xkhofmann-tfdidesign-md11-config-tweaks/README.MD

Adjustments

• Dropped idle thrust so so that aircraft doesn't start rolling when not nearly empty
  • Affected by n1_and_mach_on_thrust_table
    • Adjusted idle down on 0 mach entries only
    • Smoothed low end
    • Adjusted mach 0 curve to end at 1
    • Adjusted mach 0.25 curve to have a similar end to mach 0
    • Adjusted mach 0.74 curve to have a similar end to the surrounding
• Spool behaviour after 90 N1
  • Affected by corrected_n2_from_ff_table
    • Set idle N2 FF value directly
    • Made linear until original max
• EGT
  • Affected by itt_peak_temperature, itt_tc, egt_peak_temperature, egt_tc, egt_tuning_constant, fuel_flow_max_itt_factor, fuel_flow_min_itt_factor, itt_maxcorrection
    • At ISA, SL, 60C, EGT does not exceed 960C TO limit
    • Used online references to achieve idle EGT
    • Used Saudi FCOM for high altitude EGT
      • This may be unachievable
• Disabled sim protections
  • Affected by max_n1_protection, max_n2_protection, max_egt_protection
    • All set to zero
• SDK conformance
  • Affected by fuel_flow_gain
    • Set to zero as the SDK indicated one ought to

Additions

• New ground contact model

Observations

All test are done at SL (EHAM) and ISA (15C, 1013.25 hPa) unless otherwise noted.

The defined N1 and N2 max values are too low. as per EASA TCDS, the CF6-80C2D1F has a N1 max of 117.5 and a N2 max of 112.5. I do not know why the lower limits were chosen, it may be in our interest to adjust this to the actual limits. This may also influence the WASM since FADEC response and thrust limit selection may need to be adjusted to allow values higher than currently possible.

The curves that n1_and_mach_on_thrust_table look very strange. I do not fully understand how these were generated, and more importantly, why they have these shapes. Specifically the plateau and the bump at 25 N1 for the higher machs are odd. Comparisons with other addons yielded mixed results, however all of those curves did not have (or only in regimes unattainable during higher machs) such oddities.
Also to note is the drop in thrust for 120 N1 at mach 0 and mach 0.25. This seems backwards to what physics would suggest, with higher RPM generating more thrust.

The curves for n2_to_n1_table end in a rather sharp plateau. Without knowing how the actual CF6 behaves, this may be closer to reality than a pure logarithmic relation of N2 to N1 would suggest.

corrected_n2_from_ff_table is an oddball. If the game is told to not use this table, a default logarithmic curve is used instead. The modifications done here do not follow this due to the WASM FADEC imposing a non linear spool behaviour itself. It is to note however, that the sharp upturn at the end of the original lead to a noticeable increase in spool rate past 90 N1, after first seemingly slowing down at 75 to 80 N1.

The way the game does EGT is odd to say the least. Take the values with a hefty dose of salt. I could get SL static to look reasonable, but the EGT at high altitude remains to low. Adjusting to where high altitude looks reasonable will produce far too high SL temperatures, going so far as to reach above 1100 degrees Celsius.

TODO

• AND trim issue
• Slat drag and pitch up moment upon retraction