dimanche 13 octobre 2013

The Bloch 157, an exceptional fighter (Revised 19 / 10 / 2018)




A crucial need for speed...


Constraint by some lobbies to choose a very slow standard fighter for his Armée de l'Air, the High Staff of the French Air Forces became aware, in 1938, a bit too late, that he had opened a crucial gap of performances facing the Nazi Luftwaffe.

This Staff had got the poor 450 kph Morane-Saulnier 406 fighter, to which were added the 485 kph Curtiss H 75, the 480 kph Caudron CR 714 and the 505 kph Bloch 152 (in her last variants).

Remember: The Dewoitine 520 fighter, designed for speed between 520 and 570 kph (depending on the installed engine power) had not yet flown at all and was, therefore, not yet ordered.

At the same time, the Spitfire had demonstrated ~570 kph, as it was published by the famous British review Flight in December 1938.


So, a new French fighter program was hurriedly published in mid-1938. 

This program specified a top speed of at least 650 kph at altitude, some enhancement of the armament and so on.

For that purpose, two engines were retained: 

  • The Gnome et Rhône 14 R Météore, a 14 cylinder double row radial air cooled engine issued from a complete redesign of the previous 14 N of 1050 hp. The new engine was of the 1,600 hp class.
    • It was fitted with a 2 stage Farman CC1 supercharger with a first critical altitude of 2,000 m and a second critical altitude of 6,000 m. 
    • The maximum continuous power of 1,250 hp was obtained at 2,400 rpm.
    • The combat power of 1,580 hp was obtained at 2,600 rpm, for 5 minutes during climbing or 15 minutes during  horizontal flight.
    • This engine had successfully flown since July 1939 on the twin-engined float sea scout-bomber Loire-Nieuport LN 10, allowing her a top speed of 430 kph, a very exceptional performance for a 14,000 kg seaplane, carrying a crew of six, two torpedoes and able to fly 3,300 km. 


  • The Hispano-Suiza 12 Z, which weighted 200 kg more than the previous 12 Y engines, was also of the 1,600 hp class of power, but at a still immature stage of development, yielding only 1,250 hp. 
    • Amazingly, this engine flew for the first time with the very streamlined Arsenal VG 39, allowing her to achieve 625 kph at 5,900 m. 
    • The choice of the VG 30 fighter family to begin the flight testing reflected some oddities in the decider's minds. The VG 39 wings, structurally modified in order to accommodate six riffle caliber machine guns, conserved the area of 14 m² of the VG 33 at the same time the empty weight suffered a 250 kg increase...
    • The Dewoitine 524, more suited for such a heavier engine (wing area: 16 m²), would initiate test flying at the very time of French collapse, too late...   
    • Unfortunately, this engine, which was really very promising, was never perfected: After the German onslaught, the planning department was transferred from Paris to the South of France but without all the facilities, engineers and archives. In the same time, the German occupying power was ever present, inducing a very bad mood at work.



The fighter projects scheduled for 1941 in the other countries


To have an idea on the technological level of the different country from the end of 1939 to the beginning of 1940, I summarize here some data of the most important fighters expected to enter service in 1941, as it was expected for the Bloch 157 (and also the Dewoitine D 524 fitted with the HS 12 Z engine)

Among them, a significant amount cannot be operationally flown before some months, or even years later.

Germany:

Only two projects of conventional fighters were planed in the Hitler's Germany for 1941: A Messerschmitt one and a Focke-Wulf one.

The Messerschmitt Bf 109 F (Friedrisch) was in project since the spring of 1940. She was based on a complete redesign of the wings, of the fore part of the fuselage and, also, on a new version of the DB 601 engine (the Bf 109 F1 et F2 used the DB 601 N of 1,200 hp).

The armament was also reviewed, retaining an engine-mounted 20 mm cannon and 2 machine guns. 

