The drop-tanks were mentioned first time in Jornal #3 when detailing the Gazelle class Close Escort and have then grudgingly been added to whatever ship design rules there are. Drop tanks, in my opinion, causes all kinds of canon problems such as whu doesn't X-boats use them? Why are there no big warships with drop tanks? Why doesn't the bulk carrier ships have drop-tanks?
Simpy put; does any of you referees out there actually use them and treat them as canon and therefore common?
My design system doesn't have any provisions for drop-tanks but I have added alternative hydrogen storage systems (water, ammonia, methan all store more hydrogen per cubic meter than LHyd) and that certainly breaks canon.