Ju288A enters service in 1942

[GrauGeist]

The Luftwaffe was better off with the Ju88, to be honest.
Making a bigger Ju88 takes several hats of the 88's hat rack.
Improving the Ju88's speed would have been a plus as well as it's defensive armament (in certain applications and no turrets) would been beneficial.

But trying to make a heavy version with questionable engines was a diversion of resources, to be honest.

 

[cherry blossom]

Can I argue against the developing consensus for two reasons.

Firstly, the acceptance of the original three seat design for the Ju 288 means that the Jumo 222 will be developed and almost certainly produced with the original 135 mm bore (Flugmotorenwerke Ostmark was tooled to deliver Jumo 222s from August 1942 historically). I am guessing that when the Ju 288 A was rejected in favour of the Ju 288 B, Ferdinand Brandner confidently assumed that increasing the bore to 140 mm would be a simple way of getting the extra power demanded (and that he forgot to mention his confidence in his memoirs). We don't know if the original A1 engine would have become as reliable as engines such as the BMW 801 by August 1942, which is a fairly low bar, but it seems quite likely unless lack of tin makes the bearing problems insoluble. A reliable Jumo 222 A1 does not just allow Germany to produce the Ju 288A but also a more powerful He 219, Do 217 and perhaps a Fw 190.

Secondly, the Ju 288 A is only sensible as a night bomber and has more range than the bombers already in service. The implication of ordering a night bomber into production is that efforts are required to enable it to hit its targets. The Luftwaffe had already developed bombing aids such as were Knickebein, X-Gerät and Y-Gerät. Is it impossible to imagine something like the British Repeater Oboe being developed? If so, even a relatively small number of Ju 288As could cause significant damage to the USSR.

I had some problem finding details of Repeater Oboe. "Military airborne radar systems [MARS]" Full text of "Military airborne radar systems [MARS]" has details of the initial problems:

With Oboe, difficulty was experienced because, in prototype equipment, a given receiver-transmitter pair was only 70 per cent reliable at operating altitude. Since the repeater system used three such pairs, the system was only 35 per cent reliable. The problem of getting normal Oboe in large-scale operation was very pressing at the time, so the repeater Oboe program never got beyond the stage of trial operations.

However, Mahaddie, Thomas Gilbert (Oral history) may have details of 1944-5 use if the data were online.

 

[GrauGeist]

The main issue with the 222, is time for development.
Actually, time and materials, both of which, Germany was short of.

Many promising engine designs being developed during the war ran into trouble because of the demand for it to be done as soon as possible.
The British, Americans, Soviets and Japanese all suffered setbacks because of the demand to have engines developed within an unrealistic time frame.
Engines of the day were pushing the frontier in terms of design, alloys and technology and these things cannot be done at the drop of a hat.

This applies to both the piston and jet engines.

 

[Dimlee]

There is also the mistaken belief that it would have been immune to interception over the USSR. That overlooks the fact that the USSR did indeed have sufficient high altitude capability to limit Ju288 effectiveness. Just not made in the USSR.

Yes and no. Soviet PVO was OK in several places as in Moscow. But it failed in many others including industrial areas in Povolzhye (near Volga river) area. LW succeeded in the destruction of industry in Gorky, Yaroslavl and Saratov and to hamper shipping between Astrakhan and Saratov in the period May-June 1943 (Operation Carmen II). Losses: 18 bombers and 1 recon a/c, 13 crews.
(Source: Hitler's Strategic Bombing Offensive on the Eastern Front: Blitz Over the Volga, 1943 by Degtev and Zubov.)

 

[NevadaK]

Yes and no. Soviet PVO was OK in several places as in Moscow. But it failed in many others including industrial areas in Povolzhye (near Volga river) area. LW succeeded in the destruction of industry in Gorky, Yaroslavl and Saratov and to hamper shipping between Astrakhan and Saratov in the period May-June 1943 (Operation Carmen II). Losses: 18 bombers and 1 recon a/c, 13 crews.
(Source: Hitler's Strategic Bombing Offensive on the Eastern Front: Blitz Over the Volga, 1943 by Degtev and Zubov.)

Thank you, Dimlee.

