# Bristol's twin-engined planes?



## tomo pauk (May 5, 2012)

Bristol's Blenheim, Beaufort and Beaufighter were significant part of not only RAF, but other airforces. Later combat-plane designs, Brigand Buckingham, were too late for the ww2.

Starting date being Blenheim's 1st flight, 12 April 1935, how would you further develop the 'line' of the planes? The engines should be the historical Bristol products, yet the planes should accept other ones available for the historical users. Armament electronics also being historical types. The designs should be tailored for more roles - no tightly-knit approach (but also not too big the resulting plane) 
Timing of the designs should be 1940 (1st design), 42 (second), 44 (3rd), or, 1940 (1st design), 43 (2nd design).


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## davebender (May 5, 2012)

Bristol Beaufighter







> Fuel Capacity:
> A total of 550 Imperial gallons (2500 litres) in four fuel tanks consisting of two 188 Imperial gallon (854.5 litre) fuel tanks in the centre-section and two 87 Imperial gallon (395.4 litre) fuel tanks in each outer wing section. Long-range fuel tanks when fitted include one 29 Imperial gallon (131.8 litre) fuel tank mounted outboard of each engine nacelle. A 24 Imperial gallon (109 litre) fuel tank can be installed in the port gun bay and a 50 Imperial gallon (227.2 litre) fuel tank can be installed in the starboard gun bay, with the guns removed.
> 
> Range:
> 1,470 miles (2366 km) on internal fuel with torpedo. 1,750 miles (2816 km) with torpedo and long range tanks.


The Beaufighter carries a lot of internal fuel which means a large combat radius. It can easily strike maritime targets 600 miles away. Once the torpedo is gone it's almost uncatchable by December 1941 Japanese fighter aircraft. A few squadrons of these could cause serious damage to Imperial Japanese Army transport fleets at the beginning of the Pacific war.

Of course they need to be in the Pacific to do any good. Not piddled away in Europe or Africa.


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## Wildcat (May 5, 2012)

The RAAF did use the Beaufighter, built them too.


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## Shortround6 (May 5, 2012)

tomo pauk said:


> Bristol's Blenheim, Beaufort and Beaufighter were significant part of not only RAF, but other airforces. Later combat-plane designs, Brigand Buckingham, were too late for the ww2.
> 
> Starting date being Blenheim's 1st flight, 12 April 1935, how would you further develop the 'line' of the planes? The engines should be the historical Bristol products, yet the planes should accept other ones available for the historical users. Armament electronics also being historical types. The designs should be tailored for more roles - no tightly-knit approach (but also not too big the resulting plane)
> Timing of the designs should be 1940 (1st design), 42 (second), 44 (3rd), or, 1940 (1st design), 43 (2nd design).



Unless you can really change the engine development time line things are going to go pretty much as they did historically. Engine wise, Bristol spent just about all their time and money on the sleeve valve engines. The Mercury was just too small for any but a major rework to show much improvement (more than 10% or so). The Sleeve valve Perseus was also too small to show much improvement over the Mercury (same bore and stroke=same displacement). The Taurus turned out to be a turkey and this set back the Beaufort program a great deal and caused the Blenheim to be retained in production and service longer than if the Taurus had worked as hoped. P&W twin wasps were the preferred alternate engines for the Beaufort, unfortunately for the British a ship carrying the first several hundred twin wasps was torpedoed, forcing the retention of the Taurus. Australian Beauforts dodged the Taurus bullet. Hercules comes on line in 1940, after quite a while of production headaches with the sleeves. SO it's debut is both later than planned and in fewer numbers. It is also in demand for the heavy bomber program. Between getting the Hercules into production, futzing about with the Taurus, and Bristol firing Roy Fedden, the Centaurus was basically put on the shelf for a period of time, much like the Griffon. This delayed it's service use, no matter what airframe used it. 

In order to make major changes in the airframe you also have to get the air ministry to change a number of their requirements. The Blenheim was practically a STOL aircraft compared to later bombers. A landing speed (or stalling speed?) of 50mph and a claimed take-off run of 296yds. ALL British planes could not use more than 35lbs of air pressure in the tyres to reduce the chances of rutting the grass airfields until some time in 1938, I believe, so any design work done before that time has to deal with certain tyre sizes to handle a given weight, This sort of restriction went out the window in just a few more years but helps explain why some of the early planes suffered a lower performance than you might expect. 
Other things are the rapid development of better flaps. Early flaps weren't much more than air brakes. They created much more drag than they did lift and were used to steepen the glide slope for a shorter approach and landing run rather than operating at higher weights. This meant that lift for take-off had to come from wing area and airfoil shape. This meant the first 3 Bristol twins were stuck with a larger, higher drag wing than some other planes of similar size and mission had. A Bristol Blenheim had 4sq ft more wing area than an A-20. It's wing was probably thicker too, I haven't tired to measure them.

And again for timing, if you want the the plane to actually see combat in WW II you have had to put pencil to paper in 1942 or so. The Bristol Buckingham bomber (first production version in March of 1944) was a slow, twisted development of a bomber version of the Beaufighter first proposed in 1939. After several revisions the design that was finally built was on the drawing boards in 1941.


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## Edgar Brooks (May 6, 2012)

Bristol (just like every other British manufacturer) will respond to the procurement policy of the government of the time. The Air Ministry decide that they need a twin-engined something-or-other, and the various manufacturers are invited to tender. Their design team(s) come up with something to match the requirements, tenders go in, and the Air Ministry choose the one (or more) that they like best. For a company to arrive at a design, first, is a rarity, and even de Havilland needed the backing of Sir Wilfrid Freeman to get the Mosquito cleared.


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## Shortround6 (May 6, 2012)

Bristol (and other manufacturers) will use the existing aircraft, at times, as a starting point for a new design or as an argument to the Air Ministry ( or government Agency) that their design can be produced quicker or cheaper or both than a competitors all new design. This was part of the attraction of both the Beaufort and Beaufighter. They were low risk, hopefully quick to get into service aircraft compared to a rival design that might offer more performance but would not be available for squadron service as soon. The airframes may have been low risk but unfortunately the engines were not.


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## tomo pauk (May 6, 2012)

Beaufort was designed produced in order to equip the RAF with a torpedo-bomber. 
My take on that would be a plane with a bomb bay, mid- or high-wing, featuring maybe both slats fowler flaps, so the wings can be of somewhat thinner profile. Low-risk part of the engines would be covered by usage of the Pegasus engines (for prototypes 1st series), wing being stressed for Merlin and Hercules (such planes built from, say, Spring of 1940). The MGs would be 4 in the wing roots (replaced with belt-fed Hispano when available), space for 4-6 in outer wings, 2 in the back. An adaptation for the NF job would include 4-6 belly mounted MGs, ammo feed from bomb bay (all akin to the NF Blenheim); we should have the Merlin, or even Hercules versions by then. Radar as available. All in all, a British Ju-88?


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## davebender (May 6, 2012)

Aircraft need to be in the right place at the right time to do any good.

How many torpedo armed Beaufighters were at Rabaul and Ambon during January 1942 to fight Japanese invasion forces?


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## Shortround6 (May 6, 2012)

tomo pauk said:


> Beaufort was designed produced in order to equip the RAF with a torpedo-bomber.
> My take on that would be a plane with a bomb bay, mid- or high-wing, featuring maybe both slats fowler flaps, so the wings can be of somewhat thinner profile. Low-risk part of the engines would be covered by usage of the Pegasus engines (for prototypes 1st series), wing being stressed for Merlin and Hercules (such planes built from, say, Spring of 1940). The MGs would be 4 in the wing roots (replaced with belt-fed Hispano when available), space for 4-6 in outer wings, 2 in the back. An adaptation for the NF job would include 4-6 belly mounted MGs, ammo feed from bomb bay (all akin to the NF Blenheim); we should have the Merlin, or even Hercules versions by then. Radar as available. All in all, a British Ju-88?



