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If the LW fighters engage the escorts, then they are not engaging the bombers. And they might inflict losses on the allied fighters, but the vast industrial base of the US will replace them (pilot and aircraft) quickly.
The LW would take its losses too, but they could not replace the pilots, so the battle of attrition continues.
I see no advantage to the LW by going after the escorts or evading them to concentrate on the bombers. One way or another, they're going to be in terminal decline. The only way to inflict huge losses on the US bombers would to husband their forces and attack when they can have several hundred fighters in the air at one time. And that means being grounded for weeks at a time, till the its time to strike.
No not irrelevant, because they might attain local superiority over escorts the escorts will not be the focus, interceptors tasked with intercepting the bombers are easy prey for the escorts.
Interceptors who have numerical superiority have a choice - engage or evade. The LW controllers vectored superior forces to a weak spot to a.) overwhelm the escorts to enable a strong force at attack the bombers.
Interceptors tasked with intercepting the bombers, when confronted with escorts must make one of three decisions - fight the escorts, attack the bombers and 'evade the fighters' -losing all initiative - or simply dive away.
It was more sensible evading the fighters than fighting them, that was precisely what the allies wanted. This is what the advantage of the jets was, they could ignore the escorts with near impunity and down bombers.
Spaatz and Doolittle WANTED to Luftwaffe to stay and fight the fighters and the 8th BC assumed the role of aggressive bait.
If you believe the LW made the right decisions to flee in late 1943 up to the Invasion you are free to hold that opinion but I disagree! The LW remained the equal to near equal of USSR in the east with far fewer resources. They didn't 'run' there. The same super successful fighter pilots in the East struggled in the west. Why?
Parsifal, the USSBS indicated that the 8th AF didn't have much of an impact on the German war economy until summer 1944 when the oil offensive began in earnest.
Until then, the major contribution of the heavy bombers was to attract the attention of the LW fighters so as they could be shot down by the P51's and P38's.
Yes, and the figures show an increase in strength for June.
But June was a quiet month. Murray gives German fighter losses on the East, West and Mediterranean fronts as 373.
In July the losses soared to 782. In August 531 and September 542.
Compare those with the strength figures and you'll see there was a huge drop in July, a slight improvement in August and a slight drop again in September.
Every source I have seen agrees on this, that German aircraft production was inadequate to meet the needs of the Luftwaffe for most of the war.
From Murray:
... SNIP ...
It wasn't until late in the war that production was adequate for the Luftwaffe's needs, and even then I suspect production was inadequate, it's just that lack of fuel and pilots meant the Luftwaffe couldn't use all the fighters that were being produced.
Interesting. I have found very little information about these early turbofans, what eventually happened with them?.The bypass ratio was fairly small, the fan is only a couple of inches in height. For subsonic aircraft, the greater thrust and propulsive efficiency more than makes up for the increase in drag due to greater size. With greater speed this decreases so you have low bypass jets pure jets optimised for M1+ and M2+
I don't have a figure for the diameter but judging from my photos, the F3 is about 45" diameter, pretty similar to the centrifugal types which had no real problems fitting in Meteor nacelles. Weight was 2300lb and gave 4600lbf.
Ah okay that makes sense now.Turbine Entry Temperature or TIT, turbine inlet temperature.
Disagree here. The 004H would've been the best and fastest solution for the next generation of single engined jet fighters like the Messerschmitt prototype or the Ta 183.Things are more complicated than they seem. The J79 had variable angle stator vanes so you could adjust the pr and ease starting problems. Its not simple though. The 004H had two spools, like a lot of other paper engines. Power Jets were building the LR1 turbofan with two spools. Realistically you're creating something that is more complicated and requires more maintenance, for which its probably not worth it.
I guess i do, when it comes to these technical terms, my English sucks.Do you mean pressure ratio, not surge?
No argument here.Peak efficiency for a centrifugal single stage compressor is around 4.0 and 80%, which was achieved with these early engines. The Dart with a higher pr of 5.5ish went to two stage because its more efficient for that pr. For increased performance, the axial types can be better. The advantage the centrifugals have is simplicity and reliability.
You run into problems no matter what. That's part of development. It certainly is a lot easier though to keep the basic layout and a certain percentage of components than it is to built and entirely new engine.You run into problems with the blade stress increases, being more prone to surge with the increased pr, greater Mach number reducing efficiency. Its not a matter of "simply" at all.
Which is why the Jumo 004 or BMW 003 were the best choices for a twin engined fighter at that time. Once you went to single engined fighters, things change. And with the Jumo 004H you could get a sufficiently powerful jet with relative (again relative is the keyword here) ease.Was it best for what was needed at the time? No, which is why single spool turbojets and centrifugal types still dominate the low end of the market. Its only when you need greater thrust and lower fuel consumption (other factors as well) that more spools are useful. For the long range big jets the three spool Trent reigns supreme in terms of performance, but its not designed and built in the US so only has 40% of the market.
If advanced means overly complex, yes. Not even practical today.Lots of people had the same ideas, but Whittle's simple engine worked reliably despite offering lower performance. The most advanced engine would be Griffith's CR.1 contrafan with a high bypass ratio fan, high pr and novel 32 individual spool design for maximum off peak performance, but it didn't work with the technology of the time.
Which is why the Jumo 004 or BMW 003 were the best choices for a twin engined fighter at that time. Once you went to single engined fighters, things change. And with the Jumo 004H you could get a sufficiently powerful jet with relative (again relative is the keyword here) ease.
