the Blenheim in battle of britian

[Admiral Beez]

Hi

Harris, who had gone to, the then, Rhodesia at the age of 16 (1908) to seek 'adventure' (working in various jobs including mining, farming and coach driving) joined the 1st Rhodesia Regiment at the outbreak of WW1, fighting in the brief campaign in German South West Africa before returning to Britain to join the RFC, completing his pilot training in January 1916. He wrote the following in his book 'Bomber Offensive', pages 63-64 reference 'colonials' to put it in context:
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It should also be remembered that No. 408 (Goose) Squadron formed in No. 5 Group RAF, equipped with Hampdens when it joined, in July 1941, so that's what it got. All the RAF Hampden Squadrons flew more sorties with this aircraft than 408, as the RAF sqns had been operational since the outbreak of war. 408 moved to No. 4 Group when equipped with the Halifax. No. 6 (Canadian) Group was only formed at the beginning of January 1943.

Mike

Thanks for posting that, and it is very informative. I would agree with Harris that Imperial troops seem to get more credit or more distinction in people's eyes. The Ghurkas being the fiercest, the Canadians and Australians seemingly the toughest (if we remember them we throw in the South Africans), and only then do we rank the regular British troops, with the Scotts being the toughest. After the last of the Britons are counted, we then rank the Indians and Africans in fighting quality. It's a mix of nationalism, racism and colonialism.

 

[pbehn]

I mentioned the Hampden to correct the record. Your post seemed to imply that the RCAF didn't fly Hampdens. Since you mentioned it, I did some further research and found what I think is further ammunition for my argument. The RCAF used the Hampden in the bomber role much longer than the RAF. The last mission over Germany by Hampdens was flown by RCAF 408 Squadron in September 1942. . The RAF had withdrawn their Hampdens (7 squadrons) from Bomber Command in April, 5 months earlier. RCAF Squadron 420 flew its last Hampden in August. The counter argument is that 5 of those squadrons received Manchesters. (Out of the frying pan into the fire) As for the Stirling, luckily for the Canadians, most of the Stirling squadrons were formed before the Canadians showed up in force. Luckily for everyone, the Luftwaffe's bombing of the Shorts factory in Rochester was an own goal in that it set back Stirling production and thereby limited the number of Stirling squadrons.

In his book Bomber Offensive, Sir Arthur Harris spends a few paragraphs disparaging the capabilities of "colonials" (he specifically included Canadians in his list). I would presume that if he had any say in the distribution of aircraft, he would favour the airmen he considered to be superior. " ….and I say without hesitation that the finest fighting crews of the whole lot were beyond a doubt the British crews……" I don't know if this was a general view in the RAF but Harris generally got what he wanted.

Certainly, the Canadians were done no favours as an all Halifax group for most of the war and as I pointed out previously RAFs Group 4 received the superior Halifax Mk VI while the RCAF received the Mk VII.

The attached paper is an interesting comparison of the capabilities of the Halifax vs the Lancaster

That paper can say what people want it to say. It is a mistake to think that giving the best equipment to a squadron means you are somehow looking after them in preference to others. 617 squadron always had the best equipment, some specifically designed for a mission, they also suffered huge losses on individual missions. On the final Tirpitz raid the whole squadron came within minutes of being intercepted, and if they were intercepted they would have been destroyed because most armament had been removed. If shot down before sinking the Tirpitz it would have been a disaster, if shot down after it would have been a success and new crews recruited and trained as they had before for losses on other missions like the dams and Emms canal. Look at the table at the bottom of page 13.

 

[nuuumannn]

Note that the loss rates even for the Lancaster were well beyond sustainable. Harris almost succeeded in completely destroying his command for no real advantage. The man who always belittled others for their advocacy of "Panacea Target's" went for the biggest Panacea Target of them all. In that time frame he could have done much greater damage to the Ruhr, likely at a lower cost.

yes and no, depending on what you are comparing loss rates to. Harris is often criticised for his ridicule of what he considered 'panacea targets', but in one thing he was right, a sustained strategic bombing campaign has to be waged consistently and heavily, i.e. with lots of aircraft around the clock, with little diversion from the aims of the campaign, 'round the clock' was a phrase coined by Eaker when he was asked to consider night bombing with the RAF by Harris, but Eaker stated that with the 8th bombing during the day and Bomber Command at night. Let's put it this way, Bomber Command wasn't achieving anything before Harris entered as C-in-C and loss rates were higher and completely unsustainable and goals unachieved, even though the number of aircraft sent on raids was lower. The loss rate targets he set were achievable, but with a larger number of aircraft and with better types, better results with fewer losses could be achieved.

