Actually I recounted my ship list in hangar and it is 21 ships. It is like Pokemon, have to collect them all. The Hull series though is debatable...although that Hull E would look nice with the Orion. They share a similar design.

Vanguard,Retaliator,Redeemer,Reclaimer,3 Constellations,Orion,All Auroras,All 300 Series,All Commercial Hornets, All Hulls, Star G, Endeavor Master Set