Every surface, such as windows and panels, was warm to the touch by the end of the flight.[109] Besides engines, the hottest part of the structure of any supersonic aircraft is the nose, due to aerodynamic heating. The engineers used Hiduminium R.R. 58, an aluminium alloy, throughout the aircraft because of its familiarity, cost and ease of construction. The highest temperature that aluminium could sustain over the life of the aircraft was 127 °C (261 °F), which limited the top speed to Mach 2.02.[110] Concorde went through two cycles of heating and cooling during a flight, first cooling down as it gained altitude, then heating up after going supersonic.