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Of course, there's also the jets ... but those programs weren't quite the same 'gambles' early on so much as inconsistently supported. (and for all their offensive tactical dreams early on, there was an odd lack of emphasis on high speed jet bombers ... granted, attack and dive bombers are totally impractical due to speed and fuel consumption at low alt, but medium/high altitude level bombers would have been more interesting)
In 1941-1942 they had enough of both, plus the Me210 was less draggy and would cost less fuel per mile flown, while the Jumo 222 was the most fuel efficient piston engine the Germans had:
Junkers Jumo 222 - Wikipedia, the free encyclopedia
A shallow dive bomber focusing on lob bombing and reliant on a specialized computing bombsight. A more primitive counterpart to that earlier in the war might have been somewhat feasible, but level bombers seem more practical.Look at Henschel's Hs132, purposely designed as a dive bomber.
If they were going for fuel efficiency, wouldn't investing further into diesel designs make more sense? (not to mention the huge logistical advantages of diesel oil production over gasoline -and reduced fire hazard, among other things)Most aircraft piston engines could get down into the low .50s or high .40s. Even the Merlin which wasn't noted for being a very economical engine could get down to .52-53 lb/hp/hr in certain cruise conditions. That means it used about 10% more fuel per hp/hr than the Jumo 222. Most of the German V-12s could get under .50 lb/hp/hr meaning that they were jumping through a lot of hoops for a very poor return. Even it is true going to that level of complexity for 2-5% hardly seems worth it.
Most aircraft piston engines could get down into the low .50s or high .40s. Even the Merlin which wasn't noted for being a very economical engine could get down to .52-53 lb/hp/hr in certain cruise conditions. That means it used about 10% more fuel per hp/hr than the Jumo 222. Most of the German V-12s could get under .50 lb/hp/hr meaning that they were jumping through a lot of hoops for a very poor return. Even it is true going to that level of complexity for 2-5% hardly seems worth it.
You also have to read Wiki articles very carefully.
"The dry weight was 1,088 kg (2,399 lb), only some 17 kg (39 lb) heavier than the air-cooled Double Wasp."
Which is quite true but rather neglects the weight of the radiators and coolant needed by the Jumo 222. Comparing dry weights never looks good for air-cooled engines. As in
" Even more impressively the power-to-weight ratio was 1.7 kW/kg (1.04 hp/lb) for the 222, whereas the 605 delivered an otherwise excellent 1.4 kW/kg (0.88 hp/lb), and the 801 a fairly poor 1 kW/kg (0.60 hp/lb)."
Now which 605 are they comparing and which 801 and what happens when you add the weight of the radiators and coolant? The Jumo may still come out ahead but not by the landslide the figures given portray.
And of course the 605 and 801 actually powered aircraft that went into service. Jumo 222s were so bad that even after being flown in a few prototypes, later prototypes of the same type/s of aircraft switched back to 801s or 603s or Jumo 213s so they could get flying time on the airframe. Hanger queens with Jumo 222s installed don't tell you how the aircraft flies.
Yes, so potentially useful for long range transports, bombers, and recon aircraft where the improved fuel economy comes into play. The 2-stroke jumo engines weren't as extremely efficient as some of the contemporary (or slightly older) 4-stroke designs, but came far closer to power:weight of gasoline engines than those others. (so even more extreme long range to be advantageous in terms of total aircraft power to weight ratio)The Diesel had a problem with power to weight. The Best the Jumo Diesel did was about 1000hp for 1450lbs dry weight, granted this was for a turbo version which could maintain the power to a considerable height. It still leaves a bit to be desired for take-off though. It also meant running it at at 3000rpm which meant a higher than normal piston speed (although not as high as a Pegasus).
The Diesel was only going to be useful when the length of the mission meant that the combines weight of the engine and fuel (and diesel fuel weighs more per gallon) was lighter for the diesel than the for the gasoline engine.
Right, right, strike that suggestion ... light, usually low compression, low octane fueled engines without fuel injection and used on aircraft with where the engine weight made up a significantly larger portion of total weight. (going in the opposite direction with engines able to run on the more common 70 octane automobile fuel might have been more useful for light aircraft, but there's other trade-offs there, including power/weight and fuel economy)Diesel powered trainers requires a bigger leap of technology than you might think. Trainer engines can be pretty low tech, The Bramo radial weighed about 300lbs, ran on 80 octane gas and gave 160hp for take-off using carburetors.
Y
Edit:
On the Jumo-222: Yes, if anything the early war A/B versions should have been focused on and brought to production even if not at the power levels desired for the super-sized twin engine aircraft being forced out. (so a more useful, practical, realistic design)
If it could enter mass production significantly sooner than the Jumo 213 could, then even more potential for its usefulness. The larger/more complex follow-on designs weren't worth developing in the timescale needed or with the engineering and manufacturing resource limits.
