Strike-grade (or SG) us the term used to describe any small ship fitted with it’s own Faster-Than-Light drive. These ships are able to jump-travel short distances under their own power. This freedom to operate without a ‘mother’ ship gives them a flexibility in attack and defence unrivalled by other fightercraft. They have a price tag to match, however.
Hangar-grade (or HG) is the term used to describe any small ship reliant on landing within a larger ship to travel Faster-Than-Light. This lack of range and dependence on a larger ‘mother’ craft means this class of ship are often found defending static targets. However, miniature jump drives are very expensive to produce and maintain. Hangar-grade ships are significantly more affordable and engineers can use the space not taken up by a jump drive for weapons, shields or other functionality.
Rack-grade (or RG) is the term used to describe a small ship reliant on a larger ship for FTL travel. Unlike hangar-grade ships, however, rack-grade fighters are equipped to attach themselves to a ‘mother’ ship’s specially fitted, external mounting rack. These frames supply power, fuel and oxygen to a number of ‘racked’ ships at once. These external racks can be fitted to the smaller capital ships which traditionally have insufficient internal space for a functioning hangar bay. And although travelling for many hours on an external rack can be extremely uncomfortable for the fighter pilots, the tactical advantage of having a small number of snubfighters is often significant.