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F-22A Raptor ? Air Dominance

F-22A Raptor ✯ Air Dominance

By any measure, the development of the F-22A was revolutionary - in the technology employed and from a stealth design point standpoint - and this produced a combat aircraft that has no equal.

Being able to carry weapons internally was essential to its stealth capability, and efficient supercruise. Given the role away from dedicated air superiority, rather than incur the costs of resizing the compact main internal bays of the F-22A, sized initially around four early AIM-120A AMRAAMs, the US Air Force embarked on the 'Small Smart Bomb' program centred on the idea of carrying a payload of multiple 250 lb class bombs. Today's 385 lb GBU-39/B and GBU-40/B Small Diameter Bombs (SDB) were sized around the F-22A weapon bay. For the intended role of busting an opponent's airfields, mobile missile batteries, and command posts, the mix of either two GBU-32 1,000 lb JDAMs or eight GBU-39/40 SDBs is an excellent fit. With all-aspect stealth and penetrating supersonic at 50,000 ft AGL, the F-22A remains virtually unstoppable by surface-to-air missiles or fighters. It is likely that operational F-22As will be used far more frequently to break down an opponent's air defences than in the classical air superiority role, despite the aircraft retaining the full air superiority capabilities envisaged for the ATF.

Refined supersonic aerodynamics allowed the F-22A to exceed Mach 1.5 in military thrust at altitude - the exact top speed in dry thrust has never been disclosed. In early trials, F-15 chase aircraft could not keep up, and test pilots soon reported instances where even modest heading changes by F-22A prototypes in head-to-head engagement geometries caused opposing teen series fighters to abort engagements entirely - an experience historically seen only in engagements against Foxbats and Foxhounds.

In the simplest of terms, the supercruising F-22A kinematically defeated all opposing fighters, and even without stealth would kinematically defeat most existing surface-to-air missile types. The only design with the potential to kinematically challenge today's F-22A are advanced derivatives of the Su-30 fitted with supercruising AL-41F fans, the Russian equivalent to the F119-PW-100 engine in the F-22A, and an LRIP production item since 2004.

The unchallenged aerodynamic performance of the F-22A design required considerable design innovation, and extensive use of new materials techniques. At nearly 40 per cent of total empty weight, the F-22A had the highest fraction of Titanium alloy in any US design since the SR-71A, which compares closely to the Russian Sukhois. Resin Transfer Molded (RTM) thermoset composites, specifically epoxy and high temperature bismaleimide (BMI) composites, made up 24 per cent of total empty weight. New processes, such as Hot Isostatic Pressed (HIP) casting and vacuum chamber electron beam welding were introduced to allow complex high strength shapes to be fabricated from Titanium alloys, primarily Ti-64 and Ti-62222, minimising the number of fasteners used. Only 16 per cent of the F-22A's empty weight comprised Aluminium alloys. Like the B-2A, geometrical accuracy is critical to stealth performance, and the F-22A required similar production tolerancing.

The F119-PW-100 supercruising thrust-vectoring engine proved no less challenging. The 'short and fat' F119 engine was built with integrally bladed rotors, using high strength long chord fan and compressor blades, floatwall combustors exploiting high Cobalt content alloys. Heat resistant Titanium Alloy C was used extensively in compressor stators, the afterburner and nozzles. The part count in the F119 was reduced by 40 per cent against the earlier F100/F110 engines to improve reliability and maintainability. Extensive self diagnostic capabilities were incorporated to reduce personnel and test equipment demands on deployment by 50 per cent against the F-15. The F119-PW-100 is typically cited in the 35,000 lb static SL thrust class. The nozzles provide 20-degree deflection, used for manouevre and for supersonic cruise trim drag reduction. An Airframe Mounted Accessory Drive (AMAD) is used to couple engine power to generators, hydraulic pumps and shaft power to the engines from the Air Turbine Starter System (ATSS).
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