German heavy bombers

[33k in the air]

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.

Is it though? It's only a 4.8 percentage point difference in absolute terms. In fractional terms it's the difference between 1 in 7 bombs versus 1 in 10 bombs. Neither is a particularly great result, though obviously the B-17 is performing better.

 

[tomo pauk]

Is it though? It's only a 4.8 percentage point difference in absolute terms. In fractional terms it's the difference between 1 in 7 bombs versus 1 in 10 bombs. Neither is a particularly great result, though obviously the B-17 is performing better.

Per these percentages, B-17 is almost 50% better. Perhaps a difference between needing and not needing to send another multi-hundred bombers' sortie against the dedicated target.

 

[33k in the air]

Per these percentages, B-17 is almost 50% better. Perhaps a difference between needing and not needing to send another multi-hundred bombers' sortie against the dedicated target.

Sure, in percentage terms. In absolute terms it's 1 in 7 versus 1 in 10, which is not all that much of a difference. If it was 1 in 7 versus 1 in 15 or 1 in 20, that would be a substantial absolute difference.

 

[Reluctant Poster]

Sure, in percentage terms. In absolute terms it's 1 in 7 versus 1 in 10, which is not all that much of a difference. If it was 1 in 7 versus 1 in 15 or 1 in 20, that would be a substantial absolute difference.

That s a 50% difference which is huge

 

[Thumpalumpacus]

It still looks cool.

If by "cool" you mean "a clunky flying Lego wishbone", I completely agree.

 

[SpicyJuan11]

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.

Well Shortround, we are in the "What If" section of the forum, so I don't see why the Germans would have to stick to the historical crappy Z-2 project and are free to make changes

I have recently read your posts in other threads where you demonstrate how the He 111 really was an afterthought for the Germans (e.g. received a turret over a year after the Ju 188/Do 217, lowest priority for new engines, no major airframe updates, etc). However if the Germans see the dark clouds of war on the horizon and decide to make the He 111Z as a back up, then both it and the He 111 might be prioritized, allowing it to be developed further. Sure, this was far from ideal since the airframe was already so old, but the Germans don't really have a choice barring engine developments or the airframe manufacturers getting their shit together when making new types. Any new types wouldn't see service for quite some time due to standard developmental, not to mention any delays.

The historical Z-2 was planned to have a turret in the middle section containing MG 151/20 (1? 2?). In this timeline, perhaps the Germans are much more committed to redesigning the 111s defensive layout pre-war. Yes a big problem is the lack of suitable guns early war, but perhaps this gives the Germans a reason to adopt the Mg 17? Or maybe the Mg 81 is adopted in the 111 earlier. Ideal 111Z armament might be; Mg 17Z in nose. Powered dorsal turret with 2x Mg 17 on each fuselage. Dedicated gunner for each outboard fuselage side. Mg 17Z in central position. Instead of a turret in the center wing section, use the weight to add more armor.

Not sure why you're complaining about crew when the He 111 had 5 and the B-17 had 10. He 111Z-1 had 7-9.

You can make a center section for the stabilizers without too much trouble.

Landing gear would be interesting. Keeping the Z-1s arrangement simplifies production, but if they go for a landing gear redesign that could save weight that otherwise could be used for more fuel.

Also an overlooked factor here is training and handling. He 111Z would not take much training for 111 pilots to get used to. This is not something to be taken lightly considering the huge training problems the Germans had, especially newer types such as the 177. 111Z pilots praised the aircraft for its easy handling. Compare that to the 177 and Me 264.

 

[Shortround6]

However if the Germans see the dark clouds of war on the horizon and decide to make the He 111Z as a back up, then both it and the He 111 might be prioritized, allowing it to be developed further. Sure, this was far from ideal since the airframe was already so old, but the Germans don't really have a choice barring engine developments or the airframe manufacturers getting their shit together when making new types. Any new types wouldn't see service for quite some time due to standard developmental, not to mention any delays.