{In my opinion, after the French defeat, the German engineers were very happy to examine the French fitting of such an association - which worked perfectly - they were not able to perfect before the Summer of 1940 because their cannon seized, as reported W. Green in his Famous Fighter of WW II, vol 1. 
Remember, the first moteur-canon used operationally in the World was the system used by G. Guynemer and R. Fonck with the Spad 12 which was powered by an Hispano-Suiza 8A in 1917.}


The first weapons used in the Bf 109 F1 (1 MG FF cannon + two 7.92 mm machine-guns) was quickly replaced in the Bf 109 F2 by a better combination of 1 MG 151 cannon, with better ballistics, and two 13 mm machine-guns, with an 4 times enhanced punch! 

For the first time, the Messerschmitt fighter had all the punch needed to dominate her actual enemies.

Her top speed - in 1941 - was 615 kph at altitude and this fighter was very efficient against the early versions of the Spitfire V.

A more powerful engine, the DB 601 E - 1,300 hp - was fitted on the Bf 109 F 3, but only at the beginning of 1942, allowing at top speed of 630 kph (the only one remembered now in published data...).


The other German fighter project for 1941, but conceived in 1938, was the Focke-Wulf 190

Dr. Ing. Kurt Tank, who conceived it, wanted at first his fighter to be a true war bird, this signifying a very robust aircraft, able to withstand the worst conditions (a characteristi situation in war time). 

This fighter was designed initially to use of the 14 cylinders radial air cooled engine BMW 139 of 1,500 hp for take off at 2,700 rpm and 1150 hp of continuous power at 2,000 rpm at 5,400 m (on this site).

This engine weighted 800 kg dry, but its cooling being very difficult to perfect, Dr Tank preferred the much heavier (1,088 kg) and more powerful (1,750 hp) BMW 801, a radial 14 cylinders, air cooled engine

Owing to the induced increase of the empty weight, the wings totaling 14.90 m² were no more suited for such a fighter.

With new wings, hurriedly redesigned and having an area of 18.3 m², the modified FW 190 became the exceptional fighter everybody knows today.

{It should be noted that the redesign of these wings occurred after the "visit" of the Marcel Bloch design office (SNCASO) that Kurt Tank directed the 17 July 1940 in Bordeaux (inside the German occupied zone). 

In this occasion, Dr. Ing. Tank congratulated his French colleagues for their excellent work.

It is very likely that he had seen both the crate containing the MB 157 and the blue prints of this fighter.} 



She appeared operationally in August 1941, against the RAF Spitfire Mk V which were completely dominated, but at high altitude. 

The top speed of the first variant of the FW 190 was ~640 kph (400 mph), 40 kph faster than the British fighter, a significant asset, but the climbing performances were only average for the times.

At that precise time, the armament of the German fighter was still not very strong, with 2 bad MG FF and 2 riffle caliber machine guns.

This shortcoming was to be corrected only in 1942 (even you can read that it was fitted some 3 months earlier).


Japan:

The comparisons frequently done between the Mitsubishi A6M2 Zero-sen with the Allied land based fighters flying in 1940 are absolutely not fair: Because she was not land based, she must carry an arrester hook, a lot of fuel and so on...

Her maiden flight, in April 1939, was done with the very light Suisei engine. Her top speed was only near 500 kph.

The first use of her true operational engine and more powerful Nakajima Sakae (950 hp) occurred only in January 1940. 

With a take off weight of 2,400 kg, the top speed was 533 kph, the ferry range was ~3,000 km and the climbing time was 5' 56" to reach 5,000 m.

{comparison: The Seafire II C of 1943 was a true reference among the actually Allied carrier based fighters. 

She was tested in February 1943 (see this excellent site here), used a Rolls-Royce Merlin 32 engine delivering 1,640 hp, achieved 540 kph at 2,500 m, reached 5,000 m in ~5' at combat rating and had a ferry range of 800 km. 

The British fighter did not show any evident superiority on its Japanese counterpart, even being the carrier variant of the Spifire VC, 60 kph faster! }



Great Britain:



The Supermarine fighter project for 1941 was the Spitfire V because the scheduled Rolls-Royce Griffon engine was not yet available (not sufficiently reliable) for the Spitfire IV. 

