The F-22 Raptor, a stealth fighter aircraft from Lockheed Martin, first flown in 1997. Titanium alloy (principally grade 5, Ti 6-4) makes up around one-third of the aircraft. Hot isostatic pressing was utilised on large cast parts, such as the canopy deck and wing side-of-body, to minimise porosity and so enhance strength to weight and reliability.
Around 350 parts, one-quarter of the aircraft by weight, is made up of resin transfer moulded (RTM) carbon fibre reinforced epoxy composite. High performance carbon fibres are used, such as T700 for lower cost parts, T800 for higher strength parts and T1000 for ultrahigh strength applications. Examples include the fuselage frame, doors, wing spars and honeycomb sandwich panels. Advanced RTM resin systems for these type of applications include epoxy and bismaleimide.
The canopy consists of two sheets of polycarbonate (PC), sandwiched between two layers of glass, fusion bonded in an autoclave and drape formed. Indium-tin-oxide is vacuum deposited onto the canopy to reflect radar waves (scatters radio waves in various directions so as not to be detected by radar), which gives it a golden colour tint. Image Lockheed Martin Aeronautics.
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