Junkers Engines Jumo 222, 223 and 224

Look what I found.

Re: Jumbo 223 engine.


I was going to reply: looks like a deltic x4

but i was just checking d'wiki and it says:

"The Jumo 204 and 205 were licensed to Napier & Son, who built a small number as the Napier Culverin just prior to the war. Late in the war, they mounted three Culverins in a triangle layout to produce the Napier Deltic, which was for some time one of the most powerful and compact diesel engines in the world."

Jumo 205 is smaller version of 223.

interesting stuff. Thanks for posting the pictures.

thanks for correcting my mistake. 223 is an engine I wasn't aware of before this thread.

It make me think if info on the Jumbo 224 does assist.

Regarding both engines, the Jumo 223 and 224, you will find detailed information with many drawings and photos in Reinhard Mueller's book "Junkers Flugtriebwerke" (Junkers aero engines), Aviatic Verlag (Aviatic Press). The informations reach from the first sketches (1936) to technical details like piston speed and combustion temperature between the pistons of the prototypes.

Here are two photos one of the Ju-223 one of the back of the Ju-222 one a drawing of the Ju-224.

Thanks

Nitpick it should be Jumo-223 etc

Hello,

My first post here.

I always wondered what was wrong with the junkers Jumo 222 ?
Given the fact that it was one of the most important german engine projects for a period, but Junkers never seems to have got it right.
Was there a fundamental design flaw, or could things have been ironed out with more development.

greetings,

Inhapi

The Jumo 222 was a high power aircraft engine design from Junkers. The design failed to mature even after years of intensive development, dooming the entire Bomber B program along with it. Only a small number were built, never leaving the prototype phase, but the design nevertheless continued appearing on new Luftwaffe designs long after most had given up hope it would ever work.

Design work on the Jumo 222 started in 1937. The engine consisted of six engine blocks with four cylinders each, arranged around the central crankshaft. The engine looked like a radial due to the arrangement, but the internal workings were more like a V-engine, and it was liquid cooled. The cylinders were arranged such that neighouring banks had exhaust and intakes beside each other, resulting in simpler "piping" from the rear-mounted supercharger and having three sets of exhausts. With a bore and stroke of 135 mm, the engine had a displacement of 46.5 litres. It was forced to run at a fairly low 6.5 compression ratio, the best possible given the low-octane fuels available in Germany, but by increasing the speed of the engine to 3,200 rpm, the 222 delivered 2,500 hp (1,850 kW) at takeoff. The dry weight was 1088 kg.

The 222 was Germany's first hyper engine, engines able to deliver about 1 hp/in (46 kW/L). Compared to the contemporary BMW 801 and Daimler-Benz DB 605, the 222 was a huge leap in performance. It had only slightly larger displacement than the 801's 41.5 l, and about 1/4 more than the 605's 35.7 l, but delivered considerably more power, 2,500 hp (1,850 kW) compared to 1,600 hp (1,193 kW) in the 801 and 1,500 hp (1,119 kW) in the 605. That represents 40 kW/L for the 222, while only 29 kW/L for the 801, and 31 kW/L for the 605. Even more impressively the power to weight ratio was 1.04 hp/lb (1.7 kW/kg) for the 222, whereas the 605 delivered an otherwise excellent 0.88 hp/lb (1.4 kW/kg), and the 801 a fairly poor 0.60 hp/lb (1 kW/kg). The 222 was also about the same size as these smaller engines, 1.16 m across compared to 1.27 m for the 801, and 2.4 m long compared to 2.3 m for the 605. The comparison was even more favourable against other high-power engines under development. The DB 606 consisted of two DB 601's bolted together that delivered 2,400 hp (1,790 kW) from a whopping 3,340 lb (1,515 kg), and was 2.1 x 1.6 x 1.1 m in size. Needless to say, the RLM was excited by the possibilities of the design, and the similar DB 604.

The first prototype engine ran on April, 24th 1939, and was later air-tested on the nose-engine mount of a Junkers Ju 52. Production called for two primary models, the 222A and 222B, which differed only in the direction that they spun, intended to be used for left and right-hand engines on twin-engine designs. However, continued testing went poorly, and Junkers eventually decided it was best to stop development of these "Series I" engines and move onto a modified "Series II". The new 222A-2 and B-2 ran at a slightly slower rpm, while the A-3 and B-3 used a different supercharger for more performance at higher altitudes. Both continued to prove unreliable, and were fitted only experimentally.

By late 1941 Junkers decided the best course of action was to make more radical changes to the design, and introduced the 222C and 222D models. With a new bore and stroke of 145x140 mm, the engine displacement increased to 49.9 litres. Back at the original 3,200 rpm the C/D models could deliver just under 3,000 hp (2200 kW) when they started running in the summer of 1942. However the problems were not cured, and only a handful were built. The RLM had been waiting for three years at this point, and eventually gave up and had all designs based on it look for alternate engines. Later that year they gave up on that as well, and cancelled the entire Bomber B program outright.

