Rotor/wing aircraft having a low-drag flap are disclosed. In one embodiment, a rotor/wing aircraft includes an elongated blade having a body portion and a flap portion. The body portion has first and second edges and includes a non-symmetric portion proximate the second edge. The flap portion is moveably coupled to the body portion proximate the second edge and is moveable between a rotary flight position and a forward flight position. In the rotary flight position, the flap portion is proximate at least part of the non-symmetric portion to form a second symmetric portion proximate the second edge. In the forward flight position, the flap portion extends away from the non-symmetric portion to form a tapered portion proximate the second edge.