This fighter weighting 3,000 kg for take off had a top speed of ~600 kph at 6,000 m and climbed to that altitude in ~6 minutes. 

These performances were not sufficient to outclass the German Bf 109 F, but the British fighter was absolutely able to hold out attacks of that enemy fighter, but at relatively low altitude.

The Focke-Wulf was a much concerning threat, being more nimble, considerably faster and tougher.



The problem was completely different for the Hawker staff. 

Even fitted with the Merlin XII yielding 1,175 hp for take off, the Hurricane Mk II - issued from the technology of the Fury biplane fighter (!) - was unable to fly faster than 550 kph at 6,200 m. 

So, her great chief-engineer, Mr Sydney Camm, launched the studies for a far more advanced fighter. This fighter was the Tornado, very streamlined and using, mainly, a metallic stressed skin monocoque structure.

The Rolls-Royce Vulture II of 24 cylinders engine, delivering 1,760 hp, was retained (even resulting from the assembly of two Peregrine V 12 engines which were never perfected!) and the new fighter begin her flying testing at the very end of 1939. 

The first flights seemed extremely promising, with high performances, but at the start of the diving tests, it was discovered the Tornado thick wings and air cooler were not suited to the very high speeds, because of the compressibility problems.

In the same time, the Vulture II engine suffered severe lack of reliability and was canceled, as was subsequently the Tornado.

The Typhoon was a variant of the Tornado, differing mainly by the 24 cylinders Napier Sabre engine delivering 2,000 hp. 

This fighter demonstrated some problems during take off (nasty and quite unpredictable swings to starboard), difficult handling at low-speed, vibrations (which may cut the whole tail) and aileron reversal when approaching 800 kph in dive (the wing remained as thick as those of the Tornado).

Nevertheless, with a top speed of 650 kph (the take off weight being 5,000 kg), she was, actually, the fastest Allied fighter and the only one able to catch the German Bf 109 F and FW 190 A2 fighters at low or medium altitude. 

So, she was hurriedly pushed in the production status in 1942 when the Focke Wulf 190 demonstrated they were immune to the Spitfire V at low level. 

Unfortunately, a lot of structural failures plagued the Typhoon

Sydney Camm understood the need of a thinner airfoil and chose a thickness/chord ratio of 14.5%. 

The new fighter, initially designated as the Typhoon II, became the Tempest which prototype flew for the first time late in 1942. 

It was really a very good fighter even her tightest turning radius was considerably larger than the one of the Typhoon (in each improved variant of these fighter, the total weight increased but for the last one, the Hawker Fury of 1945). 

But her operational activities began only in April 1944... 


USA:

The US fighters were numerous in 1941.

The Curtiss P 40 and the Bell P 39 entered service early in 1941. 

Both were heavy aircrafts whose empty weights were of the same order of magnitude than the take off weight of their European counterpart.

Both were very sturdy and reliable, however they were not a challenge for normally war trained European pilots flying their exact contemporary European fighters.

They could have been useful in 1939, but they were not yet in production status. 

In 1941, against real enemies, they were relegated to low flying duties.

{Fore those who will be still skeptical about the importance of the high altitude flight: Please remember the ~50,000 casualties lost over Germany of the US 8th Air Force between August 1942 and May 1945. 

These excellent crews played a key role to silent the fuel industry of the Axis, so acted strategically on all Allied fronts.

Their colleagues who bombed Japan own territories played a similar key role.}

This was the consequence of these conclusives sentences of the report on the Curtis P-40-N, written the June 7, 1943" In speed, maneuverability, and rate of climb up to approximately twenty thousand (20,000) feet the P-40N-1 is the best of the P-40 series tested to date. 
While the P-40N-1 is the superior in performance of the P-40 series, it is generally inferior to all other current types of fighters tested at this station.



The Lockheed P 38 Lightning was a much more interesting aircraft. 

She belonged to the numerous twin-engined aircrafts dedicated, at the end of the 1930's, to fight the enemy aircrafts. 

In itself, such a concept was destined to be a failure for the very fighter role. 

