Why didn't the F4U-4 replace the F4U-1D and FG-1D in 1945?

As I understand it, the first deliveries of the F4U-4 were in November 1944, the "dash-4" made a small-scale combat debut in the Okinawa campaign in April 1945, but as of August 1945, the majority of the Corsairs on the carriers were still 1D models. What caused the slow roll-out of the F4U-4?

With the end of the war, the US didn't really want to buy more aircraft, they had plenty already in service, and a lot of pending contracts were cancelled. If there wasn't a HUGE improvement in performance, there wasn't any need to buy more of XXXYYY. It was time to get back to a peacetime economy.

They did build over 2000 F4U-4s. Slow roll out might have depended on how fast P & W could get them the engines.
The F4U-4 used the "C" series engines which were only built By P &W Hartford in 1944.
P & W Kansas city was making single stage "C" engines, Nash Kelvinator was making 2 stage Bs, Ford was making single stage Bs. Chevrolet was just getting started on single stage "C"s. There are NO interchangeable parts on a B series and a C series engine for any practical purposes.

I know that Goodyear never built dash-4s. Goodyear proposed its own F2G, but was not given a full production contract.

IMO, It also seems to be a matter of situation and necessity.

There was no clear threat at that time. Already the superiority of F4U-1s and F6F-3/5 was solid when 1944.

and for PTO squadrons, change of the aircraft was not always quickly as possible. generally, it was done when they returned from the tour(and redeployment), in addition delivery of the planes was done slowly by the transport ship or aircraft carrier. so it's delayed by their tactical or rough situation.

The frontline was far from the homeland especially when end stage of the Pacific War, and it was not the land but the sea. for combat, PTO fighters needed an island with airfield which near the frontline, or operational aircraft carrier for naval fighter.

So In fact, the deployment speed of the F4U-1 was not that fast either. The service was launched hastily declared at the end of the 1942, but throughout the 1943, Marines Corsair's peak squadrons number was just eight and usually less than that. especially in the early few months, only VMF-124 was barely operational.

F4U-4 started service with the Marines as F4U-1, but some aircraft carriers that had to leave the frontline at that time could also bring the F4U-4 on the deck.

For example, the USS Hancock, which was attacked by Kamikaze, bring the own F4U-4 to its deck when returning to Pearl Harbor for repair. As a result, the USS Hancock was able to use the F4U-4 to attack the Japanese mainland.

According to 4 August 1945 Location of US Naval Aircraft Index, The USN had more than 20 squadrons with more than 500 F4U-4s even except Marines and service squadrons, but only about 220 F4U-4s on the carrier deck.

Due to the environment of the Pacific Front and the distance from the homeland, I feel that US PTO fighters were seems disadvantageous in terms of the deployment speed compared to the most ETO fighters.

IMO, As like ETO situation - If the battlefield was close to the America mainland and there is a threatening situation where the performance of later PTO fighters like the F4U-4 or F8F-1 is strongly demanded, the deployment may have been accelerated. Of course that could not happen realistically.

It seems to me that the Navy could have been practicing a form of "first in - first out" inventory management. That would make sense especially due to the need to make sure that the front line units were supported with adequately trained personnel and spare parts.

F4U-4 deliveries to the Navy began in 1945. It would be tough to have it happen any earlier. When F4U-4 deliveries began, there were already 5,400 Corsairs in service, not all of the overseas. You don't get to replace 5,400 aircraft immediately.

Production rates ramp up from low initial numbers to maybe a couple hundred or more a month. Even if they hit 400 a month, they wouldn't replace 5,400 planes for more than a year. By that time, the war was over.

GregP said:

F4U-4 deliveries to the Navy began in 1945. It would be tough to have it happen any earlier. When F4U-4 deliveries began, there were already 5,400 Corsairs in service, not all of the overseas. You don't get to replace 5,400 aircraft immediately.

Production rates ramp up from low initial numbers to maybe a couple hundred or more a month. Even if they hit 400 a month, they wouldn't replace 5,400 planes for more than a year. By that time, the war was over.

Click to expand...

US Navy has never operated 5,400 Corsairs at the same time. It is equal to the amount of all Corsairs produced in a year.

Therefore, the USN does not need to try to replace 5,400 Corsairs. They were already being replaced by themselves, and there were far less Corsairs in service at same time.

According to August 1945 Location of US Naval Aircraft Index, USN had 38 VF/VBF squadrons with about 1200 Corsairs - including more than 500 F4U-4s.

So just before the end of the war - after more than half a year the Corsairs on carrier deck, it's still about 1200, and more than 40% of them were F4U-4.

Veering slightly off topic. What planes used single-stage "C" R-2800 engines? I guess the P-47N and P-47M did (because those planes had exhaust-driven turbochargers, but what else?

Conslaw said:

Veering slightly off topic. What planes used single-stage "C" R-2800 engines? I guess the P-47N and P-47M did (because those planes had exhaust-driven turbochargers, but what else?

Click to expand...

Typically, there's a cat series of Grumman - F7Fs and F8Fs.

They were very fast at low altitudes.

At least some F8Fs used a single-stage variable-speed supercharger. The variable speed making up for some of the limitations of the single-stage design. Some German engines also used variable speed superchargers.

Variable speed does not make up any limitations in a single stage design. It eliminates the "notch" between high and low gears.
Early Bearcats got engines with a two speed drive, 7.29:1 low gear and 9.45:1 high gear.
later Bearcats got the engine with variable drive which could vary from 7.29 to 1 up to 10.55 to one. they also had a different supercharger for this drive system to work on.

how much of the improvement was due to spinning the impeller faster and how much was due to the change/s in the supercharger itself I don't know.

The Navy works up squadrons with identical aircraft, not just planes and pilots, but also maintenance personnel and spare parts train. At some point squadrons would be rotated out of front line duty and replaced by another that had been working up. One reason the F4U's etc were not deployed earlier to carriers wasn't only deck landing, but the logistics of having more than one fighter type in inventory. Parts certainly important, at one point the Navy had Grumman stop aircraft delivery and just put out PARTS. It go so bad that, need some new tires for your F6f? Easier to push it over the side and get a new one rather than the tires. The F4U-4 was a very different airplane than it's predecessors.

Early war new model SBD's and F4F's did trickle in to replace losses. Naval Aviation living a leaner lifestyle then.