Acutally both existing
stealth planes the
F-117A and the
B-2 are bombers. The upcoming
F-22 will be an air-superiority fighter.
The reason these things are so ugly (specially the F-117A) is / was the lack of
computing power when it was designed. The knowledge on how to design
stealth planes has been around quite some time (... to-do : find out original mathematicians name) but the computing power to actually implement it, hasn't.
The trick is to have no
surface of the
airplane directly reflect
radar-energy back to the transmitting
radar (who would see a
radar-return) but to deflect it in other directions. The more modern
B-2 bomber was designed with more computing power at hand. Therefore the designers were able to use all
curved surfaces instead of the straight edges used on the F-117A and the F-22.
Also,
radar-absorbing materials are used as coating for the planes.
Talking about
undergunned: The F-117A is only able to carry two
LGB and has no other
defensive or
offensive weapons (like a
gun or
Air-to-air missiles on board).
Also the stealth planes are not
invisible as seen in the 1999
Kosovo conflict, when one was
shot down. During the
Gulf war the F-117A only went out on night-sorties so that the
enemy wouldn't be able to spot them.