I always appreciate that the majority here are better read than I am. The point I was trying to make was that the perception that the USSR was incapable of high altitude defense was erroneous. While the USSR didn't successfully build their own high altitude fighters, they did through lend-lease have capable air defense forces that would have impacted the Ju288. If the Luftwaffe did indeed field a large enough Ju288 force to threaten Soviet forces, I have no doubt that they would have been able to acquire more than enough aircraft to provide a credible defense in all areas. We know they used the Spitfire and had been offered the P-47. Since this is a What-If thread I think we can assume that the Soviets would purchase the necessary arms in response.

Thanks, again.

Kk

 

[nuuumannn]

We don't know if the original A1 engine would have become as reliable as engines such as the BMW 801 by August 1942, which is a fairly low bar, but it seems quite likely unless lack of tin makes the bearing problems insoluble. A reliable Jumo 222 A1 does not just allow Germany to produce the Ju 288A but also a more powerful He 219, Do 217 and perhaps a Fw 190.

Agree with your assessment, but a few things worthy of question. We do know that the Jumo 222A/B engines were unreliable, the type suffered ignition issues, which forced production to be shut down on two separate occasions in 1939 and in 1941. Following the dismal performance of the C/D models, the E/F versions were also never reliable, suffering issues as well.

Its worth mentioning that the armament issue was never resolved - the remotely operated barbettes were never built and while one of the B model prototypes had turrets fitted, they didn't have armament and I question whether they were operable. Germany had never developed power turrets before the Ju 288, so jumping from no power turrets to a remotely operated system took a huge leap of technical expertise. The Ju 288A was supposed to have the remote barbette operation, but none of the A model prototypes were fitted with the system.

Our fantasy scenario as per the original post has to 'imagine' that the issues with the Jumo 222 and the armament were resolved before the Ju 288 goes into service.

 

[Shortround6]

While the USSR didn't successfully build their own high altitude fighters, they did through lend-lease have capable air defense forces that would have impacted the Ju288. If the Luftwaffe did indeed field a large enough Ju288 force to threaten Soviet forces,

The assumption is that the thread's Ju 288 was be developed, manufactured and deployed in a vacuum of sorts.

The high altitude Mig-3 was available in large numbers in 1941 and early 1942. Development of follow-up aircraft (and newer versions of the AM-35) were continued even if low priority.

Had Ju-288s showed up in significant numbers the Soviets may have been able to shift some of their own production priorities around and build several hundred (or more) high altitude fighters better than the Mig-3 (enclosed canopy?) by early to Mid 1943 when the hypothetical Ju-288 would start to show up in numbers.

72 of the last Mig-3s built had a pair of 20mm ShVAK cannon in the cowl, same as the La-5, while not great it might work against bombers doing deep penetration raids. Under powered twins don't do well in engine out situations.
For a large scale bombing campaign to fail the defender only needs to inflict high single digit losses on the attacker.

Oboe (and some other blind bombing systems ) were restricted to line of sight from the ground stations. One of the reasons that the British tried to equip so many bombers with H2C radar was that it promised much greater accuracy for the bombers on targets that were beyond the range/s of Oboe.

 

[nuuumannn]

One of the reasons that the British tried to equip so many bombers with H2C radar was that it promised much greater accuracy for the bombers on targets that were beyond the range/s of Oboe.

Yup, agree, and because H2S didn't rely on external transmitters, it was a ground mapping radar.

 

[cherry blossom]

There was an attempt to get round the line of site range limit by using a repeater aircraft. From the link that I gave:

A method for extending the range of Oboe Mark I, which saw a few operational trials, depends on airborne repeater stations. The Oboe ground station and Oboe bombing aircraft are unchanged (except in radio frequency) but a repeater aircraft flies along the line joining the ground station and the target. This aircraft carries two transmitters and two receivers. It receives and retransmits pulses from ground station to the bombing aircraft and vice versa. Since the repeater aircraft can operate to the radar horizon of the ground station, there is an increase of a factor of three in range using this system. Frequencies are so chosen that when a pulse from the ground station is received it is repeated to the bomber receiver only, and conversely.
….

