While not exactly 'flapless', blown flaps have used compressed air as part of the flap system for quite some time (it's even had time to fall out of favor due t

While not exactly 'flapless', blown flaps have used compressed air as part of the flap system for quite some time (it's even had time to fall out of favor due to complexity and costs!) http://en.wikipedia.org/wiki/Blown_flaps http://en.wikipedia.org/wiki/Blown_flaps (Though it does look like the article linked refers to ailerons and elevators, not flaps proper).