A significant part of aeronautical science is a branch of dynamics called aerodynamics, which deals with the motion of air and the way that it interacts with objects in motion, such as an aircraft.
When you pour a liquid from one container to another, the liquid takes the shape of the container. The volume of the liquid is the same. The properties that solids and liquids share are that they both have definite volume.
Molecules in solids are packed a lot closer together than molecules in liquids and gases, so there is far less space between solid particles. Because of this, solid particles cannot move around quickly and freely like liquids and gases, instead they only vibrate so are fairly 'locked' into the same place, so solids have fixed volume and space.