From Wiki:

"The Beaufort came from Bristol's submission to meet Air Ministry Specifications M.I5/35 and G.24/35 for respectively a land-based twin-engined torpedo-bomber and a general reconnaissance aircraft. With a production order following under Specification 10/36" 

"The first prototype rolled out of Filton in mid-1938. Problems immediately arose with the Taurus engines continually overheating during ground testing...."

"With Blenheim production taking priority and continued overheating of the Taurus engines there were delays in production, so while the bomber had first flown in October 1938 and should have been available almost immediately, it was not until November 1939 that production started in earnest"

Designing the plane to use Hercules or Merlin engines and house 20mm guns in the wing roots would call for almost an entire new wing (especially with Fowler flaps) and slats would do squat. Twin engine bombers should not have an angle of attack of 14-15degrees or higher. 

See: http://i366.photobucket.com/albums/oo102/keithintheuk/035.jpg

you would be starting over again in 1938-39 and throwing out all the work done up to that point, delaying service entry by months if not a year or more.


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## tomo pauk (May 6, 2012)

> you would be starting over again in 1938-39 and throwing out all the work done up to that point, delaying service entry by months if not a year or more.



From April 1935 - End 1939, the British have plenty of time to design a far better airplane, than an warmed-up Blenheim. Throwing up the work is far better thing than throwing up the trained crews anyway. Biplane fighters SB-2 bombers in ww2, T-26 tanks in 1941/42, 2pdr ATGs in 1942, M3/M5 tanks, P-40s and Hurricanes in 1944, Pz-38(t)s Blenheims in 1942 - all capitalising upon the previously done work, yet hardly good examples of combat use.



> Designing the plane to use Hercules or Merlin engines and house 20mm guns in the wing roots would call for almost an entire new wing (especially with Fowler flaps) and slats would do squat. Twin engine bombers should not have an angle of attack of 14-15degrees or higher.



Okay, then no slats 
I've specified already that the new wing would be thinner - that implies it's a new design.

BTW, could we conclude that HP Hampden would be as good/bad without the slats, as it was with them?


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## woljags (May 6, 2012)

they did try griffon engines in the beaufighter briefly


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## tomo pauk (May 6, 2012)

Imagine them on something sleeker


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## Juha (May 6, 2012)

Hello Tomo
with Pegasus one easily ended up with underpowered turkey like Botha.

Juha


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## tomo pauk (May 6, 2012)

Botha's problem was indeed the lack of power, but also the lack of wing area - only 3/4s of the Hampdens, but for same empty weight. Or, for the 10% more wing area, the plane was weighting 20% more than Blenheim. On about the same engine power.


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## Jabberwocky (May 6, 2012)

davebender said:


> Aircraft need to be in the right place at the right time to do any good.
> 
> How many torpedo armed Beaufighters were at Rabaul and Ambon during January 1942 to fight Japanese invasion forces?


 
How many torpedo armed Beaufighters were in existence anywhere during January 1942? *Zero.* 

You can't just conjure up something that doesn't exist yet and then blame the RAF/RAAF for not having the right aircraft at the right place at the right time. 

The first Torbeaus weren't in service until late 1942. That leaves the Beaufort as the only reasonable alternative. 

The first Australian Beaufort wasn't flying until August 1941 and the first RAAF Beauforts didn't enter squadron service until February 1942, and even then it was a while before the aircraft was considered ready for combat service. Australian crews, unused to such large, high-speed aircraft, had a rough time with their Beauforts in the early operational period.


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## Shortround6 (May 6, 2012)

The British had a major engine problem in the late 30s. Bristol had Three 9 cylinder radials and a 14 cylinder radial, all of about 1000hp or less (down to under 900hp), and one 14 cylinder of 1300-1400hp but not in real production. The Armstrong-Siddeley Tiger was also a 900hp engine and none too good at that, Napair had the 1000hp Dagger and it wasn't quite ready either. That leaves the Merlin and in 1939 a single speed Merlin on 87 octane gas doesn't have the needed oophf for a bomber. 
Please note that the Beaufighter II was being worked on in 1939 in response to an anticipated shortage of Hercules engines.

The British did send many aircrews on missions with planes that were not good enough, the alternative of waiting for better aircraft is not undertaking the missions at all and in fact not having aircraft to undertake those missions or any other missions. 

Please note that many of the missions under taken by Blenheims and Battles in 1939-40 were not what the planes were designed for. They were light _ strategic_ bombers not tactical bombers. No tactical bomber needed a range of over 1000 miles in 1939-1940. Misuse and lack of co-ordination and escort was as much to blame for high loses as the actual design of the planes. 

Also please note that the Bristol aircraft used the space between the spars and the engine nacelle and fuselage for the main fuel tanks with long range tanks going between the spars outboard of the engine nacelles. Thinner wings mean less fuel, will the thinner wing offer enough lower drag at cruise to offset the fuel reduction? 

Anything the British could have done would be _tweaking_. The Blenheim and other British planes of the time did not have the best build quality. More careful sealing of joints and gaps and more attention to fit and finish would have helped speed a bit. good look at the planes in a wind tunnel with drag reduction in mind may have helped. Fitting a 2 speed supercharger to the Mercury (not that hard to do as the Pegasus had one) would have helped a bit, a better defensive set up would have helped, like a flexible gun in the nose rather than a fixed gun way out in one wing. A turret with twin guns instead of the single gun would also have helped. The strange notion that the turret should be retractable so that the plane had a good cruise but extended the turret to create high drag when in the combat zone needed a rethink. maybe try to desing a low drag turret in the first place rather than retractable ones? 

The problem is that all these tweaks are only going to change things by single digit percentages. A MK I with a short nose was modified for photo-recon work with about 250 hours being put into rubbing the aircraft down, sealing all joints and gaps with tape, repainting with a smoother finish fairing the lower nose with light alloy, removing the turret and installing shorter, squared off wing tips. They got the speed up to 278mph from 263mph. The plane was later fitted with Rotol constant speed propellers, a few more modifications and the engines run at 9lb of boost and 2750rpm for a true speed of 294mph at 13,000ft. 
A 280-290mph Blenheim fighter might have been more effective against bombers than the historic versions but still come woefully short against Me 110s or Ju 88s. 

Also please note that the aircraft that became the Armstrong-Whitworth Albemarle had it's start as the Bristol type 155, an improved Beaufort with tricycle landing gear and Taurus engines in 1938. 

It is the failure of the new engines to be developed in time and the failure of some of the replacement aircraft that kept the Blenheim and Beaufort in production and service for several years after it was hoped to retire them.


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## davebender (May 6, 2012)

I thought that was the point of this discussion.

Our starting date is 1935. Australia has 6 years to field effective maritime attack aircraft. If the torpedo armed Beaufighter cannot be ready then we need an interim aircraft. I would rather have stringbags during 1941 then Beaufighters during 1943.


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## Juha (May 7, 2012)

Again very good analysis, Shortround6.
IMHO Fedden with his sleeve fanatism cost GB dearly during early war years. Fedden also seems to hve underestimated the importance of good supercharger, not even at first to be interested in the advice R-R gave on that to Bristol's engine team.

Juha


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## Edgar Brooks (May 7, 2012)

tomo pauk said:


> From April 1935 - End 1939, the British have plenty of time to design a far better airplane, than an warmed-up Blenheim./QUOTE]
> To do what? In the 1930s nobody believed that France would be defeated, so there was no (visualised) chance of the Germans using the Channel, meaning that they had to go round the top of Scotland, and risk the attentions of the Navy, and all destroyers carried torpedoes.
> The Beaufighter was rushed into service as a nightfighter, to replace the Blenheim fighter, and was only considered for other roles when the Mosquito proved that it could take over the nightfighting role, especially with the two-man crew together, rather than several feet apart.


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## merlin (May 7, 2012)

Well I'm going to try and be a bit more inventive/creative! This is 'off the top of my head' so please forgive the detail on dates!

