Most of Roland Payen's aircraft were tailless designs but the Plein Air was strikingly conventional.
The wings were rectangular in plan and the lift struts were V-form pairs from the lower fuselage.
[2] The Plein Air had a flat sided fuselage which tapered to the tail.
This was conventional, with a straight edged fin and rudder with a rounded top.
The tourer had a fixed tail wheel undercarriage with main wheels on split axles mounted on the central fuselage underside; the legs were faired-in V-struts from the lower fuselage.