Per-Aircraft Settings

The plugin stores its tunable state per X-Plane aircraft, so the RV-10's setpoints don't bleed into the Cessna 172. Settings live in a plain text .prf file and load automatically each time you switch aircraft.

File location

Settings file path:

<X-Plane root>/Output/preferences/AOA-Tone-FlyOnSpeed-<acf>.prf

<acf> is the aircraft .acf filename with the extension stripped and any path separators (/, \, :) replaced with underscores. For example, Aircraft/Laminar Research/Cessna 172 SP/Cessna_172SP.acf becomes AOA-Tone-FlyOnSpeed-Cessna_172SP.prf.

Switching aircraft mid-session reloads from the new aircraft's file on the next XPLM_MSG_PLANE_LOADED callback.

Format

Plain key = value\n lines. Unknown keys, malformed lines, and missing files are silently ignored — defaults stand in. A partial file is fine; the plugin only writes keys it knows.

fLDMAXAOA = 6.000
fONSPEEDFASTAOA = 7.300
fONSPEEDSLOWAOA = 9.600
fSTALLWARNAOA = 12.500
iMuteAudioUnderIAS = 25
iMasterVolumePct = 100
iAoaMedianWindow = 5
iAoaMeanWindow = 10
audioEnabled = 1
serialPortPath = /dev/cu.usbmodem11201
indexerVisible = 1
indexerMode = 0
indexerPoppedOut = 0
indexerFloatLeft = 100
indexerFloatTop = 600
indexerFloatWidth = 320
indexerFloatHeight = 240
indexerPopLeft = 100
indexerPopTop = 100
indexerPopWidth = 320
indexerPopHeight = 240

Fields

Field	Type	Range	Purpose
fLDMAXAOA	float (degrees)	0 – AOA_MAX	Below this AOA, audio is silent. Best-glide / best-climb reference.
fONSPEEDFASTAOA	float (degrees)	0 – AOA_MAX	Lower edge of the OnSpeed band. Below it: low-pitch pulsing.
fONSPEEDSLOWAOA	float (degrees)	0 – AOA_MAX	Upper edge of the OnSpeed band. Above it: high-pitch pulsing.
fSTALLWARNAOA	float (degrees)	0 – AOA_MAX	Stall-warning threshold. Above it: stall buzz at 20 PPS.
iMuteAudioUnderIAS	int (knots)	0 – 250	Audio is silenced below this IAS. 0 disables the gate. Hysteresis: unmute at iMuteAudioUnderIAS + 5, re-mute at iMuteAudioUnderIAS.
iMasterVolumePct	int (percent)	0 – 100	Master volume scaling, applied before pan splits.
iAoaMedianWindow	int (samples)	1 – 100	Median-despike window size on the AOA dataref. 1 disables.
iAoaMeanWindow	int (samples)	1 – 100	Running-mean window size after the median. 1 disables.
audioEnabled	int 0/1	—	Sound on/off toggle. Persists across sim restart.
serialPortPath	string	OS-dependent	USB-serial port to drive a tethered M5. Empty = no output.
indexerVisible	int 0/1	—	Whether the indexer window was open at last save. Restored on XPLM_MSG_AIRPORT_LOADED.
indexerMode	int	0 – 4	Last-active indexer display mode (Primary, Attitude, Narrow AOA, Decel, G History).
indexerPoppedOut	int 0/1	—	Whether the indexer was floating inside X-Plane (0) or detached as its own OS window (1).
indexerFloatLeft / Top	int (boxels)	screen-bounds	Top-left corner of the indexer window in X-Plane global desktop boxels, when floating.
indexerFloatWidth / Height	int (boxels)	≥ 160 × 120	Indexer window size when floating.
indexerPopLeft / Top	int (OS pixels)	OS-monitor coords	Top-left corner of the indexer window when popped out into its own OS window.
indexerPopWidth / Height	int (OS pixels)	≥ 160 × 120	Indexer window size when popped out.

The four AOA setpoints share the same ordering invariant as the firmware: fLDMAXAOA < fONSPEEDFASTAOA < fONSPEEDSLOWAOA < fSTALLWARNAOA. Save fails with the same error wording the firmware uses (OnSpeedConfig::SuFlaps::SetpointOrderError) if the order is violated.

AOA_MAX is the universal onspeed::AOA_MAX_VALUE from onspeed_core/util/OnSpeedTypes.h — plugin and firmware agree on what counts as a sane AOA value.

Editing from the UI

Open Plugins → Fly On Speed → Show. The audio control window exposes the AOA setpoints, IAS mute threshold, master volume, and smoothing windows as editable text rows; audioEnabled is the Sound: On / Sound: Off button. serialPortPath is set separately via Plugins → Fly On Speed → Serial output → \<port> (see Tethering a Physical M5).

Click Save to validate, apply, and write to the per-aircraft .prf. Validation runs in two passes:

1. Per-field range and parse check. Fields that fail get an in-place !! prefix in the row's text. Invalid fields show their failing reason in the status line.
2. Cross-field ordering check on the four AOA setpoints. If the ordering is violated, all four setpoint rows are flagged together — the validator can't tell which value the user mis-typed.

A successful Save clears every !! marker, applies the values to the live audio engine, rebuilds the AOA smoothers if the window sizes changed, and writes the .prf. Any single validation failure means none of the live state changes — fix the marked rows and Save again.

Restore Defaults reverts every editable field to the compiled-in defaults (LDmax 6.0°, OnSpeedFast 7.3°, OnSpeedSlow 9.6°, StallWarn 12.5°, IAS gate 25 kt, volume 100%, median 5, mean 10) without saving. Click Save to commit them; otherwise they're gone on the next aircraft load.

Reload Plugins is an escape hatch in the same window. If OpenAL gets wedged (no audio with the toggle on, no error in Log.txt), or the indexer texture doesn't update after an aircraft change, this button reloads the plugin without restarting X-Plane. Equivalent to Plugins → Reload All Plugins but routed through this plugin's own teardown so settings are saved first.

The indexer* keys are written automatically as you interact with the window — drag, resize, pop-out, click MODE — and read back at launch. No UI for them; just put the window where you want it and it'll come back there next time. See Using the Indexer for more on the sticky-window behavior.

Limitations

The four AOA setpoints are a single set, not per-flap. The firmware stores six setpoints per flap detent and switches sets when the lever moves. The plugin currently has no flap awareness — the same fLDMAXAOA is used at every flap setting. Per-flap support is tracked in #393.

Default setpoints are RV-class. Auto-derivation from X-Plane's per-aircraft stall-AOA datarefs is tracked in #392. Until then, edit the four fields by hand for any non-RV airframe.