With a view to replacing the Caudron R-XI then in service with French escadrilles de protection (bomber-escort squadrons) Leon Kirste projected the Bleriot 107M in 1922. This was developed into the Bleriot 117M, which flew initially on 19 June 1924. The small twin fins and rudders of the tailplane proved ineffective, and flight characteristics were poor. However, Kirste persevered with the basic concept, replacing the 298kW Lorraine 12Db engines with more powerful Hispano-Suiza 12Gb units, and designed a new tail unit with a large single fin and rudder. The single Bleriot 127 prototype flew on 7 May 1926. The modified Bleriot 127/2, first flown on 10 January 1928, had more powerful Hispano-Suiza 12Hb engines, with radiators located under the wings to reduce drag. Pilot and copilot were located in open side-by-side cockpits with dual controls. After successful tests, this version was ordered to a total of 42 aircraft, built over a four-year period.
The Bleriot 127 was a mid-wing monoplane, largely of wooden construction. Its unusual feature was provided by the gunner's positions: one was accommodated conventionally in the fuselage nose, but two additional positions were provided in wing trailing-edge extensions to the engine nacelles. Intended to provide a virtually unlimited field of fire to the rear, these latter positions could be reached from the fuselage during flight, via the deep-section wing. The Bleriot 127 was in the M.4 category (four-seat multi-role aircraft) intended for bombing and reconnaissance, as well as fighter escort duties. Production aircraft equipped two escadrilles de protection of the 11e Regiment de Bombardement, stationed at Metz, first deliveries being made in April 1929. The Bleriot 127/2 proved cumbersome and ineffective in service, but was not withdrawn from first-line duties until the end of 1934.
The Bleriot 127/3 was a single night-bombing version; the Bleriot 127/4 was a Bleriot 127/2 with standard dual-wheel main landing gear units converted to.take large single wheels, initially with large 'trouser' type fairings.
Bleriot 137: this was an all-metal high-wing development, with twin midships gunners' cockpits, side-by-side just behind a large cut-out in the wing trailing,edge, replacing the Bleriot 127's nacelle positions. Two Bleriot 137s were built: the first, powered by Hispano-Suiza engines, was flown on 21 December 1930; the second, with Salmson engines, appeared a few months later. Of similar overall dimensions to its predecessor, though with more angular wing and tailplane outlines, the Bleriot 137 had a maximum speed of 230km/h.