# Mosquito - the alternative strategic bomber



## Timppa (Sep 11, 2016)

> Bomber command used the De Havilland Mosquito to improve the very poor accuracy of the heavy bombers and to reduce their losses, but it refused to consider the alternative, which was finally adopted only after World War 2 and dominates modern air power since. The alternative was to replace the big and slow and expensive heavy bombers with the Mosquito as Bomber command's main bomber. The points in favor of this alternative were also clearly presented by group commander Bennett, as a comparison between the Mosquito and the Lancaster, which was the best British heavy bomber:
> 
> Mosquito carries to Berlin half the bomb load carried by a Lancaster, but...
> Mosquito loss rate is just 1/10 of Lancasters' loss rate
> ...



De Havilland Mosquito

Any objections ?


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## drgondog (Sep 11, 2016)

Timppa - I don't recall the Mossie having the range to go to Munich with 4,000 pound bomb load. Could be wrong.


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## Milosh (Sep 11, 2016)

London to Berlin - 580mi

London to Munich - 572mi.


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## pbehn (Sep 11, 2016)

My only objection is historical, it requires a complete change in the mind set of bomber command AND the Mosquito to come into service before the start of the war. The concept of a fast bomber was not new the Blenheim and Hampden were fast when introduced and quickly became obsolete. Getting any ministry to accept the idea of a bomber with no defence apart from speed in the 1930s would be like getting the Pope to become a Buddhist. Even though the Mosquito was designed as an unarmed light bomber/recon there was a mock up of one with a turret, slapping turrets on everything was in vogue at the time.

I disagree that the Lancaster was not a precision bomber, it could do the jobs when asked to and it hit the Tirpitz, submarine pens, viaducts and V3 gun sites when asked to.


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## FLYBOYJ (Sep 11, 2016)

IMO if you used the Mosquito as a precision bomber (and say it carried a Mark XIV, Norton or Sperry type bomb sight), you've just placed yourself at speeds where you still could be easily intercepted or blasted out of the sky by flack until you delivered your bombs, and even then the chances of interception are great. I could agree with a pathfinder role (like was done with the P-38) but I think to use the Mosquito in a strategic role would have been disastrous and it would have squandered some of the best attributes of this aircraft.

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## pbehn (Sep 11, 2016)

Also dont be led too much by the weight of a cookie which is a can full of explosive. To cause serious damage to refineries water mains etc you need heavy bombs, of which the mosquito could carry a couple if any at all.

mosquito with cookie - Google Search


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## stona (Sep 11, 2016)

Timppa said:


> De Havilland Mosquito
> 
> Any objections ?



Apart from the article being based on the false premise that the Mosquito was a more precise bomber than a Lancaster or anything else?

Bomber Command did _a lot_ of work to discover which bombers and what bomb loads would do the most damage to Germany's infra structure, and a large force of Mosquitoes was not the answer it came up with. 

A Lancaster could bomb just as accurately using Oboe, H2S, Gee or any other system as a Mosquito could. At the end of the war many PFF squadrons operated Lancasters. 8 Group flew 19,601 Lancaster and 28,215 Mosquito sorties. 5 Group's more or less independent pathfinder force flew just 1,133 Mosquito sorties during the war. There is a common assumption that the Mosquito dominated the PFF which it did not. 

The Mosquito was well used in numerous other roles by all of the RAF's Commands (including Bomber Command) and excelled in most if not all.

Cheers

Steve

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## stona (Sep 11, 2016)

pbehn said:


> Also dont be led too much by the weight of a cookie which is a can full of explosive. To cause serious damage to refineries water mains etc you need heavy bombs, of which the mosquito could carry a couple if any at all.
> 
> mosquito with cookie - Google Search



The bomb loads were developed to suit the mission. A successful area raid used incendiary munitions to best effect. This in turn was discovered to be dependent on three conditions. The target had to be relatively intact (possessing considerable combustible material); the bombing had to be concentrated in time _and_ space; the overall bomb load had to contain sufficient high explosive to be a threat to fire services and anti aircraft gunners.

The Mosquito was not capable of carrying the requisite loads. If we accept the argument that it was no more capable of precision night bombing then The Command's heavy bombers (and it wasn't) then it would be tasked with a mission it could not carry out.
You can be sure that Bomber Command closely examined what the Mosquito could and could not do, before using it with considerable success, in a bombing role, in the Light Night Striking Force. In this role the aircraft caused much confusion to the Germans, taxing air defence systems and shutting down entire cities, driving the population into shelters, simply by dropping a few Target Indicators and some 'Cookies'. The Force could do this over several cities on any given night, even when the Main Force was not operating.

It is difficult to extract the bombing operations of the LNSF and 8 Group aircraft from other vital work, but Bowyer estimates that the LNSF flew 26,255 sorties for the loss of 108 Mosquitoes. About 10,000 'Cookies' were dropped, 26,000 tons of bombs. 68% of LNSF operations were flown, to keep the pressure on Germany's defences and cities, when the heavy bombers were not operating.

This aircraft does not represent a missed opportunity for a strategic bomber, in fact I would argue that the RAF exploited it to the maximum in other roles to which its unique abilities were far better suited.

Cheers

Steve

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## pbehn (Sep 11, 2016)

I agree Stona, I was just saying that with a completely different attitude and the Mosquito being available before the war started a different use could be made, it wouldnt take much effort to equal the early night bombing raids with Mosquito raids in daylight because most missed the target. As I said if everyone had a different attitude to bombing, if the mosquito was available 5 years before it was and if it was produced in huge numbers a different strategy could have been used .....but that is a lot of "ifs".

Another point is that the Mosquito only had a crew of two but they were the two who had the most training of any air crew pilot and navigator, bomb aimer flight engineer, it isnt just a question of counting the number of people.

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## stona (Sep 11, 2016)

I think it is important to emphasise the link between the need for heavy bombers to deliver sufficient bombs on a target given the likely accuracy of the attack.
I gave some figures a while ago on the density of bombs required to destroy a marshaling yard. Essentially three 500lb bombs per acre were required. Using the most accurate navigational aid (Oboe), to ensure a 50% and 75% chance of success, required 114 and 168 *Lancaster* sorties respectively. Just how many Mosquitoes is the writer of the article proposing be used by Bomber Command? Are bombers to be manufactured to the detriment of all other versions of the aircraft? Which aircraft would replace them as Intruders, Rangers, Fighter Bombers, Airliners, in Coastal Command's Strike Wings etc., etc.
Cheers
Steve

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## pbehn (Sep 11, 2016)

stona said:


> I think it is important to emphasise the link between the need for heavy bombers to deliver sufficient bombs on a target given the likely accuracy of the attack.
> I gave some figures a while ago on the density of bombs required to destroy a marshaling yard. Essentially three 500lb bombs per acre were required. Using the most accurate navigational aid (Oboe), to ensure a 50% and 75% chance of success, required 114 and 168 *Lancaster* sorties respectively. Just how many Mosquitoes is the writer of the article proposing be used by Bomber Command? Are bombers to be manufactured to the detriment of all other versions of the aircraft? Which aircraft would replace them as Intruders, Rangers, Fighter Bombers, Airliners, in Coastal Command's Strike Wings etc., etc.
> Cheers
> Steve


This is a fantasy scenario, more mosquitos instead of battles and wellingtons and halifaxes used to keep damaged targets damaged with a lot more smaller raids on refineries etc. 

I think there was a place for many more mosquitos but it is a fantasy scenario, I think I read somewhere long ago that production of the mosquito was stretching the supply of the woods used. If we head into a war in Europe again and jet engines are no longer possible maybe we should consider it.


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## stona (Sep 11, 2016)

pbehn said:


> This is a fantasy scenario, .



Well, yes. The basic premise is that the Mosquito could replace the 'heavies' as a strategic bomber because, being so much more accurate, a lesser weight of bombs would need to be delivered. This, unfortunately, is nonsense.

Incidentally, Bennett, quoted in the article slightly without context, was keen on the Mosquito. He was equally keen on the Lancaster and never to my knowledge proposed the replacement of it by the Mosquito. Bennett was just about senior enough (even in 1942 as a Wing Commander) and certainly well connected enough in 8 Group to have been privy to most of Bomber Command's ORS reports. I won't bore us all with the circulation and categorisation of said reports here, but some, particularly relating to losses and survival rates, were severely restricted, technical ones generally not. Bennett was certainly smart enough to have understood the ones he saw.

Cheers

Steve


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## pbehn (Sep 11, 2016)

Stona, I wouldnt propose replacing all the heavies just have many more mosquitos continually attacking refineries marshalling yards and airfields that had been previously attacked by heavies. Raids were done here is a brief account of one

German Jet Encounters


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## Milosh (Sep 11, 2016)

As the Mosquito carried the approx. bomb load as the American heavies, could it have replaced almost all of the American heavies?

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## GregP (Sep 11, 2016)

We see the Mosquito-only option every few years and the same old arguments come up. Perhaps we should have a dedicated "what-if" subforum so the frequent what-ifs could be made sticky posts. Then only the people interested in what-ifs would ever go there.

Just a thought, but we've dealt with this particular one at least three of four times previously, unless I recall incorrectly. Stranger things have happened.


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## pbehn (Sep 11, 2016)

GregP said:


> We see the Mosquito-only option every few years and the same old arguments come up. Perhaps we should have a dedicated "what-if" subforum so the frequent what-ifs could be made sticky posts. Then only the people interested in what-ifs would ever go there.
> 
> Just a thought, but we've dealt with this particular one at least three of four times previously, unless I recall incorrectly. Stranger things have happened.


The idea of using the Mosquito to replace heavy bombers is to my mind ridiculous it would mean massed formations over targets heavily defended by flack. My proposal would be to use its strengths, for one example not making a massed raid on a marshalling yard but many raids like the transport plan hitting trains and rail lines all over Germany.


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## wuzak (Sep 11, 2016)

pbehn said:


> Also dont be led too much by the weight of a cookie which is a can full of explosive. To cause serious damage to refineries water mains etc you need heavy bombs, of which the mosquito could carry a couple if any at all.



Like the 100lb - 250lb bombs the USAAF regularly used against refineries and synthetic oil plants?


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## wuzak (Sep 11, 2016)

stona said:


> I gave some figures a while ago on the density of bombs required to destroy a marshaling yard. Essentially three 500lb bombs per acre were required. Using the most accurate navigational aid (Oboe), to ensure a 50% and 75% chance of success, required 114 and 168 *Lancaster* sorties respectively. Just how many Mosquitoes is the writer of the article proposing be used by Bomber Command?



I'd suggest one Mosquito could do that 93 500lbs on an acre of ground) at low level in the daylight....


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## pbehn (Sep 11, 2016)

wuzak said:


> Like the 100lb - 250lb bombs the USAAF regularly used against refineries and synthetic oil plants?


Yes, a cookie was a bomb to blow off roof tiles it had most effect when it exploded above ground, such a bomb would have almost no effect on the important parts of a refinery, if you see the remains of German cities they were burned to the ground but the brick structure ws standing, a steel structure would be unaffected.

To wreck a refinery you need a huge blast to destroy or undermine the pressure vessels which take months to construct or repair, damaging pipework and instruments can be rectified in days.


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## GrauGeist (Sep 11, 2016)

Milosh said:


> As the Mosquito carried the approx. bomb load as the American heavies, could it have replaced almost all of the American heavies?


The later Mark Mossies could carry a max. of 4,000 pounds, but what was the trade-off in range and speed under a max. load condition?


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## pbehn (Sep 11, 2016)

GrauGeist said:


> The later Mark Mossies could carry a max. of 4,000 pounds, but what was the trade-off in range and speed under a max. load condition?


4,000lb was the cookie load which filled the extended bomb bay, in conventional bombs its payload was much less.


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## wuzak (Sep 11, 2016)

GrauGeist said:


> The later Mark Mossies could carry a max. of 4,000 pounds, but what was the trade-off in range and speed under a max. load condition?



The maximum load for a XVI was 5,000lb - 1 x 4000lb (HC or MC) plus 2 x 500lb MC under the wings.

Maximum speed with 4000lb bomb aboard was 408mph (Merlin 76/77) and 419mph without. Cruise speed (max weak mixture) >350mph. Range OTOH ~ 1400-1500 miles with 4000lb bomb and drop tanks.


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## wuzak (Sep 11, 2016)

pbehn said:


> 4,000lb was the cookie load which filled the extended bomb bay, in conventional bombs its payload was much less.



4000lb MC was a conventional bomb and could be carried.

2 x 2000lb AP bombs could be carried, but weren't.

Maximum load without the bulged bomb bay was 3000lb - 4 x 500lb in the bomb bay and 2 x 500lb on the wings.For bulged bomb bay 2 x 1000lb could be carried in the bomb bay.

There were proposals to carry more bombs in the bulged bay. A modified Wellington bomb bay was fabricated to fit the Mosquito. It would have enabled 8 x 500lb or 8 x 250lb bombs to be carried, though de Havilland expressed doubt as to the stability with 8 s 500lb bombs. The Air Ministry then suggested 4 x 500lb + 4 x 250lb, but I haven't seen the response to that.

Mosquitoes could carry 2 x 500lb MC bombs plus 2 x SBC with incendiaries internally if a mixed load was required.


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## Shortround6 (Sep 11, 2016)

B-17s could routinely carry 5,000lbs of HE bombs to Berlin or similar distances. When carrying incendiaries the bomb load often fell to a bit over 3,000lbs due the volume, or lack of it, in the B-17 bomb bay. This gives the 4,000lb _average _so beloved by B-17 critics and Mosquito boosters. B-17 could carry ten 500lb GP bombs or five 1000lb GP bombs in the bomb bay. 
Then the comparison is made to the Mosquito carrying the 4,000lb cookie. 
From Mike William's site. 
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkIV-merlin21_ads.jpg
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkIV_ads.jpg
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkXX_ads.jpg

Now most bombing missions weren't direct flights, dog legs and feints were part of the flight path, also a reasonable reserve might be required. 
Mosquitoes rarely, very rarely used 1000lb HE bombs. They also rarely used incendiary bombs. Perhaps they would have been modified adapted to carry such weapons if there was more need but the Mosquito bomb bay was limited in size/volume and you would need roughly 2 Mosquitoes to carry the same loads as a B-17 for practically any weapons except the 4,000lb cookie.Please note that hanging a pair of 500lbs under wing on a Mosquito can cut 225 miles off the range at high speed cruise (max weak mixture) although most economical shows little reduction.

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## wuzak (Sep 11, 2016)

Shortround6 said:


> B-17s could routinely carry 5,000lbs of HE bombs to Berlin or similar distances. When carrying incendiaries the bomb load often fell to a bit over 3,000lbs due the volume, or lack of it, in the B-17 bomb bay. This gives the 4,000lb _average _so beloved by B-17 critics and Mosquito boosters. B-17 could carry ten 500lb GP bombs or five 1000lb GP bombs in the bomb bay.
> Then the comparison is made to the Mosquito carrying the 4,000lb cookie.
> From Mike William's site.
> http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkIV-merlin21_ads.jpg
> ...



Small bomb containers could be carried on the forward fuselage positions, but not the rear, without modification of the SBC or bomber. I believe they could also be carried on the wing stations. 2 x 500lb MC bombs could be carried in the rear stations at the same time.

The Mosquito was trialled with 1 x 1000lb GP bomb and 2 x 500lb. The GP was not much of a bomb, since it had around 25-30% charge to weight ratio.

The 1000lb MC was too big in diameter to fit in the standard bomb bay, but could be fitted as a single or double adaptor in the bulged bomb bay. This was done primarily to use the 1000lb target indicator (TI).

The RAF didn't use too many 2000lb HE bombs, the only one in that weight class was he 1900lb GP bomb, not many of which were used. The next size up was the 4000lb MC - which the Mosquito could and did carry. This was the same size as the 4000lb HC cookie, but was the conventional medium capacity "aerodynamic" bomb design.

Since the Mosquito would not fly and bomb in a formation like the B-17, and would likely bomb from lower altitudes the lack of bomb load may have been compensated for by increased accuracy.


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## parsifal (Sep 12, 2016)

late in the war the mossie could carry 4000lbs all the way to berlin.