Perhaps a bit too large/heavy to fit well on the Fw-190 airframe ... but if any 222 would have worked there, it'd have been the smallest A1/B1 versions. (the DB-603 was a good fit in any case, plenty of heavy twins the 222 would have fit well on, possibly the Ju-88 itself)
The Wikipedia Comparing the Jumo 222A2/B2 to the Pratt Whitney R-2800 "Double Wasp" is unfair, the R-2800 needed 100/130 fuel and Water Injection to exceed 2000hp whereas the Jumo 222 was expected to do 2500hp on 87 octane, levels the R-2800 achieved only in 1944. The Jumo 222 was actually tested with 87 octane + MW50 and produced 2800-2900hp and 3000 with GM1(Nitrous)
A fairer comparison would be the Jumo 222A2/B2 of 1088kg weight with the CW R-3350 "Double Cyclone" of 1212kg.
The weight of radiator and cooling liquid plus oil on both would lead to equal weight, however the Jumo 222 would have a significant drag advantage.
The R-3350 produced 2200hp in 1945 using 100/130 whereas the Jumo 222A2/B2 was expected to produce 2500hp on 87 octane fuel. 87 octane is equal to about 63 PN. You can see what Junkers was trying to do. Moreover the Jumo 222 would have had substantially less drag, something quite important since its mission profile would involve a great deal of high speed low altitude work where thicker air has an impact. The Ju 288 mission profile was initially very high altitude penetration followed by a dive bombing and low altitude attacks.
One reason the Jumo 222 was preferred over its rival the Daimler-Benz DB604 was that the Jumo 222 promised a very high cruise power and very good cruise consumption. Both were elements that the German engines were characteristically good at probably due to the nature of the airframes and fuels they had. Note they were doing excellent fuel consumption on only 87 octane.
The Jumo 222 didn't fail, it was rescheduled for production on October 1944. The Junkers Ju 288 on March 1944. So what happened?
It was killed by airframe weight growth, planning and resource limitations as much as delays.
Here is a month by month chronology.
1 1937 design work begins on Jumo 222A1/B1 (note the R-3350 had run this year).
2 1937 design work also begins on the Ju 288 as EF73 but using a longer running diesel engine known as Jumo 223
3 1938 Powerplant of EF73 changed to Jumo 222 gasoline engine.
4 1939 April first test run of Jumo 222
5 1940 March 2000hp achieved 100 hour test.
6 1940 the Ju 288A had been an 11000kg three man aircraft with a 3 ton internal bomb load, it is now increased to a 4 man crew, cabin is widened to allow side by side seating, weight goes up to 14000 tons empty equipped.
At this point 2500hp is considered essential rather than option. The aircraft is redesignated as the Ju 288B. Three engines are suitable: the Jumo 222A2/B2, the Jumo 222A3/B3 which has improved supercharger hydrodynamics to raise critical altitude from about 5000m to 6000m and the Jumo 222E/F which has a two stage intercooled supercharger with a critical altitude of 9300m.
7 1941 April passes a 100 hour 2500hp test, having already reached 3000hp for short periods.
8 The Ju 288V5, a version of the light weight A series, flew on 8 October 1941 Jumo 222. The V6 also flies with Jumo 222 but crashe lands due to an engine fire.
9December 1941 RLM decides to us DB610 engine instead of Jumo 222. Removal of Jumo 222 from large scale production. Note this engine is paired DB605s (not the DB606 which is paired DB601). This version of the aircraft is known as the Ju 288C and it has increased length, span and weight to compensate for the greater fuel consumption of the DB610. The DB610 never gave any problems in the Ju 288C prototypes and its test pilots spoke highly of it.
10 1942 June confirmed 3000hp. (probably the enlarged C/D)
11 Restoration of of Jumo 222 on production program scheduled October 1944 (the program was delayed to Feb 1944 due to need to produce Jumo 213 more urgently)
12 the Jumo 222C/D which had increased volume and had run in 1942 received highest development priority.
As you can see the first flight of the Ju 288V5 is happening the same time the RLM is abandoning the engine in favour of the paired DB610 (itself a seriously delayed engine). Prior to that Ju 288 had flown with the BMW801 (which was adaquet for the smaller 3 man airframe).
So really any serious development effort on the Jumo 222 had stopped by the end of 1941 just as the flight test program was beginning.
A note here, Operation Barbarossa, the invasion of the Soviet Union is happening and this is changing priorities as well Jumo 222 supporter Ernst Udet has killed himself while Erhard Milch has taken over and is applying a new approach, perahaps even trying to break up junkers.
