USS Iwo Jima

[Don Bowen]

Anyone have any good data on the design of this ship? It was scheduled to be the last of the Essex class to complete (estimated availability 11/46, IIRC) and was selected (considered?) for an armored deck modification. Everything was shelved and the ship cancelled when the war ended.

One consideration might be the SC27 upgrade done to Oriskany upon her delayed completion. No armored deck, though.

Maybe someone on the forum has some data....

[DuckofTindalos]

SCB-27A is not a bad idea, but it would take a HELL of a lot of time. If the war's still going, the USN needs decks in service to replace ones that are put out of action due to Kamikaze damage.

[Don Bowen]

ORIGINAL: Terminus

SCB-27A is not a bad idea, but it would take a HELL of a lot of time. If the war's still going, the USN needs decks in service to replace ones that are put out of action due to Kamikaze damage.

Yeah, that was the rational behind the armored deck thing. Kamikazes made those British CVs look awful good, small air groups or no.

[DuckofTindalos]

Then I'd say an armoured deck is prioritized over a redesigned gun battery layout and stronger catapults. The jets aren't in service yet, anyway.

[m10bob]

Pertinent?


http://en.wikipedia.org/wiki/Armoured_flight_deck

[Don Bowen]

ORIGINAL: m10bob

Pertinent?


http://en.wikipedia.org/wiki/Armoured_flight_deck

Doesn't directly answer any of the questions, but very interesting - thanks.

Friedman says the Iwo Jima was to have 60 STS deck armor.

[msieving1]

ORIGINAL: Don Bowen

ORIGINAL: m10bob

Pertinent?


http://en.wikipedia.org/wiki/Armoured_flight_deck

Doesn't directly answer any of the questions, but very interesting - thanks.

Friedman says the Iwo Jima was to have 60 STS deck armor.

60lbs armor would be 1.5" thick, which is about half what the British carriers had on the flight deck.

[oldman45]

From the net;
Special treatment steel is a high-quality nickel-chrome steel that was used extensively as structural steel in U.S. warships of the Second World War. It was similar to Class B armor plate but was produced in thicknesses of less than 4". It provided significant splinter protection but was rarely expected to stop a direct hit from a shell.

Not sure what the Navy department was going for if they were using STS.

[m10bob]

Another site:

http://www.enotes.com/topic/USS_Iwo_Jima_%28CV-46%29

[dwg]

ORIGINAL: Don Bowen

ORIGINAL: m10bob
Pertinent?
http://en.wikipedia.org/wiki/Armoured_flight_deck

Doesn't directly answer any of the questions, but very interesting - thanks.

It does mention one factor that's going to be the salient factor in the rework - the hangar deck was the strength deck on the Essex, everything above that is superstructure, whereas on the UK CVs the strength deck is the flight deck. Trying to replicate that would mean a fundamental change in the Essex design and all of the stress and strength calculations would need redoing from the bottom up - effectively you're designing a new ship. So presumably what we're looking at is instead a reworking in which the strength deck remains the hangar deck, but plating is simply laid on at flight-deck level. That would likely also mean that the supporting structure for the flightdeck would need reinforcing, so it isn't simply a one-for-one swap of wood-decking for STS, but it's close. Equally the hangar sides would need to change, the USN used an open box hangar to allow aircraft to warm up before they were brought to the flightdeck, the RN relied on a sealed armoured box hangar and the Iwo Jima would need armoured sides to get the full benefit of the armoured deck, which is rendered pretty pointless if the kamikaze flies into the hangar from the side... Enclosing the hangar would mean slower flight ops and force the Iwo Jima to operate more in the RN fashion. Other changes are pretty much incidental.

The only parts of this that WITP AE simulates are deck and belt armour thicknesses, it doesn't simulate having two deck levels and different levels of protection for each, it doesn't simulate different armour levels between belt proper and hangar side, all we can do is boost the deck armour level by 38mm (1.5in) and maybe the belt armour as well.

(And of course the irony is that just as the USN looked at British style armoured hangars the RN was seriously looking at moving to US open hangars with the Maltas)

[YankeeAirRat]

Looking at U.S. Aircraft Carriers: An Illustrated Design History, Dr. Friedman mentions how the USS Iwo Jima was probably going to get the "future fleet carrier mod" to it which would have eventually become SCB-27 and SCB-27A. He also mentions how there was talk of removing the 20mm and replacing them with a 30 to 37mm auto cannon setup and replacing the 40mm with the 3/50 Mk22 style mounts. Along with movement of the elevators to the deck edge and better catapults and arresting gear to handle the F7F and the BT3D (A2D Skyshark).