When the production planes for the new 'heavy' bombers were presented the Chamberlain - in winced at the cost, and did his best to delay large scale
production - until the situation with German worsen - after all if 'peace' prevails we won't need all these big bombers.
So, I think for an ATL it could be plausible for the Air Ministry on hearing this to go get their heavy bombload another way.
Bristol put forward a design for the spec that became the Halifax Manchester - rather than the Vulture of the latter it was to have Hercules, and the span
was about twenty feet less. 
Hence, the Air Ministry order this and dress it up as a Blenheim replacement! And just in case there's a problem with the Hercules, they give AW a chance 
with their Deerhound engine. Then, a 'bright spark' mentions that the original spec includes torpedo carrying ability i.e. 2 x 18", so thinking of rationalising 
production - once the design is proven the Beaufort ( Botha) are cancelled. But to give another option because this will be a big aircraft in comparison - if 
it can be done - have the new Beaufighter aircraft the ability to carry torps.

So, with luck the bigger Bristol Twin (Buckfast) enters service in mid-late '40, in time to make a mess of the invasions barges with its bigger bomb load. The Beaufighter
also enters service slighter earlier than OTL. And in 1942 the Beaumont enters service - a bomber version of the Beaufighter - but with a bigger fuselage.


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## fastmongrel (May 7, 2012)

Would it have been possible to use the H P Hampden instead of the Beaufort. It seems to have been liked as a torpedo bomber with Pegasus engines when used off Norway, maybe modify the H P Herefords to take the Hercules instead of the original Dagger to Pegasus conversion.


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## davebender (May 7, 2012)

Handley Page H.P. 52 Hampden medium bomber [UK] - Steve Jackson Games Forums


> 785-gallon standard fuel tanks



The Hampden might work as it carries plenty of internal fuel. An essential item for a maritime attack aircraft.






- Delete bomb bay unless it can carry an aerial torpedo or aerial mine.
- Delete defensive weapons except rear facing turret behind the cockpit.
- A couple forword firing machineguns are ok for flak suppression. These would be fired by the pilot.
- Crew size would drop to 3.
- High speed @ 100 meters = survivability for a torpedo bomber. Choose engines accordingly.
- Standard maritime survival equipment such as life rafts which can be dropped. 
- Ditching is more likely then bailing out for a damaged aircraft. That must be considered as some aircaft were inheritly bad at ditching.

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## tomo pauk (May 7, 2012)

Edgar Brooks said:


> To do what? In the 1930s nobody believed that France would be defeated, so there was no (visualised) chance of the Germans using the Channel, meaning that they had to go round the top of Scotland, and risk the attentions of the Navy, and all destroyers carried torpedoes.



Think you should ask someone else the question - it was RAF that ordered not one, but two dedicated torpedo bombers in the late 30's. 



> The Beaufighter was rushed into service as a nightfighter, to replace the Blenheim fighter, and was only considered for other roles when the Mosquito proved that it could take over the nightfighting role, especially with the two-man crew together, rather than several feet apart.



It would've been interesting to have Bristol's plane with thinner wings bomb bay - something that would be faster than Beau some 20 mph, on same HP, but with same terrific firepower.



fastmongrel said:


> Would it have been possible to use the H P Hampden instead of the Beaufort. It seems to have been liked as a torpedo bomber with Pegasus engines when used off Norway, maybe modify the H P Herefords to take the Hercules instead of the original Dagger to Pegasus conversion.



Hampden in torp bomber role seems like a natural choice, even more appealing with Hercules; too bad it was not to be.


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## fastmongrel (May 7, 2012)

davebender said:


> - Delete bomb bay unless it can carry an aerial torpedo or aerial mine.



Most British mediums and heavies seem to have been specified to have a torpedo capable bomb bay. I would imagine the Hampden was the same. I would also think about getting rid of the glazed nose and use the space for guns. 2 x Vickers S guns plus 4 x mgs with lots of tracer would tick my box  thats going to put a flak gunner off his breakfast. Though if the plane is going to be used for long range patrols I cant see the RAF wanting to lose the navigator, did the Hampdens navigator sit in the front.

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## tomo pauk (May 7, 2012)

Navigator was seated behind the pilot, so your version looks very plausible.

http://media.photobucket.com/image/recent/Iainart/sc1f311.jpg

Item No.12 is the navigator's seat on the pic.


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## fastmongrel (May 7, 2012)

tomo pauk said:


> Navigator was seated behind the pilot, so your version looks very plausible.
> 
> Recent image by Iainart on Photobucket
> 
> Item No.12 is the navigator's seat on the pic.



Had a look and it looks like the navigators position is No 33 with his map table No34. No12 is the navigators position for using the sextant but there might be room to fit the navigating station behind the pilot if he is not needed for bomb aiming.


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## davebender (May 7, 2012)

It would also add a lot of weight to the aircraft. That means less payload for fuel, protective armor and perhaps a second torpedo.

I'm not saying your nose mounted weapons are bad per se but there's no such thing as a free lunch. 1930s aircraft engines are likely to produce no more then 1,000 hp so we need to keep weight as low as practical.


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## tomo pauk (May 7, 2012)

Hercules being mandatory to lift such a weaponry on Hampden?


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## fastmongrel (May 7, 2012)

I was thinking of a Hercules version when I got a bit excited about a heavy forward firing armament


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## Juha (May 7, 2012)

fastmongrel said:


> Would it have been possible to use the H P Hampden instead of the Beaufort. It seems to have been liked as a torpedo bomber with Pegasus engines when used off Norway, maybe modify the H P Herefords to take the Hercules instead of the original Dagger to Pegasus conversion.



IIRC Hampden was used out of necessarity because it was available, BC was retiring them and had range. It could carry a torpedo almost internally, with modified bomb bay doors. IIRC the modified doors were partially open at rear part of them when torpedo was carried. But IIRC the crews thought that Hampden was a bit too large for torpedo work, ie unnecessry large target to Flak gunners.

Juha


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## Shortround6 (May 7, 2012)

While the Hampden was the smallest of the 3 Pre war medium bombers it was still a large airplane. Cutting 2 feet of the bottom of the fuselage is not going to turn it into a speed demon. That is also where the bomb bay is so now you have some real redesign to do. 
Mr. Benders idea of deleting all armament except the upper rear station and some forward firing guns for flack suppression isn't worth much because the initial Hampden gun fit was exactly 3 guns, one out the top rear, one under the fuselage and one fixed in the nose ahead of the pilot. Dropping one Vickers K gun buys next to nothing. later versions doubled the armament to paired Vickers K guns top and bottom and one or two(?) fixed Brownings. The flexible mounts had no power assist so their weight was minimal. The fuselage was a skinny as an A-20, crew could not change positions in flight without extreme difficulty if at all. 

The British 40mm (2pdr) aircraft cannon is a lousy flak suppression weapon. It's low velocity means that it has less practical range than a 20mm Hispano and it's rate of fire (100rpm?) means 4-6 shots per barrel per attack compared to a 20mm Hispano's 24-36 shots per barrel. Given the weight of the Vickers S gun it really comes up short as a suppression weapon. 

here is were the lack of development of the poppet valve engines hurt the British. The Pegasus was the British equivelent of the Wright Cyclone. With more development it might have been good for 1100hp in 1940 and heading for 1200hp. Cuts the need for the early 1300-1400hp hercules considerably, especially considering the Pegasus is hundreds of pounds lighter.


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## davebender (May 7, 2012)

Unlike the A-20 the Hampden had a large internal fuel capacity. A crucial difference for maritime attack.

In a perfect world I'd prefer an A-20 with larger internal fuel tanks for maritime attack. Perhaps stretch the fuselage a bit like Junkers did with the Ju-88H or put large, well protected fuel tanks in the wings like Messerschmitt did with the Me-210. But that's a different discussion. Australia has no influence over the A-20 so such a design change must be initiated by the U.S. Army Air Corps.


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## merlin (May 8, 2012)

Sorry, but Hampden A-20 are surely irrelevant as far as the thread is concerned - they are not Bristol aircraft!
Intriguing thought about the Albemarle - if it wasn't for the need for it to be made out of non-strategic material - and of course made by Bristol - how much better would it have been??