The only reason why there were "problems" with the 004a was because of raw materials and the condition some of these engines were assembled in, and credit to the Germans, they were coming up with "workarounds" to get these engines produced and made more reliable. As far as the Russians "giving up" on this engine, can you explain where the RD-10 came from? It powered the Yak-15 and -17, and while neither one of them were raging successes it did give the Soviet Union the platform to eventually develop more successful centrifugal engines (RD-9).They never got the Jumo 004a working all that well, ild hate to see a 004h, the Russians persued developing the jumo post war and ultimately gave up.
I have found very little information about these early turbofans, what eventually happened with them?
The 004H would've been the best and fastest solution for the next generation of single engined jet fighters
It certainly is a lot easier though to keep the basic layout and a certain percentage of components than it is to built and entirely new engine.
Which is why the Jumo 004 or BMW 003 were the best choices for a twin engined fighter at that time. Once you went to single engined fighters, things change. And with the Jumo 004H you could get a sufficiently powerful jet with relative (again relative is the keyword here) ease.
If advanced means overly complex, yes. Not even practical today.
The only reason why there were "problems" with the 004a was because of raw materials and the condition some of these engines were assembled in
Hello Kurfürst
now it's funny to see you blaiming that others are biased. Now on evidence, 109 and 190 losses of ground attack units can be find from Michael's pages, you already gave the link.
On the inadequate of Jagdwaffe was clearly seen blah blah blah blah blah....
IIRC the HeS011 was a two spool aswell and certainly more complex overall. The 004H would've been a much more practical solution. Of course, the HeS011 was more developed when the war ended. And well, to my understanding the 004H did just that, improve on the 004.Probably a step too long with first engines unlikely to be around for a few years. Easier to try and make HeS011 work well (maybe another 6months+) or improve existing 003 and 004.
This line of thought is one reason why so many British developments never became operational in time. Sure the basic concept was established in short time and early prototypes follow, but the substantial time it takes to iron out bugs and set up large scale production is another story. The Jumo is a prime example for this.Today when development takes so long and cost so much yes (e.g. RR Trent's 3-spool adaptability) but when you can hammer out a new engine like the Nene in 5 months... The new technology was progressing so fast that it was much more beneficial to design from new.
I understand your point of view but disagree. As the first generation was to be driven by two engines, frontal area was an important aspect and the centrifugal compressor looses here, especially the Whittle design. Another thing that bothers me about the layout are the strict requirements to the nacelles: You easily end up with a too long air intake and lose thrust (something that is often overlooked when raw performance of the engine is compared). Other than that both designs were valid choices.Personally I think the centrifugal was a better choice for the time period. Lots of the research already done so the focus is on productionising and improvements. Easy to scale each way from a successful design. e.g. Nene scaled down to give Derwent V and scaled up to give VK-1.
Oh contrafans are being worked on by P&W for example, though cerainly geared turbofans are the next thing. Not far away actually , I think they will enter service 2013. The multi-spool thing though, that's not going to come in another decade if ever.Its more the search for the ultimate in performance, which is relatively easy in a jet engine as you can calculate performance better than measuring it. The simplicity and reliability of the centrifugal won the day. It would be interesting to reexamine Griffith's contrafan today and see if it could be made to work better. Tighter tolerances possible with ECM would probably make quite a jump.
Build quality will be poor on any German engine that was built in 1945, no matter if jet or piston. The other "problems" were manageable. For a first-of-its-kind production engine the Jumo 004 was pretty reliable.Raw materials weren't really a problem for the 004A and get a lot of unjust stick. Better heat resistant alloys improve turbine lifetime they don't magically make all the other problems disappear. Compressor surging, combustion problems and harmonic excitation won't magically disappear are are far greater problems. Build quality is rather poor on the 004B engine at RAF Cosford compared to the Derwent and Goblin on display.
The Russians were far behind ALL other WW2 nations at the time. That's why they were not able to significantly improve on the Jumo 004 for some time and then someone drops the fully developed Nene in their lap including all knowledge how to built them... what do you think they're going to use? To take this as an example that the Jumo was at the end of its road is wrong as the design progess essentially ended with WW2. It was rather to the luck of Oestrich that the French were able to collect the astonishing number 200 BMW + subcontractor employees so he could continue the 003 development into what became the Atar.The French and Russian's used the 004 as is because it was available. As soon as better engines were available it was discarded. The design of the 004 itself died and didn't really lead to anything. The Russian axial program was already extant and the Atar took a very long, convoluted path from the 003.
I think its arguable either way as to whether the supply of aircraft was adequate to keep up with losses. But what is definately the case is that this was not the major constraint affecting the frontline, operational strength of the Luftwaffe. The two major issues were, firstly the numbers of properly trained pilots, and secondly the supply of fuel.
Agree and also consider that considering the Soivets "gave up" on the Jumo, they shoved them into 280 Yak-15s and 430 Yak-17s.The Russians were far behind ALL other WW2 nations at the time. That's why they were not able to significantly improve on the Jumo 004 for some time and then someone drops the fully developed Nene in their lap including all knowledge how to built them... what do you think they're going to use? To take this as an example that the Jumo was at the end of its road is wrong as the design progess essentially ended with WW2. It was rather to the luck of Oestrich that the French were able to collect the astonishing number 200 BMW + subcontractor employees so he could continue the 003 development into what became the Atar.
There wasn't a very good program after 1943. Many of the replacements were killed before they even knew how to properly fly their fighter. Some showing up with only a few hours in a Focke-wulf. It was very bad times for the Lw starting in 44'.There was nothing wrong with the Luftwaffe pilot training program per se. There simply wasn't enough fuel to go around.