Oboe errors introduced by the repeater aircraft are of two kinds. First, the repeater aircraft may deviate from its assigned altitude, or may be displaced laterally from the course it is briefed to fly. For a representative situation, an error of 1,000 ft in altitude causes a bombing error of 40 yd, and a lateral displacement of 1 mile causes a bombing error of 7 yd. These errors are not serious. Second, as the repeater aircraft flies back and forth on its assigned track, the sum of the distances from the ground station to repeater and from repeater to a point at some given altitude over target does not remain constant. (If we consider the three points as forming a vertical triangle, the base line remains constant, but the sum of the lengths of the other two sides varies as the apex is moved.) If the repeater aircraft is at 35,000 ft and the target is at 500 miles from the ground station, and if the repeater aircraft stays between 150 and 250 miles from the ground station, the maximum error from this source is 90 yd.

 

[Dimlee]

The high altitude Mig-3 was available in large numbers in 1941 and early 1942. Development of follow-up aircraft (and newer versions of the AM-35) were continued even if low priority.

Had Ju-288s showed up in significant numbers the Soviets may have been able to shift some of their own production priorities around and build several hundred (or more) high altitude fighters better than the Mig-3 (enclosed canopy?) by early to Mid 1943 when the hypothetical Ju-288 would start to show up in numbers.

72 of the last Mig-3s built had a pair of 20mm ShVAK cannon in the cowl, same as the La-5, while not great it might work against bombers doing deep penetration raids. Under powered twins don't do well in engine out situations.
For a large scale bombing campaign to fail the defender only needs to inflict high single digit losses on the attacker.

MiG-3 production was suspended in 1942 and there was no spare capacity for this type later. In my opinion, in the discussed scenario, the Soviets could get more lend-lease a/c faster than to restore MiG-3 production and resolve all problems related to that aircraft.
But there are more obstacles besides the suitable interceptor. Radars, training of air and ground personnel and the whole organisation. In real history, despite the hard wake up call of Carmen II in June 1943 and after all measures taken to improve the strategic air defence, PVO was not able to protect the US airbase near Poltava one year later. (Operation Frantic, LW raid on June 22, 1944). There was definitely something very wrong with the PVO system itself.
So if Ju 288 show up in numbers by mid-1943 the Soviets would be able to respond but... when and at what scale? When new squadrons and ground operators are trained and more radar sets installed, there might be dozens of factories disabled. As it happened, for example, to GAZ in Gorky where over 70% of equipment was destroyed and the factory was shut down for 6 weeks and restored its capacity only 6 months after the last LW raid.

 

[Dimlee]

One picture is worth a thousand words. What about one video even it is from the flight simulation game?

Ju 288 - what if - Eastern Front

Just to add some visuals to the discussion about Ju 288. https://ww2aircraft.net/forum/threads/ju288a-enters-service-in-1942.57038/ Steven 197106 has created a real video museum of aviation in YT. Kudos to him and to the game creators and modders.

ww2aircraft.net

 

[delcyros]

Dr. Budraß supported in his PhD thesis the notion that Milch was instrumental and embarked on a project to break the Junkers monopoly established through combined airframe aeroengine research & production. The Ju-288 and JUMO-222A were instruments how he intended to do this. Apparently he cites lots of BAMA sources in his references, which indicate to me that this notion is borne out from primary source research.

Budraß has a brief summary of his phD in english but it is not as inclusive as the 1000p doc he proposed for his academic work.
L. Budrass, Demystifying the German "armament miracle" during World War II : new insights from the annual audits of German aircraft producers.

 

[delcyros]

Performances for the Ju-288A (projected) with various engines (w/o MW-injection at this time) at altitudes given:

The often reproduced 690 Km/h are for altitude optimised JUMO-222 engines (I presume turbocharged)

JUMO-211J
560 Km/h at 6,800 m max, 515 Km/h at 7,000m max cruise
900 m take off (1,300m to clear 20m)

JUMO-222A:
645 Km/h at 6,000m max, 565 Km/h at 8,000m max cruise.
600 m to take off (820m to clear 20m)

BMW-801A:
550 Km/h at 5,000m max, 510 Km/h at 5,000m max cruise.
860m to take off (1,230m to clear 20m)

BMW-801G:
575 Km/h at 7,000m max, 540 Km/h at 7,500m max cruise
850m to take off (1,200m to clear 20m)

Going by the Junkers data, the Ju-288A was viable with BMW-801 D/G engines and MW-50 injection for the low and medium altitude realm or with BMW-801 J/Q turbocharged engines for the high altitude realm. Likewise Db-603A and Jumo-213 might have worked in 1943/4. The JUMO-222 or Db-610 appears not to have been necessary.

