German heavy bombers

[Geoffrey Sinclair]

Kesselring summarises the situation quite well, but overstates things at times Expecting a jump to designs weighing something like twice as much empty as the loaded weights of the latest types, like the Do17 and He111, would require much to go right. Remembering in the late 1930's the Wellington was a heavy bomber, staying there until the 4 engined types turned up, and expected to do lots of damage to industry it bombed. In the 1930's the Germans had to generate foreign sales to pay for much of the light metals and oil it used.

The mission defined the bomber, an Fw190 flying at night to drop a bomb on London is a strategic bomber, how many Japanese strategic targets did B-17 and B-24 missions attack? The Germans did not have tactical and strategic bombing as concepts. The damage to Britain in 1940/41 and the radio navigation systems indicates the Luftwaffe had the capability to undertake strategic bombing as per doctrine that allowed for it and other air operations depending on the situation. There is no fundamental reason why the missions actually flown by the German twin engined bombers in 1940/41 could not be flown by 4 engined types, being mostly air superiority and battlefield interdiction plus night strategic raids on Britain. The 8th Air Force dropped 81,803.5 tons of bombs on airfields for example. A larger aircraft has to fly higher to cut the risk of damage from ground fire, which reduces bombing accuracy but it normally carries more bombs, as noted larger transport aircraft is generally more efficient per unit of cargo, including personnel, fuel, build and maintenance costs.

The RAF and the USAAF came up with range/bomb load requirements that meant fitting 4 engines given the available power plants in the mid to late 1930's. The only attempt at a twin engine design that reached service had engine problems. The Germans wanted to bomb targets in the Urals and in any case solved the range issue by conquest until the USSR reorganised its war economy and the Luftwaffe really had to make the jump to B-29 class performance in the east to do strategic air warfare.

Going deep into enemy areas means damage to your units hurts more and the best you can normally hope for the personnel are captured, Germany was undertaking major submarine warfare, adding major strategic air warfare would be another significant drain on highly trained personnel.

As of 5 May 1940 Williamson Murray reports the Luftwaffe had 1,369 bombers and 321 long range reconnaissance.

Starting with money as short hand for resources. Build costs are subject to economies of scale, fewer designs the better but the greater the risk of large scale failure in combat. In 1944 the USAAF thinks it cost $204,370 for a B-17, $215,516 for a B-24, $192,427 for a B-26 and $142,194 for a B-25. Looking at the breakdown in costs the big one is engines, the B-17 engines cost on average $35,541 from 4 different price calculations, the B-24 $34,265, the B-25 $29,239 and the B-26 $44,403. In money terms in 1944 the 1,000 B-24 fleet translates to 1,120 B-26 or 1,516 B-25.

Britain June 1941 expected unit costs for proposed orders, in pounds,
44,250 Lancaster
43,752 Halifax
52,300 Stirling
38,100 Warwick
27,700 Wellington
18,950 Mosquito

On that basis a 1,000 Lancaster fleet translates to 1,597 Wellingtons, Stirlings even more.

Prices quoted for France 1945/6
37-40,000 Lancaster I
40,000 Halifax
15,000 Mosquito VI
16,000 Mosquito 30
16,000 Mosquito PR XVI
16,300 Mosquito PR.34
26,000 Wellington XIII
25,000 Wellington XIV

When it comes to twins versus four engine types the exchange rate is very design dependent. Assuming the proposed German design cuts numbers to 60% of the nearly 1,700 twin engine fleet that comes to around 1,000 aircraft. If the reconnaissance force had to be maintained at the 300 aircraft level that would have the bomber force. A smaller bomber force makes escorting easier, with the higher fighter to bomber ratio available. Germany had the capacity to build a large 4 engined bomber force in the late 1930's if a suitable design was available. It would obviously reduce the number of bombers but by how much depends on how much harder it was to build than mainly the Do17 and He111. Remembering in peace time defend the budget, wartime defend the country.

