The two seat, open
cockpit C.251 was designed to replace the ubiquitous
Caudron C.59, dating from 1922, as an intermediate
trainer aircraft. It was a
single bay biplane with N-form
interplane struts, its upper wing supported over the
fuselage on a pair of short, vertical, N-form
cabane struts. The slightly shorter span lower wing was mounted on the lower fuselage
longerons a little above the fuselage underside and, unlike the upper wing had some
dihedral. The wings had significant
stagger but were of similar plan, with equal and constant
chord except near the straight but angled
wing tip. Only the lower wings carried
ailerons. It was powered by a
Lorraine 7Me Mizar seven cylinder
radial engine which had a
Townend ring type cowling and drove a two blade metal
propeller with a conical
spinner. Behind the engine the fuselage was
fabric covered and flat sided, though with a polygonal underside and decking. The forward cockpit was under the upper wing
trailing edge where a slight cut-out improved the pupil's upward view. The instructor's cockpit was further back. The C.251s
empennage was conventional, with
tailplane and
elevators mounted on top of the fuselage and having a planform similar to the wins, apart from a cut-out for
rudder movement. The
fin profile was a shallow triangle; the rudder continued its upper line to a rounded tip and straight, vertical trailing edge. The C.251 had a fixed
tail wheel undercarriage and the rudder was slightly cut away below to give the tail wheel leg room for movement. The main wheels were mounted on half-axles attached on the central fuselage underside and hinged on faired V-struts from the lower fuselage longerons. Landing loads were absorbed by legs also mounted on the lower longerons. The C.251 flew for the first time in the first half of 1931. That October it went to the military testing department at
Villacoublay and was still there in January 1932. No production order followed and by February the sole C.251 was at
Saint-Cyr, on its way to the
Istres aviation school. ==Specifications==