By Nicholas Drummond
When aircraft aficionados on the European side of the Atlantic consider the top aircraft of WW2, many tend to ignore those of the Pacific theatre. We can more or less agree that the Spifire, Lancaster and Mosquito were the finest British-designed aircraft of WW2; or that the Focke-Wulf FW190, Messerschmitt ME109, and Messerschmitt ME262 were their German counterparts, but what of US aircraft? Since many types were primarily used in the Far East, their overall contribution to the War can be overlooked or understated. Therefore, the aim of this article to is consider the Top Ten US aircraft of World War 2, so that lesser-known types, as well as the usual suspects, gain the recognition they deserve. Secondly, it is to show that behind these extraordinary machines was an aircraft industry unequalled in its scale, ambition and innovation. In Land Warfare, US industrial might was used to punch-out overwhelmingly superior numbers of armoured vehicles to counter the high quality of German tanks. In Air Warfare, however, the US aircraft industry was committed to uncompromising technical superiority and in doing so repeatedly pushed back the boundaries of what was possible. In drafting a list of the top US aircraft of the period, the final goal is to highlight some of the stunning milestones that were achieved and the fact that they were accomplished over an extraordinarily short period of time.
Tenth place goes to the Douglas SBD Dauntless dive-bomber that equipped US Navy aircraft carriers. Conceived in 1935 and introduced into service in 1940, it was approaching obsolescence by the time Japan attacked Pearl Harbour. In June 1942, when Japan attacked again at the Battle of Midway, the Dauntless was the only carrier-borne strike aircraft that existed in large numbers. Referring to the aircraft’s SBD designation, pilots frequently described it as “Slow But Deadly” and this is exactly what it proved to be. Torpedo attacks against Japanese ships by Douglas TBD Devastators at Midway were ineffective, but Dauntless squadrons managed to drop a large number of bombs with great precision, destroying three Japanese carriers, the Akagi, Kaga and Soryu, within the space of a few minutes. The attacking aircraft drew a large amount of flak, but thanks to the Dauntless’s rugged construction, many crews still managed to limp home despite gaping holes shot through their aircraft wings. Though unsophisticated in comparison to the aircraft that would soon follow, the Dauntless was reliable, easy to fly and easy to maintain. What it lacked in speed in agility, it made up for with sheer usability. These qualities would become hallmarks of all US military aircraft and were decisive in helping the US Navy to turn the tide in the Pacific.
In ninth spot is the Lockheed P-38 Lightning. This was an advanced twin-engined fighter that was designed to combine high speed with exceptionally long range. The P-38 was the first American fighter to make extensive use of stainless steel and smooth, flush-riveted butt-jointed aluminium skin panels. It was also the first military aircraft to fly faster than 400 mph (640 km/h) in level flight. Although it was used with only limited success in Europe, it triumphed in the Pacific, where its sheer speed allowed it to outclass the Japanese A6M Zero, which had dominated the skies before its arrival. The P-38 became the primary fighter of the Pacific theatre and created more aces than any other USAAF aircraft. It was flown by America’s Ace of Aces, Major Richard Bong, who achieved 40 kills in his P-38. The Lightning was a stable and forgiving aircraft to fly, while its twin-engine configuration made it safer should an engine be lost. But, the P-38 was not perfect and suffered from compression issues when diving, which could cause its controls to lock-up, sometimes with fatal results. The issue was not completely fixed until 1944. Even so, the P-38 was fast and lethal. With a 20 mm cannon and four .50 Caliber machine guns, all mounted close together in the nose, it could accurately engage enemy planes at 1,000 metres, further than most single-engine fighters.