Timeline, Do17 requirement in 1933, first flights in 1934, He111 design began in 1934, first flight in February 1935, Ju86 first flight November 1934, Ju88 project work began in early 1936, first flight in December. Fw200 design began in 1936, first flight July 1937. Any 4 engine design would probably need to fly in 1935 or early 1936 to be in mass production in 1939 in the numbers needed to create a 1,000 strong force, and with designs that gave the Luftwaffe better bomb lift, easy for replacing the Do17, harder for the He111. He111 and Do17 production were each running at about 30 a month in 1937. The Do217 proposal in 1937, first flight in mid 1938, into service in 1941

Apart from his work on Luftwaffe doctrine General Wever was important as the glue holding together the Luftwaffe high command, afterwards feuding between the senior commanders increased to the point it harmed the air force, with a new chief of staff on almost a yearly basis to 1936 to 1939 doctrine and planning became more short term. Whether Wever could have arranged for a viable 4 engined bomber in 1939 performance terms arriving then is unclear as the designs actually ordered when he was around were for attacking locations in the Urals, a requirement which set the Do19 and Ju89 designs up to fail, to have a chance the specification needed to change to targets in Britain. If he had still been around the Luftwaffe would probably have more early war staying power and willingness to absorb the lessons from 1940 while being less interested in giving most bombers dive bombing capacity which reduced performance and delayed development.

Not sure how valid the following is, using wartime averages hides the big shifts in the fighting and given the half way points for bombs on Germany was end September 1944 for Bomber Command and mid November 1944 for the 8th Air Force flatters the loss figures.

Tons are long tons for the RAF and short tons for the USAAF, losses include accidents etc. on operations, sorties are attacking for the RAF and effective for the USAAF. All war Bomber Command and the 8th Air Force. First the raw numbers

type	tons	pounds	MIA+Cat E	Sorties	%loss	lb/sortie	lb/loss	Short ton/loss
Mosquito	26,867.0​	60,182,080​	283​	24,961​	1.13​	2,411.04​	212,657.53​	106.33​
Wellington	41,823.0​	93,683,520​	1,523​	31,657​	4.81​	2,959.33​	61,512.49​	30.76​
Whitley	9,845.0​	22,052,800​	414​	7,311​	5.66​	3,016.39​	53,267.63​	26.63​
Hampden	9,115.0​	20,417,600​	499​	10,259​	4.86​	1,990.21​	40,917.03​	20.46​
Stirling	27,821.0​	62,319,040​	606​	9,409​	6.44​	6,623.34​	102,836.70​	51.42​
Halifax	224,207.0​	502,223,680​	2,113​	66,456​	3.18​	7,557.24​	237,682.76​	118.84​
Lancaster	608,612.0​	1,363,290,880​	3,726​	135,445​	2.75​	10,065.27​	365,885.90​	182.94​
B-17	477,201.7​	954,403,400​	4,228​	185,704​	2.28​	5,139.38​	225,734.01​	112.87​
B-24	209,949.0​	419,898,000​	1,630​	78,914​	2.07​	5,320.96​	257,606.13​	128.80​

Next some ratios, pounds dropped per attacking/effective sortie, read across the Wellington dropped 1.23 times the Mosquito bomb load per sortie, read down it took 0.81 Wellington sorties to equal 1 Mosquito

Aircraft	Mosquito	Wellington	Whitley	Hampden	Stirling	Halifax	Lancaster	B-17	B-24
Mosquito	1.00​	1.23​	1.25​	0.83​	2.75​	3.13​	4.17​	2.13​	2.21​
Wellington	0.81​	1.00​	1.02​	0.67​	2.24​	2.55​	3.40​	1.74​	1.80​
Whitley	0.80​	0.98​	1.00​	0.66​	2.20​	2.51​	3.34​	1.70​	1.76​
Hampden	1.21​	1.49​	1.52​	1.00​	3.33​	3.80​	5.06​	2.58​	2.67​
Stirling	0.36​	0.45​	0.46​	0.30​	1.00​	1.14​	1.52​	0.78​	0.80​
Halifax	0.32​	0.39​	0.40​	0.26​	0.88​	1.00​	1.33​	0.68​	0.70​
Lancaster	0.24​	0.29​	0.30​	0.20​	0.66​	0.75​	1.00​	0.51​	0.53​
B-17	0.47​	0.58​	0.59​	0.39​	1.29​	1.47​	1.96​	1.00​	1.04​
B-24	0.45​	0.56​	0.57​	0.37​	1.24​	1.42​	1.89​	0.97​	1.00​

Now comes the ratios, losses per pounds dropped, read across the Wellington dropped 0.29 times the Mosquito bomb load per loss, read down the Wellington loss rate per pound of bombs dropped was 3.46 times the Mosquito

