many hands on in the hanger deck waiting to be killed as was the case on the Bunker Hill and Franklin you cited. And herein is most admittedly where the glass jaw of an unarmored deck comes into play. Radar normally would keep these surprises from happening, but when that aircraft is able to sneak in, say, behind an incoming group of friendlies, catastrophe will happen. Certain strategies can minimize this risk but not eliminate it.
Where an armored deck is a godsend is when smaller bombs are detonated on the deck and particularly when flight ops are underway. However, there is no reason that an explosion within the hanger deck from a heavier bomb likelier to defeat 3-inch armor would do any less harm under an armored flight deck than above an armored hanger deck. Cherry picking a different set of outcomes might misleadingly lead one to believe that an armored hanger deck was superior by citing the two 1100-lb bomb strikes on the Indomitable that put her out of action for seven months while Yorktown took three 550-lb bomb hits but recommenced flight operations within three hours, or the Enterprise taking three 550-lb bomb hits in the Battle of the Eastern Solomons but only requiring five weeks to affect repairs. Is bomb damage easier to repair when the armored deck is under the hanger deck? Unknown. Maybe. But this is the trouble when one comes up against incomplete information coupled with cherry picked examples.
Hands down I would rather be sailing with an armored flight deck when under threat of Kamikaze attack. But that the enemy would be turning its pilots into guidance systems essentially for bombs with wings was unforeseeable back when either design had been completed. That the Illustrious Class ships were armored as they were was merely fortuitous when the Kamikaze arrived on the scene. This was no fault of the initial Yorktowns' design. Mostly due to having the luxury of a more formidable CAP flying protection over the Yorktowns, the highly trained Japanese torpedo bomber pilots were slaughtered in the early parts of the war--one of the reasons they had to move to Kamikazes that could be flown by comparatively neophyte pilots. But one can be sure that were the Japanese not taking these heavy losses, they would be dropping torpedoes up until the end of the war and probably would never have even had to resort to the suicide plane. In a way, the Kamikaze came about not in small part because of the success of the defensive weight of aircraft numbers they came up against.
Torpedo Damage
We only have one instance of the Illustrious Class ships taking a torpedo. That being the Indomitable, which took a single hit from an Italian torpedo presumably carrying a 595-lb charge. I can't find how well it fared thereafter (maybe you can) but I did see that it was out of action for repairs from July 16, 1943 through April 10, 1944--an extraordinary nine months. Did the Indomitable's design have something to do with that length of time or the three months it took to repair damage to the Formidable from two near misses by (admittedly large) 2000-lb bombs, as was suggested by Slade (et al)? Again unknown, and there's no way to know without additional information. And what would have happened if the Indomitable were carrying a full load of heavy modern aircraft parked on its flight deck and an upgraded compliment of antiaircraft weapons up top? Legitimate questions can be raised about a ship's vulnerability to rolling over. And if this were coupled with being on the unfortunate end of a Japanese Long Lance torpedo carrying a 1070 lb charge, what chance did it have of staying upright then? And herein is where I contend the glass jaw of the armored flight decks of WWII lies. Would that American sailor in the middle of the Pacific have still wanted to be on an armored carrier with six torpedos heading in--straight, hot and normal?
Yorktown took three bombs and two Long Lance torpedo hits during the Battle of Midway. Although listing and abandoned but for a recovery crew, she remained upright and afloat. The following day while waiting for a tug to arrive from Pearl Harbor to bring the carrier back in, a Japanese submarine placed two more Long Lances into her. Only then did the Yorktown slowly roll over (although I did hear it once described as more of an elegant bow).
During the Battle of the Santa Cruz Islands Hornet took two Long Lance torpedo, three bombs and two suicide bomber hits and stayed afloat. Finally a third torpedo forced her abandonment. Later, nine torpedoes were fired at her by a US destroyer in an attempt to scuttle her. The total number that actually hit and exploded I can't recall, but I seem to remember few, if any (US torpedoes sucked at that stage of the war). After that, the destroyer attempted to sink her by firing over 400 5-inch rounds into her at the water line. She stayed afloat. The destroyer then gave up when pursuing Japanese warships closed in. Finally four more torpedoes were put in her side by Japanese destroyers that had arrived on the scene. With that, she finally succumbed. Now if that doesn't firmly establish the class's resistance to turning turtle along with a healthy dose of tough-guy bona fides, I don't know what would.
Yorktown and Hornet: Still standing.
Damage Control
You wrote about the various safety systems that backed up the 3-inch armored flight deck but never established that they were any better than those designed into their American equivalent. Yorktown Class carriers, as all American carriers, were renowned for their damage control systems. They had sprinklers for both water and fire-suppressing foam, CO2 available to fill fuel lines prior to attack, portable pumps (that the Japanese would have died for at Midway), and endless redundant water lines routed along separate pathways throughout the ship. Crew members ran training exercises holding maps of water lines so they could most effectively turn on or off a multitude of valves (the locations of which all had to memorized) depending on what was hit and where the water was needed. At first most personnel were trained in fire suppression techniques but after Midway, everyone was. Making a comparative claim that one design was superior to another would require more information.
