The Rutan Model 40 Defiant is a four-seat, twin-engine homebuilt aircraft with the engines in a push-pull configuration.

In 1979 the Rutan Aircraft Factory announced they would proceed with certification of a Defiant-based light twin.

Adequate financing was not secured for this project, and the design was modified for homebuilt construction as the Model 74, with the second aircraft (built by Fred Keller) appearing at Oshkosh 1983.

The Defiant is built using fiberglass layup over Styrofoam core shapes in the same manner as the Rutan VariEze.

[3] Unusually, the Defiant has a ventral, port offset, forward mounted rudder, as can be seen in pictures of the plane taxiing.