SPCA 40T
| Industry | Aerospace |
|---|---|
| Headquarters | France |
| Products | Aircraft |
The SPCA 40T, alternatively referred to as the SPCA VII, was a mailplane crafted by the French company Société Provençale de Constructions Aéronautiques (SPCA).
This model showcased a high-wing monoplane configuration with a thick-section cantilever wing. Both the cockpit and cargo compartments were enclosed, with the cargo space adaptable to accommodate up to five passengers. Its fixed, divided main landing gear featured wheels covered by spats and a tailskid, all constructed entirely from metal.
Making its maiden flight on 21 December 1929, only three units were manufactured. The third aircraft incorporated more powerful engines, with the first two later upgraded to match this enhancement. Throughout the early 1930s, it was operated by Services Aeriens de Madagascar.
Design and development
SPCA engineered the 40T specifically for commercial aviation, emphasizing cost-efficiency and safety. The design aimed to maximize the ratio of payload to horsepower while reducing aerodynamic drag through carefully refined wing profiles and an overall sleek shape, resulting in a streamlined aircraft.
The airframe was designed to be sturdy and straightforward to maintain, suitable for consistent day and night operations under demanding conditions. The structure featured extensive metal construction enveloping both the fuselage and cantilever wing. Flight tests demonstrated stable handling characteristics and robust control surfaces mounted on ball bearings.
Engine installations were designed for maintenance convenience; each of the three engines was affixed to tubular mounts secured by four bolts, allowing rapid removal. Engine cowlings facilitated easy inspection by ground personnel. The airframe was modular—composed of three fuselage sections, two-part landing gear assemblies, tail units, and removable wing tips—enabling swift replacement of damaged components.
Safety considerations addressed fire hazards and engine failures. Fire prevention systems included automatic alarms and extinguishers; fuel tanks housed within the wings (with capacities up to 170 liters) could be jettisoned during flight. The all-metal construction helped limit fire propagation. Its trimotor layout permitted continued flight on two engines, enhancing reliability during operations.
The wing consisted of a central rectangular section flanked by tapered outer panels ending in rounded tips, spanning 20 meters with an aspect ratio of 7.28. Its internal structure comprised lattice-style spars supported by ribs; the tapered sections attached via ball joints for ease of removal. Leading and trailing edges were smooth sheet metal, while other surfaces featured corrugated stiffening. Tail surfaces employed cantilever design without external bracing; the horizontal stabilizer had an elliptical planform with an aspect ratio of 4.9.
The fuselage framework included side girders reinforced transversely and connected by bulkheads, supporting longitudinal stringers that carried the outer skin. Divided into three separable sections—cockpit, cabin, and rear extending to the rudder post—the fuselage allowed modular maintenance. The undercarriage consisted of two independent units mounted on struts equipped with Messier shock absorbers; wheels had brakes on a track measuring 5 meters. A seaplane version replaced wheels with metal floats.
Powerplant comprised three Salmson 9Ac radial engines delivering up to 120 hp each—one mounted at the nose on a vertically pivoting bearer and two installed in streamlined nacelles beneath the wings. Optional engine configurations ranged from 120 to 150 hp per unit; one setup utilized a 230 hp central engine. Oil reservoirs were situated behind each power unit.
Prepared for regular night operations, the enclosed cockpit accommodated pilot and navigator seated side-by-side; the navigator’s station was equipped with radio and navigation instruments. Access doors were located on both sides—the right side for cockpit entry and the left for cabin access. The cabin could transport approximately 350 kg of mail or cargo or be arranged for four passengers plus a lavatory facility. It also served as an air ambulance with space for two stretchers, seating for one medical attendant, a table, and medical supplies storage. Fully outfitted, the aircraft’s flying weight was around 2,900 kg.
After producing two initial 40T units, SPCA developed a single 41T variant powered by more robust Salmson 9Nc engines; it first flew on 12 December 1931 and was acquired by the French government. Services Aeriens de Madagascar utilized this model on routes connecting Tananarive and Broken Hill, Northern Rhodesia, linking with Imperial Airways. Eventually, both original 40T aircraft were upgraded to this engine specification and redesignated as SPCA 218.
Variants
- 40T – initial models powered by Salmson 9Ac engines (two units produced)
- 41T – fitted with Salmson 9Nc engines (one unit produced)
- 218 – original 40T aircraft modified to incorporate Salmson 9Nc engines (two units converted)
Operators
Bibliography
- National Advisory Committee for Aeronautics, "The S.P.C.A. 40 T commercial airplane: an all-metal cantilever monoplane", NACA-AC-143, April 1931.