(From 'Mosquito',by C. Martin Sharp and Michael J.F. Bower, Faber and Faber Limited, London, 1967):

'_At 19.00 hours on 11 July [1942] six Mosquitos of 105 Squadron made a diversionary attack on Flensburg (...). Five carried 4 x 500 lb. bombs, one had 2 x 250 lb. HE and incendiaries.' (page 190) 

'Four Mosquitos could place sixteen 500 pounders in a building (page, 196, Mosquito as a day bomber, 1942)

'On 12-13 April [1945], 4/5 Mosquitos [from 139 Sqdn.] went to Berlin, the only ones that night. Incendiaries were carried on this operation, in 4,000 lb. bomb casings. This was the standard load out for incendiary armed mosquitoes late war' (page 365)"_

Typically when carrying HE only, the Mosquito carried 4 x 550 lb bombs in the internal Bomb bay. The bombs had to be specially modified with shortened tails to fit into the limited space. Later marks of mosquito had enlarged bomb bays redesigned, increasing this capacity. these later types from early 1944 carried 1000lb bombs on a more less regular basis. 

as far as accuracy is concerned, a Mosquito does not have by magic inherent advantage over any other properly designed aircraft . if an aircraft could fly straight and level and the crew were untroubled enough by the threat of flak or enemy fighters. It wasn't that mossies were inherently more accurate, it was that the crews felt safer and less nervous than when they were in a lumbering 4 engine behemoth.

I believe it was the safety that the mossie offered in comparison to its rivals that made it a better, more accurate bomber

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## stona (Sep 12, 2016)

Comparing special low level operations with strategic bombing is irrelevant. Mosquitoes could not fly to Berlin at low level, in day light, and put '16 bombs in a building' at any time, even in the last months of the war, and hope to survive. Other similar operations showed that using these tactics they could be, and were, intercepted by Luftwaffe fighters, never mind the anti aircraft defences of Berlin which were not comparable to Copenhagen or Amiens.

How many Mosquitoes are going to be used. Four Mosquitoes dropping 16 x 500lb bombs accurately from low level on a marshalling yard equates to a pin prick.
Then the pressure must be maintained. Oil targets, not easily destroyed and easily repaired, were studied in November 1944. Using Lancasters (and with a daylight 'efficiency' of 80%, that is 80% of bombs within 300 yards of the aiming point, and 26% 'efficiency' by night) Bomber Command's ORS calculated that once location, degree of precision, bombing aids and weather were taken into account, as well as the German's ability to repair, it would take 9,000 sorties per month split between 13 day raids of 200 aircraft and 18 night attacks of 350 aircraft to keep oil plants inoperative. Given the relative average loads of the Lancaster and Mosquito, 9,186lb and 2,101lb according to the BBSU, you will need more than four times as many Mosquitoes as Lancasters. If the Mosquito was twice as accurate (difficult to see given the day time accuracy of the Lancasters) you still need to mount daytime raids with 400 Mosquitoes and night time raids with 700 to deliver enough bombs. This is pure fantasy.

The Mosquito was a great aircraft, but it simply could not carry a big enough load to be the primary strategic British bomber of the war.

Note that whilst it could carry a 4000lb 'cookie' and the theoretical bomb loads posted by various people above, it's average bomb load was just over 2,000lb and even this figure will be weighted by the relatively large number of cookies dropped late in the war.
A heavily modified Lancaster (the cookie carrying Mosquito was also modified to some extent) could carry 22,000lb, but this is meaningless in terms of general strategic operations, where the average was less than 10,000lb.

Cheers

Steve

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## michaelmaltby (Sep 12, 2016)

.. beautiful rebuttals of the thread's principle premis


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## Shortround6 (Sep 12, 2016)

Apparently there were two SBC, a small one of roughly 250lbs (obviouly varied due which bombs it was loaded with) and a large one of roughly 1000lb used by the 4 engine heavies, sometimes in combination with the small containers. 
One source gives the capacity of the small SBC as follows.
The normal 250 lb. SBC could be loaded with a variety of ordnance:
12 x 20 lb. Fragmentation Bomb
6 x 40 lb. General Purpose Bomb
24 x 9 lb. Anti Tank Bomb
60 x 4 lb. Incendiary Bomb (3 canisters each with 20 x 4 lb.)
? x 25 lb. Incendiary Bomb
8 x 30 lb. Incendiary Bomb
3 x 45 lb. Incendiary Bomb
42 x 4 lb. Smoke Bomb (3 canisters each with 14 x 4 lb.)
3 x 100 lb. Smoke Bomb
2 x 120 lb. Smoke Bomb 

There should be also a SBC with 90 x 4 lb. Incendiary Bombs (3 canisters, each with 30 x 4 lb.) 

Some of the missions the B-17s flew had payloads of 42 65lb incendiary bombs, this was nominal 100lb chemical bomb filled with one of several incendiary mixtures so the weight varied. 
B-17s could also carry 12 500lb bombs or 6 1000lb bombs on shorter range missions like Stuttgart or Schweinfurt. 
Berlin was NOT the only target of the strategic bombing campaign.


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## Timppa (Sep 12, 2016)

A few points:

1. Mosquito could - demonstrably - make two sorties in a night, when the heavies could make only one.
2. The total Lancaster/Halifax/Stirling production was about 16,000. Even if only half of this effort would have been directed to manufacturing (all metal) Mosquito, the number of Mossies produced would have tripled.
3. As I understood, Bennett did not propose massed daylight raids. Hence relative losses would have been at their historical levels.


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## michaelmaltby (Sep 12, 2016)

".... directed to manufacturing_* (all metal) *_Mosquito"

That's news.


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## FLYBOYJ (Sep 12, 2016)

Again folks, in this "what if, should have, could have" scenario, at what speeds and altitudes are these "Strategic Mosquitoes" dropping their bombs at? 

IIRC the Mosquito was prohibited from opening its bomb bay doors over 320 mph.


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## stona (Sep 12, 2016)

It doesn't matter how many sorties a Mosquito could make. Unless you can provide many hundreds of them they will not be able to deliver the weight of ordnance required in TIME and space to create the devastation of the most successful area raids. They could not bomb accurately enough, particularly by night, and more so when beyond Oboe range, to carry out a different strategy.
This was a problem experienced by the Luftwaffe and its medium bombers in 1940/41 when they effectively had to 'shuttle bomb' British cities over virtually an entire night to deliver a meaningful weight of bombs.

This is just a function of the science of bombing, something developed and studied at considerable length by the British from 1942 onward. In the simplest terms, if you can't bomb accurately enough to hit a precision target (and there were occasions in 1944 when both US and British bombers attacked the wrong city altogether, never mind the wrong target) you have to deliver sufficient weight of ordnance to devastate an area that may, or may not, include that target. Even in day light, the weight of bombs to ensure destruction of a precise target (think transport and oil plans) is much larger than the author of that article understands. He also fails to take into account the concentration of bombing required. Strategic bombing, or use of Strategic forces in a tactical role (as in the transport and oil plans) is quite different from special operations like those mentioned earlier. Such operations could also entail prohibitive loss rates when launched against anything but almost entirely undefended targets. Bluntly, the Mosquito was not the aircraft for the strategic job.

Cheers

Steve


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## stona (Sep 12, 2016)

FLYBOYJ said:


> Again folks, in this "what if, should have, could have" scenario, at what speeds and altitudes are these "Strategic Mosquitoes" dropping their bombs at?
> 
> IIRC the Mosquito was prohibited from opening its bomb bay doors over 320 mph.



I imagine that 'low level' attacks are envisaged. The same basic law applies to the Mosquito as all other bombers, the higher the release altitude the less accurate the bombing. The original articles premise is dependent on _much_ more accurate bombing than that achievable by the 'heavies'. 
PFF Mosquitoes dropped TIs from a low as 800 feet, they would not blow the aircraft up, and on a good night could mark within 100m of the aiming point. Maybe this is what the writer envisages? 
Cheers
Steve


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## wuzak (Sep 12, 2016)

FLYBOYJ said:


> IIRC the Mosquito was prohibited from opening its bomb bay doors over 320 mph.



IAS


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## Milosh (Sep 12, 2016)

Didn't the _heavies_ require a 2-3 day turnaround time?


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## stona (Sep 12, 2016)

Milosh said:


> Didn't the _heavies_ require a 2-3 day turnaround time?



No, they could and occasionally did operate on consecutive nights. The limiting factor was primarily the weather. Obviously no squadron could operate repeatedly night after night as attrition, fatigue and even supply factors would come into play. The one thing that frequently seems to have been in short supply is the small bomb container. Some Groups attempted to hoard these against future operations, reducing the percentage of incendiaries carried, and were told in no uncertain terms not to do so.
The rate of returns on a second night of operations was markedly higher, particularly for Halifax squadrons. Whether this was really due to technical issues with the aircraft at a time of high work load, or was due to other factors, was a question which troubled the Command at the time.
Cheers
Steve


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## Shortround6 (Sep 12, 2016)

Timppa said:


> A few points:
> 
> 1. Mosquito could - demonstrably - make two sorties in a night, when the heavies could make only one.



A night in Dec or a night in June?
Sunrise and sunset times in Berlin



> 3. As I understood, Bennett did not propose massed daylight raids. Hence relative losses would have been at their historical levels.



Historical loss levels or casualty rated may not have been all that good in the first year of operation, when the Mosquito only equipped a few bomber squadrons. Things got better later but the Mosquito never operated in large formations or streams of hundreds of mosquitoes crossing the target in a 1/2 hour to 2 hours time. 
And if you are only going to drop a few hundred tons (or a few dozen tons?) per raid/night it is going to take an awful long time to destroy many targets.

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## Shortround6 (Sep 12, 2016)

Milosh said:


> Didn't the _heavies_ require a 2-3 day turnaround time?


A Stona has already said a major factor was weather.
Another limitation is operational planning and supplies. Individual bombers or small groups of bombers (4-8) out of a squadron or group might have had a 12 hour or less turn around but rearming/refueling dozens of bombers per airfield in 10-12 hours (how much time between planes landing and needing to take off to be over Germany during darkness? The Erks sure didn't have 24 hours). Plotting take-off times for hundreds of bombers and routes to and from the target and getting the information to the squadrons involved is also not done on the fly or with only a few hours time.

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## Shortround6 (Sep 13, 2016)

I would note that many "post" war criticisms or alternate strategies assume the opponent will make NO changes to their defensive set up. 
Lots of Mosquitoes coming in low and fast and few large bombers at high altitude?
Build lots of 20mm and 37mm AA guns and fewer 88mm and 105mm AA guns. 
Problem for Germans is not "solved" but the loss rates for the Mosquito will change.

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## stona (Sep 13, 2016)

Shortround6 said:


> I would note that many "post" war criticisms or alternate strategies assume the opponent will make NO changes to their defensive set up.
> Lots of Mosquitoes coming in low and fast and few large bombers at high altitude?
> Build lots of 20mm and 37mm AA guns and fewer 88mm and 105mm AA guns.
> Problem for Germans is not "solved" but the loss rates for the Mosquito will change.



Indeed. Two of the five premises of the article are false, both relate to bombs and bombing (bullet points 1 and 4). The key point in the original article in this respect is the contention that the
_"Mosquito was a proven precision day bomber and the Lancaster was not."_
Quite apart from the fact that this is untrue, the Lancaster could be a remarkably accurate bomber in daylight, ask the crew of the Tirpitz, it supposes that the Mosquito would carry out this precision bombing in daylight. The sort of precision daylight attacks required and the number of aircraft needed to complete them, in conjunction with the sort of German response you give above, would not just increase the loss rate of the Mosquito, it would make such operations suicidal and a campaign founded on them unsustainable. Then what happens? A reversion to a night time campaign? Now the Mosquito is no more accurate than any other bomber and we are back to square one, it can't carry enough ordnance to wage an effective strategic campaign by night!
Cheers
Steve

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## pinehilljoe (Sep 13, 2016)

To execute MRAF Harris's strategy of raising burning cities to ground, I think required Lancaster's and Hallifax's with the larger load, including the ability to carry Tall Boys and Grand Slams. Imagine the 8th Air Force trying to do its mission with the A-26.


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## stona (Sep 13, 2016)

It was not Harris' strategy, it was the British government's.
Cheers
Steve

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## KiwiBiggles (Sep 13, 2016)

And Tall Boys and Grand Slams were target bombs, not used for urban destruction bombing.


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## pinehilljoe (Sep 13, 2016)

I thought they were also used to penetrate deep in city block and blow the entire block up?


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## pbehn (Sep 13, 2016)

pinehilljoe said:


> I thought they were also used to penetrate deep in city block and blow the entire block up?


They were much too valuable for that, taking months to produce.

from wiki
On 18 July 1943, work started on a larger version of the Tallboy bomb, which became the Grand Slam.[2] As with the original Tallboy, the Grand Slam's fins generated a stabilizing spin[7] and the bomb had a thicker case than a conventional bomb, which allowed deeper penetration. After the hot molten Torpex was poured into the casing, the explosive took a month to cool and set. Like the Tallboy, because of the low rate of production and consequent high value of each bomb, aircrews were told to land with their unused bombs on board rather than jettison them into the sea if a sortie was aborted.[8]

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## Shortround6 (Sep 13, 2016)

pinehilljoe said:


> I thought they were also used to penetrate deep in city block and blow the entire block up?


That may have been the original plan (or the mini earthquake shook the block *down *) but as Pbehn says, production and cost meant they were reserved for special targets.


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## pbehn (Sep 13, 2016)

Shortround6 said:


> That may have been the original plan (or the mini earthquake shook the block *down *) but as Pbehn says, production and cost meant they were reserved for special targets.


They must have been valuable to instruct a pilot to land a tail dragging bomber with a 10 ton bomb abord, you could wipe out half an airfield.


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## stona (Sep 14, 2016)

Both were special weapons intended for specific and precise targets (exactly what the premise of the original article claims the Lancaster was incapable of carrying out). 
Tallboys were used against various hardened structures from V weapon establishments to U-Boat pens, railway tunnels, canal viaducts and other infrastructure as well as famously the Tirpitz.
Far fewer Grand Slam bombs were used, against railway targets and hardened structures like U-Boat pens. Even a near miss (within about 100m) was often good enough to collapse a bridge or viaduct through the effect of the bomb, undermining the structure.
They were far too precious,requiring modified aircraft (very heavily modified for the Grand Slam) with the SABS bombsight, to be used in run of the mill area raids.
Cheers
Steve
.


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## pbehn (Sep 14, 2016)

Stona from what I know of the theory of the grand slam a near miss was what was desired, the explosive effect on a viaduct not only destroyed the viaduct but also the foundations making rebuilding a major operation.


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## stona (Sep 14, 2016)

pbehn said:


> Stona from what I know of the theory of the grand slam a near miss was what was desired, the explosive effect on a viaduct not only destroyed the viaduct but also the foundations making rebuilding a major operation.



The idea was indeed to achieve a huge underground explosion, so in that sense a very near miss would be ideal. The bomb aimers aimed at the target. With a typical error of just over 100 yards from 10,000ft (617 Sqn/SABS bombsight) a near miss was the most likely outcome.

I would like to address one of the other contentions in the original 'Mosquito article'.
This is the contention that a Mosquito cost just 1/3 the price of a Halifax. This may be true in terms of the cost to the government per unit produced, but it is a much to simplistic way of estimating the cost of an aircraft on operations. The BBSU used the figure of man months invested per 1000lb of bombs dropped and here the Lancaster at 9.5 man months per 1000lbs is much cheaper than the Mosquito at 16 man months per 1000lbs of bombs dropped.

It is also worth putting into perspective the total weight of bombs dropped by the two types, I've started in 1943 to be fair to the Mosquito whose 1942 contribution was negligible. The two figures ('43-'45) are 29,863 short tons for the Mosquito and 668,900 short tons for the Lancaster. This is not an entirely fair comparison, given the numbers of aircraft and roles carried out, but it does give an idea of the sheer weight of bombs required to carry out a strategic bombing campaign in WW2.

Cheers

Steve

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## buffnut453 (Sep 14, 2016)

Steve,

Those stats are interesting. It might be more worthwhile to determine the total weight of bombs carried per aircraft for the 2 types. If we determine how many of each type served in Bomber Command and then divide the relevant tonnage figures by those numbers we'd get a gross "per airframe" throw weight of ordnance. 