They could have thrown a bit of money at FW and have them modify the FW 200 a bit more than the rock bottom, bare minimum. Compare the FW 200 to a B-17 Sharkfin.
Maybe they could have done something with the Fw 200 and maybe they couldn't. But it is a better starting point than the He 111Z.
Germans really let "the best is the enemy of good" get in the way here.

Not sure why you're complaining about crew when the He 111 had 5 and the B-17 had 10. He 111Z-1 had 7-9.

It had 7-9 as a glider tug. German supermen could pilot bombers over long ranges without relief. Of course they rarely actually did that in combat
Now figure what 10 He 111z's could do that 20 He 111Hs could not do. Saving aircrew doesn't seem to be on the list.

Landing gear would be interesting. Keeping the Z-1s arrangement simplifies production, but if they go for a landing gear redesign that could save weight that otherwise could be used for more fuel.

This is a reason I dislike it. I understand why they did it for the glider tug. But a lot of people seem to thing it would be a good starting point for a long range/strategic bomber.
Then when flaws/problems are pointed out the answer is always "they could have changed it" which is true, but if they had started with a different plane or kept their expectations more reasonable they might have had the in service "long range/strategic bomber" with fewer problems just as fast. See above

 

[Thumpalumpacus]

This is a reason I dislike it. I understand why they did it for the glider tug. But a lot of people seem to thing it would be a good starting point for a long range/strategic bomber.
Then when flaws/problems are pointed out the answer is always "they could have changed it" which is true, but if they had started with a different plane or kept their expectations more reasonable they might have had the in service "long range/strategic bomber" with fewer problems just as fast. See above

A clean-sheet design is almost always better -- more efficient, mainly -- than a conversion.

 

[Shortround6]

A clean-sheet design is almost always better -- more efficient, mainly -- than a conversion.

Boeing did a lot of swapping things back and forth.
The 307 Stratoliner used the wings, landing gear, horizontal stabilizer from the early B-17s

The old vertical stab and rudder was too small, not sure if the new one predates the B-17E or if they were worked on at the same time.

Boeing had shared the wing of the B-15 with the China clippers. They had shared at least some wing parts between the B-29 and a one off twin engine flying boat and they built a new fuselage for the 377 using the wing/engines of the B-50.
But the fuselages were brand new, designed for the role.

 

[Thumpalumpacus]

Boeing did a lot of swapping things back and forth.
The 307 Stratoliner used the wings, landing gear, horizontal stabilizer from the early B-17s
View attachment 785002
The old vertical stab and rudder was too small, not sure if the new one predates the B-17E or if they were worked on at the same time.
View attachment 785003
Boeing had shared the wing of the B-15 with the China clippers. They had shared at least some wing parts between the B-29 and a one off twin engine flying boat and they built a new fuselage for the 377 using the wing/engines of the B-50.
But the fuselages were brand new, designed for the role.

Sure. All that only makes sense. But there's a significant difference between designs reusing parts and manufacturing capability, and modifications done to an airframe to allow it to perform a new mission.

 

[Geoffrey Sinclair]

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.

The USSBS Bombing Accuracy report is not as harsh on the B-24, it uses within 1,000 feet as the measurement. The majority of the targets the 8th Air Force attacked had a large footprint. The USAAF raid on Huls on 22 June 1943, after the raid the bomb craters were found over an area of 12 square miles, 20% of the bombs dropped hit the 541 acre (0.84 square miles) site. If the site were a square then each side fence would be 4,650 feet long. The USSBS excludes missions where less than 5% of bombs landed within 1,000 feet of the aiming point and boxes that had a circular error of more than 3,000 feet. Given the 8th Air Force reporting the B-24 had a higher percentage of gross errors that would help explain the USSBS difference with the 8th Air Force. If their was a problem with the B-24 versus the B-17 it appears to be about hindering correctly identifying the target.

