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polcat

Convert to JT8D-15A

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Because most operators do not have -17 equipped 737s, I feel that going with -15A 737 is more realistic. Can I get -15A engine performance by changing the original static thrust value to 15500? in the aircraft.cfg? Or would I have to also edit that part in the air file?

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>Because most operators do not have -17 equipped 737s, I feel>that going with -15A 737 is more realistic. Can I get -15A>engine performance by changing the original static thrust>value to 15500? in the aircraft.cfg? Or would I have to also>edit that part in the air file?Just change the static thrust will not provide the correct chart from EPR or even the engine readings.you must re-make the airfile tables: 1502 and 1506.to have the correct reading of EPR, you must have a formula from CN1% that fits the -15A values.also, from what I have tested, the static thrust line is a reference for the gross thrust value, not the net thrust. if you change, you may not have thrust enought to keep the climb profile.

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After a lot of studying of the thrust curves of the various JT8D variants, I think you can get a reasonable approximation of -15 performance by simply derating the power settings you use. The engines are pretty similar except that the later series produce more thrust at the high end due to the ability to drive the hot section harder (hotter).Basically the thrust vs EPR curves for the various variants sit almost squarely atop one another...so they all produce about the same thrust for a given EPR, but the later variants can be pushed up to higher max EPR values. The turbine speeds will be a percent or two low, and the fuel flow scalar may need to be tweaked up, but it's a pretty reasonable approximation to just use the lower EPR values charted for the -15, -11, -9 or whatever.This is on my list of interesting projects for the future, so a revised FDE and engine gauge set for a -9 and/or a -15 may become available at some point.CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

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