The Caudron C.251 Et-2 was a French tandem seat, open

cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

designed as an intermediate trainer and built in 1931. It did not go into production.

Design and development

The two seat, open

C.251 was designed to replace the ubiquitous

Caudron C.59 The Caudron C.59 was a French, two-seat biplane with a single engine and a canvas-covered fuselage, produced between 1922 and 1924. Suitable for a variety of roles, more than 1,800 Caudron C.59s were manufactured. Operational history The Caudron ...

, 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 The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

on a pair of short, vertical, N-form

cabane strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

s. The slightly shorter span lower wing was mounted on the lower fuselage

longeron In engineering, a longeron and stringer is the load-bearing component of a framework. The term is commonly used in connection with aircraft fuselages and automobile chassis. Longerons are used in conjunction with stringers to form structural ...

s 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 Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord ( ...

except near the straight but angled wing tip. Only the lower wings carried

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

s. It was powered by a Lorraine 7Me Mizar seven cylinder

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...

which had a Townend ring type cowling and drove a two blade metal

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

with a conical

spinner Technology *Spinner (aeronautics), the aerodynamic cone at the hub of an aircraft propeller * Spinner (cell culture), laboratory equipment for cultivating plant or mammalian cells * Spinner (computing), a graphical widget in a GUI * Spinner (MIT Med ...

. 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 The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third ed ...

was conventional, with

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplane ...

and elevators mounted on top of the fuselage and having a planform similar to the wins, apart from a cut-out for

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

movement. The

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. 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

References

{{Caudron aircraft C.251 1930s French military trainer aircraft Biplanes Single-engined tractor aircraft Aircraft first flown in 1931