If you want to protect your own country or your armies or fleets, you need nimble and fast fighters. Period! 

Nevertheless, all these so-called fighters displayed exceptional abilities for a multitude of other - and very useful - tasks, among them, sometime, even true fighting ones.

So was the Lockheed P 38. 

May be, one of the most important task she had achieved - in an unexpected field - was a start in the understanding of the handling problems in the vicinity of Mach 1.

The first flight occurred early in 1939. 

A record crossing of the USA territories from the West Coast to East Coast was successfully done two weeks later in about 7 hours, but, owing to the icing of one engine, the prototype crashed and was destroyed.

Several months later, both French and British governments selected the P 38 among the numerous aircrafts they purchased.

An US order for 13 experimental YP 38 was given, the last of which being delivered in June 1941.

These fighters had a top speed of 635 kph at 6,100 m and that altitude was reached in 6' 48", actually a very good performance.

The British government ordered dozens of P 38. 

When these fighters were about to be completed, the British tested the brand new fighter (after they had christened her as "Lightning").

They discovered a completely different aircraft than they had ordered: The two engines were rotating identically, the turbo-supercharger was missing, and so on. 

Therefore, the underrated fighter was absolutely useless against the Luftwaffe and the British government cancelled such a dishonest contract.

Fortunately for Lockheed, the Japan attacked Pearl Harbor and the so-called P 400 (for 400 mph) from the British order, re-fitted with their normal equipment, were hurriedly dispatched to the Pacific front against Japan.

At the end of 1944, with more powerful engines, the P 38 had a top speed of 710 kph.

[Antoine de Saint Exupéry's fate wondered me during dozens of years. 

The great French writer was missing the July 31, 1944, during his last recce flight, flying a F 5 version of the P 38. 

Now, we know Saint Exupéry was not in good health, as was also his F5. 

Two Luftwaffe pilots had claimed to have downed him. 

The only credible one, Robert Heichele, was downed some weeks later. 

So, it is impossible to know the truth.]



The Republic P 47 Thunderbolt summarized perfectly the very American views on what must be a fighter:
  • She was the most powerful fighter in the World, in order to be the fastest, 
  • She had the strongest armament (eight 0.5 cal. machine guns), in order to get easy kill, 
  • She had the most effective protection against enemy fire, in order to save the pilot precious life.
She was based on the 18 cylinders radial air cooled Pratt & Whitney R-2800 engine delivering 2,000 Cv (initially), with an excellent turbo-supercharger. So, her top speed was 660 kph.

Her diving speed was exceptionally fast but her climbing abilities were on the other side.

Nevertheless, a lot of teething troubles occurred, delaying her operational debut for one full year (1943).

After that, the P 47 was an excellent fighter, much more efficient than the P 38 and feared by the German fighter pilots (as said Adolph Galland). My own flight instructor (Mr. J. Litwa) had himself learn military flight in an US school (in 1943) and was, just before the end of the WW II, the happy fighter pilot of a P 47.




It is difficult - for me - to see the North American P 51 Mustang as a true US fighter, even if she was decisive to protect the daylight US bombers attacking Germany

She resulted from a British order and her conception was following exactly the European Spirit and concepts: Aerodynamics first!

This was also implicitly acknowledged by the amazingly weak interest demonstrated by the USAF deciders


Moreover, her performances were literally exploding when the Rolls Royce Merlin engine was fitted instead of the poor Allison 1710 one.

When she took off in 1940, she was already a good plane, but after some tests, she was seen as a good fighter for the low level fighting.

The first data (April 24, 1940) demonstrated she did not exceed 617 kph (384 mph) but she had a very efficient range (up to 1.660 km).

In December 1942, her prototype did not flew at more than 637 kph (396 mph) but she demonstrated a better climb ability (~6,000 m in 8' 48").

May be, some lobbies were gathered against her ?


We were very fortunate the Rolls-Royce-Packard Merlin engine was, at last, fitted on the P 51 B: 711 kph and a climb to 8,000 m in 7' 42"... 

However, the Mustang was not so tough than the P 47. "Nobody is perfect...".