Aircraft	Mosquito	Wellington	Whitley	Hampden	Stirling	Halifax	Lancaster	B-17	B-24
Mosquito	1.00​	0.29​	0.25​	0.19​	0.48​	1.12​	1.72​	1.06​	1.21​
Wellington	3.46​	1.00​	0.87​	0.67​	1.67​	3.86​	5.95​	3.67​	4.19​
Whitley	3.99​	1.15​	1.00​	0.77​	1.93​	4.46​	6.87​	4.24​	4.84​
Hampden	5.20​	1.50​	1.30​	1.00​	2.51​	5.81​	8.94​	5.52​	6.30​
Stirling	2.07​	0.60​	0.52​	0.40​	1.00​	2.31​	3.56​	2.20​	2.51​
Halifax	0.89​	0.26​	0.22​	0.17​	0.43​	1.00​	1.54​	0.95​	1.08​
Lancaster	0.58​	0.17​	0.15​	0.11​	0.28​	0.65​	1.00​	0.62​	0.70​
B-17	0.94​	0.27​	0.24​	0.18​	0.46​	1.05​	1.62​	1.00​	1.14​
B-24	0.83​	0.24​	0.21​	0.16​	0.40​	0.92​	1.42​	0.88​	1.00​

Now choose the best bomber.

 

[tomo pauk]

Now maybe the Fw 200S (super) can carry 6000lbs inside (50% more than an He111 and 3 times what the Do-17Z can carry) and carry them further. But in 1940 how far do you need to carry them and 5-7 7.9mm machine guns are not going to protect the bomber very well.

Three Do-17Zs needed 3 pilots and 3 bombardiers (I'm not sure whether there was a dedicated position for the navigator - seems like that was not the case). One Fw 200S will need just one pilot (granted, it will take a bit more to train him, but still), and one bombardier, as well as a navigator? So far we've saved 2 complete powerplants, and 1.5-2 pilots.
Have 500 of them being made instead of the last 1500 Do 17s (so the total payload is the same), that means 1500-2000 less pilots needed, as well as saving of 2000 complete powerplants.

Sorry, Albert, we're saving the money and manpower, not the other way around.

 

[OldGeezer]

The Ural Bomber initiative was the German name for a project that's been well documented. It's worth reading up on if you have an interest. Actually, for once the Wikipedia article is pretty good.

 

[tomo pauk]

The Ural Bomber initiative was the German name for a project that's been well documented. It's worth reading up on if you have an interest. Actually, for once the Wikipedia article is pretty good.

The disclaimer on the English language Wikipedia entry about the Ural bomber:

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.

 

[bf109xxl]

The disclaimer on the English language Wikipedia

There's also the German-language Wikipedia. It contains a reference to the book "Der Chef im Hintergrund: ein Leben als Soldat von der preußischen Armee bis zur Bundeswehr" by Paul Deichmann, Oldenburg 1979. According to the book, the name "Uralbomber" was already used in the Luftwaffe Management Department in 1936. The book is available in the library, I can take a look if necessary. But delivery will take two or three weeks.

 

[bf109xxl]

One more source.

Journal of Strategic Studies 1(1978)154-178 (Iss.2)
From 'uralbomber' to 'amerikabomber': The Luftwaffe and strategic bombing
R.J.Overy

In the formative years of the Luftwaffe the first chief of staff, Col. Wever, had, together with a section of his staff, decided on the necessity for a multi-engined bomber aircraft. In 1934 plans were produced for the so-called 'Uralbomber'. After the war General Nielsen confirmed that Wever 'was convinced that the important target areas would be Soviet industries and the outermost corners of European Russia and even beyond, and in the area just east of the long Ural mountain chain.'[8]
Specifications were given to the firms of Dornier and Junkers for work to begin in the summer of 1935 on Langstrecken-Grossbomber and the first prototypes of the Dornier Do 19 and Junkers Ju 89 were flown late in 1936. By this time, however, Wever was dead and had been succeeded by Albert Kesselring, whose main interest was in the development of close co-operation between army and air force. Wever had found much opposition to his idea of building up a strategic striking force of bombers. His successor and much of the Luftwaffe staff favoured a tactical air force using smaller bomber aircraft. On April 29th 1937 the 'Uralbomber'-Programme was wound up.[9]

(The full text is available online)

 

[SpicyJuan11]

Germany had the capacity to build a large 4 engined bomber force in the late 1930's if a suitable design was available

Speaking of suitable desings, what do you all think of each of these options, perhaps assuming Wever lives:

He 111Z. Historically this was proposed much later, however there is no technical reason why this could not have been developed before late 1939. This obviously is not the "Superbomber" the Luftwaffe was looking for, however maybe it would be a realistic backup in late 1938 when Jeschonnek realizes that war with Britain was on the horizon.

