|Designer||Louis Coroller and André Delaruelle|
|First flight||25th April 1936|
|Primary user||French Air Force|
The Potez 630 and its derivatives were a family of twin-engined aircraft developed for the Armée de l'Air in the late 1930s. The design was a contemporary of the British Bristol Blenheim and the German Messerschmitt Bf 110.
Design and development
The original Potez 630 was built to meet the requirements of a 1934 heavy fighter specification which also resulted in the successful Breguet 690 series of attack aircraft. The prototype first flew in 1936 and proved to have excellent handling qualities.
The Potez 630 was a twin engine, monoplane, fully metallic three-seater with efficient aerodynamic lines and twin tailplanes. The long glasshouse hosted the pilot, an observer or commander who was only aboard if the mission required it, and a rear gunner that manned a single flexible light machine gun.
Only very minor changes were required and an order for 80 was placed in 1937. Simultaneously 80 Potez 631 C3 fighters were ordered, these having Gnome-Rhône 14M radial engines rather than the Hispano-Suiza 14AB10/11 of the Potez 630. Fifty additional Potez 631s were ordered in 1938 of which 20 were diverted to Finland, although they never reached that country.
The Potez 630's engines proved so troublesome that most units had re-equipped with the Potez 631 before World War two began. The latter was an ineffectual interceptor, slower than some German bombers and 130 km/h slower than the Bf 109E, although it continued in service until the armistice.
The Potez 633 saw only brief operational service with the Armée de l'Air in Europe when aircraft from two units undertook a sortie near Arras on May 20, 1940; two days later the aircraft was withdrawn from front-line service. The Potez 633 exported to Greece and Romania saw more extensive service, in limited numbers. The Romanians used them against the USSR and the Greeks against Italy. A small number of Potez 633 originally destined for China were commandeered by the French colonial administration in Indo-China and saw limited action in the brief French-Thai War in early 1941.
More than 700 Potez 63.11 were delivered by June 1940, of which more than 220 were destroyed or abandoned, despite the addition of extra machine gun armament; the heaviest losses of any French type. The Potez 63.11 continued in service with the Vichy air force and with the Free French forces in North Africa seeing action with both. Production was resumed under German control and significant numbers appear to have been impressed by the Germans, mostly in liaison and training roles.
All members of the family (possibly except the Potez 63.11) shared pleasant flying characteristics. They were well designed for easy maintenance and later models had a heavy armament for the time (up to 12 light machine guns for the Potez 63.11). They were also quite attractive aircraft. Although not heavily built they proved capable of absorbing considerable battle damage. Unfortunately the Potez 63 family, like many French aircraft of the time, simply did not have sufficiently powerful engines to endow them with an adequate performance. In the stern test of war they proved easy meat for prowling Messerschmitts, like their British contemporaries the Fairey Battle and Bristol Blenheim. Their similarity to the Bf 110 (twin engines, twin tail, long "glasshouse" canopy) was sufficient that some were apparently lost to "friendly fire".
Unlike many contemporary French aircraft, production of the Potez aircraft was reasonably prompt and the first deliveries were effected before the end of 1938. The 63 has been designed with mass production in mind and as a result, one Potez 630 was cheaper and faster to manufacture than one Morane-Saulnier M.S.406. As production tempo increased, a number of derivatives and experimental models were also developed.
A typical feature of the 630 and 631 was the frontal armament, which originally consisted in two 20 mm Hispano-Suiza HS.404 cannons in gondolas under the fuselage, though sometimes one of the cannons was replaced by a MAC 1934. Later in their career, 631s received four similar light machine guns in gondolas under the outer wings, though it was theoretically possible to fit six.
Whereas the Potez 635 CN2 night fighter project was cancelled and the Potez 63.12 C3 with Pratt & Whitney Twin Wasp Junior radials remained a single prototype, the first batch of Potez 671 heavy fighters (derived from the Potez 670-01 prototype) were on the assembly lines when the Germans captured the SNCAN Méaulte factory near Albert.
The Potez 63.01 and 630.01 were the first two prototypes, as well as the Potez 630 CN.2 No.01 night-fighter prototype, plus the first Gnome-Rhone powered Potez 631.01 prototype.
A dual control trainer aircraft derivative of the 630 was proposed as the Potez 634, but the Armée de l'air instead chose to put a small order on its conversion with Gnome-Rhône engines, which was simply designated as Potez 631 Ins (for instruction). The Potez 63.16 T3 was a crew trainer derivative of the 63.11 with different, larger wings. Only one prototype was built.
