mardi 13 août 2013

The Hurricane Mk I, first efficient British fighter over the French front line in May 1940 (Enriched 14 / 08 / 2018)

The main British aerial defender of the first year of WW II

The first fighter sent to France, at the outbreak of WWII, was the completely obsolete Gloster Gladiator, with her unimpressive top speed of 400 kph at 4350 m (!) and her climb speed of 4' 30" to achieve 3,000 m. 

She cannot be seen as a serious contribution to the defense of the Allied front lines in France, as, e.g. she was clearly unable to make serious escort duty for the Fairey Battle bombers.

So, after only one full week of waiting, the first Hurricane squadron landed during the Fall of 1939, followed by three squadrons, and some weeks later, by two more.

The Hawker K. 5083 prototype

It's not easy to have an good idea of the performances of the Hawker Hurricane Mk I during the Phoney War as during the Campaign of France. 

The reason is the striking enhancements of performances obtained by the British fighters after the Allied defeat of June 1940, to overcome the known shortcomings in performances before the Battle of Britain. 

Especially, her two blade propeller was not well suited to achieve good performances. A similar, but less radical, evolution happened in the Luftwaffe at the same time.

But, if you want to understand the Campaign of France, you need to obtain the actual performances. 

To give you an idea about what was the current performances of the 1936 prototypes, the Curtiss P 36 flew at 450 kph, the Polikarpov I 16 at 420 kph and the Morane-Saulnier 405 at 435 kph...

For his new fighter, Sydney Camm, the Hawker chief engineer, had conceived a straightforward evolution of the Hawker Fury biplane fighter, eliminating the biplane structure substituted by a large low-wing cantilever monoplane one.

He chosen an easy-to-repair structure, with a steel tube Warren structure, the wooden stringers being fabric covered: A structure perfectly suited to colonial duties. 

Nevertheless, the more modern prototypes, as the Messerschmitt Bf 109 V1 or the Nieuport 161 (as also the Bloch 150 and the later Dewoitine 520) were all conceived as stressed skin all-metal monocoques, a much lighter structure. 

Mr. Camm chosen also to raise the cockpit, a good idea for the pilot's sights, but not for aerodynamics (because of the increased section it induced)...

The initial flying performances of the prototype of the Hurricane appeared very good in April 1936.

The Hurricane K 5083 had a take off weight of 2573 kg and her Rolls-Royce Merlin C delivered 1029 hp at 3400 m.

This aircraft was pleasant to fly, able to tight turns.

Her top speeds were:
  • 407 kph at sea level,
  • 505 kph at 4500 m (15,000 ft),
  •  454 kph at 9100 m (30,000 ft).
The climb speed were good too:
  •   5'           to reach ~4000 m,
  • 13' 30"   ------------ ~8000 m.
At this very moment, she was the fastest fighter of the World!

After some extension to the lower part of the rudder to obtain a better spin behavior, the Hurricane was ordered in production.

The warrior Hurricane Mk I

The Hurricane involved in the WWII in France was very different. 

Lately, she had got stressed skin all-metal wings, which allowed her a 130 kph increase in diving speed (a perfect illustration of the better suitability of the stressed skin for a fighter!).

She had got also some armor plates and, at last, her full armament of 8 machine guns with 500 rounds each.

Some of these Hurricane were fitted with a 2 pitch De Havilland propeller (not all, unfortunately).

Early production Hurricane MkI with a 2 blade fixed pitch propeller and ejector exhaust pipes. 

The top speed of this fighter was 515 kph at 5300 m (even if, in 1940, the review Flight published frequently a speed of 335 mph, that was better for the mood of British peoples).

The climbing speed was :
  • 6' 30" for 4500 m,
  • 9' 50" for 6000 m.
The 3' 20" needed to climb the last 1500 m told us this fighter can hardly climb to 8000 m in less than 15'.

The Hurricane had now a take off weight of ~2900 kg, and the added 315 kg have forbidden better performances.

Nevertheless, the actual performances were undoubtedly better than those of the Curtiss H 75 and of the Morane 406.

Her landing speed was less than 100 kph and the wide track of her landing gear enabled easy landing.

A pilot opinion

Many things were wrote by English pilots about that fighter. 

But, it's very difficult to eliminate some political bias which may be founded in some one. It was obviously normal to highlight the most numerous fighter of the Battle of Britain. 

However, in 1940, she was not the superlative fighter described by William Green in his book Famous Fighter of WWII.

So, the only pilot opinion I will retain is that of René Mouchotte, Free French pilot who escape North Africa to join the combat with De Gaulle at the end of June 1940. 

