Ju88 A-4

[DarkHorse2]

Guys,

The Ju88 A-4 were being mass produced by 3rd Quarter of 1940. (before Turn 1 of GC)

The setup of this distributed production was started in late 1938. But it took until 1940 to start the mass production of the Ju88. During the following 6 years a total of 15000 Junkers Ju88 were built. Therefore the Ju88 became the most built Junkers aircraft type. A total of 3000 changes were incorporated into the serial production of this aircraft and dozens of subtypes were developed through the years, which made the Ju88 useable as a bomber, fighter and surveyer aircraft.

The standard bomber version of the Ju88 was built as the A-series. Preproduction was started in 1938 with 8 Ju88A0. About 20 of the Ju88A2 were sold to Finland in 1939. The mass production of the Ju88 started in 1940 with the A4-series. About 17 major subtypes of the Ju88A were designed until the end of WWII. The A-series were used as bomber and reconaissance aircraft. Several modifications were performed during the series production of the A4. The undercarriage was strengthened, the wing span was extended from the standard 18.37m up to 20.08m. Also the defeat weapons were extended and the operating weight was increased. The Ju88-A13 was used for ground attacks and got a stronger floor armour and the Ju88-A17 was a test version of a torpedo bomber.

http://hugojunkers.bplaced.net/junkers-ju88.html

On June 21, 1941, there were 536 Ju 88s used in 17 Bomber groups and Coastal Aviation Groups, in planning to back up Operation Barbarossa. This was 56 per-cent of the 949 twin-engine bombers of all types stationed in the Luftwaffe units on the Eastern Front. By now the Ju 88A-4 had been the major operational model and, sadly for the Red Army and Red Air Force, the Ju 88 at this time involved all the lessons realized in the air fights over Western Europe: in June 1941 the Ju88A-4 had been just about the most powerful and deadly twin-engine bomber operating worldwide.

https://www.ww2-weapons.com/junkers-ju-88/

In the late autumn of 1940, German engine builders put into mass production the Jurno 21 IF and Jumo 211J variants, which differed from their predecessors in the use of a reinforced crankshaft, a DFL supercharger, an improved control system, a modified fuel pump and a new pressure cooling system. The more powerful Jumo 211J, in addition, had an additional cooling circuit for air compressed by a driven centrifugal supercharger, which made it possible to increase the charge mass of the fuel mixture. The technically more complex Jumo 211J engine (takeoff power 1400 hp) was a little delayed at the development stage, therefore, the first Ju 88A-4 modification bombers were produced with Jumo 21 IF engines (power at takeoff 1340 hp, 1350 hp at an altitude of 250 m and 1060 hp at an altitude of 5200 m). The engine nacelles for the Jumo 211J were distinguished by the presence of an additional air intake in the lower part of the frontal ring, as well as an asymmetric air duct fairing mounted under the engine crankcase. The experimental Ju 88V21 (serial No. 3113), the first of the eighty-eighths with Jumo 211J engines, first took to the skies on November 1, 1940. The prototype of the A-4 model was the Ju 88V22 (serial No. 3152), which made its first flight at the end of 1940. Instead of VDM propellers with metal blades on Ju 88A-4 aircraft, shortly after the start of mass production, VS-11 propellers with wide wooden blades began to be installed.

(translated from Russian)
http://www.airwar.ru/enc/bww2/ju88a4.html

There are countless other references I could cite giving October, 1940 as the date when the Ju88 A-4 entered production.

So, the WiTE2 Ju88-A4 is misnamed or the production dates are out of whack.

I have no idea what variant the WiTE2 Ju88-A4 (with a start date of 10-1941) is supposed to be.

[Denniss]

As said in the other thread our A-4 is a later model with the indended Jumo 211J engines, not the lower-power 211F, and uprated gun package.
the early Ju 88A-4 were slightly more powerful than the previous A-5 but still with the outdated MG 15 guns.
Plus there was no immediated changeover in production, many companies were still producing A-5 when Bernburg changed to the A-4.

[DarkHorse2]

I believe you are incorrect regarding the Ju88 A-4 in WiTE2. It was a very significant change regardless.

But never-the-less, the upgraded Jumo 211J engines were still in production before Oct-1941.