The above suggestion clearly won't be perfect (it's statistics, after all!) due to role specializations etc but most of the gross errors should cancel each other out. Either way, I think it would be an interesting comparison.

Cheers,
Mark


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## Milosh (Sep 14, 2016)

Link I came across on the Allied bombing of Europe in WW2.
Animation shows every bomb dropped by Allies during Second World War


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## stona (Sep 14, 2016)

buffnut453 said:


> It might be more worthwhile to determine the total weight of bombs carried per aircraft for the 2 types. If we determine how many of each type served in Bomber Command and then divide the relevant tonnage figures by those numbers we'd get a gross "per airframe" throw weight of ordnance.



Surely the simpler measure is the average load per aircraft type throughout the war? 9,186lbs for the Lancaster and 2,101lbs for the Mosquito.

Cheers

Steve


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## buffnut453 (Sep 14, 2016)

Certainly simpler but doesn't factor in, for example, the oft-quoted observation that the Mossie could accomplish 2 sorties per night which would skew the metrics somewhat. It's a blinding statement of the obvious to say that BC had more heavy bombers that carried more bombs than an aircraft like the Mossie, therefore the heavies delivered more bombs over the course of 3 years. I think it would be more insightful to determine an average of how much tonnage was dropped per airframe over that period and see how that compares with the simpler statistics.


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## stona (Sep 14, 2016)

The problem is to know how many aircraft were operational.
Bomber Command had 72 Mosquitoes 'available for operations' in January 1944, but 206 in January 1945. What number do you use for that year?
The Lancaster numbers rose from 627 to 1,096 in the same period, same problem.

In 1944 Mosquitoes dropped 16,980 short tons of bombs. What do you want to divide it by?
In 1944 Lancasters dropped 404,300 short tons of bombs, Same question.

The BBSU gives a weight of bombs per aircraft despatched for 1944 (8,250 lbs) but does not break it down by type. Incidentally that number for the aircraft of the US 8th Air Force is 3,980 lbs.

Cheers

Steve


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## buffnut453 (Sep 14, 2016)

As always, finding the data to develop the statistics is the hardest part. My preference would be to tally the total number of an aircraft type used by the Command (ie how many individual airframes contributed to the tonnage total overall rather than the number of operational airframes which is impossible to define). Doing so would factor in issues like loss rates, maintainability etc. Viewing the numbers over the period 1943-1945 would smooth out some of the short-term decisions that might skew numbers in a shorter timeframe. That said, I'm not sure such data exist so it may be an impossible statistic to gather at this remove.


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## parsifal (Sep 14, 2016)

It would be difficult to come up with a meaningful number of the average bombloads carried by the Mosquito. There were many subtypes where bombs were not needed to be carried, many other missions where bombs were being carried by the fighter bomber versions where the load for low level tactical strikes were inevitably about 100-2000 lbs.

This debate is looking like a total mis-manipulation of the statistics to me, and reminds of the way a hostile BC received Bennett in his report on the mosquito in 1944 as they were trying to can it as a bomber in the inventory.

'Group commander Donald Bennett, who later commanded the Pathfinder Force of Mosquito bombers which were equipped with the latest electronic navigation equipment and located and marked targets for the formations of heavy bombers which followed, described this beaurocratic attitude well: "_I test flew the Mosquito by day and by night. At a meeting at the Air Ministry on the subject, Bomber Command and the Air Ministry both very strongly opposed the adoption of the Mosquito. They argued that it was a frail wood machine totally unsuitable for Service conditions, that it would be shot down because of its absence of gun turrets, and that in any case it was far too small to carry the equipment and an adequate Pathfinder crew. I dealt with each one of these points in turn, but finally they played their ace. They declared that the Mosquito had been tested thoroughly by the appropriate establishments and found quite unsuitable, and indeed impossible to fly at night. At this I raised an eyebrow, and said that I was very sorry to hear that it was quite impossible to fly it by night, as I had been doing so regularly during the past week and had found nothing wrong. There was a deathly silence. I got my Mosquitoes_."

But even so, and despite all the accumulated information and statistics of the Mosquito's proven success and advantage as both a day and night bomber, Bennett (and others) were completely unable to pursuade people that mattered of the Mosquitoes capabilities. Bomber Command used the Mosquito until the end of the war only as a secondary bomber, very successfully operating ahead of and beside the large formations of heavy night bombers, and impressively performing as a precision day bomber, but never replacing the big and slow heavy bombers, because bomber command remained locked with its belief that the only way to destroy Germany was with big heavy bombers carrying large crews and gun turrets. This wasn't their only misbelief'. I believe that was a mistake, borne out of prejudice and not any objective appraisal of the types capabilities

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## stona (Sep 14, 2016)

So how could the Mosquito have carried the strategic bombing campaign to Germany? By day, by night or both, the choice is yours 

I think that the data does show that it was no more accurate by night than any other bomber, and operating by day, certainly through 1943 and 1944 presents another set of survivability problems. It couldn't be precise operating at the altitudes at which it was more or less immune from interception and a potential German reaction to lower level attacks has already been mentioned by another poster. I don't think this is a mistaken view born out of prejudice 

By 1944 the heavy bomber force had been developed, Bomber Command had relatively few Mosquitoes and they were very much in demand for other roles and Commands. It would have taken an enormous leap of faith to abandon the heavies, particularly the Lancaster. Harris and others fought tooth and nail to get rid of the Halifax inlieu of greater Lancaster production with no success, for reasons discussed before. Now we want them to reduce that the heavy bomber force, replacing presumably substantial numbers with an aircraft capable of carrying, at best, one third of a Lancaster's 'Usual Load' and historically about one fifth of its average load.
What would that have done to the 'bomb lift' of the Allied air forces? This was something that both the BBSU and USSBS were keen to note as an ever increasing number. Calculations of what was possible (or not) were made using this capacity as a sort of base figure.

Of course you may have another view.

Cheers

Steve


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## Milosh (Sep 14, 2016)

One Lanc is worth 5 Mossies by bomb load. If a Mossie is shot down, 4/5 of the bomb load is delivered but if a Lanc is shot down, no bombs are delivered.


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## pbehn (Sep 14, 2016)

Milosh said:


> One Lanc is worth 5 Mossies by bomb load. If a Mossie is shot down, 4/5 of the bomb load is delivered but if a Lanc is shot down, no bombs are delivered.


But 5 mosquitos are 10 merlin engines, 5 pilots 5 navigators etc etc.


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## stona (Sep 14, 2016)

Milosh said:


> One Lanc is worth 5 Mossies by bomb load. If a Mossie is shot down, 4/5 of the bomb load is delivered but if a Lanc is shot down, no bombs are delivered.



This implies you are intending to have a bomber force with five times as many Mosquitoes as Lancasters to deliver the same load.
In July 1944, having carried out the tactical diversions for the invasion and moving on with the oil and transport plans, as well as strategic bombing, you will need 4,270 Mosquitoes!!!!!! (there were, historically 864 Lancasters)
Obviously if the Mosquito is to be used as a strategic bomber it will have to be used somewhat differently to the way that the 'heavies' were. I'm interested to hear ideas on how this might have been done.
Cheers
Steve


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## buffnut453 (Sep 14, 2016)

stona said:


> think that the data does show that it was no more accurate by night than any other bomber, and operating by day, certainly through 1943 and 1944 presents another set of survivability problems. It couldn't be precise operating at the altitudes at which it was more or less immune from interception and a potential German reaction to lower level attacks has already been mentioned by another poster. I don't think this is a mistaken view born out of prejudice



Steve,

For the most part I agree with your sentiments. The bureaucratic inertia alone would have prevented any major shift towards Mosquitos from heavies. I also accept that larger-scale, low-level daylight raids would have resulted in higher losses for the Mosquito irrespective of the operating altitude. That said, even radar-laid guns struggle to acquire and track aircraft operating at treetop height unless the target is in the flatest of flat parts of Holland. Manually laid AAA would have a pretty hard time successfully engaging low-level aircraft. It must be borne in mind that, to this day, the RAF continues to train at low level so the tactic must have some merits. 

Clearly, range would be an issue for low-level missions...and this is where we start to creep into modern airpower theory. Adoption of hi-lo-hi mission profiles would offset some of the range problems, albeit at increased risk and necessitating some very careful ingress/egress planning. Then there's the whole challenge of getting enough bombs on target. Taking another leaf from modern airpower approaches, I think it's entirely possible that different tactics could have been employed by a large Mosquito force to inflict considerable damage on German infrastructure. Rather than the heavy bomber approach of putting lots of aircraft over one target and raining down tens of thousands of bombs, there would be the option of distributing the force in smaller packets to attack multiple locations in a given mission/day. The greater precision of low-level daylight attack would greatly increase the chances of hitting a target like a rail yard or a factory, with much reduced collateral damage to surrounding civilian dwellings. Such an approach would also help diffuse German defensive capabilities because the direction of approach of the incoming raids would be much less predictable, and hitting multiple targets at once would spread airborne defences more thinly. Faster revisit rates would also make it difficult for repair parties to complete their tasks and get factories back up and running.

The problem is that British policy was not just to target factories and similar targets. There was a desire to inflict as much pain on the German people as possible in a bid to reduce the number of available factory workers and make those that did get to work less productive. It's callous but there is logic to it. Additionally, it's clearly too much to expect senior officers in 1943 to have sufficient foresight to envisage Low-level "strategic" bombing using tactics and airpower operational art that only truly came of age in the postwar period. 

I'm not advocating for the Mosquito as a strategic bomber - I don't think that was possible for a whole host of reasons. But it's interesting to consider how such a campaign might have been waged as a way of exploring whether it was technically possible. 

Cheers,
Mark


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## buffnut453 (Sep 14, 2016)

stona said:


> This implies you are intending to have a bomber force with five times as many Mosquitoes as Lancasters to deliver the same load.
> In July 1944, having carried out the tactical diversions for the invasion and moving on with the oil and transport plans, as well as strategic bombing, you will need 4,270 Mosquitoes!!!!!! (there were, historically 864 Lancasters)
> Obviously if the Mosquito is to be used as a strategic bomber it will have to be used somewhat differently to the way that the 'heavies' were. I'm interested to hear ideas on how this might have been done.
> Cheers
> Steve



Only if you wanted to use the Mosquitos the same way the Lancasters were used and spray bombs all over the German countryside without hitting the target. I'm being (a little bit) facetious...but there's a valid point to be made. The bombing stats for high-level daylight and night bombing are pretty horrendous when it comes to precision and accuracy. So many of those bombs never even got near the town, let alone the aiming point, until rather late in the game.


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## stona (Sep 14, 2016)

The problem with low level bombing is the vulnerability of the aircraft to light flak. In the first Gulf war the RAF was forced to abandon this tactic, one it had trained for during many years, for precisely this reason.
It is one thing to fly across the North Sea to Denmark and attack a building in a virtually undefended city at low level, quite another to fly to and attack a target in the Ruhr or Berlin. I think it would have been suicidal. The Luftwaffe would also have a much better chance of making interceptions, the sort of force we are talking about would not overwhelm the air defence systems, one of the primary reasons for the historic concentration of the bomber stream.
The Mosquito, flown at altitude and flown fast was almost invulnerable, flown low and having to slow down to bomb, it was not. I would have to look up the cruising speed of the Mosquito at lower altitude, but I doubt it would trouble a latish war Bf 109 or Fw 190 which might have the advantage of warning and altitude.
Cheers
Steve

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## GrauGeist (Sep 14, 2016)

One of the shortcomings of the Luftwaffe's bombing campaigns, is that they relied almost exclusively on light/medium bombers for their campaigns and while they acheived a certain amount of success, it was much less effective than a strategic heavy bombing campaign.

So if the RAF were to decide that the Mosquito was their primary bomber, how long would it take to build up a sizable force that would be able to conduct comparable bombing campaigns that matched the tonnage dropped by the RAF's heavy bombers.

The Mosquito's heavy bombload capability also wasn't available in the early stages of the war, so what does the RAF do in the interim? Hundreds of small surgical strikes hoping to inflict "death by a thousand paper cuts" on German targets?


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## stona (Sep 14, 2016)

GrauGeist said:


> One of the shortcomings of the Luftwaffe's bombing campaigns, is that they relied almost exclusively on light/medium bombers for their campaigns ... so what does the RAF do in the interim? Hundreds of small surgical strikes hoping to inflict "death by a thousand paper cuts" on German targets?



This is true of the Luftwaffe.
For the second point, it isn't just mounting those strikes in the first place, it's keeping the pressure on whichever system is being targeted. This was a failing of the historic strategic campaign and would have been even more difficult with the precision strike force envisaged in this new scenario.
Cheers
Steve


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## pbehn (Sep 14, 2016)

It is all just a question of philosophy, the British didnt believe in an unarmed bomber but amazingly built 2000 Fairey Battles a single engined three man plane with one defensive gun plus one for dog fighting I presume.

Use those 2000 merlins in 1000 mosquitos which can be used instead of Hampdens Blenheims and Wellingtons on almost suicidal daylight raids. They would have been much more use from 1940 onwards "leaning into Europe" so long as we had Park doing it and not Leigh Mallory.


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## buffnut453 (Sep 14, 2016)

stona said:


> The problem with low level bombing is the vulnerability of the aircraft to light flak. In the first Gulf war the RAF was forced to abandon this tactic, one it had trained for during many years, for precisely this reason.
> It is one thing to fly across the North Sea to Denmark and attack a building in a virtually undefended city at low level, quite another to fly to and attack a target in the Ruhr or Berlin. I think it would have been suicidal. The Luftwaffe would also have a much better chance of making interceptions, the sort of force we are talking about would not overwhelm the air defence systems, one of the primary reasons for the historic concentration of the bomber stream.
> The Mosquito, flown at altitude and flown fast was almost invulnerable, flown low and having to slow down to bomb, it was not. I would have to look up the cruising speed of the Mosquito at lower altitude, but I doubt it would trouble a latish war Bf 109 or Fw 190 which might have the advantage of warning and altitude.
> Cheers
> Steve



Your statement about RAF ops in Desert Storm is only partly correct and misses some important details. Low-level tactics were employed to attack Iraqi airfields using JP233 resulting in flight profiles that were highly predictable, and which enabled the Iraqis to deploy AAA to provide overlapping arcs of fire over the airfields. Once JP233 missions were abandoned, the RAF started flying LGB missions which require operation at medium altitude for an airborne designator. For the record, the RAF's recce Tonkas flew at low level throughout the campaign with no losses. Despite over 20 years of medium altitude operations in combat zones, the RAF still practices low flying today because it remains a viable method for avoiding advanced air defence systems...but it requires the crew to plan their mission carefully to avoid threats and make maximum use of available terrain.

The key question is whether the Mosquito, at low-level cruising speed, exposed itself for sufficient time to enable German defenders to engage. From experience, low-flying aircraft are very hard to engage - even relatively small buildings and trees can provide sufficient masking to prevent manually-laid weapons, while radar must be capable of rapid traversing to keep track of the aircraft. Again, small groups of aircraft ranging widely over occupied Europe that bomb targets with accuracy would be a formidable challenge for the Germans to address. 

For the Luftwaffe to intercept, they had to have some idea of where the attackers were coming from. Radar wouldn't help once the attackers descended to low level and it's blessed hard to spot aircraft at low-level with the MkI Eyeball. Again, dispersing the attacking force over multiple targets simultaneously, rather than putting hundreds of Mosquitos over a single city, would also disperse the defending Luftwaffe fighter force. I'm not sure your assessment of the rationale for concentrating the bombing stream is valid. The USAAF daylight campaign required condensed formations to provide mutual protection and reduce bomb spread due to the entire formation dropping in concert with the lead bombardier. For the RAF, I believe the factors are far more to do with preventing friendly aircraft colliding while, simultaneously, striving to get as many bombs on the target as possible within as short a timeframe as possible (which was needed because precision and accuracy were so poor).

We can argue the pros and cons of this 'til the cows come home and there's no right answer, nor am I trying to convince you to change your mind - simply offering some additional thoughts to contribute to the discussion. This would be an interesting exercise for a wargame/modelling & simulation environment to set some rules and see how such a campaign might play out. Bottom line, though, is that such a low-level Mosquito campaign was impossible from a practical implementation perspective, not least because it required a degree of foresight that simply cannot be achieved.

