SPCA 30

{{Infobox aircraft | name = SPCA 30 | logo = | logo_size = | image = SPCA30-profile.jpg | alt = | caption = SPCA 30 with the original landing gear | long_caption = | other_names = | aircraft_type = Bomber monoplane | aim = | outcome = | related = | national_origin = France | manufacturer = Société Provençale de Constructions Aéronautiques (SPCA) | design_group = | designer = | builder = | issuer = | status = | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 2 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = 1931 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }}

The '''SPCA 30''', also known as SPCA Type III, was a bomber aircraft designed and produced by the French aircraft manufacturer Société Provençale de Constructions Aéronautiques (SPCA).<ref>{{Cite web |url=http://www.museeciotaden.org/chantiers/autour/spca.htm |title=La S.P.C.A. |access-date=10 November 2012 |archive-date=26 June 2012 |archive-url=https://web.archive.org/web/20120626221651/http://www.museeciotaden.org/chantiers/autour/spca.htm |url-status=dead }}</ref><ref>[http://www.aviafrance.com/s-p-c-a-30-aviation-france-4566.htm Aviafrance S.P.C.A. 30]</ref>

==Development and design== thumb|SPCA III photo from L'Aerophile February 1931 During 1928, the French ''Service Technique de l'Aéronautique'' (the government body responsible for producing specifications for aircraft for the French armed forces) drew up requirements for a four-seat ''Multiplace de Combat'', a multi-role aircraft capable of day and night bombing, reconnaissance and long–range escort duties.<ref>{{harvnb|Green|1967|pp=76–77}}</ref> In response, SPCA designed an all-metal twin boom low wing monoplane, the SPCA 30, the only twin boom aircraft entered into the contest. The aircraft's central fuselage had two open cockpits offset to port, and a machine gun mount in the nose, while two more machine gun mounts were in the tailbooms.<ref name="fanap42">{{harvnb|Liron|1989|p=42}}</ref> This arrangement of its firing stations, which left no field uncovered by defensive fire, was intended to permit the aircraft to effectively defend itself from would-be attackers. In particular, the effectiveness of its downwards firing arcs was bolstered by the narrowness of the fuselages.<ref name = "naca 1">NACA 1932, p. 1.</ref>

The SPCA 30 employed all-metal construction, which enabled it to fly under virtually all weather conditions.<ref name = "naca 1"/> Many elements of the aircraft were designed to be readily demountable and, where feasible to do so, interchangeable; this eased maintenance and repair tasks. When configured for this role, it could be fully equipped to function as a day or night bomber.<ref name = "naca 1"/> It was even envisioned for use as a heavy fighter, for which it was intended to escort bombardment squadrons and carry out aerial observation.<ref name = "naca 1"/> One of the more unusual features of the SPCA 30 was the ability to install and remove a detachable cabin from the underside of the fuselage.<ref name = "naca 17"/> While the aircraft was on the ground, the cabin was to be detached and towed away by a tractor. It was suggested that this function would be useful in the air ambulance role.<ref name = "naca 17">NACA 1932, pp. 1, 7.</ref>

The aircraft was furnished with a cantilever wing that comprised three separate sections, all of which were demountable.<ref name = "naca 1"/> Specifically, there was a central section of uniform section that supported the cabin, fuselages, engine bearers, and landing gear; the central section was joined to the two lateral sections via a total of four bolts each.<ref name = "naca 1"/> The wing covering was composed wholly of corrugated sheet metal and was reinforced internally using additional metal sections. Multiple panels across this covering were attached using screws that permitted rapid removal for ease of inspection of elements within the wing’s interior, such as the supports for the flight controls.<ref name = "naca 2">NACA 1932, p. 2.</ref>

The wing’s structural elements comprised a pair of lattice girder spars which had a uniform height across the central section but progressively tapered in the lateral section.<ref name = "naca 1"/> Each spar flange consisted of a pair of continuous semi-cylindrical duralumin plates and a U-shaped member that was riveted together as to form an almost circular cross section. These flanges tapered uniformly across the lateral wing sections so that they formed elongated cones.<ref name = "naca 1"/> The spar webs were formed by box cross section lattices. The covering of the wing was supported directly by the ribs, which conformed to a lattice girder style.<ref name = "naca 1"/> Rigid triangular bracing in the planes of the upper and lower spar flanges, the bracing members being extruded in the form of omega. The ailerons were hinged to auxiliary lattice spars.<ref name = "naca 1"/>