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## tomo pauk (May 9, 2012)

My take on the last verison of the Bristol twin engined plane, built from 1942, would be a 1600-1700 HP Hercules, 4-5 Hispano (two in wing roots, other added in the lower nose), 4 gun BP turret (neatly faired, not just a slapped one like at Beau V); night fighter with as good Merlin as possible, maybe with lighter turret armament (or none). Both inner- and outer-wing racks.

Any takers for the Bristol's twin engined (multi role) plane, in service, say, from Spring of 1943 until VJ day? Multitude of engines are available, from different Merlins, Hercules makes 1670-1770 HP, Griffon, LL R-2800, Centaurus for 1945... Then, the Molins cannon, S class, down to Hispano, maybe it's time to go for a tricycle, a Cookie-capable bomb bay (no bulges), laminar-flow wing, full span flaps...


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## Shortround6 (May 9, 2012)

tomo pauk said:


> My take on the last verison of the Bristol twin engined plane, built from 1942, would be a 1600-1700 HP Hercules, 4-5 Hispano (two in wing roots, other added in the lower nose), 4 gun BP turret (neatly faired, not just a slapped one like at Beau V); night fighter with as good Merlin as possible, maybe with lighter turret armament (or none). Both inner- and outer-wing racks.



Why the wing root cannon? In existing Bristol aircraft the wing roots were full of fuel tanks. Putting guns in the wing roots means fuel displaced by guns has to be carried some were else. In 1942 leave Beaufighter pretty much alone. If you want a night fighter with upward firing armament just do what the Germans did. Stick a pair of Hispano guns firing upward between the pilot and the rear seater. A lot less weight and drag than any turret no matter how well faired. If you are trying to defend from the rear give the observer of pair of .303 Brownings and get on with it. Even this will slow the plane but a 600lb turret with four .303s slows the plane more and really doesn't offer that many advantages for a twin engine fighter. 
You can't really use the same plane for too may jobs. A Beaufighter cannot substitute for a twin Hercules powered bomber. A twin Hercules powered bomber should be carriying 2000-5000lbs of bombs and that is too much to carry outside the plane without incurring too much drag. Unless you are trying for a Hercules powered Mosquito, in which case the 20mm guns and the turret start becoming redundant. Please remember that Mosquitos *AS USED* in WW II were pretty much limited to four 500lb bombs or one 4000lb cookie. No eight 500lb or four 1000lb or even two 1000lb missions. 
Bringing the Hamden back for a moment, at a certain point in WW II it was the *ONLY* British bomber that could carry a 2000lb armor piercing bomb inside the bomb bay. The Whitley even with it's 7000lb total bomb load didn't have the size bomb bay needed to house the bomb and neither did the Wellington. 


tomo pauk said:


> Any takers for the Bristol's twin engined (multi role) plane, in service, say, from Spring of 1943 until VJ day? Multitude of engines are available, from different Merlins, Hercules makes 1670-1770 HP, Griffon, LL R-2800, Centaurus for 1945... Then, the Molins cannon, S class, down to Hispano, maybe it's time to go for a tricycle, a Cookie-capable bomb bay (no bulges), laminar-flow wing, full span flaps...



Sort of the same problem, what do you really want it to do? 

"a Cookie-capable bomb bay (no bulges)" bomb bay means a big fuselage for a fighter/night fighter aircraft. 

See the Bristol Type 163 Buckingham and Brigand. They didn't to try to use the same fuselage for the different roles.

Maybe they didn't make the best use of the space but here is a cut away of Brigand. 

http://img.photobucket.com/albums/v11/leecoll/BrigandCutaway001.jpg


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## tomo pauk (May 9, 2012)

Shortround6 said:


> Why the wing root cannon? In existing Bristol aircraft the wing roots were full of fuel tanks. Putting guns in the wing roots means fuel displaced by guns has to be carried some were else.


Since 'my' 1940 Bristol is going to have a bomb bay, the cannons their ammo need to somewhere else (compared with Beaufighter). Two of them are going into wing roots, a pair can be located outboard of the engines, another pair (or 3 pcs) can use the bomb bay, installation akin to the Ju-88's one. On the variants where the bomb bay is used for the original purpose, 4-6 LMGs can be located in the nose.
The fuselage was fuel-free (in Beau), so in this instance some fuel can go at the upper part of the hull (from lower wing line towards the top).*



> In 1942 leave Beaufighter pretty much alone. If you want a night fighter with upward firing armament just do what the Germans did. Stick a pair of Hispano guns firing upward between the pilot and the rear seater. A lot less weight and drag than any turret no matter how well faired. If you are trying to defend from the rear give the observer of pair of .303 Brownings and get on with it. Even this will slow the plane but a 600lb turret with four .303s slows the plane more and really doesn't offer that many advantages for a twin engine fighter.



Yep, British 'Schraege Musik' does sound great; I did post my reservations about the rear armament of the Bristol. As for leaving the Beau alone, my proposal is looking for something of better performance 



> You can't really use the same plane for too may jobs. A Beaufighter cannot substitute for a twin Hercules powered bomber. A twin Hercules powered bomber should be carriying 2000-5000lbs of bombs and that is too much to carry outside the plane without incurring too much drag. Unless you are trying for a Hercules powered Mosquito, in which case the 20mm guns and the turret start becoming redundant. Please remember that Mosquitos *AS USED* in WW II were pretty much limited to four 500lb bombs or one 4000lb cookie. No eight 500lb or four 1000lb or even two 1000lb missions.
> 
> Bringing the Hamden back for a moment, at a certain point in WW II it was the *ONLY* British bomber that could carry a 2000lb armor piercing bomb inside the bomb bay. The Whitley even with it's 7000lb total bomb load didn't have the size bomb bay needed to house the bomb and neither did the Wellington.



If you were following my proposal for the 1940 Bristol, you will note that it would be of mid- or high-wing variety (=allowing for a decent bomb bay), with only 2 'permanent' cannons - rather a different animal than the Beau.




> Sort of the same problem, what do you really want it to do?
> 
> "a Cookie-capable bomb bay (no bulges)" bomb bay means a big fuselage for a fighter/night fighter aircraft.
> 
> ...



Again, a low-wing airplane has problem to make for a good/great bomber. 
As 'what it (a 1943 Bristol) will do', it will bomb, make torp, rocket cannon attacks - everyday stuff.

*edit: the cannon ammo can go within the 'hull part' of the wing, so the fuel carried is not that affected. The 2 of the 4 wing racks can do wonders for the combat range, though.


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## wuzak (May 9, 2012)

Shortround6 said:


> Please remember that Mosquitos *AS USED* in WW II were pretty much limited to four 500lb bombs or one 4000lb cookie. No eight 500lb or four 1000lb or even two 1000lb missions.
> Bringing the Hamden back for a moment, at a certain point in WW II it was the *ONLY* British bomber that could carry a 2000lb armor piercing bomb inside the bomb bay. The Whitley even with it's 7000lb total bomb load didn't have the size bomb bay needed to house the bomb and neither did the Wellington.


 
Someone mentioned in here a while ago that Mosquitos used, on occasion, 2 x 1000lb target indicators. Which are the same size as the 1000lb MC bomb.

Also note that the Mosquito IX and XVI with the bulged bomb bay could do a 8 x 500lb mission if required - using the 6 x 500lb Avro carrier internally, and 1 500lb bomb under each wing. But BC preferred to use the 4000lb HC Cookie or the 4000lb MC bomb.

You sure the Wellington couldn't carry the 2000lb AP bomb? IIRC the 2000lb AP bomb was a small diameter, longish bomb. And two could fit in the Mosquito's bomb bay (not sure about the rack).


