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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 colonial transport. It was an unequal span biplane largely built of wood, though with metal engines mountings and other fittings, engine nacelles and tail surfaces. The rectangular plan wings were fabric covered. On each side, towards the wing tips a parallel pair of interplane struts 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 8Bds, water-cooled V-8 engines, each producing ; cooled by cylindricalradiator
Radiators are heat exchangers 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 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 material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
-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, 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 ...
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 was conventional, with the tailplane mounted on the upper 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. The fin and rudder together were of broad 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 ( ...
, the rudder balanced. 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 struts with aerofoil 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-hardenable aluminium alloys. The term is a combination of '' Dürener'' and ''aluminium''.
Its use as a tra ...
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, uncowledBristol Jupiter
The Bristol Jupiter was a British nine-cylinder single-row piston radial engine 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 developments turn ...
radial engines. 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 1920s French airliners Trimotors Aircraft first flown in 1922 Biplanes