The central portion of the wing was attached to the two fuselages by no more than four bolts each.<ref name = "naca 2"/> The framework of each fuselage consisted of a pair of triangularly-braced girders that joined at intervals to transverse frames. The fuselage covering was smooth sheet metal.<ref name = "naca 2"/> Both the floor and ceiling of the fuselages were reinforced using stringers that ran throughout their whole length. Each fuselage contained a central corridor that connected the machine gun station, the engine compartment and the central cabin.<ref name = "naca 2"/>

The central cabin was extended by a balcony that projected roughly 13 foot in front of the wing, it shared a similar structure to that of the fuselages.<ref name = "naca 2"/> It had a continuous floor that was interrupted by a trapdoor (used for access) as well as a series of other openings that were used either by the navigator or the aerial observer. The cabin was divided lengthwise into two separates compartments by a partition with a connecting door.<ref name = "naca 2"/> The forward compartment accommodated for the chief observer, being furnished with all of the requisite instruments for navigation, observation, and bombardment, as well as a single ring mount for a machine gun. The aft compartment contained the two pilot stations, which were arranged in tandem and provided with dual flight control and supported by a pair of raised girders. Each station could be disconnected by the pilot of the other station.<ref name = "naca 2"/> The flight controls were rigid and are mounted on ball bearings. The supporting frame for the bomb rack was positioned between the spars of the central part of the wing within the lowest point of the aft compartment; this frame was also able to function as a camera support during photographic missions.<ref name = "naca 2"/>

The horizontal stabilizer connected the two fuselages with an overhang at each end.<ref name = "naca 2"/> The elevator was mounted on ball bearings. The vertical empennage comprised a fin and a rudder at the tail of each fuselage.<ref name = "naca 2"/> Both the horizontal stabilizer and vertical empennage shared an identical structure to that the wing.<ref name = "naca 2"/>

The landing gear was composed of two independent symmetrical parts, each being fitted with a special steel axle, a tube of variable thickness attached by a ball-and-socket joint to the lower flange of the front spar of the central section of the wing under the side of the cabin.<ref name = "naca 23">NACA 1932, pp. 2-3.</ref> An oblique fore-and-aft steel strut was attached to the lower flange of the rear wing spar under the centre of each fuselage. A vertical strut provided with a Messier-supplied oleo-pneumatic shock absorber was attached to the lower flange of the front spar beneath the centre of the engine bearer.<ref name = "naca 3">NACA 1932, p. 3.</ref> The lower ends of these three members were joined to form a trihedral; at the apex of this trihedral and constituting the end of the axle, there was a spindle that carried a wheel. Each fuselage carried a swivelling tail skid that was furnished with a Messier oleo-pneumatic shock absorber.<ref name = "naca 3"/>

Fuel was housed within a pair of protected drop fuel tanks, composed of L2R alloy, that were located inside the central part of the wings, one on either side of the cabin.<ref name = "naca 3"/> The fuel system enables each engine to be supplier from either or both of these tanks. Dependent on the engine used, radiators fitted were either of the frontal honeycomb style or retractable plate-type radiators located in the leading edge of the wing.<ref name = "naca 3"/>

==Prototypes and into flight== During late 1930, a pair of prototypes were completed.<ref name="fanap42"/> The first one, registration ''F-AKCA'' was powered by a pair of {{convert|650|hp|kW|abbr=on|0|disp=flip}} Lorraine-Dietrich 18Kd water-cooled W engines engines, and made its first flight on 1 February 1931.<ref name="fanap423">{{harvnb|Liron|1989|pp=42–43}}</ref><ref>[http://www.aviafrance.com/s-p-c-a-30-aviation-france-4566.htm Aviafrance S.P.C.A. 30]</ref> On 7 August, ''F-AKCA'' was being demonstrated at Villacoublay airfield when the aircraft suffered severe vibration when the engines were brought back to full power, with the tailbooms being displaced by more than a metre, leading to tearing of the skin of the aircraft's tailbooms. Despite the damage, the pilot managed to land the aircraft. The accident was eventually found to be due to flutter, caused by weakness of the wings in torsion (i.e. twisting), which was exacerbated by the unbalanced control surfaces.<ref name="fanap434">{{harvnb|Liron|1989|pp=43–44}}</ref> The second prototype, ''F-AKCB'', with two 650 hp Hispano-Suiza 12Nb engines, flew on 6 May 1933.<ref name="fanap42,5">{{harvnb|Liron|1989|pp=42, 45}}</ref> The original bulky landing gear was later replaced by a lighter one.

