Abstract: An attachable wing for an aircraft is disclosed. The attachable wing is configured to mount to the underside of the fuselage of an aircraft, such as a rotary wing aircraft (e.g., a helicopter) or a fixed wing aircraft. The attachable wing produces additional lift, which results in an increase in speed, and consequently, an increase in fuel efficiency and payload capacity. In some embodiments, the attachable wing is retractable to facilitate takeoffs and landings. Additionally, the apparatus may be made of a bulletproof or anti-ballistic material to protect the aircraft from incoming fire or crash damage. The airfoil apparatus provides additional lift, allowing for greater fuel efficiency and range of the aircraft on which it is installed.