There are a number of reasons why the entire surface of a passenger plane is not painted over. Firstly, ordinary oil-paint will not serve the purpose. Sometimes the plane is on the runway of an airport in the temperature of 50◦ Celsius and after a few minutes it is flying at the altitude of 30,000 feet above the sea level where the temperature is below the freezing point. Therefore, specially made polyurethane paint is used and it is very expansive. The job of painting takes up almost two weeks and during this time the plane remains unused. The loss of revenue on this account is substantial. As a result the cost of painting only 1/3 surface of a jumbo jet is a whopping $ 24,000 approximately. Moreover, almost 500 liters paint is necessary to paint 1/3 surface. This amounts to a permanent increase of half a ton in the payload. The engines have to work so much more and consume additional fuel. A plane traveling from Delhi to Kochi would burn up to half a ton more fuel to carry this extra load. Imagine the overall costs involved in painting the entire surface of the plane!
However, most of the passenger planes made today are painted fully.
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