Anti-aircraft
Despite beginning the war with a rather miserly 16 1.1-inch and 24 .50 caliber barrels under the Yorktowns' eight dual-purpose 5" guns, before they were ever engaged by enemy aircraft they were refitted with an additional 24 to 30 20-mm Oerlikon cannons. This compares to 48 2-pound guns on the Illustrious Class and 8 twin 4.5-inch dual purpose guns. I don't know if this was her initial complement or her final, but by the end of the war Enterprise had undergone multiple upgrades finishing the war with 54 40-mm bofors cannons and a total of 32 Oerlikon 20-mms under her eight 5-inch dual purpose guns.
The Third Elevator
Beyond being just nice to have, the center elevator allows a carrier both to launch and recover planes at the same time. An example of just how important this can be can be had by again returning to the Battle of Midway where the latest scholarship shows the Japanese never even had a chance to spot their attack aircraft on deck despite having known of the US carrier's existence for over two hours--in range with planes inbound. How could this be? Multiple air attacks took place from both Midway and the US carrier fleet during this two hours forcing the Japanese fleet to dodge and evade while--between incoming waves--its CAP patrol fighters had to come in to land, rearm, tank up and fly off again. During this time, not a single attack plane could be brought to the deck (the Japanese having only two elevators) freezing Admiral Nagumo in place. Had they been able to recover from one end while launching off the other, at least some of the planes of the three carriers that went down to the first attack--with all attack aircraft aboard and without ever having a chance to even be spotted to counter attack--might have had a chance to retaliate and the Battle of Midway may have had a very different ending.
Quantity Has a Quality All Its Own
Whether comprising a third or over twice as many aircraft as the Illustrious ships, at Midway the US fleet's heavy air complement had the planes necessary to sink three carriers (although only just) while keeping them from sinking the US carriers in kind. Somebody once said that for an aircraft carrier to move beyond its initial charge of merely conducting raids to arriving off shore and staying put until the job of taking the objective is accomplished--as was had to be done in capturing island bases enabling a forward advance across the Pacific--then very large numbers of aircraft had to be available to fully blanket their initial opponents when they first arrived offshore as well as beat back enemy reinforcing flights in order to protect the so-vulnerable invasion ships from aerial attack. What this amounts to is a strong forwardly deployed defense (with strike aircraft to smother potential counter strikers backed up by a large CAP to protect those that survived), one that relies less on the last few inches of a ship's armor and more on space and time to get the job done--a classic defense in depth.
You mentioned that large numbers of fighters weren't able to stop ships being damaged or sunk at various invasions as the war moved westward in the Pacific. True, but never did a British invasion fleet have to undergo attacks of scores or even hundreds of planes at one time, as did the American ships off Okinawa. Remember, the Yorktowns had to be designed to defend an entire invasion fleet. It would do little good for the ground crews to be safely wrapped in steel while the rest of the fleet was sinking around them. What would Okinawa have looked like if fewer than half the fighter planes were available to defend the fleet? Even with a strong defense in depth--in this case expanded all the way out to the home islands of Japan itself--many ships sank and over 400 received at least some damage from airstrikes. Only hundreds of fighters defending the skies overhead mitigated a potential disaster from afflicting the entire invasion fleet made up of 1400 ships. In fact, the Japanese were planning on foregoing the carriers all together and just targeting the more vulnerable troop and supply ships for the expected defense of their home islands.
None of the above observations takes into account the fact that (as established above) Yorktown Class ships required far fewer resources to construct than the Illustrious and what adding 43% more tonnage could have done to enhance the Yorktowns' capabilities.
This is not to suggest that an armored flight deck is better or worse than an armored hanger deck. Ships are designed for the specific tasks assigned. And as you said the ships were designed having to make restrictive choices. But in 1941 that an armored flight deck could provide anywhere near the numbers of aircraft an armored hanger deck could provide--and inso doing accomplish the tasks asked of the Yorktown carriers--will require more evidence.
The armored flight deck won out in the end in that all carriers have them today, but this was only solved by moving toward gigantism--enormous carriers that could hold sufficient aircraft while still floating a heavy deck high above. The Midway Class was eventually able to add a 3.5-inch armored flight deck only by more than doubling its displacement to a whopping 45,000 tons while gaining only 30% more aircraft. It is doubtful that the 1930s held the knowhow and capacity to accomplish this--but certainly not the luxury during the rush toward war.
(I have other points of contention, particularly with the last part of your article, but these get into areas outside the direct Yorktown-vs-Illustrious comparison.)