# Why the plane is white

In a freshman class at the Department of Physics at a Nihon University, Professor Satoshi Kudo asked a question: Why should the airplane be painted white? Indeed, approximately 90% of aircraft in the world are white in appearance.
“White is beautiful” “White is more conspicuous”… The students talked a lot, but no one could give an exact explanation.
Professor Satoshi Kudo shook his head. He told everyone that at first, except for the military aircraft painted with camouflage, the other aircraft were basically naked with metal fuselages. After the birth of the jet aircraft, the aircraft began to fly to an altitude of more than 10,000 meters, exposed to strong sunlight, and collided with dust, and the fuselage of the aircraft was prone to metal fatigue. In order to protect the fuselage, people began to paint the aircraft.
What color is it painted? this is a problem. Among the various colors of paint on the market, the cheapest one is white. Among the common coatings commonly used in airplanes, white coatings are 17% cheaper than color coatings.
”It turned out to be a cost issue!” a classmate said loudly. Professor Satoshi Kudo nodded, and then said: “Not only that.”
It turned out that to paint the airplane with color paint and make the color appear clear, you must first apply a layer of white paint as a primer before you can start the coloring. The amount of paint for a large aircraft is about 570 liters. If painted white, the cost is about 3 million yen. If it is painted red, then not only the white primer has to be applied, but also the cost of about 3 million yen for the red paint. The total cost is about 6.54 million yen-more than twice that of the white paint.
Of course, the paint also affects the weight of the fuselage. After the white paint is applied, the weight of the fuselage will increase by about 250 kg, and the red paint will increase the weight by about 250 kg. If you fly from Tokyo to London, the extra weight will cost about 55,000 yen.
In addition, 250 kg is about the weight of 3 adults. If it is a flight from Tokyo to London, when the one-way fare is 100,000 yen, the fare for three persons is 300,000 yen. If the flight is three times a day, the total is 900,000 yen. Cumulative air ticket sales in a year amounted to 328.5 million yen.
“God! There is still such an account to be settled!” The students couldn’t help exclaiming. Professor Satoshi Kudo smiled and went on to say that since the aircraft is constantly basking in the sun, the adjustment of the internal temperature of the aircraft and the cost of cooling must also be considered. In addition, whether it is rust, oil leakage or other malfunctions, the white body makes these abnormal signs more conspicuous, so it also has an advantage in terms of inspection convenience.