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My understanding was that the Me262 was uninterceptable once the right tactics were worked out going after bombers;
It can't be ready any later than it historically was, so maybe it only speeds things up for a year or 6 months, but that couldn't hurt Germany. It may not be a direct two years earlier is two years earlier to a completed engine, but even 6-18 months is an improvement, as nothing less will be learned in the meantime.A problem with some of these "early start" proposals is that often a lot was learned in the 2-5 years between the actual start of work and the "proposed" start of work. And in some cases even the historical start was done using rather inadequate test facilities let alone trying to use ( or not use) test facilities that might not have existed 2-3 years earlier.
For example there was a patent filed in July 1939 by Mueler and Junkers on the air cooling of turbine disks and blades. Even in 1940/41 work was being done on sections of the engines or scale models of the engine components to suit exiting test facilities and equipment. Again, as an example Junkers was working on a scaled down compressor such that it only absorbed 400hp to suit existing test equipment. The first Junkers jet engine, the RTO/RT 1 needed 4000hp to run it properly. The first engine/s never ran under their own power. They needed external power and a supply of compressed air to run at all. The first 12 stage axial compressor gave a total rise of 0.087 Ata at 6000rpm. Full speed was supposed to be 12,900rpm?
Some times a lot is learned even from failures.
The 004 was a simplified, austerity design. It took almost 3 years to go from initial proposal to flight test under a Bf 110. But some of the men who worked on it had worked on the earlier engine. Without the work done on the earlier engine haw much longer would it take?
They would dive through a bomber box and pull up sharply to slow down briefly and shoot up the bombers from below before speeding off again as they leveled out or dove away again. This was completely uncounterable by escort fighters because the Me 262 was traveling way to fast for the whole process except for a couple of seconds, long enough to get off a burst with their Mk108s against the much larger target of B17s (the P51s are going to have a hard time acquiring the much smaller Me262 in the brief slowdown than the Me against the b17s).Which tactics? The problem was that when flying fast enough to make it impossible for the fighters to catch them the Me 262s had very little time to line up and fire at a bomber. In order to have a reasonable chance of hitting the bomber they slowed down, but then the escorts, particularly diving from above, could catch them.
I don't think that this classic "Catch 22" was ever really resolved.
The RAF carried out an interesting experiment with a Spitfire and an EE Lightning which illustrates the problem of a large closing speed in a much faster aircraft.
Cheers
Steve
The Me 262 was so fast that German pilots needed new tactics to attack American bombers. In the head-on attack, the closing speed, of about 320 m per second (350 yd), was too high for accurate shooting. Even from astern, the closing speed was too great to use the short-ranged 30 mm cannon to maximum effect. Therefore, a roller-coaster attack was devised. The 262s approached from astern and about 1,800 m higher (5,900 ft) than the bombers. From about 5 km behind (3.1 mi), they went into a shallow dive that took them through the escort fighters with little risk of interception. When they were about 1.5 km astern (0.93 mi) and 450 metres (1,480 ft) below the bombers, they pulled up sharply to reduce their excess speed. On levelling off, they were 1,000 m astern (1,100 yd) and overtaking the bombers at about 150 km/h (93 mph), well placed to attack them.[38]
Since the 30mm MK 108 cannon's short barrels and low muzzle velocity of 540 m/s (1,800 ft/s) rendered it inaccurate beyond 600 m (660 yd), coupled with the jet's velocity, which required breaking off at 200 m (220 yd) to avoid colliding with the target, Me 262 pilots normally commenced firing at 500 m (550 yd).[39] Allied bomber gunners found their electric gun turrets had problems tracking the jets. Target acquisition was difficult because the jets closed into firing range quickly and remained in firing position only briefly, using their standard attack profile, which proved more effective.[citation needed]
Captain Eric Brown, Chief Naval Test Pilot and C.O. Captured Enemy Aircraft Flight Royal Aircraft Establishment, who tested the Me 262 noted: "This was a Blitzkrieg aircraft. You whack in at your bomber. It was never meant to be a dogfighter, it was meant to be a destroyer of bombers... The great problem with it was it did not have dive brakes. For example, if you want to fight and destroy a B-17, you come in on a dive. The 30mm cannon were not so accurate beyond 600 meters. So you normally came in at 600 yards and would open fire on your B-17. And your closing speed was still high and since you had to break away at 200 meters to avoid a collision, you only had two seconds firing time. Now, in two seconds, you can't sight. You can fire randomly and hope for the best. If you want to sight and fire, you need to double that time to four seconds. And with dive brakes, you could have done that."[39]
Eventually, German pilots developed new combat tactics to counter Allied bombers' defenses. Me 262s, equipped with R4M rockets, approached from the side of a bomber formation, where their silhouettes were widest, and while still out of range of the bombers' machine guns, fired a salvo of rockets with Hexogen-filled warheads. One or two of these rockets could down even the famously rugged B-17 Flying Fortress.[40]
Though this tactic was effective, it came too late to have a real effect on the war, and only small numbers of Me 262s were equipped with the rocket packs.[41] Most of those so equipped were Me 262A-1as, members of Jagdgeschwader 7.[42] This method of attacking bombers became the standard until the invention and mass deployment of guided missiles. Some nicknamed this tactic the Luftwaffe's Wolf Pack, as the fighters often made runs in groups of two or three, fired their rockets, then returned to base. On 1 September 1944, USAAF General Carl Spaatz expressed the fear that if greater numbers of German jets appeared, they could inflict losses heavy enough to force cancellation of the Allied bombing offensive by daylight.[citation needed]
They would dive through a bomber box and pull up sharply to slow down briefly and shoot up the bombers from below before speeding off again as they leveled out or dove away again. This was completely uncounterable by escort fighters because the Me 262 was traveling way to fast for the whole process except for a couple of seconds, long enough to get off a burst with their Mk108s against the much larger target of B17s (the P51s are going to have a hard time acquiring the much smaller Me262 in the brief slowdown than the Me against the b17s).
Historically the Jumo 004 project was started just about the time that WW2 started in late 1939, even though the jet engine design war proven by Heinkel as a viable concept in 1937; supposing that the RLM took an interest in 1937 and set up several projects (Jumo and BMW) as competitors how much of a difference would it have made?
They were aware of the concept of embedding the engine in the fuselage to reduce drag. The problem was two-fold, the first being the lack of apreciable thrust-to-weight and the other was they were simply out of time in regards to development.Germans also went for the axial flow because they thought they would need two engines to get the needed power and two under wing or in wing centrifugal engines would have too much drag. In this they were right, see Gloster Meteor with early engines. However in 1945-46 it was much easier to get modify (or scale up) the centrifugal engine to get much more power so later Meteor went much faster ( they had about double the power of early ones).
I think the futuristic axial compressor engine was too advanced and required too high a technology progress to be expected to be pushed forward significantly in operations. I think that had Germany pushed development of the centrifugal compressor engine, they could possibly have fielded a viable 2k lb thrust engine much earlier. The Brits could have also, had they been so enlightened to push the jet engine. I think the development risks of the centrifugal engine were much less than that of the axial version.
I'm under the impression Jumo 004 engine was derived from experience with earlier HeS 30 jet engine. This was cutting edge technology so unless you plan to go back in time with engine blueprints I don't see how it could begin earlier.