To Paint Or Not
To paint or not paint the fuselage is open to debate. The paint does add weight to the aircraft, depending on size, 300 to 600 pounds. If the aircraft remains unpainted, the aluminum skin, typically, Aluminum alloy 2024 (Aluminum & copper) - Good fatigue performance, fracture toughness and slow crack propagation rate, will oxidize over time, giving the appearance of not being well maintained. American Airlines has an unpainted fuselage fleet, but polishes their aircraft to keep them bright and shiny. Some claim the cost to do this outweighs the cost to have a painted fleet, eliminating the fuel savings advantage. So for pure cargo freighters, if you don't care about appearance, unpainted planes will save fuel in the long run, but, will not look very nice as the aluminum ages (oxidizes). Note: The wings are painted and use a different aluminum alloy than the fuselage for various reasons.
Turbine D