One seldom addressed issue with the F4U is that it failed carrier compatibility trials. Consider that the prototype was flying on May 29, 1940, while the F6F prototype first flew in late June of 1942. Vought had delivered less than 60 fighters by November of 1942. Two and a half years after the prototype had flown, production was merely a trickle and these aircraft suffered from many problems still. During the first months of production, there were constant changes and updates being made right on the production line. Vought was establishing themselves as a very inefficient manufacturer. It took Vought almost four years to get the F4U sorted out for its designed purpose. Meanwhile, Grumman got it right coming out of the starting gate with the XF6F-3.
Contrary to standard WWII mythology, the F6F was not designed to combat the Zero. In June of 1941, the Navy issued Grumman a contract to design and develop an improved Wildcat as a back-up to the Vought F4U. The Navy was unwilling to place all of it cards on Vought's table, especially since Vought had not established that the F4U would be a success. Hindsight shows that this caution was not only justified, but a God send.
Thirteen months after the XF6F-3 flies, the Hellcat is in combat flying from the Essex, Yorktown, Independence, Princeton and Belleau Wood with VF-33 operating from Guadalcanal as well.
Grumman's philosophy was "build 'em simple, build 'em strong and build 'em quickly." In March of 1945, Grumman's Plant #3 delivered 605 F6F-5s, a record that was never beaten by any other American manufacturer from a single factory during the war or since. In fact, Plant #3 actually delivered 658 aircraft that month, including 48 F7Fs, 2 F8Fs and 3 Goose Amphibians. During the whole of its production life, the F6F saw the fewest changes to the basic design of any fighter still in combat at the war's end. It was simply that good from the outset.
So, what about performance and general usage? Both aircraft have their merits and their weaknesses. However, the F4U's weaknesses were generally chronic and somewhat more severe than those of the Hellcat.
In terms of handling, the F6F was superior, especially "around the boat". Benign stall characteristics, good view of the flight deck and a wing that generated tremendous lift all contributed to the Hellcat being a safe and easy fighter to operate from a carrier. On the other hand, the F4U stalled far more violently, and visibility over the long nose was very poor. Stall characteristics improved a great deal with the addition of a wing spoiler to counter the violent wing drop of early aircraft, but it never came close to the F6F in that area of the flight envelope. In terms of deck handling, both aircraft were stable, even in crosswinds. Yet despite substantial improvements in the F4U, it was always inferior to the F6F in the ability of the pilot to see while on the ground or flight deck.
One can never underestimate the importance of good handling and visibility around the boat or on the flight deck. Accidents often resulted in more aircraft and pilots lost than in actual combat. Accident rates for the F6F were substantially lower than for the F4U throughout the war. It must be understood that the Navy was always willing to trade a little performance for safety and no one could credibly argue that the F6F was not the better fighter in terms of safe carrier operations.
While the F4U was far from ideal flying around the boat, it proved to be a very capable fighter away from the ship. Early models were poor climbers and slow accelerating in level flight. Nonetheless, high-speed handling was outstanding. If used according to its strengths, it could easily dominate the Japanese fighters. At low levels, the F4U was considerably faster than the F6F. This is attributed to the use of direct ram air into the intake system. In the simplest of explanations, this acted much like a supercharger, providing for pressure air and thus, a more dense air charge. On the other hand, Grumman preferred to route intake air through the accessory section where it was warmed prior to entering the carburetor. This was in line with Grumman's conservative design approach. Pre-warming the intake air eliminated the problem of carburetor icing that would often lead to the engine losing power, or simply stopping altogether.
What this boils down to is that the F4U had more power available at low altitude and that is reflected in a speed differential of nearly 30 mph at sea level. In exchange, the F4U risked carburetor icing, especially under certain weather conditions.
Maneuverability is a subjective issue, but I will delve into it using available data and calculations.
