vendredi 9 août 2013

The Spitfire, star of the Dynamo operation (may be...) and of the Battle of Britain (certainly) (revised 16 / 05 / 20187)

Superlative Spitfire...


It's really difficult to know exactly the performances of the Hawker Hurricane fighter operationally used during the 20 days of her Campaign of France.

Probably for ancient reasons of secrecy, all fans of fighters of this periods may experience the same difficulties to know the exact performances of the prototype of the Spitfire - K 5054 - during her early months of flying.


Anyway, the aerodynamic conception of this fighter was excellent, especially with her very thin wings for its times (relative thickness at 12.5%). 







Nevertheless, the sentence "Don't touch anything" attributed to her first test pilot after the first flight, the March 10, 1936, was only war - or pre-war - propaganda.

Such a policy was fair facing the high level of the Nazi propaganda. 

Today, such a sentence is completely obsolete.

Yes, this fighter was very well conceived.


Obviously, the perfecting of the Spitfire was long, as was the one of any other successful fighters in the World. 

The development team was very efficient, even after the death of RJ Mitchell.

She was a good symbol of the British war industry. 



Learning the Art of making Speed!


(all following data were found in this excellent site http://www.spitfireperformance.com/spitfire-I.html)


But, as promising was the K 5054, she was very far from an efficient operational fighter.

The first top speed to have been reached at altitude - probably in April 1936 - was 528 kph with a take off weight of 2400 kg (= without any additional weight representing armament).

One month later (in May) a much more sophisticated air-screw - but always a fixed pitch one - allowed a speed of 557 kph, 50 kph above the top speed achieved by the Hawker Hurricane


The climbing speed, also, was good:
  •   5' 40" to reach 15,000 ft (~4500 m),
  • 17' 00" to reach 30,000 ft, the same order of magnitude than the climbing performances of the Hurricane K 5083. 
So, the British government ordered 310 Spitfire, an almost wise decision (I will go back soon on this important subject in last part of the section entitled: Any shortcoming?).

A bit later, the Spitfire was fitted with ejector exhaust pipes, allowing her 16 kph more in top speed.

Such performances, as also the good flying characteristics she demonstrated, impacted all aeronautical military deciders in all European countries. 

For example, it was likely the reason for which the Luftwaffe deciders urged the fitting of the Daimler-Benz DB 601 on the Messerschmitt Bf 109.



The early operational variants 


The first production Spitfire were very late, that resulting from two reasons. 

The first one was the time needed to build a single Spitfire: About 17,000 hours, twice the value needed for a Messerschmitt Bf 109 E!

It could had been not a problem if the Vickers staff had launched the mass production of the Spitfire in the Supermarine plant. 

Instead, they preferred to build a brand new plant... and they continue to assemble the Walrus flying-boats instead...

When WWII started, the RAF had got only 200 Spitfire

That was only 40% of the Hurricane production (500), and 20 % of the Fairey Battle production (1000), an aircraft using very similar structural technical methods! 

This version was designated as the Spitfire Mk I. 




Spitfire I bis - The windshield is an armored one, so the air-screw may be a Rotol constant speed. 


Thie first operational Spitfire had a take off weight of 2625 kg, 200 kg more than the K 5054.

This version, tested during the last days of 1938, was the version used by the RAF during the beginning of WWII.

Her top speeds with the wooden fixed pitch air-screw were:
  • 460 kph at sea level,
  • 580 kph at 5,600 m,
  • 505 kph at 9,000 m.
The climbing speeds were:
  • 6' 30" to reach 15,000 ft, performance corresponding to: 
          • ~5' 30" to reach 4,000 m,
          • ~7' 20" to reach 5,000 m,
  • 22' 20" to reach 9,000 m (6 min more than the K 5054).
The service ceiling was 9,600 m.


Some few months later, a new 2 pitch metal air-screw was fitted on the Spitfire, whose weight reached 2,700 kg (275 kg more than the take off weight of K 5084).

The take off and landing runs were shorter. 

The top speed was 590 kph, a slight progression, and the climbing speed was not bad, knowing that the aircraft was significantly heavier than the version fitted with the wooden fixed pitch propeller. 

(trials of the July 12, 1939, Martelsham Heath)
  •   5' 30"  to reach    10,000 ft (3,000 m), 
  •   8' 06" ------------ 15,000 ft (4,500 m),
      • ~7' 16" ------------ 4,000 m,
  •   8' 54" ------------ 16,500 ft (~5,000 m),
  • 11' 25" ------------ 20,000 ft (~6,000 m),
  • 17' 12" ------------ 26,000 ft (~7,900 m),
  • 22' 00" ------------ 29,000 ft (~9,000 m).
She performed sufficiently to impress her enemy pilots. 

I suspect this variant to be the most numerous involved in the Dunkirk air battles.



However, no more than 2 months later, during the Battle of Britain, the Spitfire became a completely different beast!

Fitted with a Rotol constant speed air-screw and using 100° octane fuel (allowing more boost pressure), the engine yielded 1,310 Hp during 5 minutes boost.

The take-off weight increased (at least) up to 2,750 kg.

The top speed was rather slightly reduced (570 kph) but the climbing speeds became very, very better:
  •   4' 40"  to reach  4,000 m (gain of ~3 min),
  •   6' 00"    --------   5,000 m (gain of ~3 min),
  •   7' 42"    --------   6,000 m (gain of ~3 min 30"),
  • 11' 50"    --------   8,000 m (gain of ~5 min 30"),
  •  16' 25"   --------   9,000 m (gain of ~5 min 30").
The service ceiling was 10,600 m  (gain of 1,000 m).

