He believed that this arrangement would minimize the number of drag-inducing struts and bracing wires needed, improve stability and increase lift.

[1][2] Delage first tried out his design by modifying a two-seat Nieuport 10 equipped with a 90-horsepower (67 kW) Le Rhône 9C rotary engine.

[3] Delage based his next triplane, serial numbered N1388, on a single-seat Nieuport 17 biplane that was armed with a synchronized Lewis machine gun forward of the pilot.

It was powered by a 110-horsepower (82 kW) Le Rhône 9J rotary fitted with Nieuport's cone de penetration.

Reserialled as A6686, it performed time-to-height tests up to 10,000 ft (3,000 m) on 2 February and demonstrated times that were slightly superior to those of the Nieuport 17.

This was based on a Nieuport 17bis airframe with the 130-horsepower (97 kW) Clerget 9B rotary engine and was allotted the serial number N521.

11 Squadron RNAS were flown in April which revealed that the triplane was 3–4 knots (5.6–7.4 km/h; 3.5–4.6 mph) faster than the biplane at ground level.

The biplane may have been equipped with a 110-horsepower (82 kW) Clerget engine which would have caused the slight superiority in speed rather than any merit of the design.