Why haven't shrouded tail rotors or no tail rotor (NOTAR) designs taken over in the helicopter market? Most choppers in production are still using unshrouded tail rotors. - Quora
NOTAR - No TAil Rotor Helicopters - Redback Aviation
MD 902 Explorer - MD Helicopters
Want to Learn to Fly a Helicopter? Which is the Best Training Helicopter - For You? - YouTube
No-Tail-Rotor Helicopter
MD530F High Performance Helicopter Overview - The True Sports Car of Helicopters. S6|E5 - YouTube