Phallic-Aircraft

Due to the peculiar shape of aircraft (this design is not a coincidence, since it is based on engineering calculations that minimize friction with air, this is known as "aerodynamic design"), which is phallic in appearance, can be used by the giantesses as a "substitute" for the virile member.

Simply put: the aircraft are treated as if they were penises.

The size of the airplanes
Let's consider the following premises:
 * An average penis is 3.88 centimenter thick (diameter).
 * An "average" modern airplane (like the Boeing 737 ) is about 3.88 meters thick (its cylindrical part).

It is easy to notice that the relative size is 100x.

The size of the spaceship
Let's consider the following premises:
 * An average penis is 3.88 centimenter thick (diameter).
 * The Nasa's Orbiter Vehicle (Space Shuttle) ) is about 5.94 meters thick (its cylindrical part).

You can notice that the relative size is 153.19x.

Optimal absolute sizes

 * For airplanes: 175 meters (a low super-giantess)
 * For spaceships: 268 meters (an average super-giantess)

Optimal relative sizes

 * For airplanes: 100x
 * For spaceships: 153.19x

Optimal special types

 * Relative giantess, although absolute giantesses are better for this.