Eighth place belongs to the Republic P-47 Thunderbolt. This 8-tonne brute weighed more than twice as much as a Spitfire and carried eight .50 Caliber machine guns. It was the primary USAAF single-engine fighter in Europe until the Mustang arrived. Its sheer power, immense speed and imposing presence made it a favourite with pilots and a fighter feared by those who flew against it. It was one of the few aircraft that could take-down a Messerschmitt ME262 jet engine fighter. The P-47 followed a proven formula that built a robust airframe around a large and powerful engine. The Pratt & Whitney R-2800 Double Wasp 18-cylinder radial engine developed 2,000 hp (1,500 kW). As well as being able to carry bombs and rockets, the P-47’s airframe that could withstand severe punishment. These features made it a great ground-attack aircraft as well as a good fighter.
In seventh spot is the North American B-25 Mitchell twin-engine medium bomber. Developed just prior to WW2, it went into production at the same time as the faster and more sophisticated Martin B-26 Marauder. But the latter aircraft was dogged by teething troubles, which made the B-25 a dependable fall-back option. The B-25 was considered to be a solid, but unadventurous design, but in combat proved to be the better aircraft. It was more dependable, easier to fly, easier to operate and easier to maintain, earning the affection of the air crews that flew in it and the respect of ground crews that maintained it. The Mitchell achieved fame when it was used for the Doolittle Raid as a reprisal for the attack on Pearl Harbour. It was the only twin-engine aircraft capable of taking-off from a carrier and flew 2,000 miles through the addition of extra fuel tanks, to bomb Tokyo. Thereafter, it was used by America’s allies, as well as by the USAAF, in Europe, the Middle East, China, Burma, India and the Pacific. It was steadily improved throughout the war and emerged as one of the stand-out US twin-engine medium bomber designs of the period.
Coming in at number six is the Consolidated B-24 Liberator. This was one of three four-engined heavy bombers developed by the USA during WW2. Its advanced wing design gave it good lift characteristics, a high cruising speed, long range, and the ability to carry 18,000 pounds (7,200 kg) of bombs in two separate bomb bays – twice as much as the B-17. The Liberator introduced the first tricycle undercarriage in a four-engine aircraft and self-sealing fuel tanks, which did much to improve aircraft survivability when hit. It proved itself not only as a bomber, but also for maritime patrol, cargo and transport roles. Few other aircraft had better long-range reliability making it ideal as a transatlantic shuttle. Operating in all roles across all Allied theatres, 18,482 B-24s were produced, including some 4,600 manufactured by Ford. This workhorse holds records for being the world’s most widely produced bomber, the sixth most widely produced aircraft of WW2 and the most widely produced American military aircraft.
Fifth place belongs to the Grumman F6F Hellcat, which was the most important US Navy carrier-borne fighter. Superior in every way to the more numerous Grumman F4F Wildcat, which it replaced, the Hellcat used the same engine that powered the Republic P-47 Thunderbolt and Vought F4U Corsair. Although the Hellcat was slightly slower and less agile than the gull-wing Corsair, the latter aircraft was also plagued by development gremlins that were only fully resolved towards the end of the war. In the meantime, the Hellcat was available when it counted and, like the P-38 Lightning, could outperform the Japanese A6M Zero. The Hellcat achieved the highest kill ratio of any US Navy aircraft with only one lost for every 19 enemy aircraft downed. Hellcat pilots were credited with destroying 5,163 enemy aircraft, which represented 56% of all US Navy and USMC kills during WW2, creating 305 Hellcat aces. The US Navy’s top-scoring ace, Captain David McCampbell, scored all 34 of his victories in a Hellcat. Like the B-25, the Hellcat’s extraordinary reliability was a force multiplier when operating from carrier decks.
The Boeing B-17 Flying Fortress takes fourth place for its astonishing contribution to the USAAF’s daytime bombing campaign in Europe. It dropped more bombs than any other US aircraft in WW2, or some 640,000 tonnes out of 1,500,000 tonnes (which was 43% of the total). The B-17 was a four-engine, low-wing monoplane that combined the aerodynamic features of Boeing’s XB-15 bomber design, with the Model 247 transport aircraft. It was the first Boeing military aircraft to have a proper flight deck instead of an open cockpit. The B-17 carried around 4,800 pounds ( 2,200 kg) of bombs and five .30-caliber machine guns mounted in clear blistered canopies. Its enormous tail was designed to provide improved control and stability during high-altitude bombing. After raids over Germany, B-17s would return to England peppered with flak holes and only two of their four engines working. Few other US aircraft, if any, had a better record for absorbing damage. Some 12,700 B-17s were manufactured.