• Pros: The clear huge benefit of this would be economies of scale. Assuming this Z shares 80%+ of the same components of the H, you could see the Germans produce quite a few of these beasts while still producing quite a few twin engined versions due to sharing similar tooling. The historical 1941-era Z-2 variant was projected to carry 15,000 lbs of bombs over 1,100 miles. For comparison, the He 177A-3 could only carry the same bombload just short of 700 miles. Even if we reduce this somewhat to compensate for 1940 engines, this is still quite a serious bomb load in the BoB.
• Cons: 5 engines instead of four, retains the same poor defensive armament of the He 111P/H, soaks up quite a few crew members/gunners.

He 179 (He 177B). The original Heinkel P 1041 was powered by four seperate engiens (either DB 601, Jumo 211, Jumo 206, BMW 139, Bramo 329, or Argus 412; only later was the DB 606 selected. On November 17th, 1938, Heinkel requested to use the V3 and V4 to test out 4x Jumo 211 but was tyrned down. In mid-1939, Heinkel began working on a four-seperate engined version of the He 177, titled He 179. This project was canceled on September 12th of the same year. Obviously the concept was there and if Wever is around it's hard to imagine that dive-bomber requirement being issued. Perhaps under wever the 4xJumo 211 is chosen on the outset or a parralel backup project is undertaken concurrently (like B-29/B-32). In 1937 Heinkel projected first pre-production deliveries to begin October, 1939. Later that year, Udet ordered Heinkel to produce 120 He 177's/month by mid-1940. With normal engines, no redesigns due to the dive-bombing requirement (such as the landing gear), good luck, and perhaps some handwaving, Heinkel's original 1937 estimate is accurate and you have "quite a few" 177s available for the Battle of Britain, and "a lot" for Barbarossa?

• Pros: Good performance: quite good cruise speed and max speed, decent payload/range. Not many crew members required.
• Cons: Light defensive armament, new tooling required.

A developed Ju 89 (Ju 90/290). Even before Wever's death the Ju 89/Do 19 were canceled due to their disappointing performance. the Ju 89 was later developed into the Ju 90 which then was developed in to the 290/390. The 290 was later seriously considered as a bomber, but the deteriorating war situation prevented this. Thus we know the Ju 89 did offer the bones for a viable B-17/B-24 alternative. Dan Sharp mentions that Junkers offered a Ju 90 derivative in the contest with the He 177, but no competitors were seriously considered. But perhaps they should have?

• Pros: Best potential for defensive armament. Potentially large bomb load. Armor and structural integegrity could prove very difficult for .303 equipped RAF aircraft to shoot down
• Cons: Slow vs He 177. Expensive. Many crew needed.

 

[Frog]

A lot depends on what the Germans actually want it to do and when.

The Avro Manchester went into service as a 265mph top speed bomber. Issued to squadrons at the end of 1940, first combat (over Brest, not exactly long range), in late Feb 1941.
The larger Stirling, when it got 1500hp Hercules XI engines could hit 282mph but cruised at closer to 200mph. First combat in Jan 1941, 3 planes. Two Stirling factories were severally damaged by German twin engine bombers, the already mentioned Belfast raid was in March of 1941.

The French were working on several 4 engine bombers in the spring of 1940 but they went for speed, over 300mph (and yes nobody actually flew bombers at near top speed, just an indicator as to what direction they were taking) even with their low powered engines, but this meant smaller wings and lower bomb loads than the British heavies.
View attachment 780188
This was sitting on the runway with engines running when the word came that all flights were canceled, so all we have are estimates. 947 sq ft wing, four 1140hp engines.
Estimated top speed of 335mph. loaded weight 39,835lbs. It could hold a pair of 496lbs in each wing root and had a 19ft long bomb bay (future torpedo bomber?)
one 7.5mm mg in the nose, one 20mm in a power mount on top and a pair of 7.5mm mgs out the lower rear step. Maybe somebody else had range numbers?

Just pointing out that there were other paths than what Britian and the US used/planed.
But for the Germans replacing 500 or more Do-17s is going to mean an older, less sophisticated plane than this (production started in early 1939?) while a having several hundred bombers in the summer of 1941 could mean something close to this or............the old design with better engines.

SNCAO - CAO 700 :
Range : 2 200 km
Estimated cruise speed : 320 km/ h
Estimated cruise speed : 540 km/ h (altitude 5 000 m)
Max ceiling : 9 000 m
Inner engines : Gnome & Rhône 14N48 propellers turning counter clockwise
Outer engines : Gnome & Rhône 14N49 ; propellers turning clockwise
Scheduled bomb load ; 1.580 tons

All data are estimations as it never flew .

 

[special ed]

The He 111Z would have twice the defensive armament of a single He 111.