 

[Denniss]

BMW 801Q was not turbocharged unless this was one of the cancelled projects.
The Q-2 was a serial production engine based on the D-2 with changes to the oil cooler which included a thicker armor

 

[delcyros]

Correction appreciated, Denniss.

for whats worth, here is the JUMO-222 timetable

1936
RLM specifies a new 1,800 hp class aeroengine

Dec. 6th, 1936
Junkers proposed a 1,900 hp rated at 5,000m full pressure height designated Ju P 2001, designed by Brandner.

May. 4th, 1937
RLM placed an order for a prototype P 2001 engine

June, 4th, 1937
Brandner finalized the design of the P 2001 engine as liquid cooled, inline radial with six cylinder banks placed at 60 deg with a total of 24 cyl. and a compression ratio of 6.5:1 and a displacement of 46.38 L.

March 1938
First run of a single cylinder test engine

April 4th, 1938
RLM assigns the official designation 8-222 to Junkers former P 2001 engine.

May 1938
The RLM requested an increased rated power of 2,000 hp at full pressure height. Brandner accepts the increased rating, intending to provide it through a higher rpm.

June 1938
First run of a test engine with one complete row of six cylinders

April 24th, 1939
First run of a complete JUMO-222 A-1 engine briefly up to 3,000 rpm. The engine was disassembled after the test run and showed no signs of wear or issues

May 1939
Junkers submits a proposal for a Ju-88 successor, the Ju EF 73 with two 8-222 engines.

July 1939
RLM issues specifications for the Bomber-B

1939
Junkers forms the Odder-Mader engine works in Dessau to concentrate development of the new Jumo-222 piston and Jumo-004 turbojet engines

Sept. 1939
Three JUMO-222 A-1/B-1 were running on the test benches

march 1940
JUMO-222 A-1/B-1 achieves 2,000 hp at full pressure height on the altitude test stand but inadeaquate lubrication and connection rod issues are identified, requiring modifications

1940
RLM accept the JU-288A with 3 men crew as the Bomber-B.

august 1940
modified JUMO-222 A-1/B-1 running on test bench successfully

Nov. 3rd, 1940
modified Jumo-222 A-1/B-1 airborne on Ju-52 testbed

Nov. 23rd, 1940
Ju-288V1 first flight with BMW-801A. Airborne tests of JUMO-222 A-1/B-1 on Ju-52 still incomplete

April 1941
modified JUMO-222 A-1/B-1 completes 100 hours continous test run at avg. 2,000 hp and avg. 2,860 rpm. The engine is disassembled after the test run. Issues found:
until 60 hours: no issues
Spark plug damage after 60 hours
leaking oil pump controller after 75 hourts
camshaft bearing block failure after 88 hours
minor coolant and fuel leaks

April 30th, 1941
Following the 100 hour tests, the RLM officially accepts the modified JUMO-222 A-1/B-1 with a 20 hours TBO and 30 min clearing for 2,000 hp (no emergancy power clearing) and orders it into production. That was about comparable to the BMW-801A and -C engines adoped about a years earlier. Junkers and the RLM select the Flugmotorenwerke Ostmark, Vienna for tooling up production for JUMO-222 A-1/B-1.

Early 1941
RLM now insists on a fourth crewmember of the Ju-288A, which requires a new pressurized cockpit section. Hertel demonstrates that the new specifications add 700 kg weight, reducing speed by approx. 10-15 mph and the range by 40 mls. RLM also requires more remotely controlled defensive turrets, adding yet more weight to the clean Ju-288A.

