Interesting discussion. Just a wee historical note. The Blenheim and Beaufort represented the end of the line of pre-war Bristol. Its designer Scotsman Frank Barnwell had come up with those two designs before his death and it was up to Fedden and Frise to come up with the Beaufort Fighter and its subsequent replacement, the Brigand. Although theoretically based on the Beaufort, the Beaufighter was a new design altogether by the new design team (incorporating some older members, of course). Like Shortround says, re-engining the Beaufort would have required a stronger wing - why bother? The Beaufighter was already on its way. Work began before the outbreak of WW2, therefore the prospect of improving the Blenheim and Beaufort was not necessary, also, there was no doubting either type's capabilities before the war. The Blenheim was considered advanced frontline equipment in 1939.
Bristol's twin-engined planes?
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- #62
1st, I must thank you for the effort to post the valuable excerpts
The V-3420 story was not a happy one. With much of on/off and again on/off support from the military, what was a great engine in early war turned at not-needed thing in late war. To be fair, we could discuss the engines both featuring two-stage superchargers and water injection - it was those fetures that gave the 'C' series 2450 HP, operating on WER (5 min rating), while the V-3420 was producing 2300 HP in single stage, no-WI, military regime (15 min rating). The 'C' series, single stage, no-WI were good for 2100 HP.
All very agreeable.
As a twin engined bomber, the Blenheim was not capable to carry enough weight, it was unable fly fast enough to avoid interception, the single LMG was woefully inadequate defensive armament, and it was not suited to build within a dispersed production scheme. Compared with Beaufort (and many of other twin engined bombers), it was obsolete.
Shortround6
Major General
Obsolete when and how?
The single LMG was as good (or better because of the power turret) as the defensive armament on the DO-17, 1939 He 111s, early JU-88s. It was as good or better than any bomber the Japanese had in 1939. It was as good as the B-18 Bolo.
The Blenheim carried as much a bomb load as was originally requested for the Mosquito.
In 1939 there were few bombers that were faster in squadron service. This did change by 1940. But the Blenheim was handicapped by 3 things. It's Mercury engines were small and never developed much beyond 1938/39 as all the effort was going into the sleeve valve engines, It had two position propellers instead of constant speed units, Fit and finish left something to be desired.
Later versions got a two gun turret and did run on 100 octane fuel but the engine power only increased a little bit ( no extra finning or other mods to allow full use of the 100 octane).
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- #64
From Australian point of view: Bristol is testing the newer and more capable plane (ie. better bomb truck, with more defensive MGs etc). So maybe 'obsolete' is too harsh a word - second best maybe. Anyway, by the time Aussies were to field the bomber they are to produce, Blenheim will be even more behind the curve.
Comparing the Blenheim with, either domestic or foreign twin-engined bombers, will reveal that those were capable to do everything Bleneheim does, plus a great deal more. Like carrying more bombs at greater distance, or ability to take more defensive MGs aboard, or to be re-engined without too much of trouble.
The He-111P was both faster, carrying more at greater distances, along with more defensive MGs. Hampden was also far better. Maybe it's unfair to compare the bomber named 'light' vs. the 'proper' bombers, but that shows the resources spent on Blenheim were better spent on 'proper' bomber(s).
I'm currently scouting through the Australian National Archives and have found 20 entries for "Bristol Beaufort"; some interesting looking documents are available:
Overseas Indents 550 591 - Bristol Beaufort aircraft Taurus engines
Bristol Aeroplane Company terms of licence agreement for Bristol Beaufort Aircraft.
Beaufort Drawings (for Taurus and Wasp Engines) Queries and Requisitions on Bristol and USA.
Beaufort drawings (for Taurus and Wasp engines) - Queries and requisitions on Bristol and USA.
Descriptive notes on "Beaufort" 1 Aeroplane with Bristol Aero Co's amendment lists - Air Ministry Publication No. 1580A, Vol.1 1st Ed.
Beaufort wing parts made up for Vickers Mark V guns; offered by Bristol Aeroplane Company
Licence agreement re manufacture of Bristol Beaufort Aeroplanes
Overseas Indents 550 591 - Bristol Beaufort aircraft Taurus engines
Bristol Aeroplane Company terms of licence agreement for Bristol Beaufort Aircraft.