 

[Thumpalumpacus]

The He 111Z would have twice the defensive armament of a single He 111.

Almost twice the target area too, with even less maneuverability. 20mm in that central span could spell real trouble.

 

[Shortround6]

I really cannot understand the attraction of these Zwilling aircraft. If you want something strange just go to Blohm & Voss and have done it.

As a glider tug it has some merit.
As a bomber it would be a great boon to the allied forces.

It isn't any faster than a standard He 111. For a plane of it's size and cost it has crap for defensive armament, lets face it...........crap + crap = double crap.
Maneuverability is crap. Rolling ability vs even a B-24 is going to be horrible.
You need at least an 8 man crew and more likely 10 men. You can not swap men between fuselages in case of causalities. Trying to coordinated defensive fire is going to as bad or worse than allied 4 engine bombers. Trusting 3-4 men to one pilot is one thing. Trusting 7-8 to one pilot is another thing.
Just trying to keep all the controls rigged is going to be a nightmare (even P-38s and P-82s used a common elevator between the booms/fuselages.
The tails themselves look like a problem. At least in a B-17 or Lancaster if the fuselage gets "tweaked" everything in the tail is tweaked the same, on this thing you can have tails flying in slightly different directions.
Got to love the landing gear with the 4 separate retract mechanisms.
My fingers are getting tired and I may have to throw-up in a bucket contemplating this overlooked genius of German engineering.

 

[Snautzer01]

really cannot understand the attraction of these Zwilling aircraft

Developed for tugging the giant gliders that did have a important role in resuply the Heer. Besides that it took on cargo aswell.
The plane was not difficult to fly , could be maintained with not needing new or special parts.
Should be noted that the He111z + Glider combo should be come in action with air dominance.
It did well. That is untill they put engines on the glider.
So it is perhaps freaky looking but not a useless waste of space. The need for massive amounts of stuff delevered on the fronts hotspots was real.

 

[tomo pauk]

He 179 (He 177B). The original Heinkel P 1041 was powered by four seperate engiens (either DB 601, Jumo 211, Jumo 206, BMW 139, Bramo 329, or Argus 412; only later was the DB 606 selected.

A developed Ju 89 (Ju 90/290).

These two, IMO. Keep the things simple and unadventurous.
Two concurrent designs are good to have in case one is running late, and engines being in the individual positions allows for the re-engining process to be as simple as possible. Big fuselages make the retrofit of improved defensive firepower easier to do than on the smaller bombers.

 

[Shortround6]

Developed for tugging the giant gliders that did have a important role in resuply the Heer. Besides that it took on cargo aswell.
The plane was not difficult to fly , could be maintained with not needing new or special parts.
Should be noted that the He111z + Glider combo should be come in action with air dominance.
It did well. That is untill they put engines on the glider.
So it is perhaps freaky looking but not a useless waste of space. The need for massive amounts of stuff delevered on the fronts hotspots was real.

It might have been a good and expedient heavy glider tug. A substitute heavy 4-5 engine bomber it was not.
300-400 He 111Zs trying to bomb Liverpool or east of Moscow?
But it comes up in most discussions of heavy German bombers.

 

[Shortround6]

These two, IMO. Keep the things simple and unadventurous.
Two concurrent designs are good to have in case one is running late, and engines being in the individual positions allows for the re-engining process to be as simple as possible. Big fuselages make the retrofit of improved defensive firepower easier to do than on the smaller bombers.

Germans got side tracked?
The Ju 90 was too old/dated and the He 177 was a little too advanced. Not just the coupled engines but the whole thing (concept).

Efficient as the Junkers flap was it created a lot drag. That elevator set up belongs back in WW I.
Germans could have split the difference between airliner fuselages and and fuselages that were barely more than one man wide.
The Ju 90 wing was already huge, about 39% larger than a B-17 wing.
Basically a lot of built in drag (and weight).

I have said it before, the Germans tried to skip a step (B-17, B-24, Sterling, Halifax, Manchester/Lancaster) that meant no pressure cabins, just power turrets but not remoter control, and a few other things, and jump to the He 177 and Ju 288.
All the tricky stuff sucked up time, manpower, resources the Germans didn't have.

He 177 used a wing about 55% the area of the Ju 90. Maybe a 1300-1500sq ft wing might have given good results?

 

[special ed]

Almost twice the target area too, with even less maneuverability. 20mm in that central span could spell real trouble.

I really cannot understand the attraction of these Zwilling aircraft. If you want something strange just go to Blohm & Voss and have done it.

As a glider tug it has some merit.
As a bomber it would be a great boon to the allied forces.

