The water drains on the aircraft usually pops out under its belly because of the streamlined shape of the aircraft.
All aircraft, not just jets, have shapes as streamlined as possible to enable them to fly faster and use less fuel.
5x5
"A separate streamlined enclosure on an aircraft for sheltering the crew or cargo or housing an engine. "
the both fly and have a streamlined shape.
This reduces the drag caused as the aircraft passes through air
The aeroplane has evolved more slimmer, streamlined and aerodynamical.
because they cut through the atmospheres pressure with more ease than another shaped aircraft
Streamlined design, higher fuel capacity than other contemporary aircraft.
You need to make it streamlined at the front so it cuts through the air therefore making it move faster.
Because even a streamlined body is still material moving through a fluid and interacting with the fluid. This is more usually referred to as drag and consists of several componets:form dragskin frictioninterference drag
Kind of hard to understand your wording, but the body shape is generally designed to make the aircraft as streamlined as possible.