Cheers,
Mark

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## GrauGeist (Sep 14, 2016)

The Luftwaffe would have adapted to the RAF's tactics just as they did historically with the heavy bombing campaign.

This in turn would have put the Mosquitos at a disadvantage while conducting low level strikes as the Luftwaffe would have had time to get to moderate altitudes to dive on the attacking forces instead of the much longer time needed to get to the higher altitudes to intercept the heavies.


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## stona (Sep 14, 2016)

Bomber Command's ORS completed an analysis of losses versus concentration over defended areas in March 1942 and concluded that concentrations of less than 50 aircraft per hour suffered a measurably higher loss rate than higher concentrations. The recommendation was for a concentration of at least 50 aircraft an hour when there was no moon and 80 aircraft an hour on moon lit nights. Additionally there was a recommendation for larger raids as these suffered proportionally lower losses than smaller ones. In response, according to the letter (from Saundby) which accompanied the report to the Ministry, the staffs of the various Groups were planning raids with a concentration of 150-200 aircraft per hour. It is obvious that forcing so many aircraft per hour through the German defences saturated them, it led to the demise of the 'himmelbett' system in its original form (one night fighter in each area) which was easily overwhelmed.
The primary factor driving concentration was self defence, it also allowed a concentration of bombing which, at this time, was being advocated as a means of creating fire storms. For Bomber Command this must have seemed a win, win situation.
Cheers
Steve


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## buffnut453 (Sep 14, 2016)

GrauGeist said:


> The Luftwaffe would have adapted to the RAF's tactics just as they did historically with the heavy bombing campaign.
> 
> This in turn would have put the Mosquitos at a disadvantage while conducting low level strikes as the Luftwaffe would have had time to get to moderate altitudes to dive on the attacking forces instead of the much longer time needed to get to the higher altitudes to intercept the heavies.



No doubt but there are limits to the amount they could adapt. With no radar-based GCA and airborne radar ineffective due to ground clutter, the Luftwaffe would have to rely on the MkI eyeball. That's very hard - it's a lot of territory to cover and very easy to miss aircraft if you happen to be looking the wrong way. The problem isn't engaging low-flying aircraft, it's detecting them so you know where to point your fighters. That's a problem that hasn't been solved today, even with advanced ground-based radars. 

Again, I'm not saying the Mosquitos would be invulnerable, Far from it. But the challenges presented to the German defences would not be trivial to resolve. The fundamental problem for the Allies would be that overall destruction would be less comprehensive and more focused on the actual targets rather than on the wider German populace.


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## gjs238 (Sep 14, 2016)

buffnut453 said:


> The fundamental problem for the Allies would be that overall destruction would be less comprehensive and more focused on the actual targets rather than on the wider German populace.



I'm thinking more Mosquitoes attacking oil targets (and power production) and less Lancasters attacking population centers.
Unlike the bloodsucking mosquitoes we are used to, these will suck petroleum, the lifeblood of the Wehrmacht.


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## parsifal (Sep 14, 2016)

and there is less than half the chance statistically that the Mosquito will be lost compared to a 4 engine bomber. We don't have a direct correlation as to mission type, but in my view, the types of missions the historical Mosquito force was subjected to were a higher risk to the high level bombing the main force was employed in. A mosquito equipped force for BC would have expanded exponentially compared to the historical model and with less manpower soaked up. In 1944, BC hovered around the 4000 a/c mark. It had taken 4 years of bloody and costly lessons to get there. Every bomber brought down was a massive cost in lives and treasure. Its hard to say this was the best or only way the job could have been done.

And the job was one that did need to get done. a mosquito equipped force would have reached that 4000 a/c mark sometime in 1941-2 in my estimation, and be pressing 8-10000 by 1944. its ability to fly at night, bomb area or precision targets, fly high or low or some mix of both is well proven, well known and yet still challenged. far from constricting or preventing BC from its task, a Mosquito equipped main force would have opened up possibilities that we simply will never know.

I am sure that the methods settled upon for the heavies would not be ideal for the mosquito. I am also sure that other options would have presented themselves as the force became available. there is more than one way to skin a cat. after the war, area bombing as a concept more or less sank like a stone from the inventory of military theory. This descent did not even wait for new precision bombing aids and techniques to become available. By wars end, it was obvious that the moral dilemmas, the inefficiencies and sheer cost of area bombing rendered it obsolete as a weapon of war. it was, in fact, obsolete during the war, but the bomber barons would not allow any alternatives to be even considered.


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## stona (Sep 15, 2016)

I think having a Mosquito force equipped for precision attacks on Harris' 'panacea' targets seems a good idea with hindsight. The problem is still getting enough of them to the targets and destroying them. We are talking about flying hundreds of miles across enemy territory to attack some of the most heavily defended targets in the world at the time.
It is worth remembering that even after the invasion the RAF's 2nd TAF was forced to curtail its 'deep penetration' missions due to unsustainable losses to flak. In December 1944 the operational tour of duty for a 2nd TAF pilot was reduced by 60% (from 200 to 80 missions) in order to give them any chance of survival. The average survival time for a newly arrived pilot was just 17 missions. Mosquitoes were just as vulnerable to this type of light flak as Typhoons and it is what accounted for almost all these losses. A report by the ORS 2nd TAF of July 1945 stated that.
_"practically all damage sustained on operations due to enemy action was caused by light flak."_
It is inconceivable that in the face of such attacks by low flying Mosquitoes the Germans would not have reacted by increasing production and deployment of anti aircraft weapons in the 20mm-40mm calibre range. If the 'heavies' are replaced to any extent by the 'mediums' then manpower and resources could be diverted from the much more expensive (in all terms) heavy flak batteries.

I've already mentioned the sheer weight of bombs required to disable, and keep disabled, an easy and fairly large target like a marshaling yard or oil facility, but how about a harder transportation target like a bridge?
The medium bombers of MATAF had to drop 600 bombs to be sure (95% probability) of a hit on a bridge target occupying 6,000 square feet. The medium bombers of the RAF desert air force needed 2,400.

Cheers

Steve


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## stona (Sep 15, 2016)

I think that we are all, including me, confusing to some extent what we mean by 'precision' and 'area' bombing. Webster and Frankland make this point.

_"It has to be decided whether the offensive should be concentrated by selective bombing against a group of related targets all of which are associated with the same activity, that is to say a 'target system', or dispersed over a wider range of activities in a general bombing offensive. These were complicated alternatives which are sometimes confused with another choice, namely, that between precision and area bombing. In fact, however, a selective offensive, for example, could be pursued by area or precision attack. The choice between area and precision attack is primarily governed by operational factors; the choice between a selective and a general bombing offensive is a matter of strategy."
_
Bomber Command decided long before the 1942 directive (typically one or two sentences of which are quoted with no context) that area bombing was it tool of choice. In 1941 some ostensibly naval targets were in fact entire German towns.
It is this strategy which militates against the adoption of a medium bomber (which is effectively what the Mosquito was) instead of the heavy bombers. Even when Bomber Command engaged precise targets it did so by area bombing. On 30th June 1944 266 aircraft of Bomber Command dropped 1,100 tons of bombs on a road junction at Villers Bocage, effectively preventing the passage of the tanks of 2nd and 9th Panzer Divisions to attack the Allied beachhead. Mosquitoes could not have achieved this as they would have been engaged in precision attacks.
This is reflected in the attack of other 'precision' targets. On 13th November 1944 Bottomley wrote to Harris in an attempt to cajole him into attacking oil targets. First he made a point about the US attacks.

_"The weight of attack which the U.S.Air Forces could, for various tactical reasons, bring to bear against any one plant on any occasion was limited; it was barely sufficient to keep the major producers out of action between the fairly frequent attacks."_

After explaining the policy that he wished to pursue he continued.

_"The weight and density of attack of which your Command has shown itself capable, given adequate marking, far exceeds that normally achieved by U.S. Air Forces. It is considered that one successful large scale concentrated attack by Bomber Command on an oil target should, on the basis of past experience, result in the long term immobilisation of activity which is now required. If therefore you can achieve damage on the scale of the 'KAMEN' attack of 11th September, 1944, upon plants such as Leuna and Politz, you will make a major contribution to the current vital oil plan....."_

Once again it is the weight of attack that is the overriding factor. 

Cheers

Steve


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## Shortround6 (Sep 15, 2016)

Actually it is the weight of attack in a given target area (and assuming appropriate bombs are used). Bombs that fall outside the target area are pretty much wasted.
However that brings us to Bombing Accuracy which really deserves a thread of it's own. 
As in how different bombers compared _under *identical conditions*. _
Not comparing low level strikes by bomber A to high altitude formation bombing by bomber B to blind bombing by Bomber C. 

I find it very hard to believe that it made any difference to the bomb as it dropped as to what aircraft had dropped it once it was a short distance (100ft or less?) from the aircraft.
Local airflow over bomb bay and such may affect things but not enough to miss by thousands of feet.
Steadiness as a bombing platform covers two things. Stability of the airplane affecting bomb release as in plane is yawed 2 degrees when bomb leaves the bomb bay. Bomb will NOT follow a 2 degree departure from line of flight as the fins will soon soon point the bomb in direction the planes was traveling and not the direction the plane was pointed at moment of release. Worse accuracy than plane not yawing but not enough to miss large targets. 
However such a plane showing directional instability or yawing or hunting is going to make it harder to operate the bombsight. This may have a much larger impact on bombing accuracy if inaccurate inputs are made to the bombsight due to aircraft movement. 
Obviously height decreases accuracy for all bombers. 
Other factors????
Then you can get into bombsight differences and other variables.

When saying bomber A could be substituted for Bomber B for mission XXX it help a great deal if we knew the accuracy for both bombers _flying _the same mission. Granted Bomber A might be able to fly a different mission profile than Bomber B but that throws in a bunch more variables (different AA defense, etc)


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## stona (Sep 15, 2016)

I've never seen the accuracy of two or more bombers performing the same mission questioned. Bomber Command's ORS looked into just about every imaginable aspect of bombing, and it seems that a general assumption was made that any factors due to different aircraft types, when attacking the same target, in the same conditions, from the same altitude, at similar air speeds etc were not significant.
I don't think that a Lancaster was inherently considered any more or less accurate than a Halifax, Mosquito, Stirling or any other type.

There were many factors influencing bombing accuracy far more significantly than the type of aircraft, if that had any influence at all.

When the BBSU examined bombing accuracy for night time operations the formula it chose was the percentage of sorties despatched dropping bombs within 3 miles of the aiming point. This gives an idea of the size of the error generally. This figure increased from around 20% in late 1943 to over 90% by late 1944. More importantly the relative density of bombs dropped, at the aiming point, (measured by bombs per square mile per 100 dropped) increased from less than 1 in late 1942 to about 12 by late 1944. Again, the impact on these figures of different aircraft types was not significant.

As for different mission profiles, the Lancaster proved itself just as capable of making a low level precision attack as the Mosquito, it just wasn't considered a sensible use of the aircraft apart from in exceptional circumstances.
6 of 19 Lancasters were shot down by flak during 'Chastise' and another damaged. Why would that be very different for Mosquitoes making low level approaches and attacks on German targets?
Bomber Command considered 7% losses utterly unsustainable and that 5% losses over a three month period would seriously diminish the efficiency of the Command. How could losses of around 30%, to flak alone, be endured? I used the adjective 'suicidal' to describe this sort of mission in an earlier post, particularly in daylight, and I stand by it.

Cheers

Steve

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## KiwiBiggles (Sep 15, 2016)

stona said:


> Bomber Command's ORS looked into just about every imaginable aspect of bombing


And that sums up the whole argument, really. Very bright people whose sole job it was to study this, with all the information they wanted available at first hand, and with actual lives at stake, designed Bomber Command as we now look back at it. We can be sure that the idea of replacing the four-engined heavies with Mosquitos was considered and rejected.

Much as I enjoy what-iffing, the idea that sitting here at my computer three-quarters of a century later, with whatever third-hand information I can glean through Google, I could make a more-informed decision than those involved at the time, is hubris.


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## parsifal (Sep 15, 2016)

They were bright people, for sure, in about the same way as Napoleon was bright at waterloo, or Schlieffen was in the development of his plan. Within the field of there own expertise they were brilliant, but try to prise them away from what they are comfortable with and all of a sudden there is reticence, hostility, blindness. Napoleon for example when told of the possibility of an armoured steam driven ironclad warship, stated that he was not interested in such nonsense. And yet by 1814 the first steam driven warships were being built. This is precisely what happened within the RAF establishment. It was borne from the belief systems that went back a long way, 'the bomber will always get through' hence it was logical that performance didn't count that much what mattered was the tonnage dropped. 

The generally low performance of the heavy bomber concept forced a number of expedients on BC that cumulatively degraded much of its effectiveness. There were two elements that worked against them. first was the need to bomb at night, dropping accuracy to maybe 5% of a daylight equivalent. That gradually improved as time progressed, to the point I believe that night bombing was almost as accurate as day bombing in clear conditions. blind bombing im not as sure of.

The other element affecting the bombers was their need to bomb from relatively high altitudes. Altitude reduced the effects of flak markedly, but it came at the cost of many bombs falling well outside the target area. it was not possible for the heavies to bomb lower, they were too expensive and too vulnerable to risk to some 5 bob a day shooting gallery specialist with a rifle or MG.

Whatever arguments about the mosquito, it has the runs on the board to show that conceptually at least it could operate by day or night, at high, medium or low altitudes. It might as a type have needed some modification in the design to increase range, or bombload, or engine power. we should not be arguing that the mosquito was designed for the purpose we are now considering. it wasn't. It was designed as a recon machine upon which a number of secondary roles were added, and then added and then added again. There is no impediment I think to extrapolating the design because heavy bombing was never something that was considered for it. Why for example, could there not be a four engine mosquito. the concept at issue here for me isn't a straight up Mosquito. its the different philosophies behind the two groups of aircraft. On the one hand we have the lumbering behemoths very much in the tradition of Trenchard, relying on firepower over speed and manouver. We know the extent of technological progress for that class of aircraft, and what happened to them more or less immediately after the war.

then we have a different class of aircraft, at the head of which is the mosquito. Its potential is not known, because it was never selected for development as a heavy bomber. it was certainly advocated by some of the more visionary members of RAF and the supporting industry members. But such support and parallel think was rapidly smothered by vested interests who had reason and motive to act in that way.

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## Shortround6 (Sep 15, 2016)

Occasionally the very bright people pulled some real clangers. Like the Blackburn Botha. 
It doesn't take a retrospectroscope to figure out that increasing the empty weight of a MK IV Blenheim by about 20% and the max loaded weight by about 25% while increasing the power by only 15% or less was going to lead to an under powered aircraft. Compared to the MK Blenheim the Botha increased over 40% in loaded weight. 
Sleeve valves are only going to do so much on an engine with the same bore and stroke. 
Poor vision for recon _should _have been caught at the mock up stage, that is why they build mock-ups, to catch 3 dimensional problems that might not show up on flat plans, like vision from cockpit/s or observation windows. 

evaluating operational results is a lot harder as we often do NOT have all the facts or we are trying to compare things that are not actually alike (low altitude bombing vs high altitude)


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## Shortround6 (Sep 15, 2016)

parsifal said:


> It was designed as a recon machine upon which a number of secondary roles were added, and then added and then added again.



It was designed as bomber, with the roles of fighter and reconnaissance being "added" or being required at almost the same time. Out of the first order for 50 aircraft the exact mix of how many went to each role was shifted about several times before the first production plane ever flew. 

There were only about 1700 Mosquito bombers built and the majority of those were from around the Spring/summer of 1943 on (several hundred completed after VE day.) Most, if not all of the ones from the Spring/summer of 1943 having two stage Merlin's which did wonders for the performance and survivability, something like 1000 of the bomber mosquitoes had the two stage engines. However one wonders how well a Lancaster with two stage engines and a pressure cabin for the pilot/Forward crew would have performed??

Dropping 4000lb cookies from over 30,000ft is hardly a substitute for what the Lancasters and Halifaxes were doing. 
Not disparaging the Mosquito crews, ANY pilot or crewman flying wartime missions deserves full respect no matter what the location/mission. 