It isn't any faster than a standard He 111. For a plane of it's size and cost it has crap for defensive armament, lets face it...........crap + crap = double crap.
Maneuverability is crap. Rolling ability vs even a B-24 is going to be horrible.
You need at least an 8 man crew and more likely 10 men. You can not swap men between fuselages in case of causalities. Trying to coordinated defensive fire is going to as bad or worse than allied 4 engine bombers. Trusting 3-4 men to one pilot is one thing. Trusting 7-8 to one pilot is another thing.
Just trying to keep all the controls rigged is going to be a nightmare (even P-38s and P-82s used a common elevator between the booms/fuselages.
The tails themselves look like a problem. At least in a B-17 or Lancaster if the fuselage gets "tweaked" everything in the tail is tweaked the same, on this thing you can have tails flying in slightly different directions.
Got to love the landing gear with the 4 separate retract mechanisms.
My fingers are getting tired and I may have to throw-up in a bucket contemplating this overlooked genius of German engineering.

I am not an He 111Z fanboy. When merely looking at comparisons:
10 man crew - same as B-17 & B-24
Engines 5 vs 4 _ you experts figure total horsepower (yes, I use old number systems) vs B-17 or B-24
Wingspan _ you lookup the numbers I suspect very close to 17 & 24
Battle damage - many standard 111s came back with substantial damage, enough they became salvage, same as 17 & 24
Maneuverability - most likely not much worse than B-17 & possibly better than the B-24. I have never considered the maneuverability comparison of the 111Z with other similar sized aircraft

 

[Shortround6]

Maneuverability - most likely not much worse than B-17 & possibly better than the B-24. I have never considered the maneuverability comparison of the 111Z with other similar sized aircraft

Most of us do not think about throwing 4 engine bombers all over the sky although RAF bombers crews would disagree.
We argue about the "maneuverability" of the P-38 and other twin engine fighters due to inertia when rolling.
According one old book the 111Z fuselage center lines were just under 42ft apart.

Roll inertia was ????
To heck with barrel rolling. Just trying to keep formation with 12 planes in turbulent air?

 

[Thumpalumpacus]

I am not an He 111Z fanboy. When merely looking at comparisons:
10 man crew - same as B-17 & B-24
Engines 5 vs 4 _ you experts figure total horsepower (yes, I use old number systems) vs B-17 or B-24
Wingspan _ you lookup the numbers I suspect very close to 17 & 24
Battle damage - many standard 111s came back with substantial damage, enough they became salvage, same as 17 & 24
Maneuverability - most likely not much worse than B-17 & possibly better than the B-24. I have never considered the maneuverability comparison of the 111Z with other similar sized aircraft

Look at it this way: Allied heavies had 4 engines pulling them around, and the -111Z had five; but the four engines of Allied heavies were only dragging around one fuselage.

As for battle damage, sure, I bet it could take some, but SR6's point about damage imparting differential control effects seems pretty apt. And were I a fighter pilot attacking a -111Z, I'd go under, pull up, and aim for that center engine and wing section. Weakening that, even without an immediate shoot-down, would probably be fatal -- if nowhere else, then upon landing.

I didn't call you and don't believe you are a "fanboy". I respect you too much for that nonsense.

 

[SaparotRob]

It still looks cool.

 

[Reluctant Poster]

Kesselring summarises the situation quite well, but overstates things at times Expecting a jump to designs weighing something like twice as much empty as the loaded weights of the latest types, like the Do17 and He111, would require much to go right. Remembering in the late 1930's the Wellington was a heavy bomber, staying there until the 4 engined types turned up, and expected to do lots of damage to industry it bombed. In the 1930's the Germans had to generate foreign sales to pay for much of the light metals and oil it used.

The mission defined the bomber, an Fw190 flying at night to drop a bomb on London is a strategic bomber, how many Japanese strategic targets did B-17 and B-24 missions attack? The Germans did not have tactical and strategic bombing as concepts. The damage to Britain in 1940/41 and the radio navigation systems indicates the Luftwaffe had the capability to undertake strategic bombing as per doctrine that allowed for it and other air operations depending on the situation. There is no fundamental reason why the missions actually flown by the German twin engined bombers in 1940/41 could not be flown by 4 engined types, being mostly air superiority and battlefield interdiction plus night strategic raids on Britain. The 8th Air Force dropped 81,803.5 tons of bombs on airfields for example. A larger aircraft has to fly higher to cut the risk of damage from ground fire, which reduces bombing accuracy but it normally carries more bombs, as noted larger transport aircraft is generally more efficient per unit of cargo, including personnel, fuel, build and maintenance costs.

