J.Davilla, A.Soltan French Aircraft of the First World War (Flying Machines)

Voisin 4 (LB/LBS)

  It had proved possible to equip Voisin 3s with Hotchkiss guns and, based on this success, Gabriel Voisin decided to modify a Voisin 3 airframe to accept a 37-mm cannon. The wings of the new design were shifted backward 40 cm to compensate for the weapon's recoil and weight. The cannon was mounted on a metal tripod designed by Voisin and built by Aircraft Park 101. The new aircraft had identical dimensions to the Voisin 3 except for a slightly longer fuselage nacelle. The position of the crew was reversed so the gunner was in the front, where he could load and fire the cannon. The aircraft retained the Voisin 3's 120-hp Salmson M9.
  The SFA designated the new aircraft the Voisin 4, but it became far better known as the Voisin Canon. Only a small number were built, as they proved to be of limited operational usefulness. Production of the Type 4 continued until late 1916, when it was superseded by cannon-equipped Voisin 8s. The factory designation for the Voisin 4 was LB. A version with a raised motor mount was designated LBS (S for sureleve, or raised).


Operational Service

  The Voisin 4 began to arrive in front-line escadrilles by April 1915. GB 3 received some of the first and used them to equip VB 113; the escadrille's designation was subsequently changed to VC 113 (for Voisin Canon) on 25 September 1915. GB 1 also received enough to convert VB 110 to VC 110 in April 1916. VC 116 was formed from Section D'avions Canons 1, 12, 13, and 14 in February 1916. It was assigned to GB 3. VC 111 was also formed from three Section D'avions Canons Nos.5, 8 and 9 in December 1915. Flying from Bar-le-Duc, the unit was assigned to the 2nd Armee and was especially active during the Battle of Verdun.
  The Voisin 4s were soon discovered to be too slow and unwieldy to be useful as fighters. According to a note in the SHAA files, the Voisin 4s were tested by GB 3 in both the air-to-air and ground attack roles in May 1915. The aircraft were found to be of limited utility in attacking aircraft because the cannon was difficult to aim, and it was concluded that enemy planes could easily evade the slower Voisins. The Voisin 4s, however, were considerably more successful when used to attack targets on the ground, especially if the targets were stationary (i.e., railway guns and battery emplacements). It was recommended that the airframe and cannon mounting on the Voisin 4s be lightened.
  Indeed, the Voisins were more successful in the ground attack role. They used their cannons on searchlight positions, and these attacks forced the German searchlight crews to install anti-aircraft guns. In addition to escort missions, the VC 110 aircraft were sometimes used as conventional bombers. For example, on the night of 10/11 July three VC 110 aircraft bombed train stations while two other Voisins attacked searchlights that were attempting to locate the bombers. Finally, the VC escadrilles flew night-fighter missions in an attempt to bring down German night raiders.
  VC 110 and VC 116 replaced their Voisin 4s in late 1916 with Voisin 8s. VC 111 re-equipped with Sopwith 1 1/2 Strutters in March 1917. VC 113 was given Breguet 14s in May 1917.
  V 83 was formed in December 1915 with Voisin 4s as Escadrille 501.


Foreign Service

Argentina
  Argentina received a single Voisin 4 in 1917. It was apparently in poor condition as it has been described as being "worthless."

Netherlands
  A single Voisin 4 landed in the Netherlands on 3 February 1915. It was a machine from GB 2 whose crew had become lost. A year later the Dutch government bought the machine from the French and gave it serial LA 22. It served with the Dutch air service until 1917.

Russia
  Russia used a number of Voisin 4s (LBS), some of which may have been built under license (see Voisin 3).


Voisin 4 (LB) Two-Seat Cannon-Armed Fighter with 120-hp Salmson M9
   Span 14.75 m; length 9.75 m; height 2.95 tn; wing area 49.65 sq. m
   Empty weight 1,050 kg; loaded weight 1,550 kg;
   Maximum speed: 90 km/h at 2,000 m; climb to 2,000 m in 35 minutes; endurance 3.15 hours

Voisin 4 (LBS) Two-Seat Cannon-Armed Fighter with 120-hp Salmson M9
   Span 14.75 m; length 9.75 m; height 2.95 m; wing area 49.65 sq. m
   Empty weight 1,050 kg; loaded weight 1,550 kg;
   Maximum speed: 90 km/h at 2,000 m; climb to 2,000 m in 35 minutes; endurance 3.15 hours



Voisin 6

  The Voisin 6 (factory designation LAS) was the same airframe as the Type 5, but was fitted with a 155-hp Salmson R9 engine. It is not known exactly how many Voisin 6s were built, but probably about 50. The specifications were the same as the Type 5. The maximum speed was slightly higher at 113 km/h and the climb to 2,000 m was reduced to 21 minutes and 30 seconds.

A.Durkota, T.Darcey, V.Kulikov The Imperial Russian Air Service (Flying Machines)

Cannon-Voisin

  A few of this model Voisin were sent from France. One was built by Dux, with a modified nacelle to install the Colt 1.5-inch gun in the nose, The machine differed from French versions, being modified by Dux designer V.S. Denisov. It was powered by a 225hp Salmson engine and was finished in November, 1915. It passed flight tests and served at the front in a corps unit.