The Potez XVIII was a French airliner from the early 1920s, a three-engine

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 ...

carrying up to twelve passengers.

Design and development

The Potez XVIII airliner, displayed at the 1922 Paris Salon, was a development of the

Potez X The Potez X was a French 1920s general-purpose colonial transport aircraft designed and built by Potez. Development The Potez X was a three-engined biplane with a fixed nosewheel landing gear supplemented with a tailskid. The first variant was ...

colonial transport. It was an unequal span biplane largely built of wood, though with metal engines mountings and other fittings, engine nacelles and

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

surfaces. The rectangular plan wings were fabric covered. On each side, towards the

wing tip A wing tip (or wingtip) is the part of the wing that is most distant from the fuselage of a fixed-wing aircraft. Because the wing tip shape influences the size and drag of the wingtip vortices, tip design has produced a diversity of sha ...

s a parallel pair of

interplane 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 struts, which act in ...

s leaned outwards. Closer to the fuselage a parallel pair of V-form interplane struts formed a cradle for the outboard engines, mounted between the wings. These, and the third in the nose, were

Lorraine 8Bd Lorraine, also , ; ; Lorrain: ''Louréne''; Lorraine Franconian: ''Lottringe''; ; ; is a cultural and historical region in Eastern France, now located in the administrative region of Grand Est. Its name stems from the medieval kingdom of L ...

s, water-cooled V-8 engines, each producing ; cooled by cylindrical

radiator A radiator is a heat exchanger used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics. A radiator is always a ...

s hung beneath each engine nacelle.

Ailerons 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 ...

with aerodynamic balances extending past the wing-tips were fitted on the lower wing only. The flat-sided and -bottomed fuselage had curved upper decking, dropping towards the tail. Behind the engine cowling back to the rear of the passenger compartment the fuselage was

plywood Plywood is a composite material manufactured from thin layers, or "plies", of wood veneer that have been stacked and glued together. It is an engineered wood from the family of manufactured boards, which include plywood, medium-density fibreboa ...

-covered, with fabric covering aft. Pilot and engineer/navigator/radio operator sat side by side in an open

cockpit A cockpit or flight deck is the area, on the front part of an aircraft, spacecraft, or submersible, from which a pilot controls the vehicle. The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls th ...

ahead of the upper wing, with an internal door to the passenger cabin. Each passenger had a window, and there was a central passageway between the seats leading to a toilet and luggage compartment at the rear. The

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 the

tailplane A tailplane, also known as a horizontal stabilizer, is a small lift (force), 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 ...

mounted on the upper fuselage

longeron In engineering, a longeron or stringer is a 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 fram ...

s. 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. F ...

and

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw ...

together were of broad chord, the rudder

balanced In telecommunications and professional audio, a balanced line or balanced signal pair is an electrical circuit consisting of two conductors of the same type, both of which have equal impedances along their lengths, to ground, and to other c ...

. The Potez XVIII had a conventional

undercarriage Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...

with two pairs of underwing mainwheels and a tail skid. Each pair was mounted on two V-form

strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. A stay is sometimes used as a synonym for ...

s with

aerofoil An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more lift than drag. Wings, sails and propeller blades are examples of airfoils. Foils of similar function designed ...

section,

duralumin Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age hardening, age-hardenable aluminium–copper alloys. The term is a combination of ''Düren'' and ''aluminium'' ...

forward legs and rear telescopic, shock absorbing legs. Only one Potez XVIII was built. After its first flight on 5 December 1922, the flight test programme continued into the spring of 1924. It was bought by the French government but never put into production.fr:Potez XVIII

Potez XXII

The Potez XVIII was developed into the very similar Potez XXII, which differed chiefly in having more powerful, uncowled

Bristol Jupiter The Bristol Jupiter is a British nine-cylinder single-row piston radial engine that was built by the Bristol Aeroplane Company. Originally designed late in World War I and known as the Cosmos Jupiter, a lengthy series of upgrades and developme ...

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

s. It also had an extended nose, increasing the length by and an increased maximum weight of . The lower-wing, balanced ailerons were replaced with unbalanced ailerons on both upper and lower wings. The type XXII competed in Le Grand Prix des Avions de Transport (Transport Aircraft Prize Competition), held in the autumn of 1923, though without distinction.

Specifications

References

{{Potez aircraft

R18 R18, or R-18, may refer to: Media content ratings * R18 (British Board of Film Classification) * R18+ issued by the Australian Classification Board#Restricted, Australian Classification Board * R18 issued by the Classification Office (New Zealand ...

1920s French airliners Trimotors Aircraft first flown in 1922 Biplanes