The new version performed very well, even above 6,000 m, and was a true challenge for the German fighter pilots.

The clear difference between all the previous variants and the latest suggest to designate this one as the Spitfire Mk I bis (sorry!).

 This version impressed very strongly Adolph Galland...



Any shortcoming?


Of course, the Spitfire, as all fighters, was not perfect.

A first problem was highlighted by Louis Bonte in his Histoire des Essais en Vol (Docavia #3, 1974). He acknowledged the good flying qualities of the British fighter, but he feel the ailerons too heavy at high speed. 

So, he favored the Curtiss H75 - P 36 - which had the considerably more important shortcoming of being 100 km/h slower.

This problem was re-discovered by Jeffrey Quill when he fought during the Battle of Britain. 

After 3 days in a squadron and 2 victories (!), he have seen the fabric skin of the ailerons ballooning at high speed. 

Replacing the fabric by metal sheets solved the problem.


A second problem was the very light armamentThe 8 machine guns with 300 rounds each were insufficient against the German bombers.


But, when two Hispano-Suiza HS 404 20 mm cannons were fitted in the wings (Spitfire I B), they jammed quickly

One may relate this problem to the very thin (and light) structure of the wing. 

This problem was solved, more than one full year later, with the wing type C, also dubbed universal, in the Spitfire V.




A more important shortcoming resulted from the very long building time need for a single Spitfire: 17,000 hours, to compare with the 10,500 hours for a Hurricane or the 8,000 hours for a Messerschmitt Bf 109 E.

It would had no such pernicious effect if Vickers had accepted to start the mass production directly with the Supermarine plant. 

But Vickers preferred to product Walrus light amphibious flying boat... No comment!

So, Supermarine needed 2 years to deliver the first operational fighters. 


Knowing the fact that only 200 Spitfire were operational at the outbreak of WW II versus 500 Hurricane, one may dream about what happens if there were 500 Spitfire and 500 Hurricane at that very moment!



The worst shortcoming ? In the Command's mind!


Usual British sources told us that Lord Dowding, who was actually Air Chief Marshall, in command of the Fighter Command, had refused to send his Spitfire in France to fight the Luftwaffe. 

May be, such a tale is true, may be it's not...

The British democracy, as we know her, give the full power of decision to the government. 

It would be amazing that the Prime Minister, especially Winston Churchill, accepted such a decision issued from a "simple" chief of staff...

Anyway, the choice appears now as not so relevant as it was relentlessly repeated by British medias since 1940.



The counter-example of the Hurricane squadrons


The Hurricane squadrons fought gallantly in France against an overwhelming enemy. 

So, their pilots learned all the ways they can use efficiently their fighters.

They also developed a very impressive proficiency and very adequate tactics. 

During the Battle of Britain, they obtained significantly more victories than the Spitfire pilots notwithstanding to their clearly inferior fighters.

They better know their fighters than the Spitfire pilots and they can interpret faster the tactic situation of the combat.



Too much losses of the Spitfire 


On the contrary, during the Dynamo operation over Dunkirk, the Spitfire pilots discovered the German Messerschmitt 109 E. 

At that historical step, the Spitfire pilots were completely inexperienced: A very asymmetric situation when facing German pilots issued from the Spanish civil war, the Polish war and the combats against French and British pilots since May 10 in the French skies.

Fortunately for the British pilots, the German was not very proficient in aircraft recognition, so, for them, all fighter tagged with the British roundels could have been wrongly identified as Hurricane

So, the German losses were higher than expected. 

But the results of the Dunkirk Battle was not very good for the Spitfire (42 downed in 4 days), taking into account the very quality of the British fighter.

The Spitfire pilot's problem was not solved when the Battle of Britain started!

The proof is given by the losses of British fighter during July 1940: 67 British fighters were downed. Among them, 33 Hurricane and 34 Spitfire. 

We know the number of Hurricane was at least twice the number of Spitfire, such an equality suggests us the Spitfire was a very bad fighter, compared to the Hurricane

Obviously, this reasoning is wrong, so the unique solution is the pilots were insufficiently experienced. 


Oh, yes, you may answer me the Spitfire (flying since 4 years and in mass production since 2 years) was not completely finished. 

But, even with his not perfectly finished Spitfire, Mr. Jeffrey Quill was able to fight very efficiently during his very short operational time!



A chance point?


Using some Spitfire squadrons in France would have had a huge influence on the events, depending from the amount of fighters involved.


First, the Spitfire pilots would have learned perfectly in time the best methods to attack and destroy the enemy Bf 109 E.

Second, used in large number, they could give to the French artillery in the Sedan theater an efficient cover, disabling most of the Stuka threats.

So, the Campaign of France could not be the huge failure she was...


The real decision to conserve this munificent fighter at home induced a lot of losses among the British pilot's lives.


Luckily, the superiority of the Spitfire on the Hurricane was such that even the Hurricane II was used for other purposes than true fighting.

Luckily, the British ground control was, also, excellent.

That was very lucky, because, just at the beginning of 1941, the Luftwaffe switched from the good Messerschmitt Bf 109 E to the very better Bf 109 F!






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