Because non-smooth surfaces cause drag, which slows down the airplane, causes excess noise, and increases fuel consumption.
Aircraft do have propellers , unless they are jets.
It was obvious he'd merely streamlined my report! Won't today's jets fly faster if they become more streamlined? This team will operate much more efficiently after I've streamlined it.
Piston aircraft use gasoline and Jets use a form of kerosene
Streamlined Bodies
They have streamlined bodies so that they can cut through the wind and air
Aluminium
The reason streamlined bodies can move faster in liquid and air is because they have less surface area to cause resistance. For instance, on a windy day, an open umbrella has more resistance and can get caught up in the wind but a closed one with less resistanceÊcan not.
So they can swim faster (;
Many military jets can fly up to or over 50,000 feet.
To increase the average speed
aerodynamic or streamlined
They need bodies like this because they dive and swim in water. This form makes it easier to do that.