The SPCA 30, together with other competing aircraft such as the Blériot 137 and the Breguet 410, were rejected in favour of Amiot's proposal, the Amiot 140,<ref name="fanap42,5"/><ref>{{harvnb|Green|1967|p=77}}</ref> which later entered production as a five-seat night bomber, the Amiot 143.<ref>{{harvnb|Green|1967|pp=77, 79}}</ref>

==Specifications== thumb|SPCA 30 M4 3-view drawing from NACA-AC-171 {{Aircraft specs |ref= ''Parmentier'',<ref name=Parmentier>{{cite web |last=Parmentier |first=Bruno |title=SPCA30 |url=http://www.aviafrance.com/aviafrance1.php?ID=4566&ID_CONSTRUCTEUR=1146&ANNEE=0&ID_MISSION=0&MOTCLEF= |publisher=Aviafrance |access-date=11 November 2012}}</ref> ''National Advisory Committee for Aeronautics''<ref name = "naca 38">NACA 1932, pp. 3-8.</ref> |prime units?= met  |genhide=

|max speed kmh= 255 |max speed mph= |max speed kts= |max speed note= |cruise speed kmh= |cruise speed mph= |cruise speed kts= |cruise speed note= |stall speed kmh= |stall speed mph= |stall speed kts= |stall speed note= |never exceed speed kmh= |never exceed speed mph= |never exceed speed kts= |never exceed speed note= |minimum control speed kmh= |minimum control speed mph= |minimum control speed kts= |minimum control speed note= |range km= 650 |range miles= |range nmi= |range note= |combat range km= |combat range miles= |combat range nmi= |combat range note= |ferry range km= |ferry range miles= |ferry range nmi= |ferry range note= |endurance= |ceiling m= 7,500 |ceiling ft= |ceiling note= |climb rate ms= |climb rate ftmin= |climb rate note= |time to altitude={{convert|2,000|m|ft|abbr=on}} in six minutes |wing loading kg/m2= |wing loading lb/sqft= |wing loading note= |disk loading kg/m2= |disk loading lb/sqft= |fuel consumption kg/km= |fuel consumption lb/mi= |power/mass= |more performance=  |armament= |guns= |bombs= |rockets= |missiles= |hardpoints= |hardpoint capacity= |hardpoint rockets= |hardpoint missiles= |hardpoint bombs= |hardpoint other=

|avionics= }}

==See also== {{aircontent  |see also= |related= |similar aircraft= * Amiot 143 * Blériot 137 * Breguet 410 * SAB AB-80 |lists= *List of Interwar military aircraft }}

==References== ===Citations=== {{reflist}}

===Bibliography=== * {{cite book |last=Green |first= William |title=War Planes of the Second World War: Volume 7, Bombers and Reconnaissance Aircraft |year=1967 |location=London, UK |publisher=Macdonald }}

*{{cite magazine |last=Liron |first=Jean |date=1969-03-01 |title=La SPCA: SPCA 30 M-4 |url=https://gallica.bnf.fr/ark:/12148/bpt6k53231706/f71.item |journal=Aviation magazine international : les ailes, l'air et l'espace |language=fr |pages=92–93 |issue=509 |location=Paris, France |publisher= Union de presse européenn |access-date=2026-02-09 }}

* {{cite magazine |last=Liron |first=Jean |title=Les SPCA: Le SPCA III type 30 |magazine=Le Fana de l'Aviation |date=August 1989 |issue=237 |pages=42–45 |language=Fr }}

* [https://ntrs.nasa.gov/citations/19930090475 "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.

==External links== {{Commons category|SPCA III}} * [http://www.flickriver.com/photos/27862259@N02/6184218619/ Picture] * [http://airspot.ru/catalogue/aircrafts/S?page=21 Airspot (in Russian)] * [http://www.traditions-air.fr/unit/photo/div_unit_inconnu_bombardement.htm Bombardement Reconnaissance - unités à identifier]

Category:1930s French bomber aircraft Category:SPCA aircraft Category:Twin-boom aircraft Category:Low-wing aircraft Category:Aircraft first flown in 1931 Category:Twin piston-engined tractor aircraft Category:Aircraft with fixed conventional landing gear