dimanche 20 mai 2012

The Dewoitine D.520 - A perfect beast for combat ! (Enriched 14 / 03 / 2016)


An English opinion (?)


Some allied pilots who had fought Vichy pilots during the operation Torch in North Africa in November 1942 have reported some weakness of the Dewoitine 520 while dog fighting.

This can be linked to the comment of Capt. Eric Brown, commanding officer of the Royal Aircraft Establishment's Captured Enemy Aircraft Flight (sic), you can found in the Wikipedia article - in English - on the D.520 fighter. 

He tested the D.520 at RAE Farnborough, saying that “It was a nasty little brute. Looked beautiful but didn't fly beautifully. Once you get it on the ground, I was told not to leave the controls until it was in the hangar and the engine stopped. You could be taxiing toward the hangar and sit back when suddenly it would go in a right angle.” 

However, that peremptory claim cannot be seen as a true flight analysis. In this, it is absolutely different from the well documented flight analyses done in 1940 at Boscomb Dawn. 

Moreover, nothing in his telling suggests he really flew the D.520. I acknowledge that in 1945, he might had a lot of more urgent works to do. 

Nevertheless, it's clear he never had any good feeling for France, as his father and him were very close to high ranking Nazis in command of the Luftwaffe, as general Ernst Udet and Hanna Reitsch (source: English Wikipedia, May 2012)

He was sufficiently close to Nazis to spent a lot of time in the Third Reich during the lasts months of peace time and was politely escorted to the Swiss border after UK was at war with Germany...



A German opinion


Since May 2011, on Wikipedia in German, in the article on the Dewoitine fighter, it is possible to read that analysis.

The June 9 1940, German pilots of the II./JG 27 with their Bf 109 E were facing French pilots of the GC I/3 with their D. 520.

Both units and their pilots were well trained for combat and controlled efficiently their own fighters. Coming back after the combat, the French pilots claimed 6 Messerschmitt Bf 109 E downed.

In fact, 6 German fighter were downed, as one Dewoitine which had made a lucky belly landing.

German authors Ring and Girbig (in their book JagdGeschwader 27) as Jochen Prien had confirmed these strong losses […].

That example is an indication of the superiority of the D.520 over the Bf 109 E in aerial combat in spite of her lower top speed (532 versus 570 km/h).


On second thoughts


If you want to assess the maneuverability of an aircraft by her combat results, an important concept which must absolutely be taken into account: The conditions in which are the pilots have to be similar on both sides. 

It was the case in May-June 1940 combats, even the D.520 French pilots were not as used as the German or the Italian ones: all were well trained (250 to 300 hours/year).


Pierre Boillot (Grp II/7) had get a confirmed victory in April 1940 with his Morane 406. 

Some weeks later, his group have got Dewoitine 520. He told (in Icare): "We had flown only few hours with our D.520. For young pilots as I was, it was irrelevant. We needed to fly a lot, even if enemies were close. It's the only way to learn to use her by reflex. That's the very way to combat with a fighter."

The same pilot fought several Messerschmitt Bf 109 with his new fighter after less than ten flying hours: "We have done several complete turns, each of us trying to tighten his turns more hardly than the other, the Germans to shoot me, me to avoid their shots.... At a given time, I was very amazed, because they were lower than me. During a dogfight, everybody tend to loss some altitude, but they flew under my position." 

Thereafter, the D 520 fighter went to a spin, allowing Boillot to break the fighting.

Pierre Boillot gave us a very precise description - better than all of that given by the CEAM combat test between Bf 109 and D.520 - of what he lived. 

Against several German pilots, he was able to be uninjured (as was also his plane) and to conserve his altitude a while more than the others. 

So, the Dewoitine 520 used by a true combat pilot was more maneuverable in turning maneuver than the Bf 109 E.



The French pilot Michel Détroyat, after an impressive career of test pilot for the Morane-Saulnier company was chosen to give to the French Air Ministry a global assessment on all the prototypes of new Fighter.

The December 22, 1939, he send the following times for a 360° turn:

  • Curtiss Hawk 75 (P 36)           12",
  • Dewoitine 520                         15",
  • Morane 406                            18".

{These data were published by J. Cuny & G. Beauchamp, Curtiss Hawk 75, Docavia #22, 1985}
Against the Allied pilots, 2 years later, in addition to fight our Allies instead of the Germans - who remained the true enemies even for the Vichy pilots - the training of the French pilots could not be more than 4 hours a month and their dog fight skill was dwindling


In the same time, Allied pilots had learned a lot from 2 hard years of war against German and Italian fighters and had developed new tactics.