Under Harris' leadership, Bomber Command became a world-leading force to be reckoned with, from an almost useless gathering of aircraft because they couldn't find their way to the target, let alone bomb it accurately, wasting men and equipment. Under Harris, Bomber Command got the best night bombers available and lots of them, sophisticated navaids and bomb sights, better defensive equipment and high above every other consideration according to its personnel, a sense that they were finally achieving something that was contributing to the end of Nazism in Europe. Harris gets lots of criticism post-war, but he was given a thankless job, turning Bomber Command around and making it something workable, because of his skill as a leader.

 

[nuuumannn]

The attached paper is an interesting comparison of the capabilities of the Halifax vs the Lancaster

An interesting read with lots of useful detail. It pretty much confirms what I said earlier about the Halifax. It doesn't delve into why the Hali had so many airframe deficiencies when it first appeared though, the author preferring to brush over them by saying he doesn't know. To be fair, the answer is a difficult one to quantify, but HP and its designers were tackling their first all-metal four-engined heavy bomber and at the time it was a difficult thing to get right ( something people don't really take into consideration when reflecting on the time period before the war) and few manufacturers around the world were actually building big complex four-engined bomber aircraft for series production, prior to WW2 (Focke-Wulf - an airliner, so doesn't really count, Junkers, Boeing, Douglas, HP and Short Brothers to name a few of the most notable).

The HP.57 was an entirely new design, rather than an extrapolation of work done on the HP.56, which only appeared in drawing form, so to create the Halifax the aircraft was entirely redesigned on paper first - the two had virtually nothing in common, apart from similar looks and obvious lineage, so the statement about difficulties arising from its conversion from a twin-engine design doesn't really stand.

Volkert over-complicated several aspects of the Halifaxes' design; its bomb bay doors for example were in eight pieces, the lowermost retracting into the bomb bay, which restricted the ability to carry big bombs because of the location of the door actuators and the space required to store the doors, and the addition of Boulton Paul turrets, which were heavier than the Nash & Thompson ones on the Manchester added weight. This was despite being a more advanced design than the N&T ones, having their own power generation and hydraulic systems separate from the aircraft's - if the aircraft hydraulic system fails, the turrets are still useable - easier to use as well, a single joystick, leaving one hand free to deal with cocking and jamming guns - N&T turrets required both hands for operation.

These are but two things behind the Halifax that contributed to airframe deficiencies, but what the Halifax and Short Stirling do is illustrate the issue of weight creep in a design. Both Britain's first four-engined heavies suffered in that respect; both were overweight, which affected their performance and load-carrying capability. This came about from various things, the operator changing specifications mid-design doesn't help etc... Both also introduced complex electrical and hydraulic systems, the architecture of which within an aircraft design is a difficult thing to incorporate, especially if beginning with never having designed them before - the Manchester was the same, very advanced system-wise for the time, especially since the first all-metal advanced aircraft Avro had built before the Manchester was the Bristol Blenheim under licence. Its own contribution was the Anson, which even by 1936 was dated.

Then there were issues with the engines, which overheated - its radiators were inefficient, requiring input from Rolls-Royce... The list goes on...

 

[pbehn]

When comparing survival rates of Halifax and Lancaster, as the war progressed the Lancaster increasingly replaced the Halifax and also as the war progressed aircrew of allied bombers were killed instead of captured. Since these events are obviously not properly documented, only the few survivors actually give witness to it happening they completely skew the survival rates of the Lancaster.

 

[A.G. Williams]

To revert to the original question concerning the performance of the Blenheim fighter variants... The following data are included in Bowyer's Aircraft for the Few:

Results of RAE trials with Mk 1(f) L1290 with various gun tray/turret/AI combinations, mostly at 18,000 feet:
No AI or guns: 280 mph (at 11,700 feet)
Turret, but no belly guns: 261.5 mph
AI IV, no turret or gun ring: 245 mph
AI, turret up: 229.5 mph
AI, no turret, gun ring fitted: 233 mph.