Junkers still didn't give up. Returning to the original A/B design they added a new supercharger including an aftercooler for very high-altitude use, resulting in the 222E and F-series. By this point it appeared that the problems were finally being worked out, but bombing of the Dessau factories made production almost impossible. A final attempt for even higher altitude performance resulted in the turbocharged 222G and H, built only to the extent of a few testbed prototypes.

The Jumo 222 was a massive and very costly failure, 289 222's were built in total, none to see active service. It also served to seriously hamper Luftwaffe designs from 1940 to 1942, when everyone waited for the 222 to finally start working. Meanwhile all calls for four-engine adaptations in place of two-engine 222 powered designs were rejected as placing too much strain on the German engine industry. In the end there was nothing to show for it, and late in the war the Luftwaffe was flying barely-updated versions of their original designs.


SPECIFICATIONS
For the 222A:
Configuration: Twenty-four cylinder liquid-cooled "star" (five banks of four-cylinders)
Bore by stroke: 135 by 135 mm (5.3 by 5.3 in)
Displacement: 46.5 litres (2,834 in)
Compression ratio: 6.5:1
Power: 2,500 hp (1838 kW) at 3,200 rpm for takeoff, 1900 hp (1397 kW) cruise
Dimensions: Length: 2.4 m, Diameter: 1.16 m
Weight: 1088 kg (2400 lb)
SFC: 0.477 lb/hp.h (0.29 kg/kWh

I could not add much to Nick`s excellent post but, since we dwell in a "Secret Projects" forum I would include that before settling on the definitive configuration, Junkers engineers ( Kurt Erfurth at top ) considered a 16 cylinder inline ( 2 banks of 8 ), a 24 cylinder H and one made of two coupled V-12. It was Ferdinand Brandner who fixed the liquid-cooled radial configuration for the Projekt P2001, as it was called internally. It would be great to see this paper-engines !

In German sources, the Jumo 222 actually is referred to as "Reihen-Stern-Motor" (inline-radial engine),
although I'm not sure, that this term already was used by Junkers.
Below a photo and a drawing of the installation in the Ju 222 via http://www.flugzeug-lorenz.de/index.php?id=109

Thanks for all these excellent posts.

Inhapi

I have read many recountings of the Jumo 222 tale, but have always come away a little unsatisfied.
The texts on the Rolls Royce Vulture discuss the problems that RR had with the connecting rods, bearings, and the water pumps / coolant circulation, and from that we can understand. But the with Jumo 222 all I have ever read is that "testing went poorly". Is there a text / website that has more information on the Jumo 222 problems???

Nick, you copied the wikipedia article ?

Inhapi

Inhapi, yeah - IIRC it was from German Wikipedia and I cleaned up a machine translation. It's been on my hard drive for a couple of years so my memory of where I got it from is a bit sketchy.

In his book "Ein Leben zwischen den Fronten" (A life between frontiers) Ferdinand Brandner (chief designer of the Jumo 222) describes the development and the related problems of the 222 in great detail. One of the main problems were bearing failures of the master connecting rods (big end) partly because they had to use "Sparstoffe" (inferior material quality because of war time shortages) and also some vibration issues. Like in radials, each star of six cylinders had one master connecting rod with five slave rods. Later the oil passages were redesigned which solved some of the troubles. Especially high performance engines often need time and resources to mature (for example the very successful P&W R-2800 had huge vibration challenges during its early years). There was also a political battle which hindered the progress of the engine because some people in the RLM (Reichsluftfahrtministerium) favored advanced versions of Daimler Benz's DB-603 (like the DB-603L) instead of the new and unproven Jumo 222. A little later many Junkers engineers were redirected to focus on the Jumo 004 turbojet which also didn't help to finalize the development of the 222.
After the war Brandner had to "move" to the Soviet Union where he and his team of German and Austrian engineers (mainly ex Junkers and BMW) lead the design and construction of the Kuznetsov NK-12 turboprop (for the Tu-95 Bear), still the most powerful turboprop built to date.

As Basil already mentioned, apart from the worsening situation with regards to raw materials (something, that probabyl could
ha´ve been overcome, at least for prototypes and wasn't already acute at the beginning of the war), the real "killer" for many
promising projects was the overstretched situation for engineering staff. It's not enough to have a handful of masterminds, but
you need hosts of well trained technical staff for smoothing and accelerating the development phase. Germany had too few technical
students even before the war and then numbers dwindled due to the need for "hosts" in other areas.

