Sunday, May 20, 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.









Monday, May 14, 2012

The Dewoitine D.520 - her pilots told us about her maneuvrability (revised 17 / 03 / 2015)

Regarding the fighter planes, the most controversial quality is undoubtedly the maneuverability.

On almost all forums regarding the warbirds, as the most modern fighter planes, peoples are very impassioned about that question.

But very few are those who were able to compare effectively - i.e. in flight - the different aircrafts they are discussing about.



Handling vs Maneuverability



First, I want to rule out a wrong question.

When I was learning to fly, I was used with the very light ailerons of "my" first plane (a Morane-Saulnier Rallye 880 B 105 hp).
So, transferred to the much faster Robin DR 400 - 140 hp,  the ailerons were not so light and I thought the Robin as less nimble than the Morane.

Some dozens of flying hours later, I cannot feel significant difference of maneuverability between the 2 aircrafts.

British test pilots seemed to have separated the handling capacities of an aircraft from its maneuverability.

Nevertheless, reading the excellent British reports regarding the Messerschmitt Bf 109 E (http://www.spitfireperformance.com/spit1vrs109e.html), you can read that above a given speed, the ailerons of this fighter were becoming "solid" or "immovable".

So these 2 characteristics cannot be seen as independent at all.


Habits and skill



A forgotten fact is the pilots of different countries learn to fly on different school planes which don't share all the same properties.

So, once becoming operational fighter pilots, they prefer some maneuver that are not seen as natural for pilots belonging to other countries. 

In France during the 30's, the school-planes were the Morane 230 high parasol wing monoplane or the Hanriot 436 single bay biplane.

The following step used of Nieuport 62 sesquiplane, vilified by the French CEMA (official test flight center) because her landing characteristics were very sharp and also because she was directly derived from the Nieuport 42.

This last fighter, during her first full speed diving tests, had triggered the first ever recorded manifestation of the aileron flutter, resulting in a fatal crash.

The efficiently modified Nieuport 62 was much more stable and easy to fly in aerobatic (as it was said by Roger Sauvage - who was trained on this aircraft - a French ace who obtained the last 15 of his 16 victories against the Luftwaffe within the Normandie-Niemen regiment).

This fighter was used during the first year of the Spain War by both sides, and also - shortly - by French pilots in Numidia - oh, excuse-me: in French North Africa - at the beginning of the second World War.


Another reminder consist in the very interaction between any kind of vehicles (including horses...) and their pilots. In the cases of horses, it's a plenty accepted - and well known - relationship. 

In a mechanical vehicle, the pilot must also feel a full harmony with the dynamic characteristics of his vehicle. Such a relationship may be based on the relevance of the training. 


If you have some doubt about that, remember (!) how vilified was the Bell P39 Airacobra by American and West pilots and how the Soviet ones liked her. 


Really, what could have been the feeling of an American pilot if he had to fly the quite unstable and diminutive fighter Polikarpov I 16 ?



Moreover, the assessment of a fighter is never the same following the date of the flight trial was done.  


In 1939, the test pilot Michel Détroyat - former chief pilot of Morane-Saunier - after his flight test on the D.520, said the Dewoitine fighter was extremely maneuverable.

The Belgian test pilot, Major Arendt, who might have flown the British Hurricane I fighter, flew the D.520.

After he had sent his report, the Belgian government decided to buy the license of the French fighter.

One year later, the French operational fighter pilots feel that their new fighter was very nimble. The actual Capt. R. Clausse (Grp. II/3) in the foreword of the book of R. Danel, Le Dewoitine 520 (Docavia #4) - the Bible on this fighter- wrote:


"A show plane? certainly not. But an uncommon fighter, outstandingly maneuverable, as fast as any other fighter (in May 1940, of course), with an excellent rate of climb until a high ceiling, diving at fantastic speeds, fitted with an efficient armament, excellent gun platform..."

Capt. J. Pape (Grp. I/3) told us:

"The handling trials allowed us to see this fighter as very maneuverable, easy to fly. 

The pilot training being without problem, we thought we might be already operational. 

However, it appeared the plane needed more than 100 modifications! Indeed, the design of the aircraft was good and she had good characteristics and, after finalization, she was really excellent. Unfortunately, she was not truly experimented in time".

These last words regarded the people who had imposed the Hispano 12 Y 45 in place of the HS 12 Y 29.


After November 1942 and up to mid-1944, Germans had ordered new Dewoitine 520 for using them as advanced trainer.

It's a proof they feel this fighter as easy to fly and very easy in aerobatics.

The German ace Ernst Schröder was trained on the French fighter.

He did not like her ground behavior as also the frequent sabotages made by the French worker of the Toulouse plant (the present Airbus plant). However, he said:

" What a delightful plane! Very light actions on the commands were sufficient to do all the aerobatics. A loop needed only two fingers. Not any German fighter at that time was able to offer such a fineness of flying...."

Italian pilots used the Dewoitine fighter after mid-April 1943, to struggle against daylight American bomber.


The reason was the Italian designed fighters lacked of a powerful weapon.

The D.520 had a deadly Hispano HS 404 20 mm gun with unfortunately (for them) only 60 ammunition.

The engine was the same as fitted in late 1939, so the fighter appeared pretty slow.

Obviously, the Frenches never warned Italian pilots with the fact that it was forbidden to combat when the wing tanks were full of fuel: They must be used only during ferry flight, otherwise the fuel would go to and fro, altering significantly the handling properties.

So, most of the Italian pilots disliked the Dewoitine 520.

There were notable exceptions, as the pilots of night fighting and, also, the great ace Luigi Gorini, who, in an interview, explained that the difference between a Fiat CR42 and a D520 was as great as the one existing between a tricycle and a Ferrari!

In another text, he told: "tested at her minimal speed, the fighter was perfect and extremely maneuverable, as he had seen it while he was fighting over the Cannet des Maures, the June 15, 1940."

(the combat of the June 15 allowed to Pierre Le Gloan to down successively four CR42 and one Fiat BR20 in a 50' flight).

The controversy staying, another post will explain a bit more.