U.S. ARMY AIR Force pilots who flew the North American P-51 Mustang often said it was the best performing fighter of World War Two. Many might agree. Many, but not all.
Navy and Marine Corps aviators who flew the Vought F4U would argue that the Corsair, hands down, holds the title as best fighter of the Second World War.
So, who’s right? Let’s take a look at how the airplanes performed when flown head-to-head.
Mustang and Corsair: Later Arrivals to World War II
Although the first prototypes took to the skies as early as 1940, It wasn’t until early 1944 that B-model variants of the P-51 were just starting to arrive in meaningful numbers.
By that point in the war, the U.S. Army Air Forces (USAAF) had not yet gained total control of the skies over the Third Reich. Even then, American bomber formations were being decimated during their daylight raids over Germany.
During the same period, the U.S. Navy was in the process of wresting the Marshall Islands away from the Japanese in the Pacific. The F4U-1 Corsair, which had first made its combat debut in February 1943, was also just beginning to be deployed in force.
Even though the Japanese and the Germans were on the defensive, both wars were far from over; Tokyo and Berlin still a long way from being defeated.
The P-51
Royal Air Force Mustang Is, which featured normally aspirated engines, first flew in combat on July 27, 1942.
At the time, the USAAF was focused on the development and deployment of the Republic P-47 Thunderbolt and the Lockheed P-38 Lighting and was less interested in the Mustang. The British soon ordered Mustang IIs with two 20-mm cannons in each wing. Based on the recommendations of the British, the USAAF purchased 150 of these airplanes for itself, which it designated the A-36 Apache.
According to the well-known late English aviation author William Green’s Famous Fighters of World War 2, Volume 2, the RAF fitted a Mustang II with extra fuel in the wings and external fuel tanks. Major Thomas Hitchcock, the USAAF military attaché in London suggested that the RAF thought that the turbocharged Merlin-61 engine could be mated to the P-51 and create one of the best fighters in the world. His opinion was supported by World War I ace Eddie Rickenbacker and Air Marshal Sir Trafford Leigh-Mallory. Four airplanes were delivered to Rolls-Royce for the conversion.
Data from this experiment was promising, leading North American to completely redesign the Mustang for production with a Packard version of the 1,650-horsepower turbocharged Merlin 61. Two were built in the U.S. and were delivered to the USAAF for testing as the XP-51B.
Ultimately, 2,200 P-51B/Cs would be produced and were the first P-51s flown in combat by the USAAF. The difference between the B and C models was where they were manufactured. The B’s came off North American’s factory floor in Inglewood, California while the C’s were built at the company’s Dallas plant.
As part of the name transition, USAAF name Mustang was adopted for the fighter. The A-36 dive bomber version kept the Apache moniker.
Vought F4U Corsair
As reported in a previous article in MilitaryHistoryNow.com, the Corsair was designed to meet a 1938 U.S. Navy requirement for a single-seat shipboard fighter. Vought’s design team set out to create the fastest fighter ever built. Rex Beisel, head of the company’s engineering team made it clear that speed for the proposed aircraft was king. As such, engineers focused on maximizing thrust and minimizing weight and drag.
The new fighter would incorporate the largest engine under development at the time: the 18-cylinder Pratt & Whitney R-2800 Double Wasp twin row radial. The powerplant pumped out an impressive 2,000 horsepower. Water/alcohol injection in later versions could add another 450. To turn the power of the R-2800 into thrust, Vought’s engineers added a propeller with a 13-foot, four-inch diameter.
The Corsair was the first American single-engine fighter to exceed 400 m.p.h. in level flight.
The Mustang vs. Corsair Trials
In late January and early February 1944, the U.S. Navy conducted a comparison of both airplanes at the Naval Air Station, Patuxent River, Maryland. The planes tested included a P-51B, a F4U-1 and a F4U-1A.
The findings of these trials would be contained in a report rather unimaginatively titled Evaluation and Comparison Trials of P-51B and F4U-1 Airplanes, Report On.
Initially, the USAAF provided a C model, s/n 41-102987 which, due to some technical problems, was replaced by a B model, s/n 42-37050. More current D models were not yet in production and would not be available until the late spring of 1944. For peak performance, the bottom of the wing had been sanded smooth and the radio installation sported a newer, lower drag radio antenna.
Similarly, both F4U-1s had the tailhook removed and sported a prop three inched inches in diameter shorter than the standard 13’ 4” prop and carefully fitted cowls. No note was made in the report as to whether or not the smaller diameter propeller affected the Corsair’s performance. The gap where the wings fold had additional fairings to reduce drag.
Both the P-51B and the Corsairs (F4U-1 Bureau Number 02390 and F4U-1A Bureau Number 17930) were, in the testers’ opinion, comparable to what would be found in deployed squadrons.
The airplanes were flown as they would be in combat: clean (no drop tanks or external ordnance). All carried a full load of ammo for the guns.
The P-51B was flown at two different take-off weights, 9,100 lbs. and 9,453 lbs. while both F4U-1s weighed 12,162 lbs. throughout the comparison when they left the ground.
Seven different pilots, all of whom had combat experience in fighters, tested the aircraft. Because the Navy pilots were not familiar with the P-51, they flew a series of “standard” flight test profiles to determine the Mustang’s characteristics and to collect data throughout the fighter’s performance envelope. Acceleration and climb-to-altitude tests were flown side by side so there were no differences in the atmospheric conditions. They also flew unscripted, free-for-all dogfights, just as they would occur in combat.