In third place is the Douglas DC-3 Dakota / C-47 Skytrain. While not a combat aircraft, this rugged and versatile twin-engine military transport was noteworthy for its Its logistic contribution to the Allied war-effort. Frequently used to airdrop urgently needed supplies, it was fast, had good range, and could operate from short runways. The twin-engine configuration was reliable and easy to maintain. Before the war it pioneered many civil air travel routes. It could cross the continental United States and made commercial international air travel possible. It is considered to be the first airliner that could profitably carry just passengers. Total production of all variants was 16,079 and it was estimated that over 400 remained in commercial service in 1998. Few other aircraft have provided greater utility, been used more widely or shown greater longevity. This is not just a great military aircraft, but one of the most important commercial aircraft of all time.
The North American P-51 Mustang takes the second spot because it was the best all-round fighter aircraft of the war. Not only could it defeat all enemy aircraft it encountered in combat, including the Messerschmitt ME262 twin-jet fighter, it had the longest range of any single-engine combat aircraft, enabling it to escort bombers all the way to their targets and home again, which even the legendary Spitfire could not do. The P-51 started life as a private venture by the North American company, who offered it to the Royal Air Force when it was approached to manufacture additional Curtiss P-40 Warhawk fighters. North American developed and produced the first airframe within 117 days of the order being placed. Initially, the Mustang used the Allison V-1710 engine, with a single-stage turbocharger. This offered only limited high altitude performance, so the first Mustangs were used primarily for low-level reconnaissance and ground attack roles. Disappointed by Mustang’s loss of power when climbing above 15,000 feet, the RAF sought advice from Rolls-Royce. An engineer suggested fitting the Spitfire IX’s Merlin 61 engine, which had a two-speed, two-stage inter-cooled supercharger. Initial flights with Rolls-Royce’s Merlin engine took place in late 1942. The result was a power boost from 1,200 hp (895 kW) to 1,620 hp (1,208 kW) which increased top speed from 390 mph to 440 mph, while the service ceiling rose to almost 42,000 feet. The USAAF, which had been following Mustang development, while at the same time seeking to arrange for Packard to license-produce the Merlin in the USA, was astonished when it saw the performance gains. It placed an immediate order for 400 aircraft in August 1942, several months before the first Packard-Merlin equipped P-51 even flew. The first upgraded P-51Bs were delivered in the autumn of 1943 and made their combat debut soon after. Their impact was immediate. Accompanying B-17 daylight bombing raids into the heart of Germany, they comfortably outperformed German Focke-Wulf FW190A and late mark Messerschmitt ME109Gs, which had been the bane of the B-17’s existence. This massively reduced bomber losses and increased the effectiveness of the daylight bombing campaign. The definitive version was the P-51D, which had six .50 Caliber machine guns instead of four and a distinctive bubble cockpit. By May 1945, Mustangs had helped the Allies achieve total air supremacy and accounted for almost 5,000 enemy aircraft destroyed, which was half of the USAAF’s total and the most claimed by any Allied fighter in Europe.