The production schedule for the Ju 288 was essentially as follows:
Jan 1942 to December 1943: initially 3 were to be produced per month ramping to 10 per month in December 1942. These were essentially prototypes but would have provides a few dozen operation aircraft for squadron evaluation.
Jan 1943 to December 1943 ramping up from 15 aircraft per month to 285 per month in 5 factories.
The engines designer, Ferdinand Brandner, says the problem with the engine is that it was developed to death due to airframe weight growth with multiple bore and stroke changes and increasing power requirements.
1 Jumo 222A1/B1 135mmm bore by 135mm stroked, this was an early engine 46L capacity
2 Jumo 222A2/B2, Jumo 222A3/B3 and Jumo 222E/F 135mm bore x 140mm stroke. 49L capcity
3 Jumo 222C/D bore 140mm x stroked 140mm (55L capacity)
4 Jumo 222G/H with 36 cylinders with original bore and stroke.
So the Jumo 222 program was really two engine programs the Jumo 222A/B and EF to produce engines in the R-3350 class and the Jumo 222C/D and G/H to produce engines more in the PW R-4360 class.
In fact in Jan 1945 the C/D received high development priority (I know this is delusional in 1945 but a decision like this is based on long terms visions going back to 1942) for use in large scale bomber projects such as the Ju 290 since 3000-3500hp was required. (This is presumably an "Amerika Bomber")
It seems to me that once the 3000hp DB610 was selected for the Ju 288C which now increased in weight yet again and the Jumo 222A/B engine Jumo 222A/B taken of the production program that it must have been felt a 3000+ class engine would be required.
Given that the engine has passed a 2500hp test in April 1941 and is flying latter that year (October 1941 in 2000hp form) it seems to me it could have produced a reliable 2000hp production engine by the end of 1942 ready for production in early 1943.
So what would a 2000hp 1088kg engine been useful for in 1943. It's power to weight ratio was the same as the 1750hp Jumo 213A (first service early 1944 on Ju 188A) and DB603A (service in mid 1943 on Me 410 and Dornier Do 217).
The Do 217M would probably be able to fly at 362mph (up from 347mph using a cube root law) perhaps more and cruise at around 340mph. The He 219 could use it as could the Me 264.
The Ju 188, Ju 88S, Ju88G are all possible candidates as is even the Me 410 and one would expect 5% greater speed.
The Fw 190 probably can't take it but it could fit into the Ta 152 and was slated for the Do 335
The original Ju 288A with 3 man crew would have been viable.
Eventually the engine should have made it to 2500-2800hp.
Best case scenario it would be ready about the same time as the Jumo 213 at 2000hp, perhaps a few months earlier, which means most of 1943 sees a ramp up of production, but heavily delayed, as the 213 was historically, by strategic bombing of Dessau and other Jumo facilities, plus of course the Ostmark problems. So while it could be in serial production by 1944 after a delayed ramp up in 1943, it would only be in limited production like the 213 was.
What's your source on the Jumo 222?
The main problem I have with the Jumo 222 is when did they build the bulk of the 270 or so engines built? Stories of the few prototypes to fly with them are full of delays in engine deliveries and a few planes that were supposed to use them apparently never got them. Like the He 219B. Some accounts claim Heinkel had a least one prototype waiting for months in 1944 for a pair of engines.
Accounts give us the total number of engines built but don't break down the production by different models or year/s.
Getting airworthy examples seems to have been a real problem.
Passing a type test is certainly a step in going from prototype status to production but the Allies had a number of engines that passed type tests that took several years to straighten out. Passing the type test is NOT a Guarantee that the engine will be trouble free in service at that rating.
R&R Vulture passed type test.
Napier Sabre passed type test in June of 1940
Bristol Centaurus passed type test in 1938
The V-1710-C6 successfully completed the USAAC 150 hour Type Test on April 23, 1937 at 1,000 hp (750 kW) yet the production V-1710-C15 engines had to be derated from 1040hp to 940hp in 1940 until they were re-worked by the factory.
The Wright R-3350 went through TWO different designs and the 2nd one was in production by Aug of 1942 and yet look at the problems they were having in 1944/45.
There may well be others.
With all respect to the soviets, they were outclassed anyway in 1942 and any extra wouldn't have made a huge difference. Granted there communications and major factories would have been at extra risk but the Luftwaffe had the opportunities to use attack these and didn't so it would need a mindset change on the German High Command and that was unlikely
I agree that Soviets were outclassed in 1942. However, the historical LW have had next to zero capability to conduct raids on Tankograd and the like, that was too distant and/or too risky for their bombers. The fully working Ju-288 and/or He-177 would've provided them with better tools for that job.