The Tellier T.6, also known as the Tellier TC.6 was a French flying boat produced for maritime patrol during World War I.^[1] It was a development of the Tellier T.3 with added cannon armament^[1][2] (Hence the C in the TC version of the designation)^[3][4] and a lengthened fuselage.^[2] Fifty-five examples served with the French Navy in the Atlantic and Mediterranean^[1][2] from 1917 until the end of the war.^[2] After the armistice, some examples served as training aircraft until 1922.

Like the T.2 and T.3 from which it was developed, the T.6 was a two-and-a-half bay, equal-span, un-staggered biplane flying boat.^[3] The lower wings were mounted to the top of the fuselage sides, and wire bracing was used between the wings, and between the wings and the fuselage.^[3] It had a conventional tail, also braced with wire.^[3] Outrigger floats were carried underneath the tips of the lower wings.^[3] A single engine was mounted in the interplane gap, driving a pusher propeller.^[3]

The T.6's cannon armament consisted of a single 47-millimetre (1+3⁄4 in) Hotchkiss model 1885 naval gun carried on a transverse mount in an open position at the bow.^[2] This mounting allowed for the cannon to be depressed up to 55°.^[5] The open cockpit for the pilot was aft of this, just in front of the wing cellule.^[3]

The hull was covered in plywood, and the wings and tail surfaces in canvas.^[3]

The development of the T.6 was a response to a very specific military problem.^[3] By 1917, German submarines posed a threat to Allied ships in several parts of the Atlantic and Mediterranean. The small bombs carried by the flying boats deployed against them were only effective with a direct hit, but the bomb sights of the time were not accurate enough to make this likely.^[2] Cannon armament seemed to offer a solution to this problem,^[2] and in Spring 1917, the Centre d'Aéronautique Maritime de Camaret fitted a Donnet-Denhaut flying boat with a 37-millimetre (1+1⁄2 in) cannon for trials.^[5] This aircraft proved underpowered for this use, so the Navy requested Tellier to modify a T.3 to carry an even larger gun.^[5]

The 47-mm cannon, its gunner, plus twenty or thirty rounds of ammunition added around 700 kilograms (1,500 lb) to the bow, which substantially altered the aircraft's centre of gravity.^[2] Tellier compensated for this by adding a 0.87-metre (2 ft 10 in) stretch to the rear fuselage.^[2][5] The fuselage interior was also reinforced to better withstand the cannon recoil.^[5] Even so, the T.6 inherited a weak structure from the T.3,^[2] and required further strengthening when the type entered service.^[2][4]

The prototype T.6 was tested at Saint-Raphaël for its air- and seaworthiness and for its ability to fire its cannon in flight.^[5] The type was accepted for military service, and the Navy placed an order for 85 T.6s in July 1917, together with an extra 20 T.3s.^[5] Total orders eventually reached 110 aircraft,^[3] but only 55 were delivered by the armistice.^[2][3]

T.6s served alongside T.3s and other flying boats at Saint-Raphaël, Bayonne, Brest-Camaret, Cherbourg, Lorient, and throughout the Mediterranean, including Africa, Corsica, Italy and Greece.^[4] Squadron records of the time generally refer to aircraft by their identification number within the squadron, but since these squadrons operated a mixture of types, it is difficult now to be certain which types of flying boats participated in which actions.^[6]

In operational use, the T.6 proved less effective than hoped.^[7] The cannon proved difficult to aim, its sights were inadequate, and gunners were not well-enough trained to use the weapon.^[7] In February 1918, the Centre d'aviation maritime de Cherbourg recommended that a "bomb-launcher" for 52-kilogram (115 lb) bombs be fitted to the T.6s, and that the aircraft take off with only 60% of their normal fuel loads to offset the weight penalty.^[7] Such launchers were fitted to newly-built T.6s from August 1918 onwards, but the armament problem had not been resolved by the armistice..^[7]

After the war, the cannons were removed from surviving T.6s, and some were used for training until 1922.^[4]

Data from Davilla and Soltan 2002, p.535

General characteristics

• Crew: two
• Length: 12.71 m (41 ft 8 in)
• Wingspan: 15.60 m (51 ft 2 in)
• Height: 3.40 m (11 ft 2 in)
• Wing area: 47 m² (510 sq ft)
• Empty weight: 1,210 kg (2,668 lb)
• Gross weight: 2,670 kg (5,886 lb)
• Powerplant: 1 × Hispano-Suiza 8Ac V-8, water-cooled piston engine, 150 kW (200 hp)

Performance

• Maximum speed: 125 km/h (78 mph, 67 kn)
• Endurance: 3 hours
• Time to altitude: 500 metres (1,600 ft) in 7 minutes
  1,000 metres (3,300 ft) in 13 minutes
  200 metres (660 ft) in 29 minutes

Armament

• Guns: 1 × Hotchkiss canon de 47 mm modèle 1885 with 20–30 rounds of ammunition

• Balous, Miroslav (2011). "Tellier T.6". Letectvi + kosmonautika. No. 7. Bratislava: Magnet Press. pp. 24–25.
• Borget, Michel (June 1996). "Des coques et des ailes 2 – Alphonse Tellier, constructeur d'hydro-aéro". Le Fana de l'Aviation. No. 319. Paris: Editions Lariviere. pp. 22–35.
• Davilla, James J.; Soltan, Arthur M. (2002). French aircraft of the First World War. Boulder, Colorado: Flying Machines Press.
• Hornát, Jiří (1991). "Tellier T.3 (Tellier 200 HP) Tc.6 (Tellier Canon)". Letectvi + kosmonautika. Vol. 67, no. 2. Prague: Magnet Press. pp. 39/79.
• Taylor, Michael J. H. (1993). Jane's Encyclopedia of Aviation. London: Studio Editions.