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Guest Skymed

Engine Startup

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Hi, is it possible to control the engine speeds during the start cycle? In particular to stop the classic FS over-run, so the speed curve is progressive from zero to to idle revs, that is, so the max speed in the cycle are the idle revs?cheers,nick

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I am not sure I understand your question. Are you trying to control the engine RPM during the startup procedure?If yes, I have been looking for a solution to this problem (N1 value is sometimes over 90% when starting, which is totally unrealistic), but never found anything.If you have any info, I'd be glad to know ;-)Eric

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Guys,If you need the EXACT book (and/or empiric) numbers, you need to program this in a gauge (C or XML). Every aspect of an Engine startup can be simulated to real numbers, for example acceleration vs bleed air pressure, EGT increase vs acceleration; hot starts, wet starts, hung starts, whatever. Fair to say all this stuff would mean to plot a lot of curves (2/3+ deg polinomies), but it can be done with a bit of patience. Is is important also that the engine tables (150n) in .air file are well related and have the proper values, together with correct fuel_flow_gain and other config parameters.Tom

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I have been doing this sort of thing with helicopters to develop an accurate start-sequence. One thing I found out through hours of testing is that the FPS of the sim will determine speeds of certain parameters.For instance, N1 and N2 of the chopper, where N2 is also tied to to Nr( rotor blade speed). I can set N1 to the exact speed it should spool up as per the correct engine parameters, and as long as I have my FPS set at a pre-determined setting (I Use 25) then N2/NR behave in a predictable manner. However, If I let my FPS increase to 40 or so, then N1 still follows the logic, but N2/Nr are considerably faster in getting up to speed, often beating N1 to idle.The same scenario is repeated during shutdown, where FPS will determine the rate of decay of N2/NR, faster FPS shutting down quicker than slower FPS. As I said, this is all based on the extremely funky choppers in FS9, but may also be pertinent to fixed wings as well.If you do some testing with different FPS you may see similar results as well.Steve

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