5er stack lvl 1 NSF vs 1er til 3er stack frigate lvl1 can do good: after each attack go back to hospital and heal full hp's. For 5er frig stack you need at least 2 5er stacks NSF and you will lose may be 40% but kill frigates, wich are moere expensive then NSF. also win economical war scoring.
high level frigates are too biting thing. But 3 5er lvl 3 can kill it with lvl5 hospital support too. Aircrafts can heal swifter then ships.