Now with enough "forward vision" the _stick to the old ways_ AIr Marshals _might _have been able to increase production of two stage Merlins enough to make much larger numbers available from mid 1943 on to power a much increased Mosquito bomber fleet (or Lancasters with two stage engines to go along with different tactics.)

There were only 3 squadrons of Mosquito bombers operational (?) in 1942, 105 Squadron from Nov 1941 although first combat was May of 1942. August saw 109 Squadron equip with Mosquitoes but 109 squadron was primarly tasked with radar development and electronic and navigation equipment development and tactical implementation. No 139 Squadron was equipped with Mosquito Bombers in Oct 1942. It was these two squadrons that performed the bulk of Mosquito _bomber _(as opposed to Mosquito fighter bomber) day missions. 
Despite being highly publicized were these raids enough to change RAF bombing policy on? 
By July 1943 Both squadrons were being re-equipped with later version Mosquitoes with two stage superchargers and had been transferred to No 8 pathfinder group.

The two stage engines in the later Mosquitoes could make about the same power at 21,000ft as the engines in a Lancaster could make at 11,000ft. and had about 220 hp (15%) more at low altitudes.

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## wuzak (Sep 15, 2016)

parsifal said:


> Whatever arguments about the mosquito, it has the runs on the board to show that conceptually at least it could operate by day or night, at high, medium or low altitudes. It might as a type have needed some modification in the design to increase range, or bombload, or engine power. we should not be arguing that the mosquito was designed for the purpose we are now considering. it wasn't. It was designed as a recon machine upon which a number of secondary roles were added, and then added and then added again.



The Mosquito was designed as a high speed, unarmed light bomber. The PR role was a secondary one, though the first RAF orders were for this role.

I have no doubt that the Mosquito could have provided a more useful contribution to the strategic bombing effort than it already did. The limiting factor was, as mentioned previously, the numbers of available bomber variants. And that was because of the other roles it was required to fill.

I never felt that the Mosquito could replace the Lancaster. My view was that it could have acted as a replacement or supplement to the B-17 during the daylight campaign.

One raid that I thought may be possible for the Mosquito would be the first Schweinfurt raid. The range is just about within the Mosquito's capability at low altitude. 

The 200+ B-17s hit the actual target buildings with 80 1000lb bombs. 

The Mosquito couldn't carry 2 x 1000lb MC at that point, and 2 x 1000lb GP bombs would have half the explosive charge of the US bombs. So they would need to use 2 x 500lb MC for each US 1000lb GP bomb to have the equivalent explosive charge. The Mosquito could carry 4 of the 500lb MC.

So, to get the same explosive charge on the factory buildings you would need 160 hits with the 500lb MC - which means 40 Mosquitoes at 100% accuracy.

But let's say that they have 50% accuracy. That would require 80 Mosquitoes.

Factoring a high loss rate of 20% (similar to what the USAAF had) you would need 100 bomber Mosquitoes. Which probably weren't available to Bomber Command at the time.

The USAAF lost most of theirs to fighters. This occurred during several hours of fighting as the bombers entered and withdrew from the target area. In the Mosquito case it is likely that would occur on only one of the legs.

Losses would probably be mostly to flak. Mosquito attacks could not be solely low level attacks, as that would have the defenders adapting quickly. The attack altitudes would, this, need to be varied so that one type of attack cannot be expected.

There is another downside to low level attacks, as demonstrated in the Shell House raid. While the first wave scored nearly 100% hits, one of the later aircraft hit a building and crashed away from the target. The following waves then proceeded to bomb the crash site, being confused by the smoke.


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## wuzak (Sep 15, 2016)

Shortround6 said:


> There were only about 1700 Mosquito bombers built and the majority of those were from around the Spring/summer of 1943 on (several hundred completed after VE day.) Most, if not all of the ones from the Spring/summer of 1943 having two stage Merlin's which did wonders for the performance and survivability, something like 1000 of the bomber mosquitoes had the two stage engines. However one wonders how well a Lancaster with two stage engines and a pressure cabin for the pilot/Forward crew would have performed??



313mph @ 18,300ft for the Lancaster MK VI @ 65,000lb MTOW. Still over 300mph @ 22,000ft. Service ceiling 27,000ft.

Maximum cruise speed 279mph @ 23,900ft.

http://www.wwiiaircraftperformance.org/Lancaster/jb675-level-speeds.jpg

http://www.wwiiaircraftperformance.org/Lancaster/Lancaster_VI_JB675_Performance.pdf


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## nuuumannn (Sep 15, 2016)

Shortround6 said:


> However one wonders how well a Lancaster with two stage engines and a pressure cabin for the pilot/Forward crew would have performed??



They thought about it, but expediency meant that the largest number as quickly as possible was what was needed, rather than developing a new variant so soon. The Lincoln was the next Lanc variant to go into production.

The problem for Mosquito operators is what Wuzak identified, not enough aircraft to go round for all those who wanted them. Production in Canada helped, but demand was still greater than supply.

The one problem I see with this scenario is that the Americans are not going to put their bombers to waste in favour of a British aircraft and nor is the RAF, especially since it had invested so much already in larger aircraft. Bigger bomb loads in greater amounts was what Bomber Command wanted and heavies like the Lanc and Halifax gave that, despite their weaknesses.


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## wuzak (Sep 15, 2016)

As an aside, Volkert's memorandum on bombing policy in 1937 described an unarmed bomber based on P.13/36 (that gave the Manchester and Halifax) parameters. Maximum bomb load was 8,000lb and it was powered by two Vultures.

The interesting part was that he did not think that precision attacks would be possible and that attacks against population centres would be the approach. The unarmed bomber, he reasoned, would be able to do this more efficiently than the armed bomber, its higher speed helping to reduce losses while carrying the same/similar bomb load.

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## parsifal (Sep 16, 2016)

wuzak said:


> I have no doubt that the Mosquito could have provided a more useful contribution to the strategic bombing effort than it already did. The limiting factor was, as mentioned previously, the numbers of available bomber variants. And that was because of the other roles it was required to fill.
> 
> I never felt that the Mosquito could replace the Lancaster. My view was that it could have acted as a replacement or supplement to the B-17 during the daylight campaign.
> 
> One raid that I thought may be possible for the Mosquito would be the first Schweinfurt raid. The range is just about within the Mosquito's capability at low altitude.



The numbers available were not limited by supply of materials as is often touted. DeHavilland at least is clear in his statements about that. The delivery dates are also heavily skewed by the hostility the air ministry showed towards it. As a design, the DH98 was ready for production as early as October 1938, but it would take until 1940 before it began to enter production and then only at a trickle. There were no real hitches in the production of the type (it was actually faster to build than a standard Blenheim turreted bomber) , just official opposition to it as a concept. the original type was designed to meet a specification of carrying 3000 lb bombload a minimum of 1500 miles. the Mosquito , even the early marks could achieve this easily. but the opposition to it as a bomber remained, and most of the early marks were completed as either unarmed recon versions or night fighters. Geoffrey DeHavilland had a bewildering array of variants he was willing to build from the start, so if the production was entered from an early stage rather than dithered about so that the crowning achievement of the Manchester could be built instead, the type could have been shown to fulfil many of the roles that it did.

Imagine if the type had started production in early 1939. It would have been entering squadron service by about June 1939. I believe its capabilities as a type would have forced BC to completely rethink its tactics. The great unknown is how the LW would react. their existing fighters, built around the Me 109 and Me 110 would immediately be shown to be inadequate, lacking both the speed an range to deal with the new bomber. Im tempted to think along the lines of an early introduction of the Me262 but that was still years away in 1939. For the moment Im just going to leave that an open question.

turning now to Schweinfurt/Regensburg option. The first thing that strikes me is that the assumption that losses for the Mosquito being the higher than a B-17 equipped force. I think that is incorrect. Historically the raid was a strike by 376 bombers of sixteen bomb groups against German heavy industry well beyond the range of escorting fighters. 60 bombers lost and 95 damaged, about 58 beyond economic repair. 

The lead attack was the Regensburg group, which lost 24 bombers, and at least 60 damaged, 15 of the lost bombers were lost on the inbound leg. 126 of the 144 bombers released bombs over the target. The attack was late, and slow in delivery, giving the defenders plenty of time to get into position, land, refuel and be ready for the next attack.

If this element of the attack substituted Mosquito BXVIs for the B-17gs, instead of the approach speed being 180 mph, or less, it could have been 350mph for a hi approach. to increase bomb hits I would adopt a Hi-Lo-Med mission profile. Flak was noticeably low over Regensburg so losses to flak firing at an aircraft that within the target would be belting along at over 400 mph would be minimal. My guess is that for this strike element, losses might be 2-10 a/c, depending on how well it was delivered and the amount of advanced warning the LW received. One difficulty was that le mays group was tasked to stage through to Algeria after the hit, this would not be possible for the Mosquito hypothetical. 

The main attack on Schweinfurt followed the same route basically as Le Mays Group. The organization and disposition of this force left a lot to be desired, and the increasing cloud cover forced the bombers to come in at sub-optimal altitudes. You cant lay this at the feet of the B-17 as a type, but you can say that because of the higher approach speed of the mosquito, the cloud would have been higher at the time of the approach (the cloud was descending as the day wore on) , the mosquito force would be far less constrained by cloud....they would have attacked higher and faster.

This time delay and altitude constraints is very significant to loss rates. The time lag allowed more than 300 defending fighters to be concentrated over or before the target. The time taken in the attacks also allowed many of the early intercepts to attack, land, refuel/rearm and hit the stream on the way out. Moreover at least two gruppen were able to use effectively the new unguided air to air rockets firing them into the tight defensive patterns the B-17s were using.

I am sure there are people here that have a better handle on the details of the battle compared to me, but from what I do know, it was a very bloody affair. Some 22 being shot down and a further 15 or so heavily damaged within the target area . The lead wing of 57 a/c was followed 15 mins later the other wings as they began their runs in. The lead group took many of the losses because the inbound approach was so slow, allowing the germans to be perfectly positioned for their attacks. Only 3 B-17s were brought down by flak, though many were damaged. 183 bombers managed to drop 950000 lbs of ordinance on the target. a total of 30 or so bombers were brought down or damaged within the target area. more time was lost as the bombers were forced to regroup over Meningen. they needed to stay together, as their primary defences, their turreted guns needed massed firepower to keep the losses low. Unfortunately this delay was used to good effect by their enemies. 

The americans were again attacked as they retreated toward Brussels then home. At approximately 15:30 German fighters renewed their attacks, concentrating now on damaged bombers. Between 16:20 and 17:00 a covering force of 93 P-47s and 95 Spitfires arrived to provide withdrawal support, claiming 21 fighters shot down, but eight more bombers were lost before the force reached the North Sea, where three more crash-landed. The Schweinfurt force lost a total of 36 bombers and close to 60 damaged.

how might a Mosquito equipped force have fared in this scenario? It would both approach and leave faster, with no loiter time. Only head on attacks by the LW would be effective, and the numbers of fighters able to deploy might be half that achieved historically. We would need to model that battle to get a good idea of potential losses, but with half the number of defenders, only effective through half the attack angles, and no losses outside the target area you might suffer 5-10 Mosquito losses plus the 3, maybe 4 to flak There will be endless debates about how these losses might pan out, but I don't think it unreasonable to claim losses in the region of maybe 10 a/c lost . in exchange for that a force of say 550-600 Mosquitoes (roughly what I think the americans might potentially be able to put into the air) each carrying a 2000lb warload, might drop as much as 1,100,000 lbs of ordinance on the target. A critical point of argument might be the number of mosquito substitutes, but remember, my position is based on a premise of a 1938 entry into production and a 1939 entry into service, and probably a licence production agreement with the Americans. instead of building 7000 mosquitoes, 30000 would be nearer the total.


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## wuzak (Sep 16, 2016)

The problem there parsifal is that the Merlin 76/77, or even the 72/73 used for the IX and early XVIs, was not available at the time of Schweinfurt. Well, the 72/73 was just coming into production with the IX.


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## parsifal (Sep 16, 2016)

With an extra two years, there will be any number of nearly as good alternatives to choose from


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## stona (Sep 16, 2016)

Now we are into pure 'what iffery?'

The Mosquito was never planned to be in service before 1942, the stop/start prototype wasn't started until early 1940. Bowyer covers the early developments that led to the Mosquito, Contract 69990 for fifty _bomber-reconnaissance _aircraft was issued on 1st March 1940 to Specification B.1/40.

With the fall of Paris in June 1940 a plan of the month before was implemented. Production now concentrated on the Hurricane, Spitfire, Wellington, Whitley and Blenheim, research and development was to be concentrated on these five types. Any other work might be applied to second priority types, the Stirling, Manchester and Halifax, but not the Mosquito. This was not due to any innate hostility to the Mosquito. This was a rationalisation of resources in Britain's darkest hours, and the fact that the Mosquito, which existed only as a partially completed prototype and which was not expected to be in service for at least another 18 months was passed over seems perfectly reasonable, even with the hindsight that the decision makers did not have.

De Havilland, understandably, pleaded for the Mosquito to be allotted at least second priority status. Beaverbrook's right hand man (Patrick Hennessy) replied that it might be considered if fifty aircraft could be supplied in 1941. C.G. Long, de Havilland's chief development engineer went to London and showed Beaverbrook the material schedule for the Mosquito, showing that demands on the light metal industry would be light, high strength castings totalling 250 lb largely replaced forgings (only 30 lb) and machining was minimised; for instance a simple compression rubber undercarriage leg was used rather than an orthodox oleopneumatic leg.
On 11th July de Havilland promised fifty aircraft in 1941. On 12th July Hennessy re-instated the Mosquito project, with the proviso that it should not interfere with production of Tiger Moth and Oxford trainers (vital to RAF Training Command) or the repair of Hurricanes and Merlin engines which the company had recently undertaken (equally vital as the Battle of Britain began).

The Luftwaffe also had a hand in delaying the Mosquito. In the first two weeks of September 1940 the plants at Hatfield and Salisbury Hall lost 84,309 man hours to air raids. On 3rd October a hit and run raid by a single Ju 88 killed 21 de Havilland workers and wounded 70 more. About 80% of the raw materials and much work in progress for the Mosquito was lost.

If we are going to 'what if ?' let's at least stay within historical facts. The Mosquito prototype was delayed for about one month. It was never going to be in service, in numbers, years earlier. There was no innate resistance to the type at the Air Ministry, in fact, following the re-instatement, on 18th July, a letter asked that a fighter prototype also be developed. There was some unease about the concept of an unarmed bomber in 1940, but then there was unease about all sorts of other concepts too.

W4050 first flew on 25th November 1940. On 29th December a show was put on, at Langley, for Beaverbrook and assorted other VIPs (including the Hon. C D Howe, Canadian Minister of Munitions and Supply). Other aircraft showcased were the Hawker Tornado (Vulture), Gloster F9/37 (Peregrines), Philips and Powis fighter (Merlin), Short Stirling (Hercules) and Handley Page Halifax (Merlins). The D.H.98 made a good impression and such was the 'resistance' at the Air Ministry that the very next day Grp. Cpt. H E Forrow (MAP overseer at Hatfield) told de Havilland that another 150 Mosquitoes were to be ordered and that additional floor space, materials and sub-contracting capacity were to be sought, with a view to further_ 'substantial orders'._
On 11th January 1941 de Havilland were told to build a reconnaissance prototype and to finish the remaining 47 aircraft of order 69990 as 19 reconnaissance and 28 fighters (prototype ordered the previous July) but NO bombers. Bombers were likely to feature in the next order, and development flying was to continue with all three roles in mind.
The Air Ministry, far from resisting the development of the type, clearly saw it as an aircraft with potential in at least three different roles. It would eventually fulfill more than this, but we can hardly blame them for not anticipating this after one prototype had flown.

