This strange “thing” was a test vehicle employed by Messerschmitt-Bölkow-Blohm (MBB) to validate the fly-by-wire control systems intended for the future generation of fighters. With the help of ballast to change the centre of gravity CoG, this Fokker-built F-104 was transformed from a conventional naturally stable aircraft into a unstable platform. Equipped with a triple.redundant fly-by-wire system, this Control Configured Vehicle (CCV) testbed took the skies in 1977. Not having enough, in 1980 a sort of vestigial F-104’s tailplane was added on the forward spine also for aerodynamic destabilizing purposes. The very profitable data acquired during its tests helped in the design of both the X-31 and the EFA.
That extra tail sure did the trick. More and More.