Ju-88 vs He-111 & Ju-188 vs Do-217

tomo pauk · Oct 30, 2020

Acheron said:
..
tomo pauk I thought the idea of the Schnellbomber was for it to be too fast to be catched by fighters? It is that concept that I do not understand, even if two-engine designs were faster than smaller single-engine aircraft, wouldn't the opposition simply build fast two-engine fighters which would be able to catch up with bombers?

Again, I have this idea in my head, that a fighter inherently needs to carry less weight than a bomber, so all else equal, the fighter will be faster.

Schnellbomber needs to be fast enough, since the pursuing fighter needs to have a meaningful performance advantage to catch it. In other words - a 350 mph bomber should be pretty safe against a 360 mph fighter.
If you gun-up your fast bomber, guns' openings will add drag. You can compare bomber Mosquitoes vs. fighter Mosquitoes (link).

Shortround6 · Oct 30, 2020

The shelf life of the Do 17 goes back to 1934-45 when the prototypes were built with BMW V-12 engines without superchargers (and I do mean without superchargers) that had 750hp for take 0ff. These engines were used on the early production models. Engine was basically two WW I straight sixes using a common crankshaft. The radials offered much better performance at altitude due to superchargers.

However in 1937 the Do 17E was a pretty quick bomber at low altitude against the mostly biplane fighters of Germany's enemies.

However the bulbus nose stuck on the do 17Z and the increased weight meant that performance didn't keep pace with the increase in power the later radials gave.

Acheron · Oct 31, 2020

I read something about Do-17s used for low-altitude attacks during the BoB, were they esepcially suited for that, or were they simply the most expendable.

Juha3 · Oct 31, 2020

Acheron said:
I read something about Do-17s used for low-altitude attacks during the BoB, were they esepcially suited for that, or were they simply the most expendable.

It suited for that being very maneuverable for its size and also because of being shoulder wing construction

Acheron · Nov 3, 2020

Juha3 said:
It suited for that being very maneuverable for its size and also because of being shoulder wing construction

Are you referring to the usual advantages of shoulder-wings to a bomber already mentioned here or was there a particular advantage in low-altitude attacks?

And is more maneuverable easier and safer to keep at a precise height and thus better for low-altitude flights or is it something else that makes this trait important?

Juha3 · Nov 3, 2020

Acheron said:
Are you referring to the usual advantages of shoulder-wings to a bomber already mentioned here or was there a particular advantage in low-altitude attacks?

And is more maneuverable easier and safer to keep at a precise height and thus better for low-altitude flights or is it something else that makes this trait important?

As a shoulder wing plane it made it easier to the pilot to estimate the low edge of his propellers arcs, these being nearer to the bottom of the fuselage than in mid or low wing planes.

I only thought that being so maneuverable that it sometimes surprised even enemy fighter pilots, even Hawker fanatic Beaumont once over France in May 40, made it safer at very low level.

nuuumannn · Nov 3, 2020

Acheron said:
I thought the idea of the Schnellbomber was for it to be too fast to be catched by fighters? It is that concept that I do not understand, even if two-engine designs were faster than smaller single-engine aircraft, wouldn't the opposition simply build fast two-engine fighters which would be able to catch up with bombers?

Yes, and when these bombers first entered service they were facing biplanes with lower performance than themselves, and their appearance was met with the same kind of revelation society exclaims whenever the Kardashians are seen in public (! says a lot about how far we've come!). In the mid to late 1930s aviation went through rapid technology change that saw fabric covered biplanes exchanged for all metal monoplanes, open cockpits to enclosed, landing flaps, radio navaids etc, so what became considered cutting edge in say 1934 was decidedly passe by 1938.

Shortround6 said:
However in 1937 the Do 17E was a pretty quick bomber at low altitude against the mostly biplane fighters of Germany's enemies.

This is what I mean. It should be remembered that when the Do 17 first appeared the RAF's frontline fighter was the Gloster Gauntlet.

Koopernic · Nov 3, 2020

Juha3 said:
As a shoulder wing plane it made it easier to the pilot to estimate the low edge of his propellers arcs, these being nearer to the bottom of the fuselage than in mid or low wing planes.

I only thought that being so maneuverable that it sometimes surprised even enemy fighter pilots, even Hawker fanatic Beaumont once over France in May 40, made it safer at very low level.

A low wing has aerodynamic advantages. The flat portion of the fuselage acting as an efficient extension of the wing, effectively adding wing area and efficiency as well as leaving the fuselage clear., However the wing spar or spars would limit bomb bay (as happened on the Ju 88, B17, He 111, Ju 52. The Germans usually suspended the bombs vertically by the nose, angled slightly. This was effective. The B17 had horizontal bombs but stacked on top of each other using a release rail that sequences release. For a long range bombing mission this should not be an issue since it will not be able to carry a full load anyway. Lancaster's could carry more bombs than a B17 because they flew lower and carried less armour and armament and few redundant systems. not because they had a bigger bomb bay.

Obviously a bomber or transport aircraft needs to carry load and an upper or mid wing layout may ultimately be best. The Do 217 could carry one SC1000kg bomb. As far as I can tell the Ju 88 was limited to a little used 70kg bomb type and usually a 50kg bomb. Anything bigger had to be carried outside. A solution was a streamlined panier under the fuselage.

The difference in speed of the Ju 388L3 versus Ju 388LK3 with Jumo 222 E/F was estimated as 442mph versus 430 so its not a costly solution in terms of drag.

Acheron · Nov 5, 2020

So, Do-217 best German WWII bomber (at least if restricted to aircraft produced in quantity)?

