The Fouga Magister was derived from a glider post WW2 (part of the Marshal plan I believe, to develop a jet trainer.) The glider had a conventional tail, however, Fouga decided to mount a single jet engine on top of the fuselage; the tail was in the efflux! The simple solution was to move the tail surfaces into a V shape - et voila. Having done that subsequent iterations found twin engines buried in the wing roots, but the tail remained.