The Coelho AC-11 (also called the AC.11 and AC 11) is a Brazilian homebuilt aircraft that was designed and produced by Altair Coelho of Eldorado do Sul and introduced in 1994. The aircraft was intended to be supplied as a kit for amateur construction, but only one was completed.
The aircraft features a V-strut-braced low-wing, a two-seats-in-side-by-side configuration enclosed cockpit, fixed tricycle landing gear or optionally conventional landing gear and a single engine in tractor configuration.
The aircraft fuselage is made from welded steel tube, while the wing is plywood, with some surfaces covered in doped aircraft fabric and some covered in plywood. Its span wing has a wing area of and employs a NACA 4412 airfoil. The cabin width is . The acceptable power range is and the engine used for the prototype was a Volkswagen air-cooled engine with a steel-pulley and polyurethane chain-driven 2:1 reduction drive.
The aircraft has a typical empty weight of and a gross weight of , giving a useful load of . With full fuel of the payload for pilot, passenger and baggage is .
The standard day, sea level, no wind, take off with a engine is and the landing roll is .
The manufacturer estimated the construction time of the prototype as 1600 hours.
By 1998 the company reported that one conventional gear version of the aircraft was completed and flying, while a tricycle gear version was under construction.