Beaufort Drawings (for Taurus and Wasp Engines) Queries and Requisitions on Bristol and USA.
Beaufort drawings (for Taurus and Wasp engines) - Queries and requisitions on Bristol and USA.
Descriptive notes on "Beaufort" 1 Aeroplane with Bristol Aero Co's amendment lists - Air Ministry Publication No. 1580A, Vol.1 1st Ed.
Beaufort wing parts made up for Vickers Mark V guns; offered by Bristol Aeroplane Company
Licence agreement re manufacture of Bristol Beaufort Aeroplanes
But to be fair most of the pre-war twin-engined bombers proved to be lacking in armament when facing good fighter opposition in daylight, and few had great development potential.
However, when it came to design there did seem to be some design blind-spots at Bristol. For example, while the Blenheim was a good aircraft to fly it had a poorly designed cockpit, which proved to be downright dangerous in certain conditions:
(Warner 2010)
And the Blenheim/Beaufort successor, the Buckingham was really disappointing:
(Buttler)
Shortround6
Major General
It wasn't just named light. It truly was. Even a MK IV Blenheim was 2/3 the max gross weight of a Beaufort and about 1/2 the max Gross weight of a He 111H-6.
While the Hampden could carry much more it wasn't any faster and had a lower ceiling. I am not sure about field length. Blenheims could use airfields other bombers could only dream about.
As noted earlier the British had a real problem with suitable engines for light/medium bombers in 1939/40/41. Except for the Merlin and Hercules (both in short supply) none of the other engines available differed enough from each other to make much difference. If you wanted speed/ceiling the plane had to be small and light. If you wanted payload and range the plane had to be large and slow and fly at night.
Blenheims went from a Lewis gun in the power turret to a Vickers "K" gun (higher rate of fire) to a belt feed Browning (even higher rate of fire) to two Brownings.
The other gun positions weren't all that hot but the fixed gun on the Hampden wasn't all that effective either and the Do-17 and Ju-88 often had the sole forward firing gun clamped down and fired by the pilot. 75 round saddle drums don't quite equal a belt feed.
The British could have done more to upgrade the Blenheim and Beaufort but the "Mystery" of why they thought new airframes with the same powered ( or marginally more powerful) engines would offer any large change in performance has never been really explained, Botha and The Albemarle (which started as a Bristol design with the same Taurus engines as the Beaufort).
stug3
Staff Sergeant
Too bad the Brigand couldnt have been developed earlier. (without the teething problems)
- Thread starter
- #69
I agree it was light. Such twin engined, yet light bombers have the same downfalls as light fighters: they still use as many engines as 'proper' bombers, they still need good crew numbers if they're to be employed effectively, plus one needs more of those to put the same tonnage of HE on target. Sometimes they cannot perform (no torpedo for Blenheim).
I give you that - field length. A a package, Hampden should be regarded as a far better bomber.
Agreed that British had some problems. The bulky radials of modest power were unable to turn Blenheim into a fast plane, though.
Hampden have had like half a dozen of LMGs, so did the He-111P (of Polish campaign vintage).
We know all to well that those two were failures.
Expecting from a plane with tick wings to be fast is unrealistic, and Bristol planes, from Blenheim up to Buckingham/Brigand/Buckmaster were having that, along with generous wing area. Not that they were the only ones, we can take a look at 110/210/410, B-25/26 (the 'mainstream' models), Typhoon, Hurricane etc.
Shortround6
Major General
In many ways the Hamden was a better bomber. But it was also never used for some of the roles the Blenheim was, like battlefield support or interdiction. In spite of it's "speed" it was seldom used in daylight where enemy single seat fighters could get to it.
Hampden started with one fixed .303 in the fuselage and a single .303 "K" gun in the dorsal and ventral positions, one "K" gun may have been mounted flexibly in the nose. The dorsal and ventral positions were doubled up but were still manually aimed and fed with 96 round drums.
