The Blériot-Spad S.45 was a large, four engine French airliner which appeared at the 1921 Paris Salon. It could carry fifteen passengers or be adapted as a

bomber A bomber is a military combat aircraft that utilizes air-to-ground weaponry to drop bombs, launch aerial torpedo, torpedoes, or deploy air-launched cruise missiles. There are two major classifications of bomber: strategic and tactical. Strateg ...

Design and development

The Blériot-SPAD S.45 was a large, French

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 ...

airliner built shortly after the end of

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. It was designed by André Herbement and retained some of the characteristics of his earlier, smaller Blériot-SPAD airliners, notably the combination of a swept upper wing with a smaller, unswept lower one. It was his first four engine aircraft and was of largely wooden construction. Despite its size it was a single bay biplane braced by single, outwards-leaning

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 with large feet which reached between the single upper and lower

spars SPARS was the authorized nickname for the United States Coast Guard (USCG) Women's Reserve. The nickname was derived from the USCG's motto, "—"Always Ready" (''SPAR''). The Women's Reserve was established by law in November 1942 during Wor ...

and the ply-covered

leading edge The leading edge is the part of the wing that first contacts the air;Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. alternatively it is the foremost edge of an airfoil sectio ...

D-boxes. The lower wings were conventionally mounted to the lower

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

and the upper wing was held high above the fuselage by a frame including outward leaning members from just outside the engines to the fuselage.

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 ...

filled the entire

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...

of the lower wing beyond a central cut-out. The tail was conventional, with a mid-fuselage mounted

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 ...

and a fin carrying a rather pointed,

balanced rudder Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevator (air ...

. The S.45 was powered by four

Hispano-Suiza Hispano-Suiza () is a Spanish automotive company. It was founded in 1904 by Marc Birkigt and as an automobile manufacturer and eventually had several factories in Spain and France that produced luxury cars, aircraft engines, trucks and weapons. ...

water-cooled

V8 engine A V8 engine is an eight- cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration. Origins The first known V8 was the Antoinette, designed by Léon Levavasseur, a ...

s, two, close together in

pusher configuration In aeronautical and naval engineering, pusher configuration is the term used to describe a drivetrain of air- or watercraft with propulsion device(s) after the engine(s). This is in contrast to the more conventional tractor configuration, wh ...

on top of the upper wing and two, further apart, on the lower wing in

tractor configuration In aviation, a tractor configuration is a propeller-driven fixed-wing aircraft with its engine mounted with the propeller in front, so that the aircraft is "pulled" through the air. This is the usual configuration; the pusher configuration ...

. Fuel was held in two upper wing tanks and each engine was cooled with a cylindrical Lamblin

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 ...

mounted in pairs between the engine nacelles. Its fuselage was a wooden, circular section

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

built from cross-grained layers of

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

and

tulipwood Most commonly, tulipwood is the greenish yellowish wood yielded from the Liriodendron tulipifera, tulip tree, found on the Eastern side of North America and a similar species is found in some parts of China. In the United States, it is commonly ...

. The three crew sat in individual open cockpits near the nose, with the navigator in front where large windows in the lower nose gave him a wide view of the ground and the two pilots side-by-side behind. Fifteen passengers sat in the enclosed cabin on seats arranged in five rows with two seats on the

starboard Port and starboard are Glossary of nautical terms (M-Z), nautical terms for watercraft and spacecraft, referring respectively to the left and right sides of the vessel, when aboard and facing the Bow (watercraft), bow (front). Vessels with bil ...

side, one on the port side and a corridor between them. Each row had a window on either side. Entry was via a starboard-side door. There was a baggage space and a two seat toilet at the back. The S.45 had a fixed, 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 a tailskid but its weight required more than the usual two mainwheels. Instead there was a pair of wheels in tandem under a shared fairing on each side. These were joined by a horizontal cross-member with its ends on V-struts to the fuselage, each stiffened laterally with a further strut.

Operational history

Despite the interest it attracted at the 1921 Salon, there is no known record of it flying. It was still under construction not long before the Salon.

Specifications

References

1920s French airliners Blériot aircraft Four-engined piston aircraft Four-engined push-pull aircraft {{DEFAULTSORT:Blériot-SPAD S.45