SNCASE SE.520z. the ultimate D.520

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caid’s suggestion #115

I would like to suggest the last D.520 variant for France, the SNCASE SE.520Z

The origin of this plane started back during WW2. the SE.520z was based on the Dewoitine D.520. the D.520 was the main French medium fighter in 1939-1940 and was allowed to remain in service in France during the German occupation. unlike the other aircraft development, the D.520 research wasn’t halted by the Germans during the occupation, it was monitored. originally called D.520Z the aircraft was renamed SE.520Z after the liberation of France after the dismentelment of Dewoitine by the new freed french government who purged the collaborator who worked with the german to keep a firm hold on france during the occupation.
during the occupation of France, the Vichy puppet state look into the potential upgrade for the D.520. serial version was already in development back in 1939-1940 but what they really wanted was a plane who could meet the CI requiment of 1939. the need of a new engine was obvious. Dewoitine industry wanted to install the bigger and heavier Hispano-Suiza 12Z in the D.520. this would allow a theoretical top speed of 659 km/h which was a neat improvement over the 560 km/h of the regular D.520. this came with serial modification and change notably with the radiator and cooling system. the armament too was needed to be improved to meet the standard of the time. the knowledge acquired during the development of other dewoitine’s plane such as the D.524 was put into contribution.
the construction of this plane was done with the permission of the German. the development started in 1941 and the construction of the prototype in 1943 and ready to do the first flight when the German decided to forbid the plane to take off due to the too high performance of the engine who can be a treat to the german aircraft. a total of 105 was planed to be built for Vichy France. it wasn’t before 1946 that the prototype could finally be tested. by them Dewoitine industry was integrated into SNCASE and the plane renamed SE.520Z. serial test was carried out on the ground to see how the engine would perform. the plane did a couple taxi run on the runaway on his own power and could theoretically take off but never did. the plane was scrapped in 1947 because it was just not needed anymore by that time.

Firepower
the SE 520z is a pure fighter. it would be a match in the sky with some of the best WW2 aircraft. the armament planned wasn’t the same as installed. I will let Gaijin decide which armament it wants to give it.
the planned armament included 3x 20mm auto-cannon and 4x 7.5mm machine gun

  • 1x 20mm HS 404 auto-cannon, in the hub, 60 rounds carried
  • 2x 20mm HS 404 auto-cannon, in the wings, 120 rounds per guns
  • 2x 7.5mm MAC 39 machine-gun, in the wings, 675 rounds per guns

instant it got a more basic armament for the prototype

  • 1x 20mm HS 404 auto-cannon, in the hub, 60 rounds carried
  • 4x 7.5mm MAC 39 machine-gun, in the wings, 675 rounds per guns

whatever the armament Gaijin decides the give it, it would still be interesting to have. but personally, i would love to see the planned version.

No bomb was carried
Flight performance
the aircraft was mounting a powerful Hispano-Suiza 1600 hp engine with a Szydlowski-Planiol compressor to give the plane better performance. the plane was weighting 3.150 kg in max load in 1943 when it was ready to fly for the first time. the plane was estimated to have different performance according to the altitude it would flight

  • 478 km/h at sea level
  • 562 km/h at 4000m
  • 659 km/h at 9150m

the climbing rate was also interesting

  • 0-4000m = 16 m/sec
  • 4000-8000m = 15.87 m/sec
  • 8000-11000m = 8.40 m/sec

this indicates the plane will not feel any significant reduction of flight performance before 8000 m which is more than enough for the fight game. but the engine provides the best speed at around 9000m which is good for the player to fight at higher altitudes.
the plane has a flight range of up to 1250 km with a cruising speed of 400 km/h.
in take-off, it needs to run 359 m before being capable to flight at 8m.
for landing, it needs 394 m from a height of 8m to a complete stop.
the ceiling of the plane is in theory 12,300 m
the aircraft include

  • combat flap
  • landing flap
  • take-off flap

Survivability
the plane have the standard survivability of the D.520. this include most of the protection part found in the D.520

  • 38mm bulletproof glass in front the pilot
  • 8mm steel plate behind the pilot
  • 3mm steel box behind the pilot’s head

the plane is made of all metal except for the fabric covered rugged and tailwings. this makes the plane have a rather sturdy overall resistance to damage.
the part would not easily break from the Overspeed. the plane goes faster but it’s unclear if there is any significant modification to the structure of the plane. it might keep the same breaking point as the D.520.

  • Landing gear = 320 km/h
  • Wings = 800 km/h
  • combat flap = 385 km/h
  • take off flap = 365 km/h
  • landing flap = 280 km/h

Sources

Le Dewoitne D.520, by Raymond Daniel and Jean Cuny





i made this suggestion at the request of @TM_06

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Excellent as always CaID!
+1

More variants of the D.520 are really necessary, it was the bulk of the French air force from 1940 to 1942 after all.

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+1 yes trully one of the very few option that France has for a domestic fighter with mid/late-war performance, really needed

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Yes, to more 520s

Big +1! This and the D.3803 need to make appearances as the best variants of the pre-war French designs.