Cheers

Steve

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## Shortround6 (Sep 16, 2016)

The Mosquito MK XVI didn't fly until Jan 1st 1944 about 4 1/2 months after Schweinfurt, The MK IX with two stage Merlins first flew in March 24th 1943. Pretty much the same performance but lack of pressure cabin meant it was rougher on the crew than the XVI. Getting hundreds built and out to operational squadrons in 5 months????
These engines were rated 18lb boost as built (and developed) and boosted to 21lbs and sometimes 25lbs in service. Claiming that some other mark of engine could have done the Job months or year or more earlier may not be anywhere near as easy at it seems. The Original 2 stage engine, the Merlin 60 was limited to 9lb of boost and the Merlin 61 & 62 were limited to 15lbs. Granted all (except perhaps the 60) could cruise at the same limit 2650rpm and 7lbs boost. 

The early proposal for the Mosquito (or the official requirement) was *not *for a plane to carry *3000lb *for 1500miles but a plane to carry 1000lbs for 1500miles, speed not given in the book I was reading. Since the first ten production Mosquito bombers had a max bomb load of 1000lbs I believe the 3000lb number is in error. This is where the _early _(1939/40) production/service use of the Mosquito falls apart.
The 1938-39-40 engines and propellers and _fuel _were nowhere near as good as the 1941-42 single stage engines/props/fuel. 
At best you can get the Merlin X engines as used in the Whitley and modify the cooling system to fit the Mosquito. However this means 1065hp for take off instead of 1280hp from even a Merlin 21, it means 1130hp at 5250ft instead of 1460hp at 6,250 in low gear and 1010hp at 17,750ft instead of 1430hp at 11,000ft (16lb boost) and more importantly 1185hp at 18,500ft (9lb) in high gear. 

While a 1939 Mosquito would obviously be much better performing than a Blenheim, it would also be much worse than a 1942 Mosquito. In 1939 you have 87 octane fuel and the Propeller situation is questionable. Most Battles got 2 postition props but some bombers got constant speed. Even some of the constant speed props had rather restricted pitch ranges. Nobody was getting feathering props.
Blenheims went to carrying 100 octane in the outer tanks and 87 octane in the inner so they could use the 100 for take-off and combat and cruise on the 87 octane, most other bombers stayed with 87 octane until well into 1940. 

A 1939 Mosquito with Merlin X engines, if was to keep the same power to weight ratio (for take-off and climb) as the Mosquito B IV would be limited to around 17900lbs and since the tare weight was about 13,400lbs for a B IV either you accept lower performance (and the 1939 fields were usually shorter than 1942 fields). or you accept less payload and less range. 500imp gallons is about 3600lbs, crew 400lbs, 360lbs oil (15imp per engine), bomb load is one 250lb bomb??? Granted a 1938 Mosquito might not have had armor or self sealing tanks but that sure doesn't help the loss the ratio. 
Yes they would have run heavier and or cut fuel load but you don't get 1942 Mosquito Performance in 1939/40 anymore than you get Spitfire V performance in 1939. And a Spitfire V with belt fed cannon was carrying about 350lbs more guns and ammo than a Spitfire MK I.


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## stona (Sep 16, 2016)

A 1940/41 Mosquito is out of the question. The only de Havilland aircraft, flying in anything like the time frame to make this would have been the D.H. 91 'Albatross' airliner, first flight 20th May 1937 (ignoring the almost exact contemporary 'Moth Minor').
The D.H.91 might have been a remarkable aircraft (the mail carrier had a 6,000lb payload and could fly to Berlin and back at 11,000ft) but it used four engines and P.13/36 called for _'a twin engined medium bomber for worldwide use'._

Here is a very abridged time line of the development of the Mosquito concept.

April 1938. A twin engine (Merlin) Albatross estimate is made, with Hercules and Sabre comparisons.

27th July 1938. De Havilland write that the specification cannot be met on two Merlins. If speed was paramount then only half the specified load of 4,000 lb could be carried. If load was paramount then a larger slower aircraft could be built. Note that we are at the end of July 1938 and the concept of the Mosquito is still to be developed.

October 1938. De Havilland and C C Walker pitch the idea of a fast unarmed bomber to the Air Ministry for the first time. It arouses little interest. Why would it? The RAF has the Blenheim, Whitley, Hampden and Wellington in production, all metal and armed bombers. The de Havilland proposal ran contrary to the general scheme on which the RAF was being expanded and it came from a company with virtually no experience of working with the Air Ministry.
Crucially there was also a prevalent view in the Air Ministry that the Germans would develop ever faster fighters (as the British themselves intended to do) and this might leave an unarmed bomber in a precarious position.

De Havilland looked at various specifications and worked up options for some over the next 12 months. None were equivalent to what would become the Mosquito. They even looked at an adaptation of the D.H. 95 and also worked on Specification B.18/38, which became the Albermarle, but to no effect. The concept of an unarmed fast bomber had little support until the outbreak of the war. The closest we come to what would become the Mosquito was a small, unarmed, twin Merlin aircraft to carry 1,000 lbs of bombs 1,500 miles. This was one of three options (including a twin Griffon version) presented shortly after the outbreak of war, in September 1939.

22nd November 1939,. Conference with the Air Member for Development (Freeman). He supports the case for an unarmed reconnaissance-bomber version, though there is still some pressure for a third crew member.

12 December 1939. Despite efforts by some to abandon the project Freeman again argues the case for the two man, twin Merlin, aircraft. It was the reconnaissance role which kept the project alive, but bomber and fighter variants were not excluded.

29th December. Mock up conference. Specification B.1/40 drawn up on this basis.

1st March 1940. Contract issued for 50 aircraft, including prototype.

I just can't see, given this timeline, that a Mosquito carrying even 1,000 lbs of bombs could have been available in 1940/41.

Cheers

Steve


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## parsifal (Sep 16, 2016)

It s certainly a what if, but its a what if because of the entrenched opposition to the basic concept that instead preferred a bomber with heavy lift and defensive armament.

The alternatives were never seriously considered.

De Havilland claimed he could have production of the DH 98 perhaps an earlier permutation of it, from October 1938, I believe him.

What stopped it was not any major technical difficulties. but rather disinterest and downright prejudice. such prejudice was ferocious at times. So the design languished from September 1938 to March 1940. It took from March to November, 8 months, for the bomber prototype to be made ready for production, and a further 6 months to get the pru version ready. the pru role was the only one the air ministry was interested in at that time, and then only very grudgingly

I think it reasonable to undertake some what iffery for this debate. we are looking at the possibilities of the mosquito as the primary bomber in place of the Manchester/Halifax . That would pre-suppose that somehow the preconceptions that dogged the raf in that period as to how a bomber might be are overcome. It was perfectly feasible from a technical standpoint according to DH, but not from a political or doctrinal. Without such a doctrinal shift it is certainly not possible to even consider the possibility of a mosquito (or a mosquito equivalent)as replacing the slow, heavily defended bomber that the RAF finished up settling on in the finish.


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## Shortround6 (Sep 16, 2016)

stona said:


> I just can't see, given this timeline, that a Mosquito carrying even 1,000 lbs of bombs could have been available in 1940/41.


Given that time line it couldn't but even changing the time line to DH being given the go ahead in July of 1938 means they are planning the aircraft around Merlin X engines, 87 octane fuel (Rolls did announce power levels using 100 octane at the 1938 Paris air show but nobody knew when 100 octane would be available in service quantities, and 1938 100 octane may not have been the same as 1940 100 octane, 1940 100 octane was NOT the same as 1942 100/130) and the RAF preferred less than optimum propellers. 
Since a Merlin X weighed within a few dozen pounds of a Merlin XX series engine there is no weight saving their and except perhaps on the props no weight savings much of anywhere else. 
A Merlin X is pretty much a Merlin III with a two speed supercharger so it is subject to pretty much the limitations of a Merlin III. 
Like Climb rating of 2600rpm instead of 2850rpm used on the later engines. 
A Mosquito using such engines _might _be able to cruise at around 310-315mph using max weak mixture (assuming it is within a few MPH Of a Spitfire with the same basic engine [same supercharger although different ratio and same basic structure/crankcase/cylinder blocks)])

Now compare it to some of the early A-20s (R-2600 versions) which could hit 340-350mph at around 12,000ft top speed and cruise at a touch over 300mph at max cruise (rich). Granted the A-20s had the operational radius of a thrown rock with a parachute attached but the A-20s were hardly invulnerable due to speed (or guns) and their bomb load was more in the 1000-1500lb range (they got better later).

I would also note that the Halifax MK II (Merlin XX engines) had a ceiling 3,000ft higher than a Halifax MK I (Merlin X ) despite being 1000lbs heavier and fitted with that big egg shaped top turret (MK 1s had no top turret). Halifax II could also take-off and reach 50ft in 200yds less distance than the Halifax I despite the extra 1000lbs. 

Now perhaps DH was right and it was possible to build the Mosquito airframe in 1939-40, would the resulting aircraft using the engines available ( and I mean actually existing, not available in a production sense, first 75 Halifax's got Merlin X engines) and props and fuel have actually performed combat missions as some people seem to think. 
The Mosquito was a fairly tight design. 1000lbs of fuel is around 130-135IMP gallons so cutting gross weight by even 1000lbs for the lower powered engines means either a considerable cut in range or cutting the bomb load in 1/2 compared to a B IV at 21,462lbs. gross.
Light weight was 15,318lbs so you have 6144lb to play with. Crew is about 400lbs 536 IMP gallons is about 3900lbs depending on conversion so even a standard Mosquito bomber is just over max with full fuel, crew and 2000lbs of bombs.


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## tomo pauk (Sep 16, 2016)

Let's see what the Soviets managed in 1941 with Pe-2, that have had on disposition two M-105 engines of 1100 CV (1085 HP) for take off, and 1000 Cv at 13000 ft:
- max bomb load 2200 lbs
- normal bomb load 1320 lbs
- max speed (clean, at altitude) 340 mph
- max range (not radius) 745 miles
- internal fuel max 310 imp gals
- can dive bomb
- has machine guns (but not too many and not of great firepower)
- restricted bomb bay

The gun-less DH bomber of 1940 with two Merlin X engines should've been in the ballpark IMO, minus guns and dive bombing capability. So not much of a startegic bomber, but still useful when compared with what was available.

In 1940 Germany has the early Ju 88, with a better payload vs. range capability, but slower.

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## stona (Sep 16, 2016)

parsifal said:


> De Havilland claimed he could have production of the DH 98 perhaps an earlier permutation of it, from October 1938, I believe him..



He had a very selective memory, because the concept that led to the Mosquito didn't exist in 1937 (I'm giving them a year for development). The Albatross only flew in May 1937 and it was from this that, eventually, the Mosquito was derived.

The unarmed bomber concept languished for about one year, essentially 1938-1939, and the prejudice as you call it was founded on the fear that the Germans would develop ever faster fighters leaving such a machine vulnerable in the future. Such reservations were expressed in various development meetings of the time. Today we would say it was not future proof. It was Freeman that saved the project, arguing in the meeting I cited above for a high speed, unarmed, _reconnaissance _aircraft.

There was ZERO chance of having a high speed bomber with anything approaching the performance of what we now call the Mosquito in 1938 or even 1940, it was pure hubris from de Havilland.

I'd like to see some evidence of 'downright prejudice' against the Mosquito. There were arguments against the unarmed fast bomber concept, but these were always reasoned and based on genuine fears that this would not be the way to go. We have the benefit of hindsight, the decision makers at the time did not. Slower self defending bombers may have been a more conservative option, but they were also the safer option at the time.
Did any other air force adopt an unarmed bomber in the 1930s?

Cheers

Steve


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## Shortround6 (Sep 16, 2016)

The fast bomber concept got a big boost during the Spanish civil war and with the introduction of the first monoplane retracting landing gear bombers. 
For the British the Blenheim and the Gladiator were first issued to squadrons within 1-2 months of each other. The Hurricane entered service almost 9 months later (with 4 aircraft issued to the first squadron.) The Spitfire was issued to it's first service squadron about 9 months after that or 17-18 months after the Blenheim. 
A fast bomber, either unarmed or with light armament (1-3 rifle caliber MGs) might have a "window" of opportunity to operate with near immunity vs enemy fighters of a number of months but it is always going to be easier to build a faster fighter using the _same level of technology _. So the unarmed or lightly armed bomber will come to grief at some point. 
Now the heavily armed bomber didn't really work either but that doesn't automatically mean the unarmed bomber was the correct answer. 

Think of Mosquitoes trying to do daylight raids against defense of P-51 Mustangs. Both planes using essentially the same engine and fuel or similar level of technology. 
We have the luxury of knowing the Germans never got ( or capitalized on) high performance fuels and two stage superchargers. Nobody was 100% sure what the Germans might to might not introduce into service 6 to 18 months in the future at any given time during the war.

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## stona (Sep 17, 2016)

Quoting Bowyer.

"_In a second letter, sent July 27_ [1938] _they_ [de Havilland] _concluded that the specification could not be met on two Merlins...

'A good bomber could be produced using Merlins' (here is the first twinkle of the idea that became the Mosquito) 'but to meet this specification double the power would be needed.' ...

A two Merlin compromise bomber was arrived at on 11th August, with a top speed of 260 mph and a range of 1,500 miles."
_
If de Havilland were considering a two Merlin bomber with that level of performance in August 1938 it is patently impossible that anything resembling a Mosquito could have been in production two months later. There were not even any drawings for it in August, it was simply an internal company project, being discussed (in the letters) with Freeman.
I don't know when de Havilland made the claim, but I suggest it is influenced by hindsight. He must have been referring to the August 'compromise bomber' a compromise he, or at least his team at Hatfield, disliked and certainly had no intention of building.

It is obvious that a bomber with a maximum speed of 260 mph can't operate unarmed at a time when fighters capable of much higher speeds were already in or entering service. There is no conceivable reason that the Air Ministry would have supported such a project.

In October 1938, when de Havilland suggests a form of Mosquito might be in production, the company was proposing a twin Merlin Albatross retaining wooden construction, armed, with a top speed of 300 mph.
It isn't until more than a year later that a twin Merlin aircraft with a top speeds of 419 and 409 mph were being proposed. The Ministry was understandably sceptical of these figures, several other recent aircraft had failed to live up to expectation, and de Havilland was not a company which had previously done much business with the Ministry.

Cheers

Steve


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## pbehn (Sep 17, 2016)

There are arguments for and against the unarmed bomber, the arguments against seem to be well made excepting that this philosophy ended with 2000 Fairey Battles being ordered. How on earth could a Fairey Battle ever defend itself? Similarly the UKs main bombers at the outbreak of the war were completely unable to defend themselves in daylight either alone or in groups and any one with any sense could see that. They couldnt attack in daylight and they couldnt hit anything at night. The UKs strategic bombers in 1939/42 had a strategy that was no more than an aspiration.

The time lines and correspondence quoted show that the mosquito could not have ever come into being before it did simply because their client was obsessed with defensive armament maximum possible bomb load and more aircrew.

Here is a fantasy scenario. The Air Ministry is concerned about over optimistic proposals for aircraft and so commission De Havilland and A N other to produce two racers both with two Merlin engines one carrying 2000LBs and the other 4000LBs capable of 1500miles range. Contracts and first flights orders into production follow in line with the Spitfire the Fairey Battle is cancelled resulting in 500 twin engined fighter bomber/night fighters and 500 bombers in service in 1940.


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## pbehn (Sep 17, 2016)

Shortround6 said:


> Think of Mosquitoes trying to do daylight raids against defense of P-51 Mustangs. Both planes using essentially the same engine and fuel or similar level of technology.
> We have the luxury of knowing the Germans never got ( or capitalized on) high performance fuels and two stage superchargers. Nobody was 100% sure what the Germans might to might not introduce into service 6 to 18 months in the future at any given time during the war.


The problem with the allied strategic bomber effort was the strategy was frequently obvious, when the defender knows your target and you are travelling towards it at 180MPH at best then the defender has an advantage. A Mustang has a speed advantage when he gets to the bombers altitude but not before, if an intruder is doing 300MPH or more that is 5 miles a minute, in the time taken to track an intruder, scramble an interceptor and vector it to altitude the intruder is in a completely different area of the sky.


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## Ross Sharp (Sep 17, 2016)

Timppa said:


> De Havilland Mosquito
> 
> Any objections ?


The de Havilland Mosquito is an aircraft I am currently heavily involved with. As Director of Engineering and Airframe Compliance, The People's Mosquito Ltd (a Registered Charity, No 1165309), we are converting the remains of an NF.36 to an FB.VI (wing ribs are being cut in New Zealand, as we speak, see The People's Mosquito).

