Estimates of a Ju88G or R with Jumo 222?

[yosimitesam]

This is a little OT, but after capturing the H2S, why did it take so long to develop "Berlin", could it have been in service sooner? A Jumo 222 powered Ju 88 with Berlin seems like it would've been a beast.

Probably it was due to all the other components that had to be developed that couldn't be substituted by their existing meter wave components, e.g., wave guides, faster duplexer, necessary specialized tubes, etc. (The Germans didn't even recognize that polyethylene was a good insulator until examining allied electronics from downed aircraft. The Allies were always two years ahead of the Germans in radar by 1942 or early 1943.) Once the microwave generating unit (cavity magnetron) was understood, the Germans must then design their own radar units around it, and cannot simply replicate all the components. It's not just a 'device' but a whole 'electronics development system' from which the captured unit is one product. It's analogous to the long lead times for a prototype of a new aircraft design even when you have the blueprints all done.

 

[Koopernic]

Probably it was due to all the other components that had to be developed that couldn't be substituted by their existing meter wave components, e.g., wave guides, faster duplexer, necessary specialized tubes, etc. (The Germans didn't even recognize that polyethylene was a good insulator until examining allied electronics from downed aircraft. The Allies were always two years ahead of the Germans in radar by 1942 or early 1943.) Once the microwave generating unit (cavity magnetron) was understood, the Germans must then design their own radar units around it, and cannot simply replicate all the components. It's not just a 'device' but a whole 'electronics development system' from which the captured unit is one product. It's analogous to the long lead times for a prototype of a new aircraft design even when you have the blueprints all done.

The components is one thing but also the fact you need to use wave guides and special coaxial cables that needed to be precisely designed. Its sort of a plumbing job but every length has to be perfect and shortcut techniques need to be developed to design.

The Germans had a surprising knowledge of multicavity magnetrons but had not sought to use them in radar. In the 1939 they had a multicavity magnetron but with square cavities called a 'rad magnetron'. It was good for several kilowatts at about 22cm. The British magnetron that Randal and boot had developed had round cavities and Narrow slits. The Germans under Lorentz even had a multicavity magnetron with round cavities and narrow slits but it was capacitively coupled and used for small signals but could easily have been adapted. The Japanese even beat Randall and Boot to it by evolved square tooth magnetrons. The had a type of klystron called a 'heil tube', in fact Heil can be argued to have invented the klystron. They had a small magnetron for signals they adapted.

It takes a lot of time to educated, train all the people needed to begin mass production, have test instruments etc.

The German Navy under the Phyicist who headed the signals branch Dr Kunhold effectively invented radar (a little earlier than Watson Watt). Kunhold wanted to use 13.5cm microwaves for precision fire control. When Kunhold approached Dr Runge at Telefunken about his idea of radar Dr Runge scoffed and so the two most important men had a falling out. Latter Runge changed his mind and promoted the development of Wurzburg Radar. However Kunhold went to a small company that was making navy sound recording equipment and sonar GEMA and they developed Freya and Seetakt. However the poor relationship hampered develpment.

The Germans had a microwave program. They weren't going for 9cm waves but 5cm (usuing tunable split anode magnetrons of around 1.2kW power) and 25cm disk triodes. The program was cancelled in mid 1942 under objection from Dr Wolfgang Martini who headed the Luftwaffe electronic warfare branch.

A few months after the cancellation a British H2S magnetron was captured in Rotterdam from a downed Sterling bomber and around the same time extremely heavy jamming started.

The disbanding of the microwave program lead to many technicians being drafted into the army and it took a long time to get them back..

Probably 100-200 German built microwave radars were delivered from about mid 1944, mainly ground based or ship based but they had a H2S equivalent.

The 25cm program survived and created a FLAK radar with autolock called FuMO 231 Euklid for German destroyers.

The Germans developed a device called a disk triode (such as the telefunken LD7) which could produce about 16kW at 9cm but couldn't go much above (50kW at 27cm). They wanted to be able to control the 'phase' of the radar for coherent pulse doppler and precision purposes. The British achieved this by measuring the phase of the outgoing pulse and adapting it to the preceding one. Not as good but good enough. Layer klystrons came along.

 

[rinkol]

That would be crazy since DB601 / DB603 / DB605 shared development technology. Better to keep all three and kill the entirely new 24 cylinder DB604 engine.

Personally I would go so far as to kill Jumo 222 and begin development of Jumo 213 engine during 1937. However if Germany is determined to have a 24 cylinder engine program then the Junkers program is the only one I would fund.

All of the German engine development programs suffered from shortages of nickel and other important materials. The substitutes used caused serious problems, particularly with exhaust valves.

Other aspects of their planning/management left much to be desired. The Jumo 222 went through several iterations involving bore and stroke changes to meet requirements for additional power to accommodate weight increases in the Ju 288, which in turn resulted from changing requirements. DB wasted considerable effort on schemes such as surface evaporation cooling and coupled engines Furthermore, with the DB 603 having so many development problems, it was probably naive to attempt a 16 cylinder version (DB 609). BMW would have done better to forget about the BMW 803 and focus on the BMW 801 and 802.

 

[Koopernic]

All of the German engine development programs suffered from shortages of nickel and other important materials. The substitutes used caused serious problems, particularly with exhaust valves.

Other aspects of their planning/management left much to be desired. The Jumo 222 went through several iterations involving bore and stroke changes to meet requirements for additional power to accommodate weight increases in the Ju 288, which in turn resulted from changing requirements. DB wasted considerable effort on schemes such as surface evaporation cooling and coupled engines Furthermore, with the DB 603 having so many development problems, it was probably naive to attempt a 16 cylinder version (DB 609). BMW would have done better to forget about the BMW 803 and focus on the BMW 801 and 802.

To a certain extent the Germans suffered less from shortages than they imagined except right at the end of the war. However in making preparations for shortages bureaucrats specified or mandated the use of substitute materials that often compromised the development of new engines. A case in point being Jet engines which might have had alloys with 60% nickel content Tinidur versus 30% and might have used different fabrication techniques for the blades. Whereas the British were casting their blades and then machining fir tree roots and finishing of the blade with machining the Germans were stamping them out with a simple eye attachment. The RLM mandated alloy for the bearings in the Jumo 222 caused much of the engines early problems. Helmuth Schelp also promoted the use of the axial impulse compressor instead of axial reaction type because the blades could be stamped instead of machined. However this type of compressor is significantly less efficient and ultimate drove up engine weight and exhaust gas temperature. In the end the Germans started to turn to the reaction type for BMW 003C and D as well as the HeS 008.

The lack of raw materials forced the German Armistice in WW1. There was not a single allied soldier in Germany. Helmets became thinned and the reason the Germans didn't build tanks such as the successful A7V was that they lacked the steel and had to choose between guns and tanks. The former being more important.

As far as the Jumo 222C/D with increased bore and stroke: it seems to have been a separate spin of development rather than an attempted replacement of the Jumo 222A/B and the two stage Jumo 222E/F

 

[Milosh]

Germany did not consider the A7V a success and planned other designs.

 

[Koopernic]

Germany did not consider the A7V a success and planned other designs.

The A7V was a success as 95% of the western front didn't have the kind of trenches the A7V couldn't cross.

It was reliable and although it had limitations such as lead from bullets getting between armour plate but that was shared by the British tanks (though they had more time to deal with it). The various planed successors to the A7V were impressive but likely would never get manufactured since WW1 Germany was so short of iron. On top of that hundreds of other materials in often only small quantities were short. This experience, likely even a war loosing issue, haunted German planners.