Developed over the past 20 years, the next generation of helicopters and rotorcraft are ready to hit the market.

Should the bolded word be "rotorcraft" or "rotorcrafts" , I know for aircraft/watercraft/spacecraft the one word takes care both the plural and singular format.
The sentence sounds weird having a singular word after "helicopters" though, in my opinion.

http://www.merriam-webster.com/dictionary/rotorcraft

plural rotorcraft

I have seen the plural used as rotorcrafts, but the plural is rotorcraft.

Perhaps change the order of rotorcraft and helicopters.

Thanks guys, just wanted to make sure since this is for my aerospace engineering teacher lol.

since you are talking about two different technologies my recommendation would be:

Developed over the past 20 years, the next generations of both helicopters and rotorcraft are ready to hit the market.

This post was edited by brmv on Apr 15 2013 07:16am

This is the best way put. Go with that.

here's another sentence plural written without it:
"Rotorcraft generally include those aircraft where one or more rotors are required to provide lift throughout the entire flight."
so yeah without the 's'

This post was edited by Trillasecond on Apr 15 2013 07:46pm