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Tuesday, September 28, 2010

Dewoitine





Here are some images of Tamiya's 1/48 scale Dewoitine D.520. From Wikipedia "

The Dewoitine D.520 was a French fighter aircraft that entered service in early 1940, shortly after the opening of World War II. Unlike the Morane-Saulnier M.S.406, which was at that time the Armée de l'Air's most numerous fighter, the Dewoitine D.520 came close to being a match for the latest German types, such as the Messerschmitt Bf 109. It was slower than the Bf 109E but superior in manoeuvrability. Because of a delayed production cycle, only a small number were available for combat with the Luftwaffe.

The D.520 was designed in response to a 1936 requirement from the Armée de l'Air for a fast, modern fighter with a good climbing speed and an armament centred around a 20 mm cannon. At the time the most powerful V 12 liquid cooled engine available in France was the Hispano-Suiza 12Y, which was less powerful, but lighter, than contemporary engines such as the Rolls-Royce Merlin and Daimler-Benz DB 601. Other fighters were designed to meet the specifications but none of them entered service, or entered service in small numbers and too late to play a significant role during the Battle of France.

The D.520 was a modern fighter type, but was considered more difficult to fly than the older MS.406. An all metal structure was used, except for fabric-covered ailerons and tail surfaces. The wing, even if single-spar, was a solid and rigid unit with a secondary spar and many reinforced parts. The inwardly retracting undercarriage had a wide 2.83 m (9.3 ft) track, and was fitted with wide, low pressure tyres. A self-sealing fuel tank with a capacity of 396 l (87 imp gal) was mounted between the engine and cockpit, along with two wing tanks which, combined, carried another 240 l (53 imp gal), for a total of 636 (131 imp gall); this was considerably more than the contemporary Bf 109E, Spitfire I and early Italian fighters, each with about 400 l (88 imp gal) fuel capacity. The ferry range was from 1,300 km (810 mi) to 1,500 km (930 mi) at 450 km/h (280 mph) which, from June 1940, allowed D.520s to escape to North Africa when France fell. The handling changed according to the amount of fuel carried; using the fuselage tank alone fuel consumption had no appreciable affect on handling because the tank was on the centre of gravity, but, with full wing tanks, directional control was compromised, especially in a dive. The flight controls were well harmonized and the aircraft was easy to control at high speed. The maximum dive speed tested was 830 km/h (520 mph) with no buffeting and excellent stability both in the dive (depending on fuel load) and as a gun platform.

The H.S. 12Y-45 engine was an underpowered, older design, with 850 CV (840 hp) at takeoff at 2,400 rpm, or 935 CV (922 hp) emergency power at 2,520 rpm and 1,900 m (6,200 ft). The Hispano engine had some advantages over more modern engines; the weight was only 515 kg (1,140 lb), compared to the 620 kg (1,400 lb) of the Merlin III. Another significant aspect was the provision of an injection system, much the same as the DB.601, that allowed the D.520 to dive without fuel starvation problems. The 12Y-45 and -49s used either 92 or 100 octane fuel. The D.520 had a fire suppression system with a fire extinguisher activated from the cockpit. The engine was started by a simple but effective system, operating with compressed air, a system that made the D.520 essentially a "compressed air fighter". A Viet air compressor charged several air bottles (one with 12 l capacity, as well as another 8 l tank, three smaller 1 l units matched to the weapons). The 12 l air bottle was used for the brakes and later, for the propeller's constant speed adjustment. The small air bottles provided up to 12 seconds at 9,000 meters or 20 seconds pressure at low level, before the Viet air compressor re-charged them.

The pilot had a complete set of cockpit instruments and a 10 l oxygen bottle (with a Munerelle or Gourdou inalating system) behind him. Equipment included a radio set, a reflex aiming system (less effective than the Revi system) and a sliding canopy. Except over the long nose, the pilot's view was good, since the pilot was seated quite high over the forward fuselage, however, no mirrors were fitted.

Production-standard armament consisted of a 20 mm HS.404 moteur-canon, with an ammunition capacity of 60 rounds, firing through the propeller hub, and four belt-fed MAC 1934 M39 7.5 mm (.295 in) machine guns in the wings, each with 675 rounds per gun. The MAC 1934 machine guns had a high rate of fire of 1,200 rounds per minute (rpm) while the effective HS.404 fired at 600 rpm and was able to shoot accurately up to 500 meters; the ammunition capacity meant that the MAC 1934s could be fired for a total of 30 seconds, while the HS. 404 had 10 seconds worth of ammunition. In combat the MS.406 had only two 7.5 mm and was, therefore, at a disadvantage when the HS.404 had used up its ammunition, while a D.520 could continue to fight effectively because it had four fast-firing machine guns (over 80 rounds/sec), with 20+ seconds of ammunition still available.The D.520 had provisions for two BE33 "illuminating bombs" useful for night interception missions, but rarely used. D.520s were not fitted with bombs, as French fighters were primarily defensive aircraft.

The D.520 was designed to be maintained easily with many inspection panels, a rare feature for its time. Re-charging the D.520 ammunition was swift and easy; the machine gun magazines required five minutes each and three minutes for the 20 mm cannon. To fill the machine gun ammunition boxes took 15 minutes, while five minutes were needed to empty the 20 mm box (the cartridges weren't expelled).

Production was optimized with a reduced 7,000 man/hour each, roughly half the time compared to the previous D.510 and MS.406, and far less many other fighters of the time, such as the MC.200/202 (21,000 hours), but around 50% more than a Bf 109E (4,500 hours). The French Air Ministry planned for over 300 aircraft/month and managed to reach this goal, especially in June 1940, but it was too late to affect the tide of battle.

2 comments:

Pablo J. Álvarez said...

It's a great work, the camo is thruly french.

Warren Zoell said...

I would love to see more early war French and Polish aircraft but they're difficult to find.