#431
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#432
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My best guess is that there was a major difference between the Emil and Friedrich propellers (also according to the propeller effiency curves I have seen), the latter was of smaller diameter and almost certainly meant for high altitudes, and probably less efficient in denser air, hence the relative stagnation of speed near SL. The Friedrich would be probably faster with a different prop. But all of this is not so extraordinary or a surprise since the same can be noted when it comes to the Mark I / Mark V / Mark IX Spitfires's evolution. Hell the Mark I. at +12 is supposedly faster at SL than the Mark IX at +15 boost, how come..?
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Il-2Bugtracker: Feature #200: Missing 100 octane subtypes of Bf 109E and Bf 110C http://www.il2bugtracker.com/issues/200 Il-2Bugtracker: Bug #415: Spitfire Mk I, Ia, and Mk II: Stability and Control http://www.il2bugtracker.com/issues/415 Kurfürst - Your resource site on Bf 109 performance! http://kurfurst.org |
#433
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True..
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As you (and others) know the old saying.. Garbage in Garbage out! With regards to flight simulation.. You can think of the 6DOF flight simulation model as a black box.. With an input (plane parameters and current state) and an output (results) The math in the black box can be good to go.. no errors.. But if you input bad values (plane parameters and current state) you will get bogus outputs (results) With that in said.. I don't know if the 'results' of the Me262 or Spit used in the IL2Comp graph Kurfust posted have ever been validated.. As in have they ever been compared to any real world data, or checked by someone else to ensure the 'inputs' are correct. In short, in this case the IL2Comp values are suspect until validated.. Sadly I don't know of any real world turn time data of the Me262 that can be used to validate the IL2Comp, which leaves only for someone to doulbe check the input values and 6DOF math.
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Theres a reason for instrumenting a plane for test..
That being a pilots's 'perception' of what is going on can be very different from what is 'actually' going on. |
#434
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Again. We are talking 262s. In 1945.
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Il-2Bugtracker: Feature #200: Missing 100 octane subtypes of Bf 109E and Bf 110C http://www.il2bugtracker.com/issues/200 Il-2Bugtracker: Bug #415: Spitfire Mk I, Ia, and Mk II: Stability and Control http://www.il2bugtracker.com/issues/415 Kurfürst - Your resource site on Bf 109 performance! http://kurfurst.org |
#435
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Thanks Kurfurst, I’d not seen the V15 trials information before, the test-report is quite nice. Although I’d much rather have all of the pgaes in their originals, not just a few, and not have to rely on transcribed text into your html page.
The above aside, can you help me with a couple of questions: 1) What can we take from the apparent inability of any subsequent tests of the E1s or E3s (that I can find at least) to get anywhere near the “sea-level” (see question 4 below) speed of 493kmh or 498kmh? How do we explain that the prototype was able to record speeds that no subsequent 109 testing seems to have been able to achieve? I see testing data of 109E3 Nr1972, and 109E1s Nr1774 and Nr1791 (all of which are German tests, not British tests), none of which achieve above 485kmh at their lowest altitude of “0” (average is around 470) 2) Can you provide Blatt 3 of the testing documentation, the full-pressure altitude (Volldruckhohen) results – which I cannot find on your page? 3) Your tabulated summary of Blatt 5 indicates that the achieved speed (with the supposedly suboptimal engine pressures) was 493kpm at 0 altitude relative to the ground. Why does Blatt 6 indicate however that only 485 was obtained? is that because Blatt6 projects the speed down to sea level, whereas the tests were carried out at 0 altitude above ground, at a location (Augsburg?) already elevated (~440m) above MSL? If so, according to the test graph, do we get a sea-level speed of 485(490), not 493(49 for the V15? 4) the tests often make corrections for air pressure of a standard (Augsburg?) day "normaltag". Do we know what that pressure was? Last edited by pstyle; 09-27-2012 at 09:21 PM. |
#436
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Some are drawing wrong conclusions from the chart, but that doesn't change the chart. Kurfürst said the 262 can sustain a better turn time than the Spitfire at 400 mph, which is true. This will not win it a sustained turn fight though, as the Spitfire doesn't need to match the 262's speed. It can't do it in straight and level flight, so why bother in turns. Like I said, there's the chart and there's what you make of it.
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Last edited by JtD; 09-27-2012 at 05:15 PM. |
#437
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Lack of documentation for this claim noted. Still waiting for data proving the 109E had less drag than the Spitfire I.
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#438
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Il-2Bugtracker: Feature #200: Missing 100 octane subtypes of Bf 109E and Bf 110C http://www.il2bugtracker.com/issues/200 Il-2Bugtracker: Bug #415: Spitfire Mk I, Ia, and Mk II: Stability and Control http://www.il2bugtracker.com/issues/415 Kurfürst - Your resource site on Bf 109 performance! http://kurfurst.org |
#439
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Also noted
Yes that would be something to see!
__________________
Theres a reason for instrumenting a plane for test..
That being a pilots's 'perception' of what is going on can be very different from what is 'actually' going on. |
#440
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Turning is all about changing direction. If your plane is stuck at the limit of his performances there is no chance for it to turn corners. That's why fighters pilot enjoyed speed as the most valuable perfs... until reliable short range missile came The Mig17 Vs F4 is quite a good example. Pass the Mach 0.9 and then the F4 had the advantage. Especially in high G pull up and vertical manoevre. Exvatly what was teach at TopGun (see the the story of R. Cuningham). An F105 could turn with a 17... Above the mach Keep in Mind that BFM is all about E not turning circle. It's pretty easy to understand that with the late gen fighters. But so much could be said. Last edited by TomcatViP; 09-27-2012 at 08:56 PM. |
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