The Boeing B-29 Super Fortress takes the No. 1 spot, because, more than any other single aircraft, it contributed to the defeat of Japan. It was a technological tour de force that introduced a number of notable innovations, including a pressurised cabin, a dual-wheeled tricycle landing gear, and an analog computer-controlled system that allowed a fire-control officer and two gunners to direct four remote-control machine gun turrets. With a maximum take-off weight of 124,000 pounds (56,245 kg) and wing span of 141 feet and 3 inches (43.05 metres), it was one of the largest aircraft of the war. Its service ceiling was 31,850 feet (9,700 metres) and it had a top speed of 365 mph (587 km/h). While its first bombing missions from the Marianas Islands achieved only limited success, the B-29 slowly but surely began to make its presence felt over Japanese cities, culminating in the dropping of the first atomic bomb on Hiroshima and then a second on Nagasaki. Even before nuclear weapons reduced these cities to dust, the conventional bomb load of the B-29, at 20,000 pounds (9,091 kg), was significantly greater than that carried by either the B-17 or B-24. Conceived in 1940, the Super Fortress flew for the first time in 1942. The aircraft cost $3 billion to develop (equivalent to $42 billion today), which far exceeded the $1.9 billion cost of the Manhattan Project, making it the most expensive defence programme of WW2. The B-29’s advanced design allowed it to remain in service in various roles throughout the 1950s. It became a blueprint for postwar airliner design and its cockpit layout is often described as the inspiration for the Star Wars Millennium Falcon. The B-29 was retired in the early 1960s, after 3,970 had been built.
Six further WW2 US aircraft are noteworthy, but didn’t make the top 10:
- Vought F4U Corsair single-engine fighter
- Grumman TBF-1 Avenger torpedo bomber
- Douglas A-20 Havoc twin-engine attack bomber
- Martin B-26 Marauder twin-engine medium bomber
- Curtiss P-40 Warhawk single-engine fighter
- Consolidated PBY Catalina twin-engine flying boat
- North American Harvard single-engine trainer
What is exceptional about all of the aircraft listed above is that they were designed, developed and fielded within a 10-year period, between 1935-1945. All, with the exception of the P-51 Mustang and P-38 Lightning, used radial engines as the US Army Air Force and US Navy considered these to be more reliable than in-line units, with greater potential for tuning, supercharging and refinement. The Pratt & Whitney R-2800 Double Wasp was an 18-cylinder, air-cooled, radial engine that had a displacement of 46 litres. Developed in 1937, it was used in at least six different US combat aircraft. Early versions produced 2,000 hp (1,500 kW) but, by 1944, developmental versions could generate as much as 2,800 hp. Powering the F6F Hellcat, F4U Corsair and P-47 Thunderbolt, this engine offered astonishing levels of performance, enabling aircraft fitted with it to fly at speeds in excess of 400 mph. The Double Wasp remained in commercial use until the 1960s. The Wright R-3350 Duplex-Cyclone was another twin-row, supercharged, air-cooled, radial engine with 18 cylinders. Power ranged from 2,200 hp (1,640 kW) to more than 3,700 hp (2,760 kW). Developed prior to WW2, it started life in 1927 as the single-row Wasp and gradually grew in power and sophistication as Curtiss-Wright responded to requests for ever greater levels of power. The Wright Duplex-Cyclone was used in the B-17 and B-29 bombers and powered a variety of postwar airliners. More than 30 different aircraft used it and it was still in use well into the 1990s.
The leading WW2 US military aircraft also perfected the use of stainless steel and riveted aluminium construction techniques. Moving to an all-metal airframe changed aircraft manufacturing processes. Riveted aluminium offered increased structural integrity plus greater flexibility in wing design. This enabled aerodynamic performance gains through more innovative wing shapes with higher wing aspect ratios for increased lift and lower drag. It also enabled fuel and weapons could be carried within the wing. In contrast, many European aircraft designs of the period still relied on trussed airframes overlaid with canvas.
Steel and aluminium parts allowed complex sub-unit assemblies to be manufactured independently of the main airframe. Consequently, manufacturers could sub-contract the production of sub-assemblies to different suppliers. While the primary manufacturer would focus on the overall design and performance envelope of an aircraft, sub-contractors would refine the individual components for which they were responsible. This accelerated development times and pushed design boundaries. It made the development process highly collaborative as new ideas were shared and incorporated into new aircraft types. The systems and processes that were in place by 1945 enabled the US aircraft industry to surge ahead after the war and assume the global leadership position it still enjoys today.