Yes, BARNSTORMER is a Scrabble word!

Letter values in Scrabble US: B 3, A 1, R 1, N 1, S 1, T 1, O 1, R 1, M 3, E 1, R 1.

Is it a valid word?

BARNSTORMER is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an actor who travels around the country presenting plays
a pilot who travels around the country giving exhibits of stunt flying and parachuting

Also: play-actor, stunt flier, stunt pilot.