The RAF and the USAAF came up with range/bomb load requirements that meant fitting 4 engines given the available power plants in the mid to late 1930's. The only attempt at a twin engine design that reached service had engine problems. The Germans wanted to bomb targets in the Urals and in any case solved the range issue by conquest until the USSR reorganised its war economy and the Luftwaffe really had to make the jump to B-29 class performance in the east to do strategic air warfare.

Going deep into enemy areas means damage to your units hurts more and the best you can normally hope for the personnel are captured, Germany was undertaking major submarine warfare, adding major strategic air warfare would be another significant drain on highly trained personnel.

As of 5 May 1940 Williamson Murray reports the Luftwaffe had 1,369 bombers and 321 long range reconnaissance.

Starting with money as short hand for resources. Build costs are subject to economies of scale, fewer designs the better but the greater the risk of large scale failure in combat. In 1944 the USAAF thinks it cost $204,370 for a B-17, $215,516 for a B-24, $192,427 for a B-26 and $142,194 for a B-25. Looking at the breakdown in costs the big one is engines, the B-17 engines cost on average $35,541 from 4 different price calculations, the B-24 $34,265, the B-25 $29,239 and the B-26 $44,403. In money terms in 1944 the 1,000 B-24 fleet translates to 1,120 B-26 or 1,516 B-25.

Britain June 1941 expected unit costs for proposed orders, in pounds,
44,250 Lancaster
43,752 Halifax
52,300 Stirling
38,100 Warwick
27,700 Wellington
18,950 Mosquito

On that basis a 1,000 Lancaster fleet translates to 1,597 Wellingtons, Stirlings even more.

Prices quoted for France 1945/6
37-40,000 Lancaster I
40,000 Halifax
15,000 Mosquito VI
16,000 Mosquito 30
16,000 Mosquito PR XVI
16,300 Mosquito PR.34
26,000 Wellington XIII
25,000 Wellington XIV

When it comes to twins versus four engine types the exchange rate is very design dependent. Assuming the proposed German design cuts numbers to 60% of the nearly 1,700 twin engine fleet that comes to around 1,000 aircraft. If the reconnaissance force had to be maintained at the 300 aircraft level that would have the bomber force. A smaller bomber force makes escorting easier, with the higher fighter to bomber ratio available. Germany had the capacity to build a large 4 engined bomber force in the late 1930's if a suitable design was available. It would obviously reduce the number of bombers but by how much depends on how much harder it was to build than mainly the Do17 and He111. Remembering in peace time defend the budget, wartime defend the country.

Timeline, Do17 requirement in 1933, first flights in 1934, He111 design began in 1934, first flight in February 1935, Ju86 first flight November 1934, Ju88 project work began in early 1936, first flight in December. Fw200 design began in 1936, first flight July 1937. Any 4 engine design would probably need to fly in 1935 or early 1936 to be in mass production in 1939 in the numbers needed to create a 1,000 strong force, and with designs that gave the Luftwaffe better bomb lift, easy for replacing the Do17, harder for the He111. He111 and Do17 production were each running at about 30 a month in 1937. The Do217 proposal in 1937, first flight in mid 1938, into service in 1941

Apart from his work on Luftwaffe doctrine General Wever was important as the glue holding together the Luftwaffe high command, afterwards feuding between the senior commanders increased to the point it harmed the air force, with a new chief of staff on almost a yearly basis to 1936 to 1939 doctrine and planning became more short term. Whether Wever could have arranged for a viable 4 engined bomber in 1939 performance terms arriving then is unclear as the designs actually ordered when he was around were for attacking locations in the Urals, a requirement which set the Do19 and Ju89 designs up to fail, to have a chance the specification needed to change to targets in Britain. If he had still been around the Luftwaffe would probably have more early war staying power and willingness to absorb the lessons from 1940 while being less interested in giving most bombers dive bombing capacity which reduced performance and delayed development.

Not sure how valid the following is, using wartime averages hides the big shifts in the fighting and given the half way points for bombs on Germany was end September 1944 for Bomber Command and mid November 1944 for the 8th Air Force flatters the loss figures.