Comparisons of technical an scientific staff numbers just prior to war put the ascendancy with the Germans; the reason that Rolls-Royce kept pruning engine development tasks was to move people onto the engines that would immediately deliver what was needed.,, hence Peregrine stops, Griffon delayed, same thing at Armstrong Siddeley. Bristol suffered in bringing on the 'big' radials and also had to help Napier... whilst German companies seemed to have loads of different projects as well as material shortages. Also there were tensions in cooperation between departments and companies and military... just part of being in a right wing regime! Just look at Merlin vs DB 600 series as an example of focus vs dilution of effort.

Tartle, totally correct. The same parallel story could be told for aircraft radar or proximity fuse development. Many different German companies and organisations had fine developments in their labs like the centimeter wave magnetron etc but there was a lack of a nationalized effort like in Britain or USA. As you mentoned - not untypical for radical regimes.

Given two factors - confidence in quick victory and aggressive militarism - it's interesting to speculate as to how many potentially good technical people in Germany did the manly thing and joined the Luftwaffe or Wehrmacht.


Meanwhile, the Brits made heroes of their boffins - First of the Few released in 1942 and The Small Back Room published in 1943.

Basil,
You are right about our ability, during the twenties and thirties, building on the better ideas on Command, Control, Communications and Intelligence to join up the pieces better than the Germans. Curious that in the period 1910-1920 we found it hard to take on board Gottingen's (Prandtl, and others) pioneering work on circulation theory of aerofoil that helped the Germans so much. Lanchester had qualitatively had the idea in the 1890's onward but was derided by the scientific establishment who were a Cambridge University Wrangler network. They did not allow concepts that were only viable over a small (but useful) range of the aerofoil's operating envelope, i. e. the bit that aeroplanes needed to fly well, whereas the Germans embraced the theory and moved forward. I guess the Wranglers behaved a bit like Hitler's coterie.
[/size]Brandner's comments on the 222 development can also be read in the context of British efforts to build 2,000 hp class engines... the Napier Sabre took a huge effort to get right, involving Bristol and Rolls-Royce and a take over of Napier by English Electric. RR also were asked to look at aa big engine like the Sabre in case it all went pear-shaped.. resulting in the Eagle 22 (inspired by the Sabre but not a copy of it). An earlier effort ..The Vulture was abandoned as RR did not wish to do a Junkers and spread the development and production team too thinly, especially as they were diverting technical resource to support the creation of factories at Packard (USA), Ford (Trafford Park) and RR's own at Glasgow. Also a small effort was put into looking at the Crecy and Pennine type engines but gas turbines were looking a winner... most effort there coming from a team from Rover plus a few engineers from Derby... contrast that with Junkers... also think of RRs problems with bearings on putting two vees together (Vulture) vs the 222 in drawing below. Also I think that RR showed great focus ... even they they had a technical solution for Vulture they still stopped.... end of brainstorm !

As Tartle points out, in comparing the wartime British and German aircraft engine industries, one of the most revealing issues is that of the control exercised by the different governments. The German industry was permitted to loose focus and indulge in flights of fancy as well as the pursuit of projects of marginal or long term merit. Speer's reforms of 1942 pulled the German industry back on track but the worsening war situation and the descent of the Nazis into delusion meant that the tendency to pursue technically interesting projects of questionable utility had re-asserted itself by 1944.

While the British government did a better job of forcing the aircraft and aero engine industries to maintain focus, I wonder to what extent it is true that this proved disastrous in the long term. My impression is that the UK government, (being rightly pleased with itself over its role in the success of the UK aerospace industry in wartime) then continued it into peace time where its focus on spending as little as possible, its limited grasp of the industry's needs and workings and (most crucially) its control of the UK industry's income, meant that its engagement with the industry became more meddlesome and less helpful.

A comparison would be governments role in the destruction of the UK car industry. While I don't say that government were solely responsible for that, I would contend that it was generally unhelpful and concentrated on the wrong issues.

Tartle's 'Cambridge Wrangler Network' observation strongly reminds me of the oft noted antipathy of UK society towards engineers!

British engineers... a maligned lot!
I was lunching with the managing director of an aircraft galley company who before he had that job was an engineer on BAC 111 and went out to head the start up of 111 production in Romania... the wife of the UK ambassador, at an embassy reception in Bucharest on hearing he was an engineer asked if he had a moment to slip down to the kitchens and see if he could get the dishwasher going as it had broken down at lunchtime and the staff were worn out doing it by hand!!! Don't get that in Germany!
I think the problem with our post war governments was that the welfare state took precedence and we had to get the money from somewhere and innovation investment in the short term is expensive.....tbc

Another very serious problem for the German aviation industry were the constant questions of
authority between the airforce, the ministry for armaments, later the SS and in some cases even
Hitler himself, or other high ranking staff.

tartle said:

Don't get that in Germany!