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## Shortround6 (May 15, 2012)

Getting back to the original premise.



tomo pauk said:


> Beaufort was designed produced in order to equip the RAF with a torpedo-bomber.
> My take on that would be a plane with a bomb bay, mid- or high-wing, featuring maybe both slats fowler flaps, so the wings can be of somewhat thinner profile. Low-risk part of the engines would be covered by usage of the Pegasus engines (for prototypes 1st series), wing being stressed for Merlin and Hercules (such planes built from, say, Spring of 1940). The MGs would be 4 in the wing roots (replaced with belt-fed Hispano when available), space for 4-6 in outer wings, 2 in the back. An adaptation for the NF job would include 4-6 belly mounted MGs, ammo feed from bomb bay (all akin to the NF Blenheim); we should have the Merlin, or even Hercules versions by then. Radar as available. All in all, a British Ju-88?



The Beaufort was designed as an easy development from the Blenheim. While the British had a lot of aircraft companies, none of them were very big with large design staffs. This is one reason some contracts got shifted around and why some company's proposals were turned down. Supermarine may have had some good ideas (sketches) for twin engine fighters or bombers but they were way behind schedule on the Spitfire so the likelihood they could turn those sketches into working hardware in the time needed was pretty slim. Same with Bristol, first attempt (type 150) at the Beaufort was a slightly stretched Blenheim, Pilot moved forward 4 feet and turret moved aft a bit. Navigators position was eliminated and Bristol Perseus VI engines specified. RAF turned down the idea of a long range torpedo bomber without a navigator and the plane started to grow. Here is were the time line gets interesting.

Blenheim first flight 12 April 1935 but this was not the full military version. 
First full military version is first flown 25 June 1936. Hundreds of Blenheim's are already on order. 
1936 the RAF orders the first 78 Beauforts off the drawing board. 
March of 1937, Blenheim I goes into service with first squadron. 
24 Sept 1937 Prototype Blenheim IV first flies. 
15 Oct 1938 First production (and 1st prototype) Beaufort flies. Production moves slowly as first aircraft is tested. 
Fall of 1938, proposal for fighter version of Beaufort made (Beaufighter) and accepted. 
19 July 1939, First Beaufighter flies about 8 months after work begins. 300 Beaufighters ordered two weeks earlier. 
Nov 1939, First Beaufort issued to service squadron (literally, first Beaufort to fly) First real production machines show up in Jan 1940. 
July 27 1940, first 5 Beaufighters handed over followed by 5 more on 3 Aug. 

Taking time to design new wings with high lift devices and test them would have delayed things even more. 
The Taurus engines in the Beaufort were giving trouble in ground running even before the first flight and many of the losses suffered by Beauforts in the spring/summer of 1940 were not due to enemy action but the Taurus engines.

Sometimes it takes time for things to develop. Fowler flap was "invented" in 1924 but not test until 1932 by the NACA, it was first used on the martin 146 prototype in 1935 and then the production Lockheed 14 Airliner in 1937. Any practical experience on how it works is not available until about the middle of the Bristol development history.


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## tomo pauk (May 15, 2012)

Would it be easier for Bristol RAF to introduce the all-new combat aircraft within 4 years, or to introduce two major redesigns of an existing plane in the same time frame? While both Beaufort and Beaufighter surely show lineage with Blenheim, I strongly doubt that anything from Blenheim was usable on those two planes (cockpit instruments and LMGs only?). 
Anyway, I wouldn't bet my house on anything proposed in an what-if form. But saying that Bristol was incapable to introduce a completely new aircraft within 4+ years is a tad too much.



> Taking time to design new wings with high lift devices and test them would have delayed things even more.



I'm fine with that - instead in Autumn of 1938, the new Bristol flies 1st time in Autumn of 1939, in service for BoB?


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## Shortround6 (May 16, 2012)

I am not so sure about the "major" redesigns. Beaufort may have used pretty much a Blenheim wing with a bit under 2 feet added at the center. A "new" fuselage or an added to fuselage? Blenheim I went 12,500lbs loaded but a Blenheim V went 17,000lbs. Beauforts went to 22-23,000lbs, Beaufighters went to 25-26,000lbs. A selling point of the Beaufighter was that it used the Beaufort wings, tail and landing gear with a new fuselage. The selling point is born out by the 8 months from start of work to first flight. While not a record it is one of the faster developments of the WW II era. Putting the Hispano guns were the old bomb bay was solved the room problem, solved the center of gravity problem and solved the reload problem. First 400 Beaufighters used drum feed cannon with 3 spare drums per cannon. reloading done by rear seat man. Far from an ideal solution but better than one drum per gun until landing.
Bristol may have been able to come up with a new design in 1936-37 and gotten into service by the BoB. But it means realizing that one of the most advanced aircraft in the RAF in 1936-37 ( the Blenheim was the fastest bomber in the world at that time) will be obsolete in just 1-2 years, stopping all development of the basic design and starting all over again with a new airframe using an engine that won't be in production until 1940. Many other aircraft evolved during those years rather than have all the old work thrown in the dust bin and new starts made. 

There were several screw ups that lead to the Blenheim staying in combat service as long as it did. There were several screw ups in the government specifications that also lead to a less capable aircraft.
The Specification that lead to both the Beaufort and Botha was both not far reaching enough and yet too ambitious. If you have a twin 840hp bomber in hand asking for a twin 900hp machine to succeed it is not very far reaching. Asking for twice the bomb load at the same or greater range and as much or more speed while carrying a heavier defensive armament one only slightly larger engines (specified by the government, not the airframe makers)pretty much doomed the successors (it doomed the Botha anyway) and the failure of Bristols own Taurus engine meant the Beaufort was both late and made in small numbers. WIth no other small twin bomber in hand the British were forces to continue with the Blenheim.
Specifing basicly the same defensive armament as a WW I DH-4 for a 1936-40 bomber when the RAF was ordering 8 gun fighters shows a real disconnect in thinking. And the idea that ANY bomber, no matter how well it might roll or turn or loop for a bomber, had the ability to bring a single fixed .303 gun to bear on an enemy fighter simply boggles the mind. 
The British could have done a lot to improve things without going to a whole new design but it requires the development of a lot of auxiliary equipment. Getting a small turret with twin belt fed Brownings in service sooner. Getting into the constant speed propeller business sooner ( adjustable/controllable 2 pitch props doesn't really cut it). Spending a bit more time improving the Mercury and Pegasus engines, if you are going to build a few thousand more Mercurys' after 1938-39 for combat planes spending a little time/money might not be a bad thing. SOmebody come up with a wind tunnel so some form of scientific drag reduction could be done on a number of airframes.


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## tomo pauk (May 16, 2012)

We have a plane that grows from 12500 to 26000 lbs, in two steps; Blenheim V is no stepping stone for Beaufort/Beaufighter. I do not buy that it took simple changes, like cutting the front fuselage, or installing the new engines: if that was the case, a Blenheim suddendly grown to Beaufighter would've disintegrated in mid air because the structural limits would've been to great to bear. 
Seem to me that Beaufort was the step where the most of the redesign took place?

After reading the second part of the your post, going with a design tailored for Hercules/Merlin (instead of Taurus), for 1940, seem like a missed opportunity. My idea about Pegasus-powered version of the plane does not seem like a bright one.


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## Shortround6 (May 16, 2012)

The Beaufort was a redesign, It used light alloy in places where the Blenheim had used steel, Structural weight of the Beaufort was actually less than the Blenheim. But it kept much of the original Blenheim design, much like the LA-7 kept much of the LA-5 and Lagg-3 or the various Yaks kept much of the design even though wing spars changed from wood to metal and so on. Or like the P-51H kept much of the design of the P-51D even though there are few interchangeable pieces. 
The British had a major problem with engines in 1938-41, they had no easy way to upgrade from their 800-900hp class engines unless the plane was rather big. The Wellington was big enough to go from an 1100 pound engine to 1600-1800lb engines (Hercules or Merlin with radiator). The British had no 1200-1450 pound engines like the P&W R-1830 or the Wright R-1820 or the ones they had were low powered (Tiger/Dagger) or unreliable (Taurus). 

For a somewhat comparable aircraft see the Martin Maryland and Baltimore. 