Mason's The British Fighter Since 1912 states that the Blenheim Mk 1F reached 282 mph at 13,600 ft with 840 hp VIII Mercury engines, while the long-nosed Mk IVF managed 292 mph at 13,100 ft with 920 hp Mercury XV.
It is not clear which had the most effect on the speed - the engine power or the different aerodynamic shape of the nose? The claimed speeds seem high, if the planes still had their turrets.

Back to Bowyer again:
In October 1940 Fighter Command decreed that its Blenheim 1(f) should all have their turrets removed with then hole covered by a plywood panel. A speed increase of up to 80 mph was gained (that's what the book says although I find it impossible to believe!) and 100 modification sets were ordered. However, this was soon dropped when it was realised that the much superior Beaufighter was becoming available.

It is worth noting that as early as 1938 Dowding was pressing for a single-seat long-range fighter version of the Blenheim, with the turret hole plated over. That was probably a bit extreme as the pilot's view was poor, so a navigator/observer using a teardrop dome like the Beaufighter's might have been better.

From the above, there are clearly inconsistencies in published performance data. So, what were the realistic maximum speeds of the fighter Blenheims, with or without turrets?

 

[fastmongrel]

with or without turrets?

Slow and slower

 

[ThomasP]

Hey A.G. Williams,

Blenheim B Mk I_____283 mph at 15,000 ft (10,960 lbs, Mercury XIII engine, 1x .303 cal top turret).
Blenheim B Mk IV____266 mph at 12,000 ft (13,500 lbs, Mercuey XV engine, 2x .303 cal under nose rear defense blister and 2x .303 cal top turret).
Blenheim F Mk IV____260 mph at 12,000 ft (13,800 lbs, Mercury XV engine, 4x .303 cal belly pack and 2x .303 cal top turret).

All data from Air Ministry ADS, both Mk IV dated 1941, the Mk I dated 1942.

 

[Thumpalumpacus]

Harris gets lots of criticism post-war, but he was given a thankless job, turning Bomber Command around and making it something workable, because of his skill as a leader.

Flaws and all, Harris turned BC from a farce to a killing machine.

The morality of it is another thread, one which I definitely won't start.

 

[Shortround6]

The claimed speeds seem high, if the planes still had their turrets.

Turret up or down?

Retractable (or semi-retractable turrets) may have been good for cruising speed/range but deploying an air brake just when you need max speed/evasion seems counter intuitive

 

[A.G. Williams]

Hey A.G. Williams,

Blenheim B Mk I_____283 mph at 15,000 ft (10,960 lbs, Mercury XIII engine, 4x .303 cal belly pack and 2x .303 cal top turret).
Blenheim B Mk IV____266 mph at 12,000 ft (13,500 lbs, Mercuey XV engine, 2x .303 cal under nose rear defense blister and 2x .303 cal top turret).
Blenheim F Mk IV____260 mph at 12,000 ft (13,800 lbs, Mercury XV engine, 4x .303 cal belly pack and 2x .303 cal top turret).

All data from Air Ministry ADS, both Mk IV dated 1941, the Mk I dated 1941.

Thanks for that, but it adds to my confusion!

What I would ideally like to do is put together a "menu" of the variables as follows, starting with the assumption of a "bare Mk I" plane (no turret or guns):
- bare Mk I
- increase in speed from increasing engine power from 840 to 920 hp
- change in speed from adopting long-nose Mk IV fuselage
- decrease in speed from adding a turret, lowered
- further decrease in speed from raising the turret
- decrease in speed from adding a four-gun belly pack
(I've ignored the effect of under-nose rear-firing guns as these couldn't be fitted to the fighter version)

I started to try to fill in some of the gaps, but the available data doesn't seem to make much sense. Offhand, I can't think of another common WW2 plane for which the claimed speeds vary so much, from supposedly authoritative sources. To give one example, for the Mk IV(f), Mason gives 292 mph while the ADS says 260 mph. Even assuming that the first figure is with the turret lowered and the second with it raised (unlikely - wouldn't max speed measurements generally be taken with the turret retracted?) that's still quite a difference.