First, let's examine an Energy Management Diagram created by one of our Trainers; Badboy, and currently part of his excellent energy management article located at SimHQ
here. I suggest reviewing the article so as to understand what the diagram demonstrates. This diagram is based upon the Aces High F6F-5 and F4U-1C. Nonetheless, it generally represents real world reports and performance calculations, although some other sources give the Hellcat an even larger advantage.
Rather than repeat what Badboy states in his article, I will simply state that the F6F could easily turn inside the F4U. You might question this because these aircraft were of similar weight and the F6F's wing area is only 20 square feet greater than that of the F4U. What apparently makes the difference is the lift coefficient. In Francis Dean's epic work on US WWII fighters, he calculates a minimum turn radius index based upon how much a wing is loaded divided by how efficient the wing is in lifting. The Maximum Lift Coefficients used by Dean are 2.27 for the F6F-5 and 1.48 for the F4U-1D. Dean uses test data for 3g stall speeds, which corresponds to 139 IAS for the F6F-5 and 172.5 mph IAS for the F4U-1D. Resulting calculations show an index differential of 35% favoring the F6F.
However, turning ability alone does not establish a winner. Both aircraft were very capable fighters and many consider the F4U superior overall. Each has its proponents and detractors. Grumman never improved rearward visibility, which virtually everyone who flew the plane in combat thought was its single greatest weakness.
Maximum speed issues have been discussed elsewhere in this thread. Let it be stated that there was no great difference between them at their critical altitudes.
If we examine how each type impacted the war, we can only conclude that the F6F was a more important fighter than the F4U. Because it was aboard carriers in mid 1943, the F6F fought the major air battles of the Pacific war and utterly crushed Japanese Naval air power. Yet, had the F4U passed carrier qualification a year sooner and had been aboard the carriers, the result would have been the same. Although statistical evidence suggests that the F4U may have suffered greater loss.
Final war time stats give the F6F a 19:1 kill to loss ratio, while the F4U comes in with an 11:1 ratio. Both are impressive, but the Hellcat's borders on rediculous.
Another interesting fact not generally known centers on the F6F and F4U as bomber escorts. Generally, most people think of the P-51 as the premier bomber escort of WWII. Yet, within the context of their environment, the Hellcats and Corsairs did an equally impressive job. From December of 1944 through mid August of 1945, Navy bombers (SB2C and TBMs) escorted by F6Fs and/or F4Us suffered only 8 aircraft shot down by Japanese fighters.... just eight. Moreover, many of these raids were over the Japanese home islands.
Maybe we should let the Japanese tell which they thought was the better of the two. Historian and author Henry Sakaida surveyed a number of surviving Japanese aces and when asked what American fighter they feared most, the majority said, "the Hellcat". Some examples:
Sadumu Komachi- "I think the best enemy fighter plane I fought against was the F6F. It was faster than our Zero and more powerful. It could dogfight, whereas the F4U could not. There was nothing more frightening than a Hellcat on your tail."
Takeo Tanaimizu- "The F4U was a tough plane, your bullets would just bounce off. I think the toughest opponent was the Grumman F6F. They could maneuver and roll, whereas planes like the P-38 and F4U made hit and run passes. The F6F could actually dogfight with us, and it was much faster and more powerful than our Zero."
Saburo Sakai- "The F6F was the best U.S. Navy fighter. I fought them over Iwo Jima for the first time in June of 1944 and I was shocked at how much Grummans had improved since 1942."
Sadaaki Akamtsu- "In my opinion, the P-51 was the most dangerous American fighter because of its incredible speed. After the P-51 I believe the F6F was the most dangerous, because it was faster and more maneuverable than my Raiden."
You can draw your own conclusions as to which was better, but within the context of history, there's little doubt about which was the war-winning fighter in the Pacific. It shot down more Japanese aircraft than the F4U, P-51, P-47 and P-38 combined. It scored the highest number of kills by one pilot during one sortie (9 kills, 2 probables). History shows that the honor of most important Naval fighter goes to the Grumman F6F.
My regards,
Widewing