If the British had had a 1000-1200hp engine of 1200-1400lbs perhaps a better Blenheim or Beaufort could have been built. The Sleeve valve problems mean even a Hercules powered plane started in 1937-8 won't show up in more than handfuls until late 1940, much like the original Beaufigter. And for a twin to be any good with Merlins it needs the MK X. The 880hp take-off rating of the MK III without 100 octane fuel doesn't bear thinking about in a 16,000-20,000lb plane.

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## Tankworks (May 16, 2012)

i think, like the Martin and A-20, the Bristol designs were too small to allow much development without designing a completely new aircraft. The B-25 would be an example of an aircraft large enough to allow all sorts of tweeking.


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## Shortround6 (May 17, 2012)

Tankworks said:


> i think, like the Martin and A-20, the Bristol designs were too small to allow much development without designing a completely new aircraft. The B-25 would be an example of an aircraft large enough to allow all sorts of tweeking.



While the B-25 does allow for quite a bit of tweaking it is also too large to fill at least one of the roles Tomo wants to fill, that of night fighter. To be even a moderately successful night fighter a plane has to have enough of a performance advantage over it's contemporary bombers (using same class/power engines?) that it is usually too small to be a first class bomber (Mosquito excepted, with reservations).


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## Juha (May 17, 2012)

Shortround6 said:


> ...And the idea that ANY bomber, no matter how well it might roll or turn or loop for a bomber, had the ability to bring a single fixed .303 gun to bear on an enemy fighter simply boggles the mind...



I agree but still had to add that some Finnish Blenheim pilots claimed that a light short-nose Blenheim Mk I could out turn the standard 1937-40 FiAF fighter Fokker D. XXI, now tests seems to contradict this. And for all pilots Beamont, incarnation of company loyality, told a story how he had a hard turning combat in France in May 40 with an aggressive Do 17Z pilot, who had initiated the combat by attacking Beamont who was flying Hurricane.

Juha


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## tomo pauk (May 17, 2012)

Shortround6 said:


> The Beaufort was a redesign, It used light alloy in places where the Blenheim had used steel, Structural weight of the Beaufort was actually less than the Blenheim. But it kept much of the original Blenheim design, much like the LA-7 kept much of the LA-5 and Lagg-3 or the various Yaks kept much of the design even though wing spars changed from wood to metal and so on. Or like the P-51H kept much of the design of the P-51D even though there are few interchangeable pieces.



Thanks for the details about the changes Blen - Bfort. Unfortunately, the empty weight grew for an 1/3rd (circa 3500 lbs), the heavier engines being main culprit (2 x 350 lbs, dry). 



> The British had a major problem with engines in 1938-41, they had no easy way to upgrade from their 800-900hp class engines unless the plane was rather big. The Wellington was big enough to go from an 1100 pound engine to 1600-1800lb engines (Hercules or Merlin with radiator). The British had no 1200-1450 pound engines like the P&W R-1830 or the Wright R-1820 or the ones they had were low powered (Tiger/Dagger) or unreliable (Taurus).



Well, I'm surely not proposing a 'Welington a-la Bristol' here  A Bf-110-sized plane, powered by Hercules or Merlin and here we go.



> For a somewhat comparable aircraft see the Martin Maryland and Baltimore.



As above - Bf-110 sized, or akin to A-20.



> If the British had had a 1000-1200hp engine of 1200-1400lbs perhaps a better Blenheim or Beaufort could have been built. The Sleeve valve problems mean even a Hercules powered plane started in 1937-8 won't show up in more than handfuls until late 1940, much like the original Beaufigter. And for a twin to be any good with Merlins it needs the MK X. The 880hp take-off rating of the MK III without 100 octane fuel doesn't bear thinking about in a 16,000-20,000lb plane.



Yep, the Hercules seem like logical 1st call.


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## Shortround6 (May 17, 2012)

tomo pauk said:


> Well, I'm surely not proposing a 'Welington a-la Bristol' here  A Bf-110-sized plane, powered by Hercules or Merlin and here we go.
> 
> As above - Bf-110 sized, or akin to A-20.



Well, the Bf-110 and A-20s had smaller wings but the Bf-110s smaller fuselage makes for a poor bomber. Hanging the bombs outside means more drag than the enclosed bomb bay. The multi role is going away and being replaced by a fighter and bomber wannabe. 

The Beaufort could carry a 2000lb SAP inside (or partially inside) and carry 2000lb a longer distance than the A-20 could. Since you can't have everything, even with 1700hp engines, what attributes do you want to down play in order to get the performance you want? Also please remember that a Beaufighter was carrying almost 500lbs worth of 20mm guns and over 700lbs of 20mm ammo + 130lbs worth of .303 guns and over 360lbs of .303 ammo for about 1800lbs worth of guns and ammo, not counting mounts, heaters, ammo boxes, chutes, etc, which can run 20-40% more in weight. Carrying heavy gun armament + bombs and going fast and far isn't going to happen. Pick 2 or even 3, ALL 4 is out. 

I will try to post picture of a Blenheim IVF fighter later. The machine gun pod was about as crude as you could get. The Blenheim could have been 15-20mph faster without too much trouble even with the same engines.


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## fastmongrel (May 18, 2012)

Shortround6 said:


> The machine gun pod was about as crude as you could get. The Blenheim could have been 15-20mph faster without too much trouble even with the same engines.



I think just hanging the guns underneath with no cover would have been more aerodynamic than the pod they used. If they had given a first week apprentice 2 hours, some plywood, fabric and dope he could have done a better job.

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## Juha (May 18, 2012)

Shortround6 said:


> ...I will try to post picture of a Blenheim IVF fighter later. The machine gun pod was about as crude as you could get. The Blenheim could have been 15-20mph faster without too much trouble even with the same engines.



IIRC the mg pod was made by a firm whose usual production was connected with railroads/rolling stock.

Juha


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## Shortround6 (May 18, 2012)

Here are a couple of pictures.

http://plawner.org/plane1/compressed/bristol Blenheim Mk IVF_2.jpg

and 

http://www.grahamtall.co.uk/wgs1955...etters/Coe Gordon/Coe-Bristol-Blenheim-IV.jpg

Sorry, I am getting invalid URL when I try to attach them.

The First really shows how "dirty" a Blenheim could be. External bomb racks under the rear fuselage, The Fuel jettison pipes, the large gaps around the main wheels. The large "box" holding the under belly guns. 
For a night fighter version a decent aerodynamic clean up could have done wonders. Loose the turret and replace with small observation dome/bubble, clam shell landing gear doors instead of the apron style to close up a lot of the gaps and fair the wheels a bit better. Smaller or different fuel pipes. Get rid of the bomb racks for interceptor duty. 
You might be able to pick up a quick 10-15mph without too much trouble even with the same power plants. Getting some constant speed propellers instead of the controllable pitch ( a way of saying two-pitch without sounding bad?) may help performance. 
If Bristol had manged to fit the Mercury engine with a two speed supercharger drive from the Pegasus it would not have done much for altitude performance but it might have increased take-off and low level power by about 13%, 820hp instead of 725hp. That is with 87 octane fuel.


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## tomo pauk (May 18, 2012)

Shortround6 said:


> Well, the Bf-110 and A-20s had smaller wings but the Bf-110s smaller fuselage makes for a poor bomber. Hanging the bombs outside means more drag than the enclosed bomb bay. The multi role is going away and being replaced by a fighter and bomber wannabe.
> 
> The Beaufort could carry a 2000lb SAP inside (or partially inside) and carry 2000lb a longer distance than the A-20 could. Since you can't have everything, even with 1700hp engines, what attributes do you want to down play in order to get the performance you want? Also please remember that a Beaufighter was carrying almost 500lbs worth of 20mm guns and over 700lbs of 20mm ammo + 130lbs worth of .303 guns and over 360lbs of .303 ammo for about 1800lbs worth of guns and ammo, not counting mounts, heaters, ammo boxes, chutes, etc, which can run 20-40% more in weight. Carrying heavy gun armament + bombs and going fast and far isn't going to happen. Pick 2 or even 3, ALL 4 is out.
> 
> I will try to post picture of a Blenheim IVF fighter later. The machine gun pod was about as crude as you could get. The Blenheim could have been 15-20mph faster without too much trouble even with the same engines.