It is quite true that the loss rate/per sortie was vastly improved compared to the Lancaster ('Bomber' Harris stated that the cost of a Lancaster and the training of its crew, could be recouped in terms of damage to the enemy in THREE sorties - provided they dropped their bomb on the target on the third sortie!) Yes, the bomb load options were as laid out earlier in this string (although I would have prefered to travel on 'Platforms 1, 2 or 3' to the Big City in the comfort of a pressurised Mk. XVI with its two-stage Merlins, than the earlier B. Mk IV).

The value of the LNSF was not just in its low loss rate, or its bomb load, or even the smaller crew numbers, but the fact that it could operate when the Main Force could not, due to weather conditions. Not only that, but the superb low-level marking techniques by our friends in No 627 Sqn (please go on our website to see them in action, in COLOUR) meant that the Lancasters of No 5 Group were turned into a precision night bomber force in the later stages of the war (627 could mark the four corners of a football field for you). However, you would still need a proportion of heavy bombers (Harris wanted an all-Lancaster Main Force by 1946) to carry large loads, including the Tallboy and Grand Slam, or the 8,000 HC or 12,000 HC blast bombs. If you could find enough good Canadian Yellow Spruce (and only one tree in 10 is good enough for the main spar) and enough balsa wood (it took a whole Ecuadorian forest, as it is), then I would have gone with a 60/40 mix 'heavies' and Mossies; please remember that the superannuated Stirlings, and the Hastings, also supported the Resistance movements throughout Europe and were excellent heavy glider tugs, etc.

We have chosen to restore RL249 as an FB.VI, but a bit of 'badge engineering' and some care additions/subtractions will allow us to change her into an FB.40, T.27, T.III, FB.XVIII, prototype Sea Mosquito and many other versions. The potential colour schemes and individual markings run into the hundreds

Please watch out for our stand at major U.K. air shows (we were at RIAT, Cosby, Sunderland, Cosford and Duxford this year) and consider supporting us, either by purchasing an item from our online store, or, even better, joining our new People's Mosquito Club bit.ly/TPMClub The Club has its own newsletter, its own website with exclusive articles on Mosquitoes, Club 'swag' (the badge is rather tasteful) and no less than five forum strings. All in all, good value at £25 a year!

There, commercial over......

Cheers

Ross Sharp
The People's Mosquito

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## Snowygrouch (Sep 17, 2016)

This may help.

(Img #3 is hard to see but is dated 2nd Sep 1943 - all images from Ministry of Aircraft Production archives)

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## stona (Sep 18, 2016)

I'd like to know which department/who wrote the third document. It contains some assertions that would have been vigorously challenged by Bomber Command. At the very least it takes a very simplistic view of bomb loads (what would the 4000lb Mosquito load comprise?) and the average Lancaster load given for the first half of 1943 does not reflect the 'Usual Bomb Load' for aircraft of any UK based Groups, nor does it reflect the average Lancaster bomb load for the entire war.
Someone was obviously hoping to promote the Mosquito as a potential strategic bomber (and other roles) for use in the PTO, but without knowing who it is difficult to understand their reasons for doing so.

Nothing ever came of this, which is probably self explanatory! I wonder if someone was trying to flog the Mosquito to the Americans?

I notice one of the performance tables bears a stamp for R N Liptrot, presumably the same one who originated P.13/36 and one of the early supporters of a four engine 'Manchester'.

Cheers

Steve


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## Snowygrouch (Sep 18, 2016)

Oops.... sorry how do you delete posts...ugh


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## Snowygrouch (Sep 18, 2016)

Like many documents, the signature at the end of that letter (which is 4 pages long) is utterly illegible, but I attach the front cover
so you get the general idea, and the 2nd page of the same letter.

I cannot quantify simplistic, but I would mention that the rest of the letter indicates (at least at the time) it would appear this was indeed a very serious high level discussion. Many of the notes later on (regarding other issues) are from Sir Charles Portal, so its fairly big time people talking.

Whoever C.H. S..... is - he was also very involved with "highball" (the bouncing bomb for the Mosquito), as he has signed several others (equally illegibly)
regarding that later on. (But its definetly not C.H. Medhurst... which would have been the obvious choice)

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## tomo pauk (Sep 19, 2016)

Thank you for the docs, Calum.
BTW - I'm still very much interested in that book...


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## stona (Sep 19, 2016)

There was from time to time serious discussion about extending the role of The Mosquito force. This became most strident immediately after the Battle of Berlin, when even Harris to doubt whether the offensive could be maintained by _'the existing methods and types of heavy bombers.'_
It was much too late (and would have been even two years earlier) to change the front line composition of Bomber Command, but it did raise questions about the all heavy bomber policy of the RAF adopted years earlier. Of the 2,034 Mosquito bombing sorties (excluding Serrate and reconnaissance sorties) to Berlin during the battle, just 10 (0.4%) failed to return, though 89 (4.3%) were damaged. Here, once again, we have the benefit of hindsight not available to those making the policy decisions in the immediate pre-war period.

Webster and Frankland hit the nail on the head in the official history when they wrote.

_"Though the value of Mosquito bombers was out of all proportion to their numbers, it was, nevertheless, strictly limited by the fact that they were so few. It was not until March 1944 that the Mosquito bomber components showed signs of expansion, and in that month the average number of these aircraft available with crews for operations was no more than fifty eight. Meanwhile, the Wellington component was disappearing so that in the Battle of Berlin the ideal dating back to 1936, of an 'all heavy' bomber force found its ultimate expression, if not its vindication."_

There was never any suggestion that the Mosquito would operate at low level or by day, at least not as routine, just that equipped with the latest versions of the navigational aids it would operate as a night bomber. In this role it would, as it did historically, suffer far lower losses than the heavy bombers. It could never have delivered the devastation of the successful area raids, or the more precise raids undertaken from time to time. The often repeated suggestion that it could carry half the load of a Lancaster (on similar missions) is nonsense.

Cheers

Steve


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## Timppa (Sep 19, 2016)

stona said:


> The often repeated suggestion that it could carry half the load of a Lancaster (on similar missions) is nonsense.



Mosquito had the proven capability to carry 4,000 lbs to Berlin from the start (Mark B.IV mod).
The figures of the average Lancaster bomb load to this distance I have seen quoted is about 7,500 lbs.


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## stona (Sep 19, 2016)

The first raid with Mosquitoes carrying a 4000lb cookie took place on *23rd February 1944 *carried out by three modified Mk.IVs with 4000 pounders, backed up by another aircraft with 4 x 500lb bombs, all following six 105 Squadron Mosquitoes which marked the target (Dusseldorf). Throughout the last six months of 1943 Mosquitoes raided Berlin with a maximum load of 6 x 500lb bombs (two carried externally), a respectable 3,000lbs. This was above the average carried by the type throughout the war, but early versions could not manage anything like this load.

The possibility of carrying a 4000lb bomb, eventually General Purpose, Medium Capacity and High Capacity versions would all be shoe horned in, was first raised in April 1943. It was not a straight forward adaptation and it wasn't until 9th October 1943 that a decision was made to modify all Mk. IVs and Mk. IXs in service and that all Mk. IXs and Mk. XVIs in production would be built with the capacity to carry the larger bombs. This NEVER happened.
In January 1944 Boscombe Down provisionally passed the Mk. IV for service, but only with the large elevator horn balance, rear camera removed and 60lb ballast in the nose. Stability problems were never solved on the Mk. IV and this is why very few Mk. IVs or Mk. IXs were modified.
It was only the B. Mk. XVI which, having been designed from the outset to carry a 4000lb bomb, did so successfully and in numbers. Operations with this aircraft didn't begin until* March 1944.*

It wasn't until November 12th 1941 that the possibility of carrying the often quoted 4 x 500lb bombs was even investigated. This was to be for a proposed B. Mk. VB version. This load wouldn't fit in the bomb bay of the Mosquito which had been designed for a 1,000lb load (2 x 500lb or 4 x 250lb bombs). It was only after experiments with telescopic fins on the bombs that the short finned versions were adopted. The extra load led to instability problems and a new tailplane with a 10 degree dihedral was designed to mitigate these, longer nacelles were also developed.

Lancaster Marks varied, as did the distance of their operational airfields from Berlin, but most could a 12,000lb load to Berlin. The Mk.I and Mk.III could both carry 14,000lbs for 1,660 miles. Not all did for reasons already mentioned. The average bomb load carried by Lancasters and Mosquitoes throughout the war I have already given in this thread, the Lancaster's is nearly 5 times that of the Mosquito, at least in part because the Mosquito did not have the ability to carry the 4,000lb so often referred to until the last year of the war.

Average figures must be carefully examined. For example, the average bomb load for ALL RAF bombers for 1943 was 6,903 lbs and for 1944 8,250 lbs. Sometimes I wonder if these figures get attached to particular aircraft in some way. Incidentally, both these figures are more than twice those for the bombers of the USAAF the same periods (3,220 lbs and 3,980 lbs, whatever the theoretical maximum loads of the B-17, B-24, etc. might have been).

Cheers

Steve

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## tomo pauk (Sep 19, 2016)

Whether we agree or don't agree with the original premise, this turned out to be an excellent thread.

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## stona (Sep 19, 2016)

[QUOTE="Snowygrouch, post: 1287619, Many of the notes later on (regarding other issues) are from Sir Charles Portal, so its fairly big time people talking...

Whoever C.H. S..... is - he was also very involved with "highball" (the bouncing bomb for the Mosquito), as he has signed several others (equally illegibly)
[/QUOTE]

I'm sure you know your Portals, but there was an Admiral Portal (Charles Portal's brother) involved with 'Highball' in the Pacific. It was this Admiral Sir Reginald Portal who informed No. 618 Squadron, on 29th June 1945, that it was about to be disbanded. The weapons were destroyed by an order of 10th July, rattling windows and causing considerable alarm to the usually unflappable citizens of Sydney 
Cheers
Steve

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## GrauGeist (Sep 19, 2016)

I'm not sure if this has been addressed before and if it has, my apologies, but what was the performance penalty on the Mosquito when at max. load?

In otherwords, was it under risk of being caught by standard Luftwaffe interceptors (Bf109, Fw190, etc.) until it dropped it's load?


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## Hop (Sep 19, 2016)

pbehn said:


> Yes, a cookie was a bomb to blow off roof tiles it had most effect when it exploded above ground, such a bomb would have almost no effect on the important parts of a refinery, if you see the remains of German cities they were burned to the ground but the brick structure ws standing, a steel structure would be unaffected.
> 
> To wreck a refinery you need a huge blast to destroy or undermine the pressure vessels which take months to construct or repair, damaging pipework and instruments can be rectified in days.




The cookie was very effective against structure and machinery.

From the USSBS, describing attacks on refineries:



> Blast walls and reinforced concrete "dog houses" were useless against 4,000-lb. bombs, but prevented serious damage from near misses by 1,000-lb. bombs and were effective against even direct hits of 500-lb. and smaller bombs. But the utility systems were vulnerable, and the oil attacks were therefore successful.



and



> Vital process installations were so effectively protected by blast walls and reinforced concrete "dog houses" that essential, hard-to-replace equipment was seldom destroyed by the munitions generally employed. In a few instances, of which the Bottrop-Welheim (Ruhroel) hydrogenation plant is the most striking example, this destruction was accomplished. In two raids, 27 September and 31 October 1944, the RAF hit the high-pressure compressor house with three 4,000-lb. and eight 1,000-lb. bombs. The seven heavy compressors and boosters, through which was funneled every cubic foot of the hydrogen required for the process, were completely destroyed. The plant could not operate until new compressors were installed. This meant a twelve-month shutdown if new compressors had to be built and a delay of three months of replacements had to be "lifted" from another plant. The four subsequent attacks were unnecessary. The results may be compared with those at Leuna, which, after being hit by 1,643 tons of bombs in 22 attacks, could have reached 70 percent of normal production capacity within a few months without the importation of any new heavy equipment.

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## Shortround6 (Sep 19, 2016)

The Mosquito as a strategic bomber replacement for the 4 engine bombers requires several time line shifts.
It also requires a change in bombing tactics/techniques that may or may not have been as effective as what was used. 

The Early Mosquito was limited to the 1000lb bomb load. The documents provided by Snowygrouch show this even in reference to _planned/proposed _versions using Merlin 60 engines as of July 25th 1941. By May of 1942 the bomb load had gone to 2000lb inside the bay using the shortened 500lbs and a further 500-1000lbs under wing. Or even six 250lb bombs. Not sure if this was due to supply or doctrine or a combination of both. Documents show _estimated _performance with a Melrin 61 _type_ (power level) engine as the Mosquito could not use Merlin 61s due to the radiator placement (difference was minor). 
An early Mosquito (service use in 1940 or early 1941) would not have had Merlin XX engines (Hooker supercharger) and would either have had shorter range or been limited in bomb load even if short fin bombs were available.
And it doesn't matter what kind of airplane is dropping the bombs, the RAF in 1940-41 couldn't find the right city on too many of it's missions at night so there would have no change in effectiviness, in fact one might argue that it would have been less on the occasions the right city was found as finding even a large factory was still very difficult and dropping less bombs would not have helped. (and in 1940-41 the Bombers in use were pretty much Wellingtons and Whitleys which were much closer in price to the Mosquito). 

An awful lot is made of the 4000lb cookie and _average _bomb weights. The Mosquito's bomb bay was much more limited by volume than by weight (even with the bulged doors) and a lot of times the* average *weight of the 4 engine bomber loads is skewed by their large use of incendiaries. The Incendiaries having a larger volume to weight ratio. This varies a bit by type/s of incendiaries but what was the Mosquito's ability to carry incendiaries or small bombs? 




Could a Mosquito fit four of those incendiary bundles in it's bomb bay? The Lancaster could hold 15 without the big bomb. 
the Halifax wasn't far behind.




Up to six small bomb carriers in the wing bays in addition to the bomb bay. 





Pictures from an Oct 1944 raid. 

By the time the Mosquito had demonstrated it's capability (say mid 1943) for even a 3000lb bomb load. it would have taken well over a year to change production around. Maybe two years. 

Lets not forget that the _Specification_ for the Manchester called for a CRUISING speed of 275mph. What they got was a plane that had a TOP SPEED of 265mph and cruising speed much lower. Unfortunately high speed and short field performance where conflicting requirements, even if you ditched the gun turrets a 1937-39 bomber trying to use existing RAF airfields has a real problem with airfoils, wing size, and even the size/weight of it's landing gear (large engine nacelle needed) all affecting the drag over an optimized high speed design, making an "early" Mosquito even more unlikely.


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## wuzak (Sep 19, 2016)

Shortround6 said:


> The Early Mosquito was limited to the 1000lb bomb load. The documents provided by Snowygrouch show this even in reference to _planned/proposed _versions using Merlin 60 engines as of July 25th 1941. By May of 1942 the bomb load had gone to 2000lb inside the bay using the shortened 500lbs and a further 500-1000lbs under wing.



The under wing stores came later with the universal wing for the FB VI.

I don't believe any Mosquito bomber went into operation service with the 1,000lb restriction. By the time they went into service they had the 2,000lb restriction.

Testing later in 1942 even included a load of one 1,000lb GP and two 500lb MC.




Shortround6 said:


> An awful lot is made of the 4000lb cookie and _average _bomb weights. The Mosquito's bomb bay was much more limited by volume than by weight (even with the bulged doors) and a lot of times the* average *weight of the 4 engine bomber loads is skewed by their large use of incendiaries. The Incendiaries having a larger volume to weight ratio. This varies a bit by type/s of incendiaries but what was the Mosquito's ability to carry incendiaries or small bombs?
> Could a Mosquito fit four of those incendiary bundles in it's bomb bay? The Lancaster could hold 15 without the big bomb.
> the Halifax wasn't far behind.