During the course of the war, the engine division of the Junckers company attracted the best design forces and significant resources in an effort to improve the performance of the Jumo211 family of engines. In the late autumn of 1940, German engine builders put into mass production the Jurno 21 IF and Jumo 211J variants, which differed from their predecessors in the use of a reinforced crankshaft, a DFL supercharger, an improved control system, a modified fuel pump and a new pressure cooling system. The more powerful Jumo 211J, in addition, had an additional cooling circuit for air compressed by a driven centrifugal supercharger, which made it possible to increase the charge mass of the fuel mixture. The technically more complex Jumo 211J engine (takeoff power 1400 hp) was a little delayed at the development stage, therefore, the first Ju 88A-4 modification bombers were produced with Jumo 21 IF engines (power at takeoff 1340 hp, 1350 hp at an altitude of 250 m and 1060 hp at an altitude of 5200 m). The engine nacelles for the Jumo 211J were distinguished by the presence of an additional air intake in the lower part of the frontal ring, as well as an asymmetric air duct fairing mounted under the engine crankcase. The experimental Ju 88V21 (serial No. 3113), the first of the eighty-eighths with Jumo 211J engines, first took to the skies on November 1, 1940. The prototype of the A-4 model was the Ju 88V22 (serial No. 3152), which made its first flight at the end of 1940. Instead of VDM propellers with metal blades on Ju 88A-4 aircraft, shortly after the start of mass production, VS-11 propellers with wide wooden blades began to be installed.

The defensive armament of the Ju 88A-4 has also been noticeably improved. Instead of MG 15 machine guns, faster-firing and easier-to-use MG 81 machine guns were mounted in almost all firing points, and heavy machine guns MG 131 began to be installed on later machines. Several main variants of defensive weapons are known. One of them provided for the presence of two front MG81 machine guns in "apples" (750 rounds per barrel), two of the same machine guns in the rear upper defensive firing points (1000 rounds per barrel), one more removable MG 81 for side brackets and one coaxial MG 81Z (1800 rounds) in the lower mount Bola 39Z.MG 131 machine guns of 13 mm caliber were introduced gradually: first one was mounted instead of the hatch MG 81Z, then the second such machine gun appeared in the upper front firing point and, finally, instead of two upper mounts with MG machine guns 81 began to install one central with a third MG 131. In combat units, they preferred to dismantle some of the machine guns. This concerned primarily the front firing points; sometimes, instead of real machine guns, mock-ups were installed without cartridge boxes and supply sleeves. The crews explained such amateur performance by the extreme crampedness of the cockpit and the irreparable deterioration of conditions review at the workplaces of the pilot and scorer.

The most massive modification of the Ju 88 bomber was precisely the A-4 model, which was produced in ever-increasing quantities from the spring of 1941. It was first used during the German attack on the Soviet Union in Operation Barbarossa.

And this included the upgraded Jumo 211J engines.

[DarkHorse2]

The initial versions of the Ju88 A-4 may have used the Jumo111F and was later upgraded to the Jumo111J.

But, as you can see they are not all that different. But there were significant changes made to the A-4 regardless of it using the Jumo111F or Jumo111J.

EngineOptions_3.jpg (374.74 KiB) Viewed 937 times

For the Jumo-211F / J variants, in order to increase the power developed by the engine, at the end of 1940, attempts were made to develop and launch a more advanced version of the engine in the amount of 150 units, in which the compression ratio was increased from 6.5 to 8.0 units. For this engine, gasoline with an octane rating of 100 units was needed. Since such gasoline was produced in limited quantities and it was needed primarily for engines that were installed on fighter jets, this idea eventually had to be abandoned. After that, engine builders continued to improve the engine, primarily in terms of refining the supercharger in order to use the reserves available in the Jumo-211 design

and only in the Jumo-211F variant, again, after a series of improvements to the crankshaft, crankshaft bearings, crankshaft counterweights and connecting rods, it became possible to increase the maximum engine speed and get the one that meets all the main requirements for aircraft engine requirements with a motor resource reaching, as a rule, a value of 200 hours. At that time, such a motor resource for bomber engines was not large. ...

From the beginning, the blower used a Jumo-designed Gt4 blower impeller with a higher angular velocity, which, starting from the Jumo-211F variant, was closed by 30%, which allowed a 40% increase in the charge air pressure. Starting with the Jumo-211F/J variant, the supercharger received an additional charge air cooling system with a recuperator. The Jumo engine plant in Dessau already had some experience in this area gained during work on the Jumo-207 diesel aircraft engine and during the work on the Jumo-211F / J, the results obtained earlier were further improved, although not all possibilities were realized. So, in the Jumo-211F variant without charge air cooling, a significant decrease in charge air pressure at high altitudes was noted.