Click to expand...

I would say that the crucial difference between the German and British engineering industries post WW2 has been cultural. If we take WW2 as a baseline (useful because the circumstances of industrialised war put the engineering abilities of a country to a meaningful test) then I would say that overall, Germany and the UK had the most creditable engineering performances - far better than those of either the US or Japan. Germany and Japan are now engineering colossi, the US was until recently, Britain is very much an also ran, but Germany (like Japan) has a culture that respects engineering and does not denigrate engineers. Ing. has the same cachet as Dr. for instance.

Curious fact that of all the mighty 24 cylinder/'Hyper' engine projects started..

..Only the much maligned Napier Sabre actually amounted to something..

..& in time to do something useful..

Roy Fedden wrote this article for 'Flight' - that reviewed German aero-engine development.

http://www.flightglobal.com/pdfarchive/view/1945/1945%20-%202393.html

One point that has been mentioned in Nick's excellent summary but perhaps not sufficiently stressed is that the Jumo 222 was a family of engines with different cylinder dimensions. The initial models, perhaps called Jumo 222 A-1 and B-1, had 135 mm bore and stroke, giving a displacement of 46.4 litres. The Jumo 222 A-2 and B-2 had a bore of 140 mm, giving a displacement of 49.88 litres. The C and D models according to Wikipedia http://en.wikipedia.org/wiki/Junkers_Jumo_222 had a bore of 145 mm and a stroke of 140 mm, giving a displacement of 55.5 litres. Unfortunately, http://www.enginehistory.org/German/Jumo222.shtml includes a specification for the C/D models with the stroke remaining 135 mm in the specification. It also describes a measurement of 150 mm for the bore of a captured example (perhaps measured by Wing Commander G.E.F Proctor). The E and F models returned to the 140 mm bore and 135 mm stroke of the A-2 model.

Even if everything else had gone well, spreading the engineering effort over the three different displacements would have almost guaranteed failure, although keeping the stroke constant would have slightly simplified development. Ferdinand Brandner's autobiography http://www.amazon.de/Leben-zwischen-.../dp/3853391257 may be biased but he is quoted as saying that the Jumo 222 was developed to death. The thread at WW2aircraft http://www.ww2aircraft.net/forum/aviation/jumo-222-whats-truth-39301.html seems to go over the puzzling story and offers most plausible possibilities without coming to a conclusion.

I wonder if the 222 suffered from the basic layout of an even number of cylinder banks. Most multi bank radial can be thought of as coupled radial engines.

Indeed KR, there may well be something in that, harmonic sympathy-wise.

There were quite a few X-crank mills, but none seemed to deliver on their 'simplicity' promise..

Addit: the 222 configuration was of course a six (*-wise) rather than 4 (per X)..

Yet the Napier Lion while being effectively 1/2 that layout - did work well.

J.A.W. said:

Curious fact that of all the mighty 24 cylinder/'Hyper' engine projects started..

..Only the much maligned Napier Sabre actually amounted to something..

..& in time to do something useful..

Click to expand...

It took the engineering brains of both Bristol and Rolls-Royce to sort the problems that enabled some sort of success to come out of the design; and English Electric's organisational and management skills to sort out the company itself.

The splendid Sabre design - however (arcane production matters aside), - did prove itself a standout,
& indeed - uniquely as a 'hyper' type mill, as even Roy Fedden acknowledged..

(See the 'Flight' article posted as #19 - in this thread)..

There were other engines that were cancelled, failed, too late or just not enough. In the US there was Packard's 1A-2775 http://www.enginehistory.org/Packard/jpgs/1A-2775%20supercharged.jpg , Continental's XR-1740 http://www.enginehistory.org/NASM/Continental%20XR-1740-2%20Sleeve%20Valve-1.jpg , Lycoming's monster XR-7755. Add in the odd balls. Curtis's hex designs, Pratt & Whitney's 20 cylinder corncob http://www.enginehistory.org/P&W/Museum/Recips/R-2060_015.jpg plus all of the barrel type engines. If one can think up an engine configuration it was most likely tried

I wonder just how much potential the 1A-2775 really had.

& not to exclude the Napier Cub, the 1st 1,000hp aero-engine..

..which was too much for most/all of the airframes of its (early 20s) era..

The 'big tea chest'@Kew revealed these curves for the Exe.

What would the firing order be on such a beast. Each bank of 4 as a 4 cylinder? Or as 4 off timed rows of 6? Maybe 2 addition cylinders on each bankwould allow the engine to be considered 3 V-12's on a common crankshaft. Just a thought

Here, - contemporary (`40s) British engineering appraisal of Ju 222..

http://www.enginehistory.org/German/Jumo222.shtml

I found this on a Russian site

Interesting. What were the specs?