The SPAD S.A (also called S.A.L.) was a French two-seat tractorbiplane first flown in 1915. It was used by France and Russia in the early stages of the First World War in the fighter and reconnaissance roles. It was a unique aircraft that carried its observer in a nacelle ahead of wing, engine and propeller.
The SPAD A.1 prototype was the first aircraft produced by SPAD following its reorganization from the pre-war Deperdussin company. The chief designer, Louis Béchereau, had been involved in designing that firm's successful monocoque racing monoplanes, and many design details were carried over from the Deperdussins.
The aircraft was designed to carry not only its pilot in the normal position, but also an observer in a streamlined nacelle ahead of the propeller. This configuration was an attempt to combine the advantages of the tractor and the pusher types, giving the observer a clear field of view to the front and sides without the drag penalty of the typical pusher. However, communication between the pilot and the observer was nearly impossible. The pulpit (as it was known in English) or basket (as it was referred to in Russian) vibrated badly and, in multiple cases, parted company from the rest of the aircraft while in flight. Like many pushers, it also put the observer at risk of being crushed in even a relatively mild crash or "nose-over". A British evaluation of the type suggested "it would be expensive in observers if flown by indifferent pilots".[1]
While not originally designed explicitly as a gunner's position,[2] early combat experience had shown a need for forward-firing machine guns. But mechanisms to allow a gun to fire through the propeller were not yet available, and the observer's nacelle on the S.A-1 represented a temporary solution.
As well as the 2-seat S.A versions a single seat fighter, the SPAD S.G, was also produced with fixed forward-firing guns in the nose nacelle, without any occupant. The S.G.'s guns were not accessible to the pilot which caused problems when stoppages occurred and with cocking the guns for combat.[3]
On all but the earliest prototypes and the SPAD S.G, the nacelle was fitted with a light machine gun on a flexible tubular mount, and it incorporated air intakes on its sides and underside to redirect air toward the Le Rhônerotary engine, which was otherwise masked by the nacelle. Starting the engine required the prop to be swung from alongside the fuselage. The nacelle was hinged at the bottom to provide some access to the engine for maintenance, but this was insufficient, and additional sliding panels were added to the sides of the fuselage. A mesh screen behind the observer was intended to prevent propeller strikes. The first prototypes were unarmed, but the production S.A was soon eclipsed by more conventional fighter, such as the Nieuport 10 and Nieuport 11.
Aside from the unorthodox configuration, the aircraft was of standard wood and fabric construction for the period. The wings had a single bay, but to prevent the long flying and landing wires from vibrating in flight, light vertical struts were added mid-bay to brace the wires, giving the aircraft the appearance of a two-bay biplane, much as was done for the later, more conventional SPAD S.VII and SPAD S.XIII single-seat fighters.
SPAD S.A-2 at Somme-Vesle in 1915
The SPAD S.A.2 was an improved version of the S.A.1 which first flew on 21 May 1915.
The S.A-2's 110hp engine frequently suffered from overheating, so the design reverted to the S.A-1s 80hp Le Rhone in the S.A-4, with the same engine being retrofitted to some S.A-2s.[4] Other changes included dispensing with the lower ailerons on the narrower chord lower wings and a larger tailplane to eliminate the need for a bungee to help with trimming.[5] Russian models had minor structural differences to the top wing, incorporating a separate center section rather than each wing panel being joined along the centerline.[5]
In spite of its lack of success, the design brought valuable experience to Béchereau and his team. The successful S.VII fighter was a direct development of the A series. It had much in common. However, the differences included the pulpit being dispensed with, being re-engined with a Hispano-Suiza V8, having a delta-shaped tailplane, the fuselage being fitted with additional fairing stringers, wire trailing edges, reduced rib spacing, and proportions adjusted slightly. Most other design details were retained.
Operational history
SPAD S.A-2 "Ma Jeanne"
The S.A had a short and inauspicious career in the French Aviation Militaire, and it was quickly replaced in service by less dangerous aircraft. Contemporary sources indicate that it was seldom used. Few details are available concerning the careers of the 42 S.A-2 airframes delivered, and it never supplied the entire equipment of an escadrille.[6]
The Imperial Russian Air Service operated the SPAD S.A-2 and S.A-4 for a longer period of time due to a shortage of available aircraft. Some 57 S.A-2s and S.A-4s went to the Imperial Russian Air Service. During winter operations, Russian aircraft were fitted with skis instead of wheels. Although Russian crews also thought very little of the SPAD (not made any better by the acronym SPAD (СПАД) in Russian meaning "slump" or "plummet"), at least two crews achieved successes with it.
On November 25, 1916, Russian pilot Karpov and his gunner, Bratolyubov Jurij Aleksandrovich, claimed a German aircraft near the village of Vulka.
At least one example survived to be used briefly by the Soviet Union before they retired all obsolete types.
