go get gold medals on beggar's canyon, death star trench run, and battle of hoth, and you *should* be able to get all ships on all levels except for the speeder missions, rescue on kessel, taloraan, and the bonus levels.
Battle is a pure form of expression. It is heart and discipline, reduced to movement and motion. In battle, the words are swept away, giving way to actions-- mercy, sacrifice, anger, fear. These are pure moments of expression.