Side note on maneuverability, wasn't the Short Stirling surprisingly agile for a four-enginged bomber or am I confusing it?

Juha3 · Nov 6, 2020

Acheron said:
So, Do-217 best German WWII bomber (at least if restricted to aircraft produced in quantity)?

Side note on maneuverability, wasn't the Short Stirling surprisingly agile for a four-enginged bomber or am I confusing it?

Only to define, Do 17 was maneuverable and nice plane to fly, Do 217 not so because its much higher wing loading

Koopernic · Nov 7, 2020

Acheron said:
So, Do-217 best German WWII bomber (at least if restricted to aircraft produced in quantity)?

Side note on maneuverability, wasn't the Short Stirling surprisingly agile for a four-enginged bomber or am I confusing it?

Barely 1000 Do 217 were produced compared to over 15000 Ju 88. The Do 217 was the better bomber in my view due to its large internal bomb bay but the Ju 88 was established in earlier mass production and easier to adapt into a night fighter due to its smaller size and lessor dependence on the precious BMW 801 engine.

The Do 217M with the 1750 metric hp DB603A engine managed 557kmh/346mph. By the second half of 1944 engines like the DB603E which could provide much higher power at altitude due to a better supercharger probably would have pushed speed to 356mph. This engine could also provide 2250 hp with water methanol injection and C3 fuel. Also a potential power plant was the Jumo 213A with 1900hp on B4 fuel and 2100hp on B4+MW50, again with a better supercharger.
By early 1945 two stage superchargers were becoming available on the DB603LA and Jumo 213E. It's possible to see speeds 15% higher so around 390mph.

However shortly after the allied invasion all bomber production was stopped In order to concentrate on fighters and jets. The ju 88 survived because it was a night fighter and could develop into the Ju 388.

Greyman · Nov 7, 2020

Koopernic said:
... bomber production was stopped In order to concentrate on fighters ...

Anyone know if there is there any indication what would have been the new mainstays of German bomber production had things continued normally?

Koopernic · Nov 8, 2020

its important to note the differences of the key Ju 88 variants
Ju 88A1 was the initial version. Faster than following Ju 88A5.
Ju 88A5 was an interim version because the Jumo 211F & J were not available improved with more armor, armament, protection and strength
Ju 88A4 had more powerful engines, reinforcement, the larger wings of the A5. This was the definitive version.

The speed drop of carrying external bombs was not too much. A Ju 88 lost no more than 20mph with 4 x SC250 and not worse with 4 x SC500.. It also had its dive bombing capability which no other aircraft of its size had and was very successful.

With the deletion of the dive brakes and bomb racks speed could be 317mph, about the same as the Ju 88C. From about 1942 the Stuvi 5B with BZA computer allowed shallow dive bombing and dive brakes were removed.

tomo pauk · Nov 8, 2020

Koopernic said:
The speed drop of carrying external bombs was not too much. A Ju 88 lost no more than 20mph with 4 x SC250 and not worse with 4 x SC500.
...

Any source for the speed figures?

With the deletion of the dive brakes speed could be 317mph, about the same as the Ju 88C.
...

With or without bombs & racks?

tomo pauk · Nov 8, 2020

Greyman said:
Anyone know if there is there any indication what would have been the new mainstays of German bomber production had things continued normally?

German bombers' program was in shambles by 1943/1944. He 177 and Ju 288 didn't materialized in the expected measure (although the He 177 was debugged by 1944), the Me-210/410 were too much of investment for no return, Do 217 was cold meat on the table.
The Ju 388 with bomb tray is perhaps the least risky proposal, with jet bombers following?

Koopernic · Nov 8, 2020

Greyman said:
Anyone know if there is there any indication what would have been the new mainstays of German bomber production had things continued normally?

The fighter emergency program was declared on July 4th, a month after the allied landings. It lead to the almost complete cancellation of bomber production and the development of some aircraft such as the He 162. Adolf Galland resisted the program, seeing the He 162 as a waste of time, but Goring supported it.

Eventually the 1945 production program reduced to the jets Me 262, Ar 234 and the He 162. The Ju 388, Ta 152/Fw 190D, Do 335 survived.
Joseph Kammler was planning on getting rid of even these and having an all jet Luftwaffe. If allowed to develop as normal probably would have meant the a pbove plus Ju 488 and the He 277.

The Ta 183, Messerschmitt P.1011, P.1112 and Blohm and Voss BV212.03 continued development and prototype testing Was expected.
These were the lightweight emergency fighters not the Volksjager (He 162)

Acheron · Nov 8, 2020

Juha3 said:
Only to define, Do 17 was maneuverable and nice plane to fly, Do 217 not so because its much higher wing loading

Well, carrying many bombs seems more important than being pleasant too fly.

tomo pauk said:
German bombers' program was in shambles by 1943/1944. He 177 and Ju 288 didn't materialized in the expected measure (although the He 177 was debugged by 1944), the Me-210/410 were too much of investment for no return, Do 217 was cold meat on the table.
The Ju 388 with bomb tray is perhaps the least risky proposal, with jet bombers following?

What was wrong with the Do 217?

tomo pauk · Nov 8, 2020

Acheron said:
...
What was wrong with the Do 217?

It was a decent bomber, but nothing special.

Denniss · Nov 8, 2020

Do 217 looks a bit like a german B-26 - a good bomb hauler but not loved very much.

nuuumannn · Nov 8, 2020

The Do 217 was a good workhorse with a good bomb load but was hampered by being underpowered. If it had an engine failure, it's remaining engine would take you swiftly to the crash site. Mind you, a lot of twin engined aircraft of the time were like that.

Ju-88 vs He-111 & Ju-188 vs Do-217

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