USSR:

The soviet fighters during the 1939-1940 period were frozen, by Staline decrees, to the diverse variants of the Polikarpov I 15, I 153 and I 16...


All these fighters were very maneuverable, sturdy, slow, with a marginal stability, but, nevertheless, easy to fly.

They were also perfectly fitted to withstand the devastating Winter conditions of Russia and Siberia.

In 1937, the Russian engineers understanding the vicinity of a new war launched many projects of modern fighters.

Among these projects, two of them deserved the attention: The Mig 3 and the Yak 1


The Mig 3 was issued from the initial Polikarpov I 200 project. 

Because the soviet dictator Joseph Stalin disliked engineer Polikarpov, all the work was transferred to a new team led by engineers Mikoyan (a brother of one of the leaders of the communist party) and Gurevitch.

The fighter was conceived to fit the powerful 1,350 hp Mikuline AM 35, 12 cylinders, liquid-cooled engine, whose weight was 830 kg.

The structure chosen was selected to avoid as much as possible the use of light alloys!

She was 8.25 m long, her wingspan was 10.20 m and the total wing area was 17.44 m².

This way, the Mig 3, whose shape was amazingly similar to that of the French Dewoitine D 520 but 0.40 m shorter, had a empty weight of 2,700 kg, identical than the take off weight of the French fighter! 

So, with a take off weight of 3,355 kg, the wing loading was 192 kg / m², not well suited for dog-fighting at low level!

The will to avoid the use of aluminum alloys for an interceptor was somewhat odd when one remember that, at the same time, USSR had launched the mass production of the excellent T 34 tank, which used an all aluminum engine! 

Nevertheless, the Mig 3 was a fast fighter, a bit slower 
than the Bf 109 F at seal level - 495 kph - but clearly faster at altitude with 640 kph at 7,800 m.

She needed 6' 30" to reach 5,000 m and 10' 17" to reach 8,000 m.

Her service ceiling was superior to 11,500 m. 

Her total range exceeded 820 km at an altitude of 7,850 m.

So, she was perfectly suited to intercept all the German spy planes. 

Nevertheless, the landing speed of 145 km/h was somewhat too fast for inexperienced pilots. 

So, she was initially plagued, operationally, by the too short training of the young pilots, as also by a poor ground control. 




The Yakovlev Yak 1 was conceived during the Summer of 1939 and made her maiden flight in January 1940. 

Her excellent maneuverability, rather high top speed and easy maintenance was highly praised.

She was among the lightest modern fighter issued by the same program.

The top speed was ~560 kph at 4,800 m and she climbed to 5,000 m in less than 6' 50".

She outclassed the "old" Messerschmitt Bf 109 E but experienced some concerns against the Bf 109 F.

Nevertheless, she appeared as the most effective soviet fighter during the Barbarossa operation. 

Two years later, the French pilots of the GC 3 Normandie, sent by General De Gaulle to fight the Germans in USSR, chosen the Yak fighters, because they share most of the handling qualities with their previous Dewoitine D 520.

Her numerous derivatives (Yak 9 and Yak 3) performed very well. 

The Yak 3 was among the best dog-fighter of the WW II, according to a personal communication of Jean-Marie Garric (a French pilot living in Texas and who build a completely new Potez 63-11 - from the authentic original plans - some years ago).




Identikit picture of most of the 1941 fighters:

The 1941 fighters had a top speed at altitude of, at least, 600 kph, were able to climb to 5,000 m in less than 6 minutes and to 8,000 m in about 10 minutes

The armament was very diverse, according to the countries, but the riffle caliber machine-guns were about to disappear as standard weapons. 

The only exception was the initial Typhoon with 12 of these inefficient weapons, but they were quickly replaced by cannons.

The range was another subject of divergences, with an average value of about to 800 km.

All these fighter were able to reach an altitude of at least 10,000 m  


All, but the Japanese fighters, used armored windshields and self-sealing fuel tanks.

All, but the soviet fighters, used radio communication emitters / receivers.