The Mosquito B.IV/B.XX could carry four 160lb or 250lb Small Bomb Containers internally, but only two of the larger 500lb SBCs - these were on the forward stations (last of the internal stations to release). I would have to check, but I believe two 500lb MC bombs could be carried on the rear racks at the same time as carrying the 500lb SBC. They could also be carried on the wing racks.



wuzak said:


> Canadian built Mosquito MK XX VB328 was checked for its bombing installation and found to be be the same as the IX.
> 
> Tests conducted were with standard bombs - 500lb MC/GP and 250lb GP/SAP, 500lb SAP as well as the 250lb SBC. It was noted that the 500lb SBC could only be fiteed to the forward carriers, as when fitted to the rear they fouled the hydraulic door mechanism. It was noted, from prior experience, that 4 of the 160lb SBC could be carried, though they didn't have any to test.



Incendiaries didn't just come in small bombs. They also had sizes similar to the GP bombs. I believe they also had a 4,000lb IB. I will have to check when I get home.


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## stona (Sep 20, 2016)

Bomber Command dropped almost exclusively 4lb and 30lb incendiaries. 
There was some debate about the relative effectiveness of the two, but the 4lb incendiary in its various forms was used almost exclusively from 1943, on area raids, until the end of the war.
The 250lb incendiary bomb was converted into a TI bomb. The 500lb (phosphorus) incendiary bomb was used by Mosquitoes according to some sources.

During the war Bomber Command dropped 80,000,000 4lb incendiaries and just 3,000,000 30lb incendiaries. 7,000 250lb incendiaries were dropped and IF Mosquitoes did indeed drop the 500lb version I can find no record of it.

The load in the Lancaster bomb bay above was code named 'Usual'. It is a typical blast and incendiary load designed for an area raid. Other aircraft would drop some HE loads to interfere with flak, fire fighting efforts and hopefully to fracture gas and water mains.

The Mosquito couldn't carry enough bombs to carry out some of the missions assigned to the heavy bombers. I have already mentioned the problem of incapacitating and keeping out of action selective targets, like those of the oil and transport plans. I also mentioned the sheer weight of bombs dropped in support of ground troops following the invasion.

Obviously the Mosquito was not suitable to carry out area type raids. The weight of bombs required was beyond that of even a force of hundreds of the type. There is no saying that precise targets could be hit, at night, and from altitude by a Mosquito anymore than a Lancaster.
Dresden is an outstanding example of the concentration of bombing in space and time to achieve a really successful area raid.

The first wave, comprising 5 Group (244 aircraft) dropped 881.1 tons of bombs on the centre of the city in 15 minutes (between 22.13 and 22.28). 57% by weight were HE and 43% incendiary. This would have been enough, but then a second wave arrived.

8 Group (60 aircraft including master bomber, markers and illuminators) bombed from 01.21 to 01.45 and dropped another 135.7 tons of bombs, including 10 tons of TIs and 550 Illuminators (Christmas Trees)

1 Group (248 aircraft) bombed from 01.23 to 01.52 and dropped 387.3 tons of high explosive and 558.3 tons of incendiaries. (219,933 4lb stick incendiaries, 28,467 4lb incendiaries with explosive charge, 70,266 4lb incendiaries 'bundled' in clusters, No. 14 cluster was 158 x 4lb incendiaries, a No. 15 cluster was 104 of the same.)

3 Group (151 aircraft) bombed from 01.25 to 01.55 and dropped 234.8 tons of high explosive and 233.0 tons of incendiaries.

6 Group (65 aircraft) bombed from 01.27 to 01.45 and dropped 216.8 tons of high explosive.

Total number of 4000lb cookies dropped, maximum load of a Mosquito, was 356. 2,647 tons of ordnance fell on the city in the two waves. The idea was to devastate the city in support of the Soviet offensive. It succeeded in that. What could a force of even several hundred Mosquitoes have achieved? They might have attempted to attack the railway station and other rail and transport infrastructure, but who knows if they would have hit it.

It is, as I intimated elsewhere, not fair to compare the Lancaster and Mosquito as strategic bombers. The Mosquito was not designed to be one, nor could it fulfill that role, whereas the Lancaster was and did. The Mosquito had many other strengths, and performed outstandingly in various other roles.

Cheers

Steve


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## stona (Sep 20, 2016)

wuzak said:


> I don't believe any Mosquito bomber went into operation service with the 1,000lb restriction. By the time they went into service they had the 2,000lb restriction.



That is correct. The first bomber version (B. Mk. IV) had a 2,000lb bomb load with 539 gallons of fuel. 
The largely unsuccessful 'cookie' conversion could carry the 4,000lb bomb, but reduced fuel capacity to 497 gallons (and operational radius to 535 miles.)
Cheers
Steve


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## Shortround6 (Sep 20, 2016)

stona said:


> That is correct. The first bomber version (B. Mk. IV) had a 2,000lb bomb load with 539 gallons of fuel.
> The largely unsuccessful 'cookie' conversion could carry the 4,000lb bomb, but reduced fuel capacity to 497 gallons (and operational radius to 535 miles.)
> Cheers
> Steve



Thank you. 
I was going by the documents in Snowygrouch's posts, not as what was in service but but what was planned or intended at earlier than service dates as an check on_ when or if _a change in direction could have been made. The loads listed for the MK V bomber and MK VI fighter bomber 




going by the date on the bottom 13-5-42 would seem to indicate that at around that time the wing stations were _planned_ at 250lbs each and the internal bomb stations were planned for 250lb bombs. Work being done on the 500lb bombs with telescoping fins? Since no Mosquito ever flew using either Merlin XX (Merlin 21,23,and 25 differed in detail from the XX but not in performance) or Merlin 61 engines this would be estimated performance using those engines as a reference point. 
In the Spring of 1942 a 2500lb bomb load would hardly be looked at as a substitute for a strategic bomber in planning for future production (1-2 years ahead)


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## stona (Sep 20, 2016)

Hop said:


> The cookie was very effective against structure and machinery.



Does the report refer to 'cookies' that is High Capacity bombs? Not all 4,000lb bombs were 'cookies'.

The 4,000lb High Capacity bomb was specified in September 1940 and sometimes referred to as a 'mine-bomb'. I have seen it referred to as a 'mine' in Bomber Command Squadron ORBs even in early 1945.

The original specification included requirements that,
_i) It could be carried by a Wellington
ii) It was for the attack of ships in shallow waters, harbours, canals and land targets such as oil plants _[which were top of targeting lists at this time]
_iv) To be released from 1,500 feet without breaking up
v) Instantaneous and delay fusing
vi) Capability to be used as a magnetic mine, with a magnetic fusing system._

I don't know that it was used for these objectives, I can't find any evidence for it being used as a magnetic mine. It was soon discovered that the blast complemented other ordnance dropped as Bomber Command developed its tactics for area raids, and in this sense pbehn is correct. For incendiaries to be most effective it is important that they lodge inside buildings, roof spaces, etc. Blowing in windows and blowing off roof tiles with high capacity bombs greatly increased the chances for this happening.
It was a bonus that the blast from a 4,000lb High Capacity bomb was calculated to destroy 3.2 acres per ton dropped, much better than the 0.56 acres per ton of the 1,000lb GP bomb. This acreage destroyed was for typical city areas, housing, shops and small businesses.

Cheers

Steve


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## stona (Sep 20, 2016)

The Mark V bomber (B. Mk. V) was a projected project and the wing stations were indeed planned for two x 250 lb bombs or 2 x 50 gallon fuel tanks. Various versions were projected (the redoubtable W4057 served as a prototype for these among many others) but none were built. As far as I know the planned engine was the Merlin 21.

The F.B.VI was built and did could carry 4 x 250lb bombs, two externally, as well as a bewildering array of other ordnance in various configurations.

Cheers

Steve


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## wuzak (Sep 20, 2016)

Shortround6 said:


> Since no Mosquito ever flew using either Merlin XX (Merlin 21,23,and 25 differed in detail from the XX but not in performance) or Merlin 61 engines this would be estimated performance using those engines as a reference point.



W4050 did fly with Merlin 61s. First flight June 20 1942, short wingspan, short nacelles and short No 1 tailplane. Fitted with snow guards on the intake it achieved 428mph @ 28,500ft and without snow guards 437mph @ 29,200ft.

Of course the main difference between the 21 and the XX was the reversed flow cooling system. This was installation specific, but otherwise the 21 was as the XX.


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## stona (Sep 20, 2016)

wuzak said:


> W4050 did fly with Merlin 61s. First flight June 20 1940,.



Surely not 1940!!!!!

I think you meant 1942. 

On the second flight, in the configuration described, the aircraft supposedly reached 40,000 ft, but tail buffeting occurred and subsequently, at the end of the month, long nacelles and a No. 2 tailplane were fitted.

The Merlin 61 seems to have been by-passed in production Mosquitoes, maybe required for Spitfires? The next variants were Merlin 72/73 or Merlin 76/77 powered.

Cheers

Steve


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## wuzak (Sep 20, 2016)

stona said:


> Surely not 1940!!!!!
> 
> I think you meant 1942.
> 
> ...



Yes, I meant 1942. Fixing it now!


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## Hop (Sep 20, 2016)

stona said:


> Does the report refer to 'cookies' that is High Capacity bombs? Not all 4,000lb bombs were 'cookies'.
> 
> Steve



It doesn't specify which type of 4,000 lb bomb, but the only likely options were the 4,000 lb High Capacity (cookie) or 4.000 lb Medium Capacity. The Mosquito could drop either, but according to Harris, the MC bomb wasn't used much by the heavies, and most were dropped by Mosquitoes. 

The two raids in question were carried out by heavies (there were 8 Mosquitoes on the first one, which I presume were pathfinders) so the bombs were almost certainly cookies.

In general, destroying buildings and machinery required lots of explosive. The shrapnel from bomb cases wasn't effective against buildings or machinery. Against a really hardened target with several feet of concrete a cookie would be ineffective, but "reinforced" factory and plant buildings couldn't withstand the explosion of 3,000 lb of HE in contact with the building.

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## stona (Sep 20, 2016)

27th September. Bottrop. 175 aircraft attacked (96 Halifaxes, 71 Lancaster, 8 Mosquitoes). Bombing on Oboe place sky markers due to conditions. Some aircraft bombed through gaps in the cloud. No losses.

31st October. Bottrop. 101 Lancasters of 3 Group carried out a G-H attack on the oil plant.

The 11 hits mentioned by the USSBS were the result of bombing by at least 275 aircraft, and this, in the context of the thread, is the problem facing the Mosquito and its relatively light bomb load. If I had to bet I'd put my money on the damage being done on the second raid, as bombing on sky markers was usually relatively inaccurate.

Cheers

Steve


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## Shortround6 (Sep 20, 2016)

wuzak said:


> W4050 did fly with Merlin 61s. First flight June 20 1942, short wingspan, short nacelles and short No 1 tailplane. Fitted with snow guards on the intake it achieved 428mph @ 28,500ft and without snow guards 437mph @ 29,200ft.
> 
> Of course the main difference between the 21 and the XX was the reversed flow cooling system. This was installation specific, but otherwise the 21 was as the XX.



Thank you. Main difference between a Merlin 61 and a Merlin 72 was the cooling system, although the 72 was rated for higher boost. First two stage reverse flow Merlin being the Merlin 67 although that was built in small numbers (under 75?) and Lumsden does not list any aircraft fitted with it?


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## tomo pauk (Sep 20, 2016)

stona said:


> 27th September. *Bottrop.* 175 aircraft attacked (96 Halifaxes, 71 Lancaster, 8 Mosquitoes). Bombing on Oboe place sky markers due to conditions. Some aircraft bombed through gaps in the cloud. No losses.
> 
> 31st October. *Bottrop.* 101 Lancasters of 3 Group carried out a G-H attack on the oil plant.
> ...



<shivers>

Brabus immeditely comes to mind of a proper gearhead


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## wuzak (Sep 21, 2016)

I have a book, Simons, _Mosquito, the Original Multi-Role Combat Aircraft_, which has a list of what was carried by Mosquito bombers during the war.

It lists 3 types of 4000lb bomb - the 4,000lb HC, around 770-780 of those, the 4,000lb MC of which 141 were dropped, and a 4,000lb M2 of which some 6-7,000 were used.

I am wondering if the M2 is the Mk II version of the 4,000lb HC?

It also lists some incendiaries, including the 4lb Mk 14 and 15, which were used in bundles. 

I will put up the list when I get home.


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## wuzak (Sep 22, 2016)

Aozora posted the bomb chart a few years ago:

WW2 Strategic Bomber Characteristics


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## stona (Sep 22, 2016)

wuzak said:


> It also lists some incendiaries, including the 4lb Mk 14 and 15, which were used in bundles.
> .



I'm not sure why he refers to 'Mk' 14 and 15 incendiaries. The Mark, usually given as 'Number' in ORBs, refers to the bundle/cluster not the bombs of which most were versions of the Mk. IV incendiary. I mentioned earlier in this thread that the No. 14 cluster was 158 x 4lb incendiaries, a No. 15 cluster was 104 of the same. The incendiary bombs had a hexagonal shape, making them easy to bundle.
Armourers liked these as otherwise they had to load each bomb individually into the SBCs. When we consider the 80,000,000 x 4lb incendiaries dropped that's a lot of loading!

Around 10,000 x 4,000lb bombs dropped is the figure usually attributed to the Mosquito, so the figures you give are in the ball park.
Mosquitoes under Bomber Command flew 39,795 sorties during the war and dropped just over 10% of all 4,000 lb bombs, a significant contribution given their numbers.
Bomber Command dropped a total of about 90,000 x 4,000 lb bombs of various types during the war, principally HC (68,000) and MC (21,000).

I think M2 does refer to the Mk II version, and probably of the HC bomb but it is not clear (the MC bomb had Mks. I and II in service too).
Maybe someone will find some clarification, I'm not familiar with the M2 designation.

Cheers

Steve


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## wuzak (Sep 22, 2016)

WW2Equipment lists the number of 4,000lb HC bombs used as 93,245.

The breakdown given is:
1941 531
1942 4,335
1943 25,476
1944 38,035
1945 24,868

The site also states that "Over 21,000 4,000lb MC bombs were dropped by Bomber Command with 13,000 of these being dropped in 1944." on the page for the 4,000lb MC bomb.

Sharp and Bowyer agree with Simons on the numbers of HC, MC and M2 bombs used by the Mosquito, as well as the 8 4,000lb IBs!

Both agree that 141 4,000lb MC bombs were dropped, which isn't a lot. I know that some were used on an attack on an oil refinery about the middle of 1944. I will have to check the ORBs I have to see which squadron. 

Sharp and Bowyer list the number of incendiary clusters dropped as 6,678 x Mk 14 (106 x 4lb) and Mk 15 and 3,160 x Mk 15 (158 x 4lb).


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## wuzak (Sep 22, 2016)

109 squadron dropped some 4,000lb MC bombs on Homburg in the night of 25/26 June 1944.


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## stona (Sep 22, 2016)

I think the figures all tally fairly well. I took my numbers from MacBean and Hogben (Bombs Gone). 

They are also quoted in the RAF Historical Society Journal from time to time, when the subject comes up. Journal 45 has some good stuff on this and related subjects.

Cheers

Steve


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## stona (Sep 26, 2016)

Flicking through the book above I came across an illustration of a 'Cluster Projectile 500 lb no. 14', the one containing 106 x 4lb incendiaries, sometimes referred to as 'aimable bomb clusters'.







The authors (who know a thing or two about British ordnance) make the following comments.

"_The latter's effectiveness_ [4 lb incendiary] _improved enormously in 1944, when it was dropped in aimable bomb clusters. These disintegrated at low-level altitude, permitting greater concentrations of the contained bombs (child stores), rather than showering them down from small bomb containers (attached to the aircraft) from high altitude. The advent of the clusters also largely circumvented the possibility of a bomber at higher level inadvertently hitting his colleagues flying below with, in the case of the Lancaster, something like 3,000 four pounders." _

A two squadron bomber station like East Kirkby (Nos. 57 and 630 Squadrons), where one of the authors was the armaments officer in 1944, typically loaded 190 tons of ordnance on its 35-40 four engine bombers everyday. This is what they wrote about the workload imposed by the incendiaries.

_"Incendiary bombs produced the greatest workload, many hours being expended in unboxing well sealed four pounders and restowing them in Small Bomb Containers for carriage on the aircraft. The advent of made-up clusters of incendiaries in 1944 eased that burden somewhat."_

Cheers

Steve

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