The BS.17 was intended to complement the earlier and successful BS.16 primary glider by providing the enhanced performance required to take new pilots to qualifications beyond the A certificate.

Centrally, the wings were supported over the fuselage on the same cross braced trapezoidal structure used originally on the BS.16 and later on several other Bonomi gliders.

The tail was different from that of the BS.16; although the same triangular tailplane and parallel chord, cropped tipped elevators were used, they were mounted on top of a low, straight edged fin.

A new, large, balanced, angular rudder, hinged at the extreme tail extended down to the keel, operated in a cut-out between the elevators.

[1] The Allievo Cantù was well received by Italian gliding clubs, who used it to take novice pilots to their B certificate and gain experience above that level.