Doh 

'Sized' needs to be read here as 'about same length, wing span area'. I've twice stated that my idea is to have a mid- or high wing plane, not too thick a wing, only 4 LMGs being a 'permanent' gun armament (replaced by 2 belt fed Hispanos as they become available). The LMG/cannon ammo is in the space above fuselage. The bomb bay does not need to be too wide (accomodating a torpedo or two decent bombs (2 x 1000 lbs?) in tandem, or one big bomb(2000 lbs)), so two fuel tanks can be located aside the bomb bay. 4-6 LMGs in the nose, the night fighters can use the bomb bay to bulk out their gun armament, so the night fighter can have either 8-10 LMGs, or 4-5 cannons, when available.
So a 'Hercules Bristol' for 1940-42 can carry, say, 4 wing-root LMGs (or 2 cannons), plus 4-6 nose LMGs AND a torpedo, while being fast with decently long legs (it has far less drag, since it has a thinner wing, and the torp is in the bomb bay). Or, with some good Merlins, really fast long legged, we avoid the drag increased consumption of extra 2 x 1000 cubic inches of powerplant (like the A-20 had to). 
Hmm, that being said, an A-20 with inlines really sound tempting, starting with single stage Allison F series, via V-1650-1, up to 2-stage Allison. Faster than Zero Oscar at any/most of the altitudes, much better range than A-20?

For the general layout, my Bristol would looked like the A-20 as tail dragger, or like Ta-154 tail dragger.


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## wuzak (May 19, 2012)

tomo pauk said:


> Hmm, that being said, an A-20 with inlines really sound tempting, starting with single stage Allison F series, via V-1650-1, up to 2-stage Allison. Faster than Zero Oscar at any/most of the altitudes, much better range than A-20?



If you can keep the nacelle small enough to take advantage of the in-lines. If you start with the A-20 you'd probably want to keep the nacelle and firewall as is to minimise changes for production. That means that some of the aerodynamic benefits of using an in-line will be lost. Still, that should be plenty of space for a radiator, oil cooler and intercooler (I stll don't know why Vega put th eradiators in the leading edges of the XB-38 - surely having it all in the nacelle would have allowed for easy conversion?).

The R-2600 is a fairly wide engine. You know what in-line is aout the same width? Yep, the V-3420.

Push the V-3420 development harder and you may get some production by 1943. Then they become available for the B-29/B-39 program. Again, mount every thing in the nacelle so the conversion is basically a bolt on proposition.

Maybe then Martin will build the proposed V-3420 powered B-26!


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## tomo pauk (May 20, 2012)

> If you can keep the nacelle small enough to take advantage of the in-lines. If you start with the A-20 you'd probably want to keep the nacelle and firewall as is to minimise changes for production. That means that some of the aerodynamic benefits of using an in-line will be lost.



Agree with that. An A-20 with in-lines should harvest on the increased aerodynamic efficiency (even if the engine installation is less than perfect), along with having the engine with substantially less swept volume. Weighting against that is the decreased take off power (2 x 1600 HP vs. 2 x 1150 up to 2 x 1350 HP for single stage engines (unless overboosted/WER in service, for take off?); more power with two stage engines). So both in-line radial 'versions' of the A-20 being produced?
The A-20 using at 1600 HP, WER, of the two stage V-1710 would've been quite a performer from early 1944.



> Still, that should be plenty of space for a radiator, oil cooler and intercooler (I stll don't know why Vega put th eradiators in the leading edges of the XB-38 - surely having it all in the nacelle would have allowed for easy conversion?).



Agree again. 
The installation from the P-40 seem like natural choice for A-20 (of course, no intercooler here, unless we go with two-stage Merlin, or the turbo V-1710).



> The R-2600 is a fairly wide engine. You know what in-line is aout the same width? Yep, the V-3420.
> 
> Push the V-3420 development harder and you may get some production by 1943. Then they become available for the B-29/B-39 program. Again, mount every thing in the nacelle so the conversion is basically a bolt on proposition.
> 
> Maybe then Martin will build the proposed V-3420 powered B-26!



Yep, I've seen the artist's impression in the 'Vee's for victory'. Quite a sleek bird. The V-3420 for the A-26, too?


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## stug3 (Jan 1, 2013)

German transport column on the Agheila-Agedabia road, south of Benghazi, under cannon attack from Bristol Blenheim of No. 113 Squadron RAF. The first two lorries are running off the road.


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## Aozora (Jan 1, 2013)

Just for interest, here is Bristol's proposed design for a single-seat, twin engine day/night fighter, the Type 153...resembles something else...guesses? (From Buttler, British Secret Projects, Fighters and Bombers 1935-1950)


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## Aozora (Jan 1, 2013)

Shortround6 said:


> The Beaufort was a redesign, It used light alloy in places where the Blenheim had used steel, Structural weight of the Beaufort was actually less than the Blenheim. But it kept much of the original Blenheim design, much like the LA-7 kept much of the LA-5 and Lagg-3 or the various Yaks kept much of the design even though wing spars changed from wood to metal and so on.



Beaufort construction v Blenheim








The modular construction was one reason why the Australians selected the Beaufort over the Blenheim, plus the torpedo and better overall performance, made even better by replacing the bugged Taurus with the R-1820s.

Re the A-20 with V-1710s and A-26 with V-3420s; changing from radials to inlines would make both more vulnerable, for not enough gain (if any) in overall performance. As it was the R-2600s of the A-20 put out more power than most V-1710s, without having the added weight and complication of a liquid cooling system.
The engine cowlings and nacelles of the A-26 were very carefully designed to provide minimum drag and maximum cooling for the R-2800s; simply bolting V-3420s to the firewall would have been a waste of time because such an installation would have created aerodynamic problems which would have nixed any possible performance advantages. The same thing happened with the B-29 when one of them was redesigned for the V-3420; there wasn't enough of a gain in performance to warrant the change.

And, after all that, they would both have been far more vulnerable to flak.


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## tomo pauk (Jan 1, 2013)

The main reason the Aussies choosing anything over Blenheim being the planes obsolescence?
The B-29 trial installation of the V-3420 was too late to matter, since the R-3350 was finally gotten to work okay. The Flak was of no concern for B-29 duties historically, either when flown during daylight or night.


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## wuzak (Jan 1, 2013)

Aozora said:


> Re the A-20 with V-1710s and A-26 with V-3420s; changing from radials to inlines would make both more vulnerable, for not enough gain (if any) in overall performance. As it was the R-2600s of the A-20 put out more power than most V-1710s, without having the added weight and complication of a liquid cooling system.
> The engine cowlings and nacelles of the A-26 were very carefully designed to provide minimum drag and maximum cooling for the R-2800s; simply bolting V-3420s to the firewall would have been a waste of time because such an installation would have created aerodynamic problems which would have nixed any possible performance advantages. The same thing happened with the B-29 when one of them was redesigned for the V-3420; there wasn't enough of a gain in performance to warrant the change.



An A-26 with V-3420s would have 300-400hp more per engine, but potentially 400hp more on top of that (ie 3000hp per engine). Longer term the V-3420s would have been capable of pumping out 4000hp.

A V-1710 with all cooling systems should be comfortably lighter than an R-2600, though it will have less power early in the war.

The XB-39 was 50mph faster than the B-29A.... The XB-39 program was delayed because of the sudden urgent need to develop a long range fighter - the XP-75 - which took engineering resources away from the program.


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## Aozora (Jan 1, 2013)

wuzak said:


> An A-26 with V-3420s would have 300-400hp more per engine, but potentially 400hp more on top of that (ie 3000hp per engine). Longer term the V-3420s would have been capable of pumping out 4000hp.
> 
> A V-1710 with all cooling systems should be comfortably lighter than an R-2600, though it will have less power early in the war.
> 
> The XB-39 was 50mph faster than the B-29A.... The XB-39 program was delayed because of the sudden urgent need to develop a long range fighter - the XP-75 - which took engineering resources away from the program.