Tons are long tons for the RAF and short tons for the USAAF, losses include accidents etc. on operations, sorties are attacking for the RAF and effective for the USAAF. All war Bomber Command and the 8th Air Force. First the raw numbers

type	tons	pounds	MIA+Cat E	Sorties	%loss	lb/sortie	lb/loss	Short ton/loss
Mosquito	26,867.0​	60,182,080​	283​	24,961​	1.13​	2,411.04​	212,657.53​	106.33​
Wellington	41,823.0​	93,683,520​	1,523​	31,657​	4.81​	2,959.33​	61,512.49​	30.76​
Whitley	9,845.0​	22,052,800​	414​	7,311​	5.66​	3,016.39​	53,267.63​	26.63​
Hampden	9,115.0​	20,417,600​	499​	10,259​	4.86​	1,990.21​	40,917.03​	20.46​
Stirling	27,821.0​	62,319,040​	606​	9,409​	6.44​	6,623.34​	102,836.70​	51.42​
Halifax	224,207.0​	502,223,680​	2,113​	66,456​	3.18​	7,557.24​	237,682.76​	118.84​
Lancaster	608,612.0​	1,363,290,880​	3,726​	135,445​	2.75​	10,065.27​	365,885.90​	182.94​
B-17	477,201.7​	954,403,400​	4,228​	185,704​	2.28​	5,139.38​	225,734.01​	112.87​
B-24	209,949.0​	419,898,000​	1,630​	78,914​	2.07​	5,320.96​	257,606.13​	128.80​

Next some ratios, pounds dropped per attacking/effective sortie, read across the Wellington dropped 1.23 times the Mosquito bomb load per sortie, read down it took 0.81 Wellington sorties to equal 1 Mosquito

Aircraft	Mosquito	Wellington	Whitley	Hampden	Stirling	Halifax	Lancaster	B-17	B-24
Mosquito	1.00​	1.23​	1.25​	0.83​	2.75​	3.13​	4.17​	2.13​	2.21​
Wellington	0.81​	1.00​	1.02​	0.67​	2.24​	2.55​	3.40​	1.74​	1.80​
Whitley	0.80​	0.98​	1.00​	0.66​	2.20​	2.51​	3.34​	1.70​	1.76​
Hampden	1.21​	1.49​	1.52​	1.00​	3.33​	3.80​	5.06​	2.58​	2.67​
Stirling	0.36​	0.45​	0.46​	0.30​	1.00​	1.14​	1.52​	0.78​	0.80​
Halifax	0.32​	0.39​	0.40​	0.26​	0.88​	1.00​	1.33​	0.68​	0.70​
Lancaster	0.24​	0.29​	0.30​	0.20​	0.66​	0.75​	1.00​	0.51​	0.53​
B-17	0.47​	0.58​	0.59​	0.39​	1.29​	1.47​	1.96​	1.00​	1.04​
B-24	0.45​	0.56​	0.57​	0.37​	1.24​	1.42​	1.89​	0.97​	1.00​

Now comes the ratios, losses per pounds dropped, read across the Wellington dropped 0.29 times the Mosquito bomb load per loss, read down the Wellington loss rate per pound of bombs dropped was 3.46 times the Mosquito

Aircraft	Mosquito	Wellington	Whitley	Hampden	Stirling	Halifax	Lancaster	B-17	B-24
Mosquito	1.00​	0.29​	0.25​	0.19​	0.48​	1.12​	1.72​	1.06​	1.21​
Wellington	3.46​	1.00​	0.87​	0.67​	1.67​	3.86​	5.95​	3.67​	4.19​
Whitley	3.99​	1.15​	1.00​	0.77​	1.93​	4.46​	6.87​	4.24​	4.84​
Hampden	5.20​	1.50​	1.30​	1.00​	2.51​	5.81​	8.94​	5.52​	6.30​
Stirling	2.07​	0.60​	0.52​	0.40​	1.00​	2.31​	3.56​	2.20​	2.51​
Halifax	0.89​	0.26​	0.22​	0.17​	0.43​	1.00​	1.54​	0.95​	1.08​
Lancaster	0.58​	0.17​	0.15​	0.11​	0.28​	0.65​	1.00​	0.62​	0.70​
B-17	0.94​	0.27​	0.24​	0.18​	0.46​	1.05​	1.62​	1.00​	1.14​
B-24	0.83​	0.24​	0.21​	0.16​	0.40​	0.92​	1.42​	0.88​	1.00​

Now choose the best bomber.

Accuracy also counts. As shown in the papers I posted recently the B-24s clumsy handing characteristics resulted in much fewer bombs on target. In 1944 B-17s put 15.0% of bombs within 500' of aiming point whereas the B-24 could only manage 10.2% a huge difference. This was in good visibility. I would assume the poor handing of the Halifax as compared to the Lancaster also resulted in a disparity.

I recall a study of Crossbow bombing results which showed the Mosquito to be by far the most effective bomber in that particular circumstance.