The United States military has long been a leading pioneer of fifth generation technologies, developing the world’s first modern stealth aircraft in the 1980s and inducting the world’s first fifth generation fighter, the F-22 Raptor, into service in 2005. Since 2015 the U.S. military has fielded two fifth generation fighter aircraft in complementary roles, the heavy F-22 air superiority fighter and the lighter and unspecialised F-35 multirole platform. While the two aircraft were until 2017 the world’s first and only fifth generation fighters, there are significant differences between the two platforms in the roles they were designed to fulfil and in their capabilities. An understanding of these differences is key to understanding the roles of the two platforms in the U.S. military today and the strengths and shortcomings of each. Much like in previous generations, two U.S. fighters were designed with complementary roles to best fulfil the country’s needs in the fifth generation. The F-22, much like the F-15 Eagle and F-4 Phantom before it, was designed as an elite heavy fighter to engage the most advanced enemy combat aircraft and ensure a continuing U.S. advantage in the air. These air superiority platforms are more costly both to acquire and to operate, make use of more sensitive technologies, and are far more restricted in their exports compared to their lighter counterparts - with the F-15C exported to just three leading American allies and the F-22 banned from export entirely. The F-35 on the other hand follows on from the F-16 Falcon and the F-5 Freedom Fighter in fulfilling the role of a low cost and versatile light fighter capable of fulfilling any number of roles on the battlefield - but specialised in none of them. These fighters were designed to minimise costs, and were widely exported to all manner of U.S. allies and non aligned states. They lacked both the cutting edge capabilities and the sensitive technologies of their heavier counterparts and their export thus had far less risks associated should the fighters be compromised by an unreliable foreign operator - as occurred with both the F-16 and the F-5 in several cases.&nbsp; The F-22 was originally intended as a replacement for the F-15 as the Air Force's elite air to air combat platform, with an FB-22 strike fighter variant having also been designed to replace the F-15E Strike Eagle. The fighter’s elite combat role relative to the F-35 is strongly reflected in its air to air combat capabilities, with a number of leading figures in the U.S. military leadership having repeatedly stressed that the F-35 was never designed for and would struggle in an air superiority role.&nbsp;Former Air Force chief of staff Gen. Mark Welsh stated to this effect that the F-35 "was never designed to be the next dog fighting machine. It was designed to be the multipurpose, data-integration platform that could do all kinds of things in the air-to-ground arena.. it had an air-to-air capability, but it was not intended to be an air-superiority fighter. That was the F-22."&nbsp;Air Combat Command chief General Mike Hostage stated to much the same effect: "If I do not keep that F-22 fleet viable, the F-35 fleet frankly will be irrelevant. The F-35 is not built as an air superiority platform. It needs the F-22.” The F-22 can fly far faster and far higher, reaching speeds of Mach 2.25 and altitudes of 20km compared to the F-35’s below average speeds of Mach 1.6 and 15.3km altitude. This makes the F-35 by far the slowest modern fighter jet&nbsp;in the&nbsp;world, with among the lowest operational altitudes. Despite being 30% heavier, the F-22 remains far more manoeuvrable with its two F119 engines giving a respectable thrust/weight ratio of 1.08. The F-35’s single F135 engine on the other hand gives it a thrust/weight ratio of just 0.87. The F-22’s wing loading stands at just 377kg per square meter compared to the F-35’s 525, again demonstrating the F-22’s far superior manoeuvrability making it better suited to combatting the elite of an enemy Air Force in air to air combat. As a heavy air superiority fighter the F-22 was designed to penetrate deep into enemy airspace, and this is reflected in its formidable range of almost 3000km. The F-35, as a light short ranged platform, can in a range extending configuration reach ranges of just over 1,400km. Other significant advantages the F-22 retains over its lighter counterpart include a superior AN/APG-77 radar and an larger armament, with the Raptor able to carry eight air to air missiles where the F-35 carries a tiny payload of just four. The Raptor is designed to deploy advanced AIM-120D long range air to air missiles, the most advanced ever produced by the Air Force with a 180km strike range, whereas the F-35’s most formidable missile remains a low manoeuvrability variant of the AIM-120C, a missile restricted to just 105km. Not only does the Raptor have more and better missiles, but due to its higher speed and altitude it can impart more energy onto its AIM-120 missiles when firing than the F-35 can.&nbsp;Despite using a significantly older airframe designed in the 1980s, the F-22’s radar cross section remains over ten times smaller than that of its successor the F-35 making it far more survivable in beyond visual range combat - and leading some Western analysts to term the Lighting II a ”˜pseudo stealthy’ fighter.The F-35’s advantages over the Raptor remain its lower cost, lower maintenance requirements and higher potential for export to U.S. partners across the world. Another key advantage stems from greater investments in the platform’s long term production, which allows the military to regularly apply software upgrades where they today struggle to do so for the F-22. As the F-22 is a specialised air superiority platform, it also lacks the ability to carry high payload air to ground munitions internally, and while some bombs such as the B61 can be deployed by the Raptor other such as the AGM-154 cannot. Considering the F-35’s significant shortcomings in air to air combat relative to its heavier and more specialised counterpart, special considerations will need to be taken by both the U.S. military and their allies deploying the fighter against elite enemy air superiority platforms. The F-35 was never built to go head to head with elite fighters such as the fourth generation Russian Su-35 or Chinese J-11, and it is likely to struggle against these platforms without the support of the F-22. With U.S. allies such as South Korea, Japan and Israel unable to deploy the F-22, and with the U.S. Air Force itself having just 25% of its requirements for the Raptor met due to the premature termination of the program&nbsp;(and 0% for the Navy), this has serious implications for all these parties when facing capable adversaries with near peer aerial warfare capabilities. The situation is particularly dire when considering China’s induction of the Chengdu J-20 in 2017 and Russia’s induction of the Su-57 the following year, both highly capable heavy fifth generation fighters. While these platforms have at times been compared to the F-35, the only similarity shared with the lighter U.S. fighters is that they are currently in production where the F-22 is not. Both are heavy air superiority platforms with analogous roles and similar capabilities to the Raptor. Given the vast superiority of specialised heavy fighters when performing an air to air combat role, reliance on the F-35 for air superiority against such next generation is set to have dire consequences for the U.S. and its allies if facing the latest Russian or Chinese air superiority fighters systems.