The HE-111P "(of Polish campaign vintage)" may very well have had just 3 MG 15s. One in the nose, one dorsal and one out the bathtub. After the losses in the Polish campaign a fixed gun was added forward (probably of no more use if as much as the fixed gun in the wing of the Blenheim) a gun out each side along with an extra crewman for them and an occasional fixed gun in the tail cone. ALL flexible guns used 75 round drums and were manually aimed.
Late Blenheim MK IVs had 5 LMGs but only the pair in the turret were really effective.
True but then the thick wing offered high lift without "trick" devices and offered volume for fuel tanks.
The Blenheim was outdated but the British, perhaps due to the engine problem, had nothing to really replace it. Look at the time the Americans were designing the B-25 and B-26 bombers (or even the B-23) the R-2600 was a working 1500-1600hp engine, in part due to 100 octane fuel. The R-2800 was coming along nicely (at least in the single stage version). The Merlin was in the MK X for bombers stage and moving to the MK XX and the Hercules was below 1400hp on 87 octane. Only high power engine really available to the British at the time was the Vulture and we know how that turned out. Perhaps a Hercules powered Beaufort improved could have been schemed but with 1300-1400hp engines in 1940 how much of an improvement would it have been?
Wings with extra moving surfaces are harder to build and maintain and unless you get the British to increase allowable runway lengths you were always going to have problems with British early war designs.
The Blenheim could have been improved with minor (relatively) modifications. Better fit and finish and better fairing. Clip the wings just a bit. Constant speed propellers vs two pitch. Two speed supercharger vs one speed. Low drag twin turret. Crop fins on the 250lb bomb like was done on the 500lb for mosquito.
The Blenheim could carry 1320lbs of bombs, four 250lbs inside, and two racks of four 40lb bombs behind the bomb bay externally (not under wing). Not much of a stretch to put either two 500lb (which it could carry anyway) with two 250lb bombs. or perhaps 4 250lb bombs with cropped fins in the inner bomb cells and one 250lb in each outer cell?
Problem comes with lack of British production of constant speed propellers and perhaps production capacity of two speed supercharger drives. The design exists for the Pegasus so using it on the Mercury is no great stretch of design. It would be worth over 100hp for take-off even with 87 octane fuel.
Changing landing gear doors to Beaufort type might help with both streamlining (tighter fit to tires) and the engine out situation.
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- #71
While for Hampden it was a risky business to venture into airspace likely containing the enemy fighters, sending Blenheim in the same was not something prudent either. Not that I ever claimed Hampen was fast, either
Thank you for detailing about the defensive LMGs. Think we could agree that those were better suited to insert more courage into bomber's crew, than to serve as a viable defense. Also, Blenheim had no means to defend vs. attacks coming from lower hemisphere, nor to simultaneously defend vs. multiple attackers.
In mid 30s, the engineers can be excused for going for thick wing, since all that theory practice about high-lift devices was a slippery thing. Projecting a mid-40 plane, pretending that slats, or split-, Fowler- or Youngman flaps are not well within state of art, is something else, bringing out the planes that need 2 x 2450 HP to make 350 mph, or to carry one torpedo externally, on same power, or to create a trainer with said power.
Calling the simple flap, or even the slotted flap as a 'trick device' is a tad too much, the humble Hurricane was flying with flaps installed.
As for the plane's fuel tankage, we can see that Mosquito, Hornet, A-26 still can carry plenty of fuel, despite thiner wings. Plus, in a classic twin engined plane, fuselage can carry plenty of fuel. Especially in planes without a sizable bomb bay. In case the bomb bay is there, even better, since different combinations of fuel + ordnance can be put to a good use.
There was no bomber in 1940 with 2 x 1400 HP, in service. Most were what, like 2 x 900 up to 2 x 2 x 1100, plus Italian 3-engined jobs. So the bomber with 2 early Hercules engines, even on 87 oct fuel, would be that best in the world. Come 100 oct fuel (late 1940 for the Bomber Command?) - almost 2 x 1600 HP.
Don't think we should make the hype about 'extra moving surfaces'. Hampden was equipped even with lengthy slats, nobody was complaining. What were the manufacturers to do - dump the flaps other from their designs?
Building maintaining a plane that is just a more than target practice for enemy fighters AAA was recognized even by Stalin as a faulty business.