Even though both airplanes had the same armament – six .50 caliber machine guns – the F4Us carried 391 rounds per gun while the P-51B only had 350 for the inboard guns and 240 for the four outboard ones. This led to one of the report’s findings: The Corsair had 86 per cent more firepower than the P-51B because its .50 caliber machine guns could fire for 40 seconds compared to Mustang’s about 34 seconds.
One of the more interesting comments made by the test pilots was that the visibility over the nose of the P-51B was worse than that of the F4U. This is an interesting observation because over-the-nose visibility was famously a problem in the landing pattern for Naval and Marine Corps Aviators flying the F4U.
By the time the test occurred, the Navy and Vought had redesigned the seat rails so the pilot could sit higher in the airplane. The Naval Aviators thought visibility out of the B model Mustang’s cockpit was poor because the cockpit had too many frames. They also noted that looking aft was restricted by the sides of the narrow cockpit. Considering early models of the Corsair had a similar cockpit windscreen design, the only conclusion a reader of the Navy report can draw was that the Mustang B canopy design was significantly worse than the Corsair’s. Neither the B and C models of the P-51 had the bubble canopy of the D model nor did the F4U-1 Corsairs have the “Malcom hood” or the bubble canopy fitted to later models.
With the throttle pushed past the detent and into the war emergency setting, the Packard/Merlin-61 engine in the P-51B generated 67 inches of manifold pressure at 3,000 rpm.
Both Corsairs had water injection to reduce detonation at high power settings. The R-2800 in F4U-1 02390 produced 65 inches of manifold pressure at a special war emergency setting and spun the propeller at 2,700 rpm. F4U-1A’s (Bureau Number 17930) engine was kept at 60 inches at the same rpm.
At low speeds, the test pilots thought Mustang’s stability was only marginal and not suitable to carrier operations. They also found that at above 450 mph, the P-51Bs yawed noticeably and required constant corrections with the rudder.
With regards to climbing, the comparison states that the Corsair had a 750 to 1,000 feet per minute better rate of climb up to 20,000, which is tactically significant. Above that, the Mustang had the advantage, however.
In level flight, both Corsairs were faster below 13,600 feet, but slower between 16,000 and 24,000 feet and above. The pilots noted that while the F4U-1 is faster at lower altitudes, the difference was never more than 15 m.p.h. Of the two Corsairs tested, the F4U-1A was noticeably slower than the F4U-1. No reason why was given.
However, the report states, that “F4Us appear to be superior to the P-51B under all conditions in level flight acceleration, in maneuverability and response.”
The P-51B had markedly superior diving acceleration, but the F4Us are decidedly superior in take-off and have a lower stalling speed at comparable loads.
Four sentences from the report summarize the findings of the pilots who flew both types.
The report states:
- It is concluded that, in general:
- There is little to choose between the P-51B and F4U-1 airplane in speed between sea level and 25,000 feet, and that above 25,000 feet, the P-51B is superior.
- That the F4U-1 is everywhere considerably superior in climb, at any comparable loading and superior in all other performance elements except diving speed.
- The F4U-1 is everywhere superior in maneuverability and response.
- With equal endurance, the F4U carries about 86% more armament and that it is a better gun flatform.
- In summary, the F4U-1 airplane appears to be the superior fighter for Naval or Marine employment, either land for ship-based except in the case where substantially all the fighting occurs above 25,000.
Pretty strong stuff. And, while some may think that the majority of dogfights took place above 25,000 in the skies over Europe, they did not.
Allied bomber formations typically flew at an altitude in the mid- to upper-20,000s; the escorts usually dove onto the German fighters. As described in a previous article in MilitaryHistoryNow.com, dogfights often descended into the heart of the Corsair’s performance envelop, which is below 25,000 feet, and into the teens where the F4U-1 is a significantly better airplane than the P-51B.
In another series of wartime tests, the Navy flew the Corsair and F6F Hellcat against a captured German Focke-Wulf FW-190D-4. Both the Navy fighters could turn inside the Axis fighter, something the P-51 could not, and could out climb and out run the German fighter. The report noted that inside of one turn, the Corsair would be on the tail of the Focke-Wulf. This, however, is another article for another day.
Mustang vs. Corsair at War
So, what does all this mean? Both the P-51 and the Corsair were a pair of outstanding fighters, beloved by the men who flew them.
The nature of the war in Europe was different than the war in the Pacific. In Europe, except for several raids on Occupied Norway, the U.S. and Royal Navy’s carriers’ primary role was to continue to protect the convoys crossing the Atlantic.
Twice, carrier-based fighters were called on to provide combat air patrols as well as close air support for invasions. U.S. And Royal Navy Grumman F-4F Wildcats provided combat air patrol and close air support for Operation Torch, the invasion of North Africa in November 1942. Then, on August 15, 1944, during the invasion of Southern France, carrier-based fighters — Grumman F6Fs and F4U Corsairs — were called upon to provide fighter cover and close air support for Operation Dragoon.
However, in the Pacific, the reverse was true. The war against Japan was a carrier war. Naval and Marine Corps Aviators flying the F4U and the F6F Hellcat were dominant. Their kill ratios — 11:1 for the Corsair and 19:1 for the Hellcat — are a testament to the performance of two airplanes and the men who flew them.
Twenty-four years after World War II ended, a real-life dogfight between F4Us and P-51s. In that showdown, it was the Corsair that came out on top.
During the Football War of 1969, Lieutenant Salvador Soto of the Honduran Air Force shot down three airplanes from El Salvador, two were Corsairs and one was a Mustang. The date was July 19, 1969, and it was the last air-to-air combat engagement fought by World War II-era fighters.