General

Changes are marked with a comment //KH and their respective original value above the change itself. In cases where the original values were too large or new sections were added, the changes are enclosed in //KH START Modified and //KH END Modified comments.

The package only adjusts the GE freighter version, the pax version was kept unchanged to allow to see the differences more easily.

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
• Slat drag and approach N1
  • Affected by slat drag
    • Lowered drag_scalar

Additions

• New ground contact model

Observations

General

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

Engines

General

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.

Approach N1

A rough formula for 3° approach N1 at F35 is GW (in metric tonnes) / 10 + 52. A MLW aircraft with ~205t would hence require ~72.5 N1. The current N1 is above 80.

Trim

There have been reports of flights where the aircraft was not able to keep attitude with full AND trim. In essence, the APT would trim full AND, but the pitch kept rising. These flights were conducted with differing payloads, all of which set by the EFB, thus ensuring a valid CG.
Given the MD-11 far back placement of the wing and the subsequent 1° AND vs. 15.5° ANU trim limits, most flights would never use all of the AND trim authority. There seems to be some issue here.
I had tried a lot, but nothing conclusive. I see this as a limit of my understanding for MSFSs flight model configurations.

Slat drag

Users reported a strong pitch up momentum upon slat retraction, strong enough at times that sever trim changes were required. This ties in with the Trim issue noted above, where AND trim authority was not sufficient.
I attribute this to in parts the drag the slats exhibit, the resulting slow speed increase suddenly shifting to a rather large speed increase hence requiring large trim inputs. Smoothing out the speed changes would lessen the effect.
On a more personal side note, I can't see how the slats would create this amount of drag to begin with.

Approach attitude

Approach attitude should be (as per Centurion Cargo FCOM):

• F35, CG of 12%
  • 2.5°: Body angle of ~6.1°
  • 3.0°: Body angle of ~5.6°
  • 3.5°: Body angle of ~5.1°
• F35, CG of 34%
  • 2.5°: Body angle of ~4.7°
  • 3.0°: Body angle of ~4.2°
  • 3.5°: Body angle of ~3.9° No weight is given I assumed MLW of 204.8t.

Current attitude is ~0.5 to 1.5 degrees too low