Some other avenues: install the Pegasus, maybe Merlin XX, or Wright Cyclone, so both take off power power at altitude is increased. Shortcomings: greater drag from Pegasus engines, Merlin XX in short supply, Cyclone is a foreign engine. Further shortcomings: the more people is reworking the Blenheim more is in production, the better planes would be delayed.
vinnye
Senior Airman
They used Merlin XX engines at one point because the Short Sterling bomber had a higher priority call on the Pegasus engines.
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- #73
vinnye
Senior Airman
Hi, should have made it clearer - I believe the Beaufighter II was fitted with Merlin XX engines because the Bristol engines were needed for the Stirling heavy bomber.
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- #75
stug3
Staff Sergeant
Two Bristol Beauforts (N1173/`MW-E' and AW242/`MW-B') of 217 Squadron, Royal Air Force patrolling the British coast near St Eval, Cornwall.
stug3
Staff Sergeant
The German heavy cruiser PRINZ EUGEN was torpedoed and severely damaged by a British submarine off Norway in February 1942. On 16 May she sailed from Trondheim in an attempt to reach her home port in Germany for further repairs. Coastal Command organised a strike for the following evening involving 12 No 42 Squadron Beauforts, inluding the Mk IIA seen here with its crew preparing for the operation.
A crew of a Bristol Blenheim Mark IV of No. 404 Squadron RCAF, prepare to take off from Dyce, Aberdeen, in the evening of 17 May 1942, to take part in the attack on the German heavy cruiser PRINZ EUGEN off Norway. Six Blenheims were detailed to accompany the strike force of Bristol Beauforts in order to make dummy torpedo attacks on the cruiser so as to confuse the enemy anti-aircraft defences, and to provide fighter cover.
A crew of a Bristol Blenheim Mark IV of No. 404 Squadron RCAF, prepare to take off from Dyce, Aberdeen, in the evening of 17 May 1942, to take part in the attack on the German heavy cruiser PRINZ EUGEN off Norway. Six Blenheims were detailed to accompany the strike force of Bristol Beauforts in order to make dummy torpedo attacks on the cruiser so as to confuse the enemy anti-aircraft defences, and to provide fighter cover.
stug3
Staff Sergeant
The first production Beaufighter Mark IIF night fighter, R2270, fitted with dihedral tailplanes and equipped with AI Mark IV radar, in flight. This aircraft served with No. 406 Squadron RCAF.
Beaufighter cockpit
Beaufighter cockpit
stug3
Staff Sergeant
Beaufighter Mark VIC, X8035 'J', of No. 235 Sq. RAF, taking off from Luqa, Malta, during the Italian naval attack on the HARPOON
Three Beaufighter Mark IF night fighters of No. 600 Squadron RAF based at Colerne, Wiltshire, flying in starboard echelon formation. The wartime censor has removed the AI Mark IV airborne interception radar aerials from the photograph.
The Women's Auxiliary Air Force (WAAF): RAF and WAAF flight mechanics working together on a Bristol Beaufighter Mark VI in a servicing hangar at No. 51 Operational Training Unit, Cranfield, Bedfordshire. They are pictured adjusting the undercarriage, working on the propeller and carrying out an inspection of the engine.
WAAF personnel prepare and refuel a Bristol Beaufighter Mark VIF for a night-flying sortie from No. 51 Operational Training Unit at Cranfield, Bedfordshire
Three Beaufighter Mark IF night fighters of No. 600 Squadron RAF based at Colerne, Wiltshire, flying in starboard echelon formation. The wartime censor has removed the AI Mark IV airborne interception radar aerials from the photograph.
The Women's Auxiliary Air Force (WAAF): RAF and WAAF flight mechanics working together on a Bristol Beaufighter Mark VI in a servicing hangar at No. 51 Operational Training Unit, Cranfield, Bedfordshire. They are pictured adjusting the undercarriage, working on the propeller and carrying out an inspection of the engine.
WAAF personnel prepare and refuel a Bristol Beaufighter Mark VIF for a night-flying sortie from No. 51 Operational Training Unit at Cranfield, Bedfordshire
Wildcat
Major
Great photos!