A large amount of the fighters conceived in 1939 did not enter service before the end of 1942, or even 1943, because they need a lot of perfecting.



The Bloch 157, first masterpiece of engineer Lucien Servanty


(My main source on the Bloch 157  and her engine was the reference book of Serge Joanne: Le Bloch 152, Lela presse, 2003)

The new French program for the fighters focused on a top speed of 650 kph.

The first idea was to fit the new GR 14 R engine on the Bloch 155, renamed Bloch 156.

However, it was discovered the 200 kg heavier engine would induce some cg concerns and its very larger power would induce handling difficulties.

The Bloch 155 achieved 535 km/h with the GR 14 N 49 engine delivering 1 070 Cv at 3,700 m (Henri Deplante, A la conquête du Ciel, Edisud, 1985). 

The 14 R 04 engine delivered 1 580 Cv (for 15 minutes), so calculations showed the Bloch 156 has - theoretically - a top speed of 609 km/h. 

Taking into account the highest altitude obtained with the Farman supercharger, the top speed of the Bloch 156 may be 658 km/h at ~ 8,000 m.

So, to conserve the excellent flying qualities of the Bloch 155, a totally new aircraft was needed.

Mr Marcel Bloch, in charge of the SNCASO (the nationalized company which replaced the Marcel Bloch private company), charged engineer Servanty (who, later, designed Concorde) to develop the new fighter with the technical constructive solutions already used in the MB 155.

If the Bloch 157 resemble to the Bloch 155, she was a bit larger. 

The fuselage was 10 cm longer, the wing span was 13 cm larger, the chord of the wing was also enlarged - giving a thinner relative thickness - and the wing tips were less sharp. 

All these modifications increased the wing area from 2 square meters. 

So, the wing loading of the excellent MB 155 (167 kg/m²) was conserved.

Compared to that of the previous fighter, the armament conserved the 2 Hispano-Suiza HS 404 long barrel cannons but two machine-guns were added to the 2 already existing.

The landing gear was enlarged and the vertical tail was taller, all of these modifications allowing a better control of the ground trajectory during take off.

The tail wheel became retractable, a new air-screw of 3.35 m in diameter was chosen instead of the 3.0 m diameter of the MB 155 (the reduction gear box of the GR 14 R being a 9/16 one, allowing the propeller to run at 56% of the rotation speed of the engine).

The armored triplex windshield (of 40 mm thickness) of the MB 155  was conserved, as was also the 700 fuel tank.

The empty weight was a bit less than 2,400 kg and the take off weight was 3250 kg.

At the end of Mai 1940, the prototype was ready but the new propeller. The German Army being alarmingly menacing, the MB 157 was put in crate and send by road to the South of France. 

But, the lorry, embedded in the crowd of refugees, was captured by a German column.

The German send the crate to Bordeaux SNCASO facility to be reassembled. As in all other plants, the work was deliberately done as slow of possible.

Nevertheless, the fighter was ready to fly at the end of the 1941-42 winter and her maiden flight occurred in March 1942, with the French pilot Zaccharie Heu - former test pilot for the Marcel Bloch company - at the controls.





A outstandingly advanced fighter


The flight tests of the MB 157 were totally successful.



Marcel Bloch MB 157 


The Germans engineers were especially stunned by the performances she demonstrated, this old prototype having a top speed at continuous power significantly better than all their operational fighters.

The performances were as follow:
  • top speed at max continuous power                  670 kph at 8,500 m
  • top speed at military power                               710 kph  at 7,800 m
  • time needed to climb to 8,000 m                       11' 00"   
  • service ceiling                                                   11,000 m
  • economical cruising speed                                400 kph
  • ferry range at that speed                                   1,100 km
  • range at max continuous power                          700 km (< 1 hour)
  • patrol time at 70 % max power                            1 hour and 30 minutes
  • landing speed                                                     110 kph
  • take off run                                                          200 m

You can read, in several sources, the MB 157 was transferred in flight from Bordeaux-Merignac to Paris Orly (in 1943). 

It was also said that the German were amazed by the very short flight time used, expecting a 40 minutes longer one.

