vendredi 13 avril 2012

The Dewoitine D.520 - as seen by her pilots (version II) (revised 17 / 03 / 2015)

The Dewoitine D.520 was undoubtedly the best fighter plane used  by the French Armée de l’Air before the defeat of June 1940.
Her capability of fast cruising - 480 kph - was a major asset even several year after 1940. 

It allowed to  Bulgarian pilots, in 1943, to make frontal attacks to B17 ou B24 bomber formations while avoiding the escorting P 38, even the later were strikingly faster, but clearly less nimble. 

Only in 1944, the P 51 ( wiped them from the Bulgarian sky!

In 1940, the climbing speed of the Dewoitine fighter, average up to 4,000 m, was very good above, giving her a one minute margin over the Bf 109 E when climbing from 5,000 m to 8,000 m, because she use a supercharger of very better technology (Szyldowski-Planiol S 39).

Her diving speed (about 850 kph) was, may be, a bit better than that of the Bf 109E. 
But the D.520 was especially more maneuverable than the German fighter at high speed. 

Several French pilots of 1940 had said to Danel and Cuny : "A 109 which was dive flying was already dead."

A good roll rate gave her a clear asset at the beginning of an evasive or of a scissor attack.  

The Dewoitine fighter enjoyed a larger range than any other European single seater. 

The Hispano-Suiza 12Y45 was very reliable for its times. 

These two assets allowed easy change of location. 

For example, all of the D.520 of the French Air Forces crossed the Mediterranean sea during the third week of June 1940. 
To my knowledge, only one fail to land safely in Algeria and ditched near a beach, the pilot being safe. 

As early as the June, 25, 1940, three French pilots flew successfully from Toulouse-Francazal airport to continue the fight for the Free France with General de Gaulle. 

All three landed safely near Southampton, the complete distance they flew being likely much more than  the ~1000 km in bee-line, owing to the need to avoid German fighters.  

Personnel document of the author - in Cyan, the combat range of a Dewoitine D 520 taking off at Le Bourget Airport.                                                        - in Red, the combat range of a Messerschmitt Bf 109 E starting from the same place.

The true shortcoming of the D.520 was her tendency to make ground loops, because production aircrafts fitted a tail-wheel, a device the first 3 prototypes did not have. 
Moreover, this device was ill-designed.

All the French test pilots had begun to fly on Nieuport 62 fighters which were rather special when running on the usual rough surface of the actual French airfields. 

So, they were "Darwinianly" selected to steer perfectly such planes on such surfaces and also they flew the production aircrafts after a long use of the prototypes. 

So, they had not perceived the landing problem for more recent pilots or for pilots being used to very comfortable airfields.

 Very late, after the experimental fixing of the ground looping obtained by the Italian pilots, the French staff understood the problem and introduced a similar patch: The standstill of the tail weel.

Regarding the flying qualities, most of the pilots agree to acknoledge the very good qualities of the D.520 as a fighter, as it appears in the Colonel de Turenne report, who was in command of the groupement 24 (in 13 Juin 1940, premières frappes en métropole, les combats franco-italiens, Batailles Aériennes, #11, 2000):

"The D.520, used for the first time by confirmed pilots holder of several victories, was seen as fast, manoeuvrable, allowing easy attacks against the Italian bombers. However, the pilots warned us to avoid any turning manoeuver while shooting an aircraft in order to be efficient, because the D.520 skids during turn".

The pilots think the cannon is most efficient than the machine guns. They said me: "the cannon kills, the machine gun hurts only". They have learn unofficially that the cannon will be no more fitted on the Dewoine fighter. They asked me to use my influence with the command to reject such a project. I have done that with pleasure because I'm convinced one may take into account of the advise of three pilots who have been victorious several times each.

This report is significant of the contrast the Dewoitine 520 instituted in the mind of her pilots by comparison to the previous fighters.

[NB: To my knowledge, the D.520 was never projected to be without her cannon, however the alleged rumor regarded only the lighter D.551, for which there was proposed three types of armaments. The first was only the cannon, the second 5 light machine guns and the third 4 light machine guns.

