Wolfox

Wasnt there this one gundam that could transform into a fighter jet? The nose section becoming the head?

Anyway, the head may also have some aerodynamic function when flying at high speed in the atmosphere. You always see them fly headfirst after all. Minimize drag = extend effective combat radius

@Busti  That can apply to a few different U.C. Gundams, but the most prevalent would be the Zeta Gundam and it's Waverider form.  Not sure if that's the one you are thinking of.

Actually, mobile suits aren't designed to fight aerial combat under gravitational pull. So the head doesn't have any role for providing aerodynamic function of the mobile suit.

Even for transformable mobile suit like Zeta Gundam and Wing Gundam, which has fighter-jet form, its aerodynamic function are covered by parts such as curvy shield that attached to the front in flight mode. Later transformable mobile suit like Delta Plus or ReGZ, has some parts integrated to provide aerodynamic support in flight mode.

Non transfomable mobile suits mostly rely on support flight unit like Base Jaber or Dodai, which used similar to hoverboard, to allow them fight in aerial battle. They also could be attached to the mobile suit as well.

Of course, the concept don't really apply to mobile suits whose body parts are made up of fighter units, like ZZ Gundam.