The aircraft mechanics usually put propellors on.
There were no jet engines in the World War I era. Only with propellers could powered flight be accomplished.
To identify the pilot and the country he flew for.
I don't believe so. A hangar is a building for airplanes; a hanger is what you use to put clothes in the closet or frames on the wall.
The Wright Brothers put propellers on all of their planes. There were no jet engines then.
Airplanes have propellers and/or jet engines that create very powerful winds, much more than the wind caused by passing cars. These winds can pick up salt granules and throw them at high velocity, which can cause damage, depending upon where they strike.
sometimes, but they need to be on both sides or else the helicopter will lose its balance and crash! it is not beneficial if you put the lights on the propellers because they will move so fast you can't see them...
they were modifyed or put in muesuems
World War 2
You can't!
They had to have rubber to put tires on all the vehicles, airplanes, to make rubber washers, and anything the war enterprise needed rubber for.
Airplanes release greenhouse gases. They can cause ozone depletion.
When they don't work!
they didn't have any place to put their pets because the war was every where... :(