The aircraft was powered by a single 150 hp (112 kW) Hispano-Suiza 8 water-cooled V-8 engine in the nose driving a tractor propeller.

[5] The type demonstrated excellent handing during testing, being capable both of flying aerobatic manoeuvres while still being stable enough to be easily flown "hands-off".

[6] Despite this, the type was rejected for service as a patrol aircraft, but it was recommended that it instead be adapted into a float-plane trainer.

[5] Sage also designed a revised version, the Sage Type 4c with folding wings of increased wingspan (39 ft 7+1⁄4 in (12.07 m) compared with 34 ft 6 in (10.52 m) for the earlier aircraft and powered by a 200 hp Hispano Suiza engine, with a prototype flying on 12 October 1918.

[7] Both the Type 4b and 4c were adopted as standard training floatplanes for the RNAS, but the end of the First World War resulted in production plans being abandoned.