USSBS Average attacking altitude B-17 21,542 feet, B-24 19,800 feet, average attack size B-17 6.64 aircraft, B-24 6.23, average box size B-17 14 aircraft, B-24 11. All of which should make the B-24 more accurate, but for bombs within 1,000 feet of the aiming point, 8th Air Force B-17 40.77%, B-24 37.8%, 15th Air Force B-17 32.4%, B-24 30.4%, based on data from 1,348 8th and 800 15th Air Force Missions The half way point for bomb tonnage dropped was second half of September 1944 for the 8th Air Force and end August 1944 for the 15th Air force. Part of the 1944 difference between the 8th Air Force B-17 and B-24 results is as of end 1943 there were 18 B-17 and 7 B-24 groups operational as of D-Day that was 21 B-17 and 18 B-24, when the 21st B-17 group went operational on 6 May there were 11 B-24 groups operational. The B-17 units had on average more experience until the second half of 1944.

The USSBS says the effects of bombing order were, % of boxes placing at least 10% of their bombs within 1,000 feet of the aiming point, box 1 82%, box 2 60%, box 3 48%, box 4 47% box 5 or more 30%. Richard Davis figures have from October 1943 to the end of the war attacking Germany the 8th dropped 41.2% of bombs visually. The 15th Air Force started non visual bombing in April 1944, from then to the end of the war it managed 89.4% visual bombing.

One query is the number of boxes of B-24 attacking a target, the same number of bombers in smaller boxes would mean more subject to the problems of smoke and dust obscuring the target.

If you go to the 8th Air Force September to December 1944 accuracy report it has 38.3% of B-17 and 28% of B-24 bombs dropped in good visibility landing within 1,000 feet of the aiming point. Below 12,000 feet it was 31.7% B-17, 19.8% B-24, over 24,000 feet 12.6% to 11.8% as the bomb sight limits were being reached. The 8th noted 37% of visual attacks were done at 21,000 feet or higher in Q1/1944, going to 97% in Q4/1944. Similarly raids using visual bombing that had over 9 boxes average 28% for 1944, but 55% in the final quarter. The idea of deliberately setting the sight incorrectly so when it sees a nearby landmark the bombs released will hit the target was considered, not possible with the Norden, it was possible with the mark XIV.

The Visual Bombing Summary for 1944 notes 19.8% of B-17 attacks in good visibility resulted in gross errors, for B-24 29.5%, that would imply the major difference in accuracy between the two bomber types is in target identification, rather than better bombing arrangement in the B-17. The sweet altitude for the B-17 was 3.3% gross errors at 15 to 17,900 feet, compared with 10.3% below 12,000 feet and 26.2% at 24,000 feet or higher, B-24 sweet altitude was below 12,000 feet at 14.9%, next was 18 to 20,900 feet at 25.8%, every other altitude it was 30.8% or more. The B-24 had a higher percentage of attacks when the visibility was poor.

The 1 January to 15 July 1943 8th Air Force accuracy report rejects gross errors, aiming with radial errors of 3,000 feet or more, however the all missions table, with between 6.3 and 13% of bombs within 1,000 feet of the aiming point looks like it includes gross errors as the successful group attacks table has 18.3% to 28.7% of bombs within 1,000 feet of the aiming point. This report showed bombing by group was the most accurate, plus the fall off in accuracy with bombing order, from 23.4% for the first to 4.2% for the 5th or later formation (within 2,000 feet went from 49.9% to 19.8%). Gross errors comprised 10% of first formation attacks, 72% of 5th or later attacks. Exclude gross errors and it was 26.2% within 1,000 feet for the first attack, 15% for the 5th or later. In other words it was the target becoming obscured that was a big problem. Go from 1 minute between attacks to 5 minutes and the accuracy goes up, mostly by eliminating gross errors, the 5th and over attacking formation go from 4.2% to 19.8% of bombs within 1,000 feet of the aiming point. As of mid October 1943 24% of group attacks were gross errors.

There is a definite difference between the 8th Air Force B-17 and B-24 accuracy using visual bombing, yet it could mostly be the B-24 bombed on average with less time between formations.

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

Mosquito VI fighter bombers versus the light, medium and heavy level bombers.