Curtiss Aeroplane's success in delivering a U.S. Army fighter was in the classic P-40 "Warhawk" line. However, this was a pre-war design through and through and many attempts by the company to secure additional Army contracts in the fighter field ultimately failed. There were also attempts to improve upon the original P-40 product itself and these also fell to naught as competitors like Lockheed, Republic, and North American swooped in to nab the potentially lucrative Army deals on the table.
The XP-62 was devised by Curtiss to build a very fast fighter platform around the then-largest radial piston engine available - the Wright R-3350 "Cyclone 18". The work began even before the United States was to commit to the World War which came in December of 1941. During January of that year, Curtiss approached U.S. Army authorities with its plans and convinced them about the fighter's potential, managing to secure funding for the endeavor before the end of the month.
The Cyclone engine was already in the works, begun in 1936, but it had proved itself wholly temperamental to the point that delays were commonplace. Beyond its sheer size, the engine was rated for over 2,000 horsepower output and found its best use as the drive plant for the famous Boeing B-29 "Superfortress" heavy bomber still to come (this bomber used four such engines). Perhaps more interestingly was its use to power a more compact fighter aircraft - giving it unprecedented speed and performance factors to be unrivaled at the time. During this period, the Wright product was one of the most powerful of its kind - the Wright R-3350-17 model was selected to power the XP-62 design and provide upwards of 2,300 horsepower output. A turbo-supercharger was to also form part of the engine's installation. Because of the forces at play, a large diameter (over 13 feet) six-bladed contra-rotating propeller would be fitted to the front of the aircraft.
Beyond its massive radial, the aircraft was to feature modern metal skin construction, a pressurized cockpit for high-altitude flight and a then-impressive armament fit of 12 x 0.50 caliber Browning heavy machine guns. Alternatively, the machine guns could be supplanted by a battery of four to eight 20mm cannons for an even more powerful frontal "punch".
The end product became a stout monoplane aircraft featuring a deep fuselage with its turbo-supercharger intake duct fitted under the nose, ductwork being used to funnel air to the unit amidships. A raised fuselage spine aft of the cockpit restricted views to the rear but added internal volume for fuel, avionics and other vital components. The cockpit was covered over in a greenhouse-style canopy and sat just aft of the engine installation. The tail unit consisted of a rounded vertical tail fin emanating from the dorsal spine as well as mid-mounted horizontal planes. The undercarriage was of the typical tail-dragger arrangement and all-retractable. Instead of the intended machine gun array, the armament had now specifically centered on all-cannon armament - as many as eight.
Curtiss developed the aircraft under the "Model 91" product name and submitted its streamlined proposal in April of 1940. This was approved the following month and covered the prototype XP-62 and a production-quality XP-62A - the first to be readied by late 1942. As Curtiss engineers set to work but it was soon discovered that the troublesome engine would not be ready in time.
Despite this, a mock-up was available for review during December of 1941. By this time, the product's weight had ballooned and it was ordered that she be lightened (this led to a 4 x 20mm cannon armament as the agreed upon standard). The Army handed Curtiss an official production contract in May of 1942 to produce the finalized P-62A. However, this contract was rescinded as soon as July when the Boeing B-29 project required the selected Wright engine stock. Army authorities were also concerned about disrupting the Curtiss commitment to producing its P-40 and the Republic P-47 "Thunderbolt" fighters.
The XP-62 prototype continued in a reduced state as it no longer was given the sense of urgency it once had. First flight was finally recorded on July 21st, 1943 but this model was still stripped of its vital components and not representative of anything close to a production fighter aircraft. Within a few short months, the XP-62 program was cancelled in full (this occurring on September 21st, 1943) as better alternatives were available to the Army heading into the final years of the war. Curtiss attempted to convince the Army of the merits of converting the new aircraft to a low-altitude ground attack platform but there was already plenty of competition in this field from existing effective types as well as in-development models.
In the end, the XP-62 marked one of the final Curtiss products to emerge during the war years. Its P-40 design was its only truly classic fighter contribution and was never bettered before the end of the conflict. Only a sole prototype of the XP-62 was realized and its flying time only short-lived. If completed, the XP-62 would have showcased a maximum speed of up to 450 miles per hour (the original spec was closer to 470mph), a range out to 1,500 miles, and a service ceiling of 35,700 feet (hence its cockpit pressurization system - which also proved problematic). Dimensions included a length of 39.5 feet, a wingspan of 54 feet, and a height of 16.25 feet.