the McDonnel-Douglas 520 helicopter has no tail rotor and instead has a fan in the tail which utilizes the coanda effect to counter act main rotor torque http:

the McDonnel-Douglas 520 helicopter has no tail rotor and instead has a fan in the tail which utilizes the coanda effect to counter act main rotor torque http://en.wikipedia.org/wiki/MD_Helicopters_MD_500#MD_520N http://en.wikipedia.org/wiki/MD_Helicopters_MD_500#MD_520N http://en.wikipedia.org/wiki/NOTAR http://en.wikipedia.org/wiki/NOTAR