So, Lt-Colonel Michel Marias (grp III/3) confirmed  the considerable relief he felt when he have got his first D. 520: 
"We managed to go somehow or other with our Morane until to the May 24, when we went to Toulouse-Cazaux to got our D.520. 

This time, our moral cheered up suddenly. This fighter was an outstanding one. 

The feeling that I had actually - that all of us had until that day - to be puppets at the enemy's mercy at last vanished"

This opinion is close to that of Marcel Albert (grp I/3 "les chats" and, later, GC 3 / Normandie – Niemen in which he finished the War as second French ace with 23 victories - at least) :  

"The Dewoitine, with her four machine guns and her cannon, was an excellent fighter. They were pretty numerous at Toulouse, at Châteaudun, all over the place, but in the squadrons".

Vaclav Cukr (Czech – grp II/3) said : 

"The front line situation was critical... We thank the Destiny to have got the Dewoitine D.520. Each time we encounter Germans, the were two or three times more numerous as we were. Thanks to the Dewoitine, these first quality fighters, our losses were not too high..."
Some lines further, Vaclav Cukr underlined the powerful armament and the soundness of this aircraft, after having downed a Henschel 126 with one of his friends:

"Five Me 110 rushed at me. I don't know what happened thereafter, but I came back at home absolutely uninjured, and it was possible to count 127 holes of machine gun bullets and 2 from cannon shell."

About her maneuverability, some debates have been heard later. 

Their subject was the French overestimated the value of their actual best fighter - a question induced when one knows the overestimation of the Lioré-Olivier 451 bomber, and, worst, of the Morane-Saulnier MS 406 fighter. 

This subject need a complete post (click here).
{Sources: Most of the pilots testimonies of this post were published in the Icare review, in it series on La Chasse (#54, 55,145, 156).}

2 commentaires:

  1. Bonjour monsieur,
    Dans tous vos articles relatifs au D520, vous faites d'une facilité de manœuvre et des évolutions supérieures ou équivalentes à l'ensemble des chasseurs qu'il rencontré en juin 1940.
    Je crois que vous connaissez le jeu Warthunder, le D520 est décrit peu manœuvrant et nécessitant de maintenir de haute vitesse pour toute figure. Seul tactique valable selon le site wiki du jeu le boom and zoom.
    j'avoue être perplexe.
    Pourriez avoir la gentillesse d'éclairer ma lanterne.
    Cordialement votre.


  2. Hello,
    Here, you suffered from a lot of anachronism.

    British and US pilots, after their African landing in November 1942, discovered a lot of worn out French fighters, which have not been upgraded since June 1940

    The YS engine of the 1940 Dewoitine 520 delivered 930 hp, the one of a 1942 Spitfire V delivered ~1,500 hp.

    Moreover, the French pilots had lost their excellent training because the German forbade totally a monthly training exceeding 4 hours in a month (a normal training was 25 hours/ month).

    From the other hand, the Dewoitine not able to turn as tightly as the British fighter (wing loading: 135 kg/m²) but her real roll rate would be better. A similar comment for a confrontation with a Grumman Wildcat.

    In June 1940, the Spit was not so well defined and her roll rate was 25°/sec!

    The June 1940 enemy fighters were only Bf 109, Bf 110, Fiat CR 42.

    The Fiat was highly maneuverable, the Bf 110 was very heavy, the Bf 109 was slightly faster but clearly less nimble.

    If you want to dog fight the Curtiss P 40, in historical condition, you must fly above 5,000 m: The D 520 supercharger was better than the one of the US fighter.

    Don't try to engage an A6M2 in 1942, except above 6,000 m or in dive.

    Remember, it's only a game, not a historical reconstitution.

    When the French pilots went to Russia in 1943, they chosen the Yak fighters, because they were similar to the D 520 from a pilot point of view.
    You may explain this to the Gaijin company;-)