The Potez 633 B2 was designed to fulfil a requirement for a two-seated, light level bomber. The Potez 633 retained the fuselage, wings and engines of the 631 but the observer's position and cannon gondolas were deleted and a small bomb bay was added between the pilot and rear gunner. Front armament consisted of a single light machine gun in the nose. The bomb bay could house eight 50kg-class or two 200kg-class bombs. There was no bombardier position, as the rear gunner was supposed to direct the bombing run through a periscopic bombsight fitted ahead of him, a disposition that proved unworkable in the field. The first Potez 633.01 two-seat bomber prototype flew in late 1937. The Armée de l'air ordered 133 Potez 633s in 1938, but two months later decided all aircraft in the light level bomber category should be 3-manned, like the Douglas DB-7 and Bloch MB.175. The French order for 633s was converted into an order for more 631s. The 633 was however offered for export and attracted orders from Romania, China and Greece.
One example of the Potez 632 Bp.2 dive bomber prototype was started, but completed as a 633 however with Hispano-Suiza engines. It was sold to Switzerland for evaluation. Similarly, the single two-seat attack bomber Potez 639 AB2 prototype was converted as a standard 633.
Dissatisfied with its strategic reconnaissance aircraft such as the troublesome Bloch MB.131, the Armée de l'air required the development of a derivative of the Potez 631 for this role. The observer was to be housed in a gondola under the fuselage. While particularly uncomfortable, this arrangement resulted in a Potez 637 that retained most of the qualities of the 631. 60 examples were ordered in August 1938 and delivered.
At the same time, the Armée de l'Air was desperate to re-equip its army cooperation units which had particularly antiquated equipment, but since the development of the 637, had completely changed its mind about how the observer position should be arranged. Potez was therefore required to develop a variant that, while retaining the wings, engines and tail surfaces of the 631, hosted the observer in a more conventional nose glasshouse.
Because the pilot needed to be seated above the observer, the Potez 63.11's fuselage was taller, which resulted in degraded top speed and manoeuvrability. As a result the 63.11 proved very vulnerable, despite being protected with some armour and basic self-sealing coating over the fuel tanks. As a secondary light bomber capability was part of the requirements (though it was rarely if ever used), the fuselage accommodated a tiny bomb bay, carrying up to eight 10kg-class bombs. This bomb bay was replaced by an additional fuel tank on late examples. Additionally, two 50kg-class bombs could be carried on hardpoints under the inner wings. Frontal armament was originally one, then three MAC 1934s under the nose, and many 63.11s were equipped with the same additional guns in wing gondolas as the 631s.
The first Potez 63.11 No.1 and second No.2 prototypes first flew in December 1938, and no less than 1,365 examples were on order in September 1939, of which 730 were delivered, making the 63.11 the most numerous variant of the family by far.
- Polish Air Forces on exile in France
Specifications (Potez 63.11A.3)
- Crew: three
- Length: 10.93 m (35 ft 11 in)
- Wingspan: 16.00 m (52 ft 6 in)
- Height: 3.08 m (10 ft 1 in)
- Wing area: 32.7 m² (352 ft²)
- Empty weight: 3,135 kg (6,911 lb)
- Loaded weight: 3,845 kg (8,488 lb)
- Max. takeoff weight: 4,530 kg (9,987 lb)
- Maximum speed: 425 km/h (264 mph)
- Range: 1,500 km (932 miles)
- Service ceiling: 8,500 m (27,885 ft)
- Rate of climb: 500 m/m (1,640 ft/min)
- Wing loading: kg/m² (lb/ft²)
- 1x fixed, forward-firing 7.5 mm MAC 1934 machine gun
- 1x fixed, rearward-firing 7.5 mm MAC 1934 machine gun
- 1x flexible, rearward-firing 7.5 mm MAC 1934 machine gun
- 4x 50 kg (110 lb) bombs
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- Breffort, Dominique and Jouineau, André. French Aircraft from 1939 to 1942, Vol.2: from Dewoitine to Potez (in French). Paris, France: Histoire & Collections, 2005. ISBN 2-915239-49-5.
- Brindley, John.F. French Fighters of World War Two. Windsor, UK: Hylton Lacy Publishers Ltd., 1971. ISBN 1-85064-015-6.
- Danel, Raymond. The Potez 63 Series (Aircraft in Profile Number 195). Leatherhead, Surrey, UK: Profile Publications Ltd., 1967. No ISBN.
- Ehrengardt, C-J. "Le Potez 63 et dérivés". Aéro-Editions, November 2005.
- Ehrengardt, C-J. "Le Potez 63.11 au combat". Aéro-Journal n°43, June 2005.
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