Usually, I'm not very impressed by such performances, because, as a private pilot (some 20 years ago), I know several methods which allow the average speed to be superior to the real top speed: Use of a strong tail wind, or flying in the tail end of a depression just beneath of the cumulus, or a combination of these two methods. 

So, you may explain how a Hurricane I with a top speed at altitude of 510 kph (may be!) flew - at night - from Scotland to London at an average speed of 640 kph! 

Such performances are usually good only to impress press reporters or politicians (nevertheless the pilot was absolutely excellent!).

In the Bloch 157 case, that may not be the good explanation: All the informations were of German origin

I suggest two hypothesis:
  1. The MB 157 flew faster than the German fighters used to escort her and landed 40 minutes before them. In such case, the German authorities may have been very angry against their own system. 
  2. After the defeat of the Allied armies in France, in June 1940, the German propaganda had obviously used the racist way to explain this defeat was an only French defeat, based on absolutely bad material, bad weapons, coward or incompetent soldiers and so on. When the German technicians and pilots had seen the performances and qualities of the Bloch fighter - Bloch being a current Jewish name - they discovered that the French prototype of 1940 was better than all their operational aircraft
Both hypotheses may explain the removing of the engine - said to be sent to Germany (without proof) - as also the destroying of the plane - said to be destroyed by an Allied air raid (without proof too).




Dispute and establishment



Somebody, in forums, told us solemnly that, once her armament fitted, the Bloch 157 would have been very far from the measured performances.

That was the case for some aircrafts at that time (e.g. for the LaGG 1), but it reflected only the lack of experience of their engineers and their technological slowness.

The MB 157 may had lost up to ~10 kph with the fitting of her armament. 

That cannot be the consequence of an unexpected increase of empty weight, because, for all the French aircrafts, the prototypes were thoroughly ballasted.


Now, replacing the Bloch 157 in the historical context, it is obvious that, in the middle of 1941, she would have been tremendously superior to both the Messerschmitt 109 F and the Focke-Wulf A1 to A8 (she was the equal to the FW 190 D9). 

The only advantage of the Friedrisch would have been in climbing, but in all other specification, the Bf  109 was outclassed.

In armament as in armor, the MB 157 outclassed also both of these potential opponents until the end of 1942!

The fuel tank was certainly the same as the one of the MB 155, avoiding all cut of fuel to the engine in negative g's.

Her relatively low wing loading ensured her to be more nimble.


In 1939, only three years after the difficult debut of the Bloch 150, Marcel Bloch (known now as Marcel Dassault) and his engineers staff had successfully cleared all the obstacles which separated the average aircraft builders from the very few exceptional ones.








3 commentaires:

  1. I think you overstate the quality of the M.B.157 airframe design. The exceptional performance (if true) was rather rooted in the engine, which provided much power at high altitude. High altitude = less air pressure and density = less drag = faster. The M.B. 157 was likely nothing special at the altitudes most relevant for ground campaigns; 1,000 m to 4,500 m.

    A proper comparison would be with Spitfire Mk. IX or P-47B.

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    1. Thank you for your comment, S O.

      But I cannot agree with you: The Bloch airframe design was excellent.

      The engine cowling was very well streamlined, the aircraft used the same thin thickness of the wings of all Block 15x fighters (14.5 % at the root, 8.5% at the extremity), much thinner than most of the actual fighters, but sufficiently tough to accept two 20 mm canons.

      I agree absolutely with you about the role of high altitude, but, for most of the combats in the West of Europe (were France stay), the fighting altitudes were comprised between 6,000 m (20,000 ft) to 10,000 m (33,000 ft).
      That was one of the asset of P 51 B and D.

      The Bloch 157, at full load take off, weighted less than 3,300 kg, some 1200 kg less than the empty weight of the Republic P 47.

      She needed 1/3 less wing area than this good american fighter, and as France was far closer from Germany than UK, she need 25% less combat radius, thus less fuel, than her (obviously, Marcel Dassault - ex-Marcel Bloch - did not have foreseen the French collapse...).







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