1939
1940
1941
1942
1945-7
maneuverability
 Excellent

 excellent 
good
controversial
excellent
   pilot's training
    hours/month
 25 
30 
< 4 
25 
           
            Table summarizing the French pilots feeling about the D.520 maneuverability following their own training

The feeling of the French pilots about the maneuverability of the Dewoitine fighter evolved a lot from 1939 to 1947. 

So, André Deniau told (in Icare) the Dewoitine 520 was very touchy to fly: "When you want to make a tight turn, the Dewoitine gave two bumps in the stick: toc-toc. You may not wait for a third bump, you needed to release immediately the pressure on the stick, otherwise you will stall suddenly and the aircraft go to make two snap rolls. It was the reason of several casualties." 

What it is said here looks like some addresses given to inexperienced pilots by some only average monitor. 

That was not only true for the Dewoitine: The French pilots of the Lafayette squadron have got a complete re-equipment from their P 36 fighters to P 40 ones by the USA. 

But they were not very efficient. 

As a consequence, all French pilots belonging to the previous Vichy Air Force were later intensively re-trained on Dewoitine 520 at the Mecknes Fighting School in Morocco.

Another pilot, Jacques André, flew the D.520 before going to the GC3 - Normandie-Niemen, and said (in Icare):" Three months ago, we flew the Dewoitine, a very good fighter, but under-powered, with just 900 Hp, this implying she was touchy to fly. 

However, flying the Yak 9 fighter [with her 1200 hp engine], we have already seen that it was rather impossible to trigger a snap roll even while turning very tightly. 

We experienced a total black-out but no stall at all." 


The training problem: Not only for the French pilots!


In their book on the Dewoitine D.520, Danel and Cuny insisted on a possible misreading of the warning announcing the stall. 

However, the accidental losses were of the same order than for other fighters, suggesting the Dewoitine was rather easy to fly.

OK, you are thinking I'm using a very complicated thinking to prove the D. 520 was a very good fighter? 

But, at the kurfurst site, you can read the result of the tests made by Morgan and Morris in September 1940:

 When the Me.109 was following the Hurricane or Spitfire, it was found that our aircraft turned inside the Me.109 without difficulty when flown by determined pilots who were not afraid to pull their aircraft round hard in a tight turn. 

In a surprisingly large number of cases, however, the Me. 109 succeeded in keeping on the tail of the Spitfire or Hurricane during these turning tests, merely because our Pilots would not tighten up the turn sufficiently from fear of stalling and spinning."


Among the British pilots, those who feared the tight turns were not sufficiently accustomed to fly their Spitfire

In my opinion, it was only a training problem. 


Only very skilled AND perfectly trained pilots are able to profit from a very maneuverable fighter.

Late in 1942, the lack of training in dogfight deterred the French pilots to "tighten up the turn sufficiently from fear of stalling and spinning". 


A pilot lacking from self confidence exaggerate his safety margins and release the stick a bit too early.



Nevertheless, the pilots of the French Aéronavale stay rely on the Dewoitine 520, as explained the 2nd M. Bédard (2 AC - Port Lyautey - 1942 - source: L'aviation de Vichy au combat, C.J. Ehrengardt & C.F. Shores): 

"I read the Dewoitine was outclassed by the Wildcat. 
I cannot agree. 

The D.520 was sturdy, reliable and well armed. 

I relied completely on this aircraft. 

Obviously, the Wildcat was more maneuverable because she was slower and had a larger wing area. 

You need only to avoid to be lured into the trap of her maneuver.


The Wildcat was a carrier plane with a 132 kg/m² wing loading, the D.520 having 165 kg/m². 

The  better asset of the French fighter against her was her own climbing speed as her superior diving acceleration.

This French Navy pilot succeeded to down one Wildcat and to damage another during the opening stage of the operation Torch.


You can see also the same training problem for the Russian pilots when they were confronted with the Mig 3 fighter, 200 km/h faster than the Polikarpov I 16 of the previous generation, and, also for the Japanese pilots confronted with the Nakajima Ki 44 (Tojo). 

In all of these cases, the pilots lacked self confidence as also they lacked the knowledge needed to use efficiently their fighters.









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