Variants
SPAD S.A-1 – initial production variant with 80hp Le Rhône 9C engine and tapered tailplane – 11 built.[4]
SPAD S.A-2 – main production variant with constant chord tailplane and 110hp Le Rhône 9J.[6] – 35 built
SPAD S.A-3 – dual-control trainer, with both pilot and observer being given flexible gun mounts – two built with 110hp Le Rhône 9J.[7]
SPAD S.A-4 – an improved A.2 with a less powerful 80-hp Le Rhône 9C engine.[4] – 59 built.[6]
SPAD S.D – slightly larger aircraft with an additional gunner position behind pilot, powered by a 220-hp Renault 8Fg engine – one built
SPAD S.G – S.A with observer replaced by guns mounted in the nacelle – one built and one modified.[6]
SPAD S.H – unbuilt development without pulpit, precursor to SPAD S.V (5), which was SPAD S.VII prototype
SPAD was a French aircraft manufacturer active between 1911 and 1921. Its SPAD S.XIII biplane was the most produced French fighter airplane of the First World War.
The Morane-Saulnier Type P was a French parasol wing two-seat reconnaissance aeroplane of the First World War. Morane-Saulnier built 595 for the French air force, and it was also used by the British until 1916-17.
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The Hanriot HD.1 was a French World War I single-seat fighter aircraft. Rejected for service with French squadrons in favour of the SPAD S.VII, the type was supplied to the Aviation Militaire Belge and the Corpo Aeronautico Militare of the Royal Italian Army, with both of which it proved highly successful. Of a total of about 1,200 examples built, 831 were produced by Italian companies under licence.
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The Potez XV was a French single-engine, two-seat observation biplane designed as a private venture by Louis Coroller and built by Potez and under licence in Poland.
The Bleriot-SPAD S.51 was a French fighter aircraft developed in 1924 in response to a French Air Force requirement for an aircraft to replace their obsolete Nieuport-Delage NiD.29s.
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The Caudron R.11, was a French three-seat twin-engine long range escort fighter biplane developed and produced by Caudron during the First World War.
The SPAD S.XII or SPAD 12 was a French single-seat biplane fighter aircraft of the First World War developed from the successful SPAD VII by Louis Béchereau, chief designer of the Société Pour L'Aviation et ses Dérivés (SPAD).
The SPAD S.XI or SPAD 11 was a French two-seat biplane reconnaissance aircraft of the First World War. The SPAD 11 was the work of Louis Béchereau, chief designer of the Société Pour L'Aviation et ses Dérivés (SPAD), who also designed the highly successful SPAD 7 and SPAD 13 single-seat fighter aircraft. It was developed under military specification C2, which called for a two-seat fighter aircraft. As a result of its failure to meet the levels of performance and agility demanded by the C2 specification, the SPAD 11 was used, along with the more successful Salmson 2 and Breguet 14, to replace ageing Sopwith 1½ Strutter and Dorand AR reconnaissance aircraft. Persistent problems with the SPAD 11 led to its early replacement by the SPAD S.XVI or SPAD 16 variant.
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The SPAD S.G1 and SPAD S.G2 were French single seat tractor biplanes of ca 1915/16, following similar arrangements to the SPAD S.A2 family with the propeller and engine buried in the fuselage and a pod suspended in front of the engine. A single SPAD S.A-1 was converted with a small circular section pulpit nacelle mounting a mock-up of a fixed forward-firing machine-gun and smaller wings.
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The Blériot-SPAD S.91 was a French light-weight fighter aircraft. It would be later developed into the Blériot-SPAD S.510, the last biplane produced by the French aeronautic industries.
The Lorraine Hanriot LH.130 is a French racing aircraft designed and built in the early 1930s, to compete in the Coupe Michelin air races.
↑ Davilla, Dr. James J.; Soltan, Arthur (1997). French Aircraft of the First World War. Mountain View California: Flying Machines Press. pp.482–483. ISBN978-0-9637110-4-5.
↑ Davilla, Dr. James J.; Soltan, Arthur (1997). French Aircraft of the First World War. Mountain View California: Flying Machines Press. pp.474–479. ISBN978-0-9637110-4-5.
↑ Parmentier, Bruno (25 September 1997). "SPAD S.A-2". aviafrance.com (in French). Retrieved 28 December 2019.
Connors, John F. (1989). SPAD Fighters in action. Squadron/Signal.
Cony, Christophe (January 1997). "L'histoire inconnue des SPAD type A (première partie)" [The Unknown History of Type A SPADs (Part One)]. Avions: Toute l'aéronautique et son histoire (in French) (46): 28–35. ISSN1243-8650.
Cony, Christophe (February 1997). "L'histoire inconnue des SPAD type A (deuxième partie)" [The Unknown History of Type A SPADs (Part Two)]. Avions: Toute l'aéronautique et son histoire (in French) (47): 28–33. ISSN1243-8650.
Cony, Christophe (April 1997). "L'histoire inconnue des SPAD type A (quatrième partie)" [The Unknown History of Type A SPADs (Part Four)]. Avions: Toute l'aéronautique et son histoire (in French) (49): 32–38. ISSN1243-8650.
Cony, Christophe & Kulikov, Victor (January 1999). "Du nouveau sur les SPAD-Nacelles" [Again on the SPAD-Nacelles]. Avions: Toute l'aéronautique et son histoire (in French) (70): 37–44. ISSN1243-8650.
Durkota, Alan; Darcey, Thomas; Kulikov, Victor (1995). The Imperial Russian Air Service: Famous Pilots and Aircraft of World War I. Mountain View, CA: Flying Machines Press. ISBN0-9637110-2-4.
Herris, Jack (2005). SPAD Two-seater Fighters Of World War I. Great War Aircraft in Profile 7. Mountain View, CA: Flying Machines Press. ISBN978-1891268199.
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