July 1941
RLM requires a change of specification from 2,000 hp at full pressure height to 2,500 hp on account of the now heavier Ju-288A
(it is here that Budraß, with good reasons, demonstrates that the change of specifications all originated from the RLM. Instead of accepting the JUMO-222 A-1/B-2 with 2,250 hp at SL / 2,000 hp at full pressure height -developed and already accepted by the RLM- the JU-288A is respecified to become heavier so that new specifications can be imposed on the JUMO-222A/B. The RLM already knows by this point that the 8-222 is already uprated from 1,900 hp to 2,000 hp and therefore developmentally tighter)
The issue also pertains to Junkers because Mader and Brandnder do fail to articulate their objections, presumably because they may have believed a significant increase in power was doable. Yet, an increase of rpm >3,000 was difficult with the original design. Some JUMO-222 A-1/B-1 were run for brief periods at 3,200 rpm and 2,500 hp at the expense of lifetime, eventually requiring an enlarged design, which became the ill fated and enlarged JUMO-222 A-2/B-2.

mid 1941
JUMO-222 A-2/B-2 run for the first time at 2,500 hp (briefly taken to 3,000 hp). Several issues encountered: harmonic resonances causing vibrations, connection rod bearings and internal corrosion

oct. 8th, 1941
Ju-288V05 successfully makes the first flight with two of the modified JUMO-222 A-1/B-1 (rated at 2,200/ 2,000 hp) with Brandner on board.

late oct, 1941
Manufacturing plant near Vienna was tooled up and nearing completion but it was clear that the JUMO-222 A-2/B-2 (rated 2,500 hp) was yet not ready for production.

Dec. 24th, 1941
Milch withdraws the JUMO-222A/B from the JU-288 program entirely and orders separate engine and airframe development. At this time, twenty (mostly Jumo-222A-1/B-1) engines had passed the 100 hour tests and five had passed airborne tests. Junkers felt that the -A1/B-1 were ready -by all means- for production. Milch blamed Junkers for the failure to provide a reliable 2,500 hp rating on the JUMO-222A/B because only the 2,000 hp rating was cleared.
In fact, the -A-2/B-2 engine continued to suffer conection rod and resonance issues, requiring another redesign to the JUMO-222 A-3/B-3, which received low developmental priority.

Dec. 1941
JUMO-222 A-3/B-3 was run for the first time on 2,500 hp

May 26th, 1942
JUMO-222 A-3/B-3 was run for the first time at 3,000 hp

august 1942
RLM is interested in the JUMO-222 A-3/B-3 and orders production for a new plant near Prague to commit production in 1944

Dec. 9th, 1942
JUMO-222 A-3/B-3 clears 50 hours type tests

March 13th, 1943
JUMO-222 A-3/B-3 clears 100 hours type tests

1943
JUMO-222 A-3/B-3 was airborne tested in Ju-52 and Ju-288B

June 1943
RLM cancels Bomber B projects and all JUMO-222A/B

autumn 1943
Junkers starts developing the JUMO-222 E/F out of the JUMO-222 A-3/B-3 as a dedicated high altitude engine

 

[delcyros]

When reviewing Junkers official projected data on the Ju-288A´s level speed, I am almost certain that the level speed of 645 Km/h was given for a presumtive of 2,500 hp rated JUMO-222 A-2/B-2 or -A-3/B-3. This is borne out from the speed delta with other powerplants of known output at given altitude. Therefore, the JU-288A with JUMO-222 A-1/B-1 rated 2,000 hp should be reduced accordingly to

v=645 * SQRT[3] (2000/2500)
= 599 Km/h
or 370 mph at altitude, give or take at the 30 minutes power.

Cruise speed (565 km/h or 350 mph) would not be affected.


attached is a comparison of key figures between B-26B and Ju-288A. They both are somewhat comparable in many key aspects. The former has a wider body, offers more space for crew and defensive guns but considerably less weight for payloads, less cruise speed and range in correspondence. The difference in % weight of both, fuel and bombload compared to MTOW is substantial, indicating detailed attention to questions of the structural design. Despite deviating from the circular fuselage, the Ju-288A indicates somewhat better aerodynamics with considerable achievements made both in drag reduction and high lift devices.