SPCA 30
| Industry | Aerospace |
|---|---|
| Headquarters | France |
The SPCA 30, also identified as the SPCA Type III, was a bomber aircraft engineered by the French company Société Provençale de Constructions Aéronautiques (SPCA).
Development and design
In 1928, the French Service Technique de l'Aéronautique released requirements for a four-seat Multiplace de Combat, a versatile aircraft intended for bombing, reconnaissance, and escort missions. In response, SPCA introduced the SPCA 30, an all-metal, low-wing monoplane with a distinctive twin-boom configuration—the sole twin-boom entry in the competition. The design incorporated two open cockpits positioned offset to the port side and multiple machine gun placements arranged to ensure extensive defensive coverage, including downward firing arcs facilitated by the narrow fuselage profiles.
Constructed entirely of metal, the aircraft was capable of operating effectively under various weather conditions. Its design emphasized multi-role functionality, enabling use as both a day and night bomber as well as a heavy fighter tasked with bomber escort and reconnaissance duties. A notable feature was a detachable cabin located beneath the main fuselage; this cabin could be removed while on the ground and towed independently, providing potential adaptability for air ambulance purposes.
The cantilever wing structure consisted of three detachable segments: a central section that supported the cabin, fuselages, engines, and landing gear, connected by bolts to two lateral wing panels. The wing covering was composed of corrugated sheet metal enclosing lattice girder spars with tapered flanges forming near-circular cross-sections. Internal bracing combined with rib supports allowed for quick access during maintenance and inspections.
Each fuselage was built from triangularly braced girders clad in smooth metal skin reinforced with longitudinal stringers. A central passageway linked gunner positions, engine compartments, and the cabin. The elongated central cabin featured forward and rear compartments separated by a bulkhead: the forward section housed navigation and observation stations alongside a machine gun mount; the rear section contained tandem pilot cockpits equipped with dual controls.
Flight control systems were mounted rigidly on ball bearings to ensure precision. A bomb rack frame located between the wing spars also served as a mounting point for cameras during reconnaissance operations. The horizontal stabilizer spanned between the two fuselages with overhanging sections at each end; elevators and vertical fins with rudders were designed with wing-like forms.
The landing gear comprised two symmetrical assemblies with steel axles connected through ball-and-socket joints to wing spars beneath the cabin area. Struts extending from wing spars under each fuselage supported wheels fitted with Messier oleo-pneumatic shock absorbers. Each fuselage was equipped with an independently swiveling tail skid also incorporating shock absorption.
Fuel tanks were housed within protected drop tanks inside the central wing segment adjacent to the cabin, supplying fuel either individually or simultaneously to both engines. Radiator configurations varied depending on engine type, ranging from frontal honeycomb designs to retractable plate radiators integrated into the leading edge of the wings.
Prototypes and Flight Testing
By the end of 1930, two prototype models had been constructed. The initial prototype, designated F-AKCA, was powered by a pair of 650 hp Lorraine-Dietrich 18Kd W-18 water-cooled engines and completed its maiden flight on 1 February 1931. During a demonstration held on 7 August at Villacoublay airfield, this aircraft encountered intense vibrations caused by flutter, which resulted from insufficient wing torsional rigidity and control surfaces that were not properly balanced, leading to damage on the tailbooms. Despite these challenges, the pilot successfully executed a safe landing. The second prototype, F-AKCB, fitted with two 650 hp Hispano-Suiza 12Nb engines, took to the air for the first time on 6 May 1933. Subsequently, the original heavy landing gear was replaced with a lighter alternative.
The SPCA 30 was evaluated alongside competitors such as the Blériot 137 and Breguet 410; however, it was ultimately passed over in favor of Avions Amiot’s Amiot 140. This model advanced into production as the five-seat night bomber known as the Amiot 143.
See also
Bibliography
- Green, William. War Planes of the Second World War: Volume 7, Bombers and Reconnaissance Aircraft. London, UK: Macdonald, 1967.
- Liron, Jean. "Les SPCA: Le SPCA III type 30." Le Fana de l'Aviation, August 1989, issue 237, pp. 42–45.
- "The S.P.C.A. 30 M.4 military airplane (French): a multiplace low-wing airplane." National Advisory Committee for Aeronautics, 1 September 1932. NACA-AC-171, 93R19765.