I'm an engineer Cmdr ... all my awards and drops are for Battle Cruisers?

Can I fly a battle cruiser as a commander? I thought it was only Heavy Cruiser?

What am I missing?

It may say battlecruiser because it can be used by klingons also.

I'd be ok with that ... if anything was dropping for the Heavy Cruiser .... but its not. Seriously, everything that is coming my way is Battle Cruiser.

Then get yourself an Escort - anything that can be equipped on a Klingon Battle Crusier can be equipped on and escort - or Vendor/Put on the Exchange and get what you want. Yeah, the prices in general are a but outrageous, but if you're patient and look through all the pages of stuff you want - you'll eventually find a 'lowball' price. LT Cmdr. 15 and all MkIV gear of my choosing (and some in game research crafting) - picked up 4 or so items from the Exchange to get there. Kinda said in a way as I like my ship equpment so much, I doubt I find any further 'upgrades for the next 6 Levels/Grades.