He was a very skilled pilot, he love absolutely the Great Britain, and wrote his Carnets only for himself. 

So, his opinion is absolutely fair.

He was one of the few French involved in the Battle of Britain (and was killed when leading the Biggin Hill Wing in September 1943).

In the Armée de l'Air, previously, he was very happy with the MS 406, doing easily aerobatics at very low level above ground level.

In the RAF, piloting the Hurricane, he praised very much her speed. Then, he forget completely the Morane fighter (demonstrating how slow flying was the MS 406...).

Against the Messerschmitt Bf 109 E, he praised the tighter turning ability of the British fighter.

Embedded, at last, in the Churchill squadron, he appeared a bit disappointed. 

His criticism regarded the top horizontal speed because the bombers are difficult to catch.

(this may be seen as a confirmation of Air Chief Marshall Dowding revealed very later: 

The average top speed of the Hurricane during BOB was only 304 mph - 490 kph - 25 kph slower than it was told to the peoples).

Also, he did not like the too weak climbing ability, enabling the Bf 109 E to down so easily his team mates.

Some time later, his mood became positive again when he piloted the brand new Hurricane II A, but it was too late, in 1941...

In action

It's not easy to determine accurately the real efficiency of the Hurricane against the Luftwaffe.

The best documented data are those of the BoB, but the Hurricane used in Summer and Fall 1940 were absolutely better than those of the Campaign of France : 
  • They used 100° octane gas, allowing a far greater climbing speed (8' 24" to reach 6,000 m), owing to the 250 hp more powerful engine (for 5'). 
  • The Rotol constant speed air-screw allowed both a better top speed and a much better climbing ability (nevertheless, the Fleet Air Arm preferred the much more lighter de Havilland propeller). 

All currently published data for the Hurricane Mk I are those of this last variant..

{German fighters were, also, upgraded, but with less efficiency. 

The DB 601 engine delivering 1050 Hp during the Campaign of France was able to deliver 1175 Hp for BoB (+ 125 hp).}

Anyway, the grand total of German losses during the Battle of Britain was 1887 (German sources) or 2739 (Fighter Command sources). 

According to RAF, 55% of these victories were obtained by Hurricane.

This fighter was the most numerous British one: About 2/3 of the total number of single engined fighter belonged to the Fighter Command (e.g., the August, 17, 1940, the Fighter Command had 675 Hurricane and 378 Spitfire). 

Comparing the great Hurricane number (ratio among the single seat fighter : 65%) to the ratio of their victories (55%) suggest a clear lack of fighting efficiency of the Hurricane compared to the Spitfire one. 

An abnormal flaw

During he Campaign of France, which lasted only 14 days for most of the British fighter squadrons, the published Hurricane losses were 386, that may be translated in 27.6 Hurricane destroyed per each day! 

On the other hand, during the 100 days long Battle of Britain, 538 Hurricane were downed (5.38 for each day), an amazingly low number. (The Hurricane downed 1038 German aircrafts, an average of 10 per day.)

One may rely the heavy losses during the French campaign to a great flaw which originated in the mounting of a central tank, a flaw discovered when, in 31 days (10 July-11 August) the fire of the German rear gunners hit 25 Hurricanes and 25 Spitfires, inducing 2 Spitfires downed vs 11 Hurricanes downed. 

This flaw was discovered when it appeared that the central fuel tank, just in front of the pilot, was absolutely unprotected. The reason given was it was a too small a target!

The honorable deciders should think that the main target for a gunner was the pilot himself, so all flammable objects in the vicinity of this pilot was a source of additional danger.

After this, this tank was secured with Linatex coating... 

Personal data of the author (adapted from Flight, 1938)- The unprotected tank was just in front of the pilot!

The hard lessons of a new war...

If the RAF had accepted the replacement of 2 riffle caliber machine-guns by two 20 mm cannons, as it was suggested very early by Sydney Camm, the results could have been much more dramatic for the Luftwaffe (as it was operationally confirmed a full year later...).

Attacked only with riffle machine-gun fire, the German bombers might be seen as complicated traps. 
They were tough and there gunners were very well trained.
Being attractive for the eyes of the British fighter pilots, they might allow, some times, deadly rearward attacks from their escort fighters.

The efficiency of the Hurricane fighters and of their pilots during BoB cannot be separated from their role during the Campaign of France:

Their pilots had learned perfectly the tactics of the Jagdwaffe, the performances of its fighters and the flying patterns of the Luftwaffe.

A lot of these impressive pilots were transferred to Spitfire squadrons and they performed very well. 

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