V-1710 with cooling systems would have been about on a par with the R-2600, but simply bolting it to the front of an engine nacelle designed for a radial would have created too much drag without a redesign to take advantage of the V-1750's smaller frontal area. 

The V-4320 was heavier than the R-2800 and still needed the cooling systems on top of that. At the very least a redesign of the A-26s engine nacelles would have been needed and, again, for the A-26's role as a medium bomber and for ground strafing the V-3420s would have been far more vulnerable to flak, without extra armouring. It would have been much easier adapting the design to a 'C' series R-2800, which was reliably giving 2,400 hp and was much easier to maintain. The B-29 (B-39) with Allisons did perform better than the B-29 but, then again, the R-3350 didn't become fully reliable until the late/post war period.

Anyway, back to the Bristol designs...



tomo pauk said:


> The main reason the Aussies choosing anything over Blenheim being the planes obsolescence?


 No, the Blenheim was not considered obsolescent at the time the Beaufort contract was signed - the Beaufort was chosen partly because the Aussies wanted a flexible, multi role aircraft which could carry a torpedo, and partly because the Beaufort would be easier to build in dispersed locations.


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## wuzak (Jan 1, 2013)

Aozora said:


> V-1710 with cooling systems would have been about on a par with the R-2600, but simply bolting it to the front of an engine nacelle designed for a radial would have created too much drag without a redesign to take advantage of the V-1750's smaller frontal area.



Surely not 700lbs worth of cooling system? Sounds a bit far fetched to me.

It depends on the size of the nacelle at the firewall (where the R-2600 is taken off and the V-1710 put in its place) as to whether much could be done about drag reduction.





Aozora said:


> The V-4320 was heavier than the R-2800 and still needed the cooling systems on top of that. At the very least a redesign of the A-26s engine nacelles would have been needed and, again, for the A-26's role as a medium bomber and for ground strafing the V-3420s would have been far more vulnerable to flak, without extra armouring. It would have been much easier adapting the design to a 'C' series R-2800, which was reliably giving 2,400 hp and was much easier to maintain.



More vulnerable to flak....we've had this discussion before.

I thought the A-26 did use C-series R-2800s.

A QEC engine module could have been designed to bolt up the R-3420 in place of the R-2800. As was done for the XB-39, and in many cases in Germany.

Annular radiators could have been used too.

http://www.warbirdsresourcegroup.org/BARC/images/tempest-4.jpg
http://farm6.staticflickr.com/5070/5674825997_6c4f6de516_z.jpg

The Germans liked their annular radiators
http://www.nationalmuseum.af.mil/shared/media/photodb/photos/071017-F-1234S-015.jpg

Annular radiators would also be easier to armour.




Aozora said:


> The B-29 (B-39) with Allisons did perform better than the B-29 but, then again, the R-3350 didn't become fully reliable until the late/post war period.



The problem with the XB-39 program was that it was delayed, as mentioned before, so could not be evaluated early enough to put it into production. There was also the matter of interrupting production to make the change, though the V-3420 installation was designed as a QEC which would have been basically a bolt up job.


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## nuuumannn (Jan 1, 2013)

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.


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## tomo pauk (Jan 2, 2013)

Aozora said:


> V-1710 with cooling systems would have been about on a par with the R-2600, but simply bolting it to the front of an engine nacelle designed for a radial would have created too much drag without a redesign to take advantage of the V-1750's smaller frontal area.
> 
> The V-4320 was heavier than the R-2800 and still needed the cooling systems on top of that. At the very least a redesign of the A-26s engine nacelles would have been needed and, again, for the A-26's role as a medium bomber and for ground strafing the V-3420s would have been far more vulnerable to flak, without extra armouring. It would have been much easier adapting the design to a 'C' series R-2800, which was reliably giving 2,400 hp and was much easier to maintain. The B-29 (B-39) with Allisons did perform better than the B-29 but, then again, the R-3350 didn't become fully reliable until the late/post war period.



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.



> Anyway, back to the Bristol designs...
> 
> 
> No, the Blenheim was not considered obsolescent at the time the Beaufort contract was signed - the Beaufort was chosen partly because the Aussies wanted a flexible, multi role aircraft which could carry a torpedo, and partly because the Beaufort would be easier to build in dispersed locations.



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.


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## Shortround6 (Jan 2, 2013)

tomo pauk said:


> 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.



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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## tomo pauk (Jan 2, 2013)

> Obsolete when and how?



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).


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## Aozora (Jan 2, 2013)

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


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## Aozora (Jan 2, 2013)

tomo pauk said:


> 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).



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)


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## Shortround6 (Jan 2, 2013)

tomo pauk said:


> 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).



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).


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## stug3 (Jan 2, 2013)

Too bad the Brigand couldnt have been developed earlier. (without the teething problems)


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## tomo pauk (Jan 2, 2013)

Shortround6 said:


> 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.



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).



> 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.



I give you that - field length. A a package, Hampden should be regarded as a far better bomber. 



> 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.



Agreed that British had some problems. The bulky radials of modest power were unable to turn Blenheim into a fast plane, though.



> 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.



Hampden have had like half a dozen of LMGs, so did the He-111P (of Polish campaign vintage).



> 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).



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.


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## Shortround6 (Jan 3, 2013)

tomo pauk said:


> 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.



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. 



tomo pauk said:


> have had like half a dozen of LMGs, so did the He-111P (of Polish campaign vintage).



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. 





tomo pauk said:


> 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.



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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## tomo pauk (Jan 3, 2013)

Shortround6 said:


> 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.



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 



> 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.



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.



> True but then the thick wing offered high lift without "trick" devices and offered volume for fuel tanks.



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. 



> 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?



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. 



> 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.



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.



> 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.



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.


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## vinnye (Jan 3, 2013)

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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## tomo pauk (Jan 3, 2013)

> They used Merlin XX engines at one point...



Hi, 
Who used it?


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## vinnye (Jan 4, 2013)

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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## tomo pauk (Jan 4, 2013)

Yep, it was used in Beau, but instead of Hercules engines, not Pegasus


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## stug3 (May 17, 2013)

Two Bristol Beauforts (N1173/`MW-E' and AW242/`MW-B') of 217 Squadron, Royal Air Force patrolling the British coast near St Eval, Cornwall.


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## stug3 (May 17, 2013)

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.


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## stug3 (May 23, 2013)

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


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## stug3 (Jun 14, 2013)

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


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## Wildcat (Jun 14, 2013)

Great photos!


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## Kryten (Jun 15, 2013)

Wildcat said:


> Great photos!


+1 on that, Have been reading up on the Beau the last year or so, fascinating aircraft!


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## stug3 (Jun 15, 2013)

Aircrews of No. 39 Squadron RAF gather round Flying Officer A O S Jepson in front of his Bristol Beaufort Mark II as he recounts his part in the Squadron’s attack on the Italian Battle Fleet on 15 June 1942, for the benefit of the press cameras at Fayid, Egypt. A force of 12 Beauforts set out from LG 05 near Sidi Barrani to attack the Fleet, but was soon reduced to five following an attack off Derna by German fighters. The remainder attacked two battleships, and a further three aircraft were badly damaged in the process before the survivors flew on to Malta. Although strikes on the warships were claimed, the Italian Fleet was undamaged, except for one hit on the battleship LITTORIO with a 500-lb bomb dropped by aircraft of the USAAF ‘Halpro’ Detachment which also participated in the attacks.







Airmen ground crew, assisted by soldiers and sailors, load a Mark XII aerial torpedo into the bomb bay of a Bristol Beaufort Mark I at Luqa, Malta, in preparation for a sortie against the Italian naval force threatening the ‘HARPOON’ Convoy.


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## stug3 (Dec 11, 2019)

Bristol Beaufighter TF Mk X


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