 

[ThomasP]

Hey A.G. Williams,

My apologies, but I have been doing most of my posting late at night lately and have made a number of typos. I have edited the post on the Blenheim ADS above. The B Mk I in the ADS does not have the 4x .303 cal belly pack, just the single-gun top turret.

 

[Shortround6]

I would tend to doubt (very highly) that the MK IV Blenheim fighter ever came close to 292mph, I am a bit skeptical about the bomber (even with out the under nose guns).

I will try to look it up later but I Believe Sydney Cotton didn't get a modified Blenheim over 300mph when trying to make a photo-recon plane.
He was using a MK I but used sheet metal fairings on the nose, clipped the wings, removed and plated over the turret hole, fitted constant speed propellers, used 100 octane fuel and over boosted the engines. (9lbs boost????) They also used 20 coats of paint, sanded between coats. There may have been other modifications I have forgotten.

In any case here is a link to an account by Cotton. part way down the page. PDU Blenheims 1939/40

 

[Greyman]

From the above, there are clearly inconsistencies in published performance data. So, what were the realistic maximum speeds of the fighter Blenheims, with or without turrets?

80 mph -- good lord. I think they made a typo and a zero accidently got tacked on.

292 mph for a Blenheim IV also has to be an error. Unless it is some strange souped-up example like the 'Camotint' L.1348.

Retractable (or semi-retractable turrets) may have been good for cruising speed/range but deploying an air brake just when you need max speed/evasion seems counter intuitive

I guess the thinking was that it was better to have a deployable air brake than a permanent air brake.

For what it's worth, in a report from Blenheim fighter squadrons one of the few items in the 'positives' column -- they reported that use of the turret had very little effect on handling/manoeuvrability.

 

[nuuumannn]

Turret up or down?

Putting that into context (always lacking here), what are we comparing it with? When the Blenheim entered service in the mid-1930s, how many other bombers were there with retractable power-operated turrets as defensive armament? None is the right answer. The Blenheim was one of the fastest bombers in the world in 1937 when it entered service.

 

[nuuumannn]

another thing about the turret, too, The Blenheim was one of the very first bombers in the world fitted with a power-operated turret, something that became a necessity in the war. Now, had the turret not been applied, I'm sure people since WW2 would have complained that it could have done with a gun in that position! The thing was, the Bristol turret was very compact and light and whilst not as sophisticated as the BP and N&T turrets, it made up for this in its ease of use. I worked with a guy who restored a Blenheim turret and I got to look at the thing and its lack of complexity - it was a clever and compact design that translated into later Bristol designed turrets, and that aspect of it gets lost in the Blenheim's history and the baggage that has.

 

[Shortround6]

Quite a few 1930s bombers used retractable ventral "dustbins" and even the LeO 451 used retractable ventral gun position.
Photo of a model but gives the idea.

British were certainly not alone. He 111B

Speed with gun "positions" in extended form are seldom noted.

 

[GrauGeist]

Grant, the Douglas B-18 (DB-1) had a retractable upper turret (with a single .30 MG) that I beleive was powered.

 

[ThomasP]

I do not know if this will be any help.

The early Mk I with 2-pitch props (course or fine) was limited to a VNE of 285 mph IAS due to the engine rpm overspeed limit. (from Pilot's Notes)

The 3x Blenheims referenced in my post above were all fitted with 2-pitch props, and the engine rating was 840 BHP at 14,000 ft.

In addition the ADS for the Mk V, fitted with uprated engines (955 BHP at 8,300 ft) and CS props, gives the following:
Blenheim B Mk V____244 mph at 6,000 ft (14,670 lbs, Mercuey XV engine, 2x .303 cal under nose rear defense blister and 2x .303 cal top turret).

The CS props of the Mk V allowed an increased VNE of 325 mph IAS even though the engine rpm overspeed limit was the same. (form Pilot's Notes)

I did not include the Mk V with the other 3 originally, due to the rather large difference in mean flying weight. When an aircraft gains enough it sometimes loses the ability to fly at even the rated height for the engines, as is possibly the case for both Mk IV and the Mk V mentioned here?

The Blenheim Mk I above has the short stepless nose, Mk IV and V are long-nose types.

 

[Shortround6]

I am not sure it was powered but even if it was it made the Blenheim turret look like a thing of beauty.