During the course of the war, the engine division of the Junkers company attracted the best design forces and significant resources in an effort to improve the performance of the Jumo211 family of engines. In the late autumn of 1940, German engine builders put into mass production the Jurno 21 IF and Jumo 211J variants, which differed from their predecessors in the use of a reinforced crankshaft, a DFL supercharger, an improved control system, a modified fuel pump and a new pressure cooling system. The more powerful Jumo 211J, in addition, had an additional cooling circuit for air compressed by a driven centrifugal supercharger, which made it possible to increase the charge mass of the fuel mixture. The technically more complex Jumo 211J engine (takeoff power 1400 hp) was a little delayed at the development stage, therefore, the first Ju 88A-4 modification bombers were produced with Jumo 21 IF engines (power at takeoff 1340 hp, 1350 hp at an altitude of 250 m and 1060 hp at an altitude of 5200 m). The engine nacelles for the Jumo 211J were distinguished by the presence of an additional air intake in the lower part of the frontal ring, as well as an asymmetric air duct fairing mounted under the engine crankcase. The experimental Ju 88V21 (serial No. 3113), the first of the eighty-eighths with Jumo 211J engines, first took to the skies on November 1, 1940. The prototype of the A-4 model was the Ju 88V22 (serial No. 3152), which made its first flight at the end of 1940. Instead of VDM propellers with metal blades on Ju 88A-4 aircraft, shortly after the start of mass production, VS-11 propellers with wide wooden blades began to be installed.

[DarkHorse2]

I have also found:

Ju 88A-4s with 1340/1400hp Jumo 211F/J motors begun arriving in sizeable figures about mid­-1940. This would end up being the main manufacturing version of the A models and became the starting point for a number of additional models. By the end of 1940 the Ju 88A-4 included structural improvements enabling more weights, even more improves in standard bomb load of 5,519 lb (2,500 kg) as well as much better defensive armament. The armament at this time made up 1 x 7.92 mm MG within the front cockpit, and 1 x 13 mm or 2 x 7.92 mm MGs inside a ventral gondola. Manufacturing averaged approximately 2,000 aircraft each year in 1940 to 1943

But lacking verifiable citations - and not comfortable using it.

Also have the following, with listed sources, but cannot verify.

The most important bomber version was the Ju 88A-4, with longer span wings, a stronger airframe, and Jumo 211J engines. It appeared in the summer of 1940.

https://uboat.net/technical/ju88.htm

However, I can provide the following (dated April 1941), where it gives a breakdown of major Ju-88A variant features, to include "Developed from the A-5 series, reinforced chassis", "2 x Jumo 211J" for the Ju 88A-4.

In the appendix, a new edition of the designation of aircraft entered into the Luftwaffe with a clarifying text of their series designation is sent to the whereabouts there

Ju88A_a.jpg (86.83 KiB) Viewed 930 times

Ju88A_a2.jpg (83.67 KiB) Viewed 930 times

[DarkHorse2]

From the Junkers site ( http://hugojunkers.bplaced.net/junkers-ju88.html ), which I feel is fairly credible, they list the following:

Ju88A_variant_production.JPG (433.92 KiB) Viewed 908 times

Ju88 A-Series (Bomber)
Ju88A0 horizontal and dive bomber with 2 x 882kW Jumo 211B-1, 8 built in 1938
Ju88A1 with 2 x 882kW Jumo 211G-1, 69 built in 1939
Ju88A2 as A1, to be started from catapulte, 20 built for Finland
Ju88A3 as A1, training aircraft
Ju88A4 with 2 x 1040kW Jumo 211J-1, dive bomber aircraft with larger wing since 1940, larger tail since 1942
Ju88A4trop as A4 for tropical regions
Ju88A5 as A1 with larger wing, 2 x Jumo211G, bomber and surveyer aircraft
Ju88A6 as A5 with balloon destroyer
Ju88A6U as A5 used as long range sea surveyer with 2 x 880kW Jumo 211H
Ju88A7 as A5, training aircraft with 2 x Jumo 211B1 or 211H
Ju88A8 as A4 with 2 x 990kW Jumo211F-1 and Kuto nose
Ju88A9 as A1 dive bomber for tropical missions (also known as Ju88A1trop)
Ju88A10 as A5 for tropical missions
Ju88A11 as A4 for tropical missions
Ju88A12 as A5 with larger wing and cockpit with 2 x Jumo 211G-1, training aircraft
Ju88A13 as A4, combat aircraft
Ju88A14 as A4 with larger wing, Kuto nose with 2 x 1040kW Jumo 211J-1, ship attacks
Ju88A15 as A4 with Jumo 211J-1 and bombs in a wooden bomb compartement below fuselage
Ju88A16 as A14, training aircraft
Ju88A17 as A4 with larger wing and 2 x Jumo 211-J1, torpedo bomber

I, personally, think they over-simplified their chart and did not list that the Ju 88A-4 was initially being equipped with the Jumo 211F engines. When looking at all references as a whole, tend to believe the Ju 88A-4 with the Jumo 211J were not really being cranked out until the beginning of 1941. Prior to that, it was most likely the 211F. (which really, there was not much difference).