Safe Flight N1 Computer for the TorqueSim CitationJet 525

The Safe Flight N1 Computer add-on for X-Plane 12 provides a detailed simulation of the Safe Flight N1 Display specifically for the TorqueSim CitationJet 525. This instrument continuously reads key aircraft data, such as ram air temperature and pressure altitude, to calculate the optimal fan speed setting without requiring manual user input. Featuring automatic adjustments for engine anti-ice and various operational modes, this plugin is tailored solely for the Citation 525, offering a real-time, data-driven solution for managing engine performance in flight.

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Description

An X-Plane 12 recreation of the Safe Flight N1 Computer/Display (P/N C-12732-1) — the three-digit amber panel instrument that tells a Citation 525 crew what fan speed to set.

It reads ram air temperature and pressure altitude straight from the aircraft, looks up the performance charts, interpolates between them, and shows you the max N1 for your conditions. No configuration, no data entry, no switching to a tablet.

Requires the payware TorqueSim CitationJet 525

This is an instrument for one aircraft. It stays completely inert with anything else loaded — it is not a general-purpose N1 calculator.

What it does

Four schedules on a mode knob: TO/GA, CLB and CRU, each in a normal and an anti-ice version
Reads ram air temperature and pressure altitude from the aircraft continuously — the number on the display is always current for where you actually are
Interpolates between the four surrounding chart points, doing by machine what you would otherwise do by eye
Follows engine anti-ice automatically and switches to the anti-ice schedule
PUSH TEMP SET for an assumed temperature, exactly like the real unit: dial in a warmer temperature for a reduced-thrust takeoff. It saturates at ±99 °C and is discarded at liftoff
Dashes rather than guesses when you are off the edge of a chart — it never extrapolates
Power-up self-test, avionics bus dependency and a working N1 IND breaker, so it fails the way the real one does
Tenths below 99.95 %, whole percent above, because the real unit only has three digits

Installation

Unzip and drop the SafeFlightN1 folder into X-Plane 12/Resources/plugins/, so you end up with:

X-Plane 12/Resources/plugins/SafeFlightN1/

Load the CitationJet 525 and open it from Plugins → Safe Flight N1 Computer. To remove it, delete the folder.

Requirements

X-Plane 12.3.0 or newer
The TorqueSim CitationJet 525 (payware)
macOS 12+, Windows 10+, or Linux

macOS builds are universal (Apple Silicon and Intel), signed and notarized, so Gatekeeper lets them through without a right-click dance.

Manual

A 21-page illustrated manual ships inside the download as SafeFlightN1-Manual.pdf. It covers normal procedures, limitations, systems description, troubleshooting, and the published datarefs and commands for home cockpit builders.

It is also a standalone download, so you can read it before installing anything: SafeFlightN1-Manual.pdf

Staying up to date

Two ways to get new versions:

SkunkCrafts Updater. The plugin ships a SkunkCrafts manifest, so the updater offers new versions automatically once the folder is installed.
GitHub releases. Every build is published at github.com/RISCfuture/c525-n1-computer/releases with notes on what changed.

For home cockpit builders

Every piece of state is published as a dataref and every control as a command, so you can drive a real knob and a real display. There is also a test-override mode that feeds the device synthetic conditions in any aircraft. See section 7 of the manual.

Credits and acknowledgements

The N1 schedules are not my work, and this plugin would have nothing to display without them.

They were transcribed from the TorqueSim Cessna Citation 525 Performance Manual, a community-built chart set — not a TorqueSim, X-Aviation or Textron document — assembled and published free by hornetaircraft, with Aviationsocal, Kaboom, Jetpipeoverheat and Cptlee assisting:

TorqueSim Cessna Citation 525 Performance Manual

Licence and disclaimer

The plugin is MIT licensed and fully open source: github.com/RISCfuture/c525-n1-computer

Not affiliated with, endorsed by, or supported by Safe Flight Instrument, LLC, Textron Aviation, or TorqueSim. The performance data is community-sourced and approximate. This is an advisory simulation for entertainment — not for real world use.

Support

Bugs and feature requests: github.com/RISCfuture/c525-n1-computer/issues

Changelog

v0.2.0 31. Aug 2026

Changed

The takeoff target now holds after liftoff. Leave the knob alone through the climb-out and the display keeps the takeoff target it was showing on the ground — computed from the temperature you selected and the field elevation you left — until you move the knob. Go-around arrives when you reselect TO/GA, which is how the supplement introduces it.

Previously the display switched to go-around at the live temperature and pressure altitude the instant the wheels came up, so a crew that dialled an assumed temperature lost their target and then watched the number drift through the climb. A selected temperature now lives as long as the hold and is released with it, at the first mode change or on touchdown, rather than being discarded at liftoff.

Added

Hot-and-high trim for climb and cruise, off by default. Set isa_trim=1 in config.ini beside the .xpl to apply the Operating Manual's reduction: climb at or above 25,000 ft and cruise at or above 30,000 ft lose 1.0 %N1 at ISA+11…20 °C and 2.0 at ISA+21…30, on the anti-ice-off schedule only. The supplement does not say the real device does this, so the default keeps the supplement's behaviour.
config.ini, for options that should outlive the window state. settings.ini is rewritten wholesale every time the window closes and would drop them.
sfn1/isa_trim, a writable dataref mirroring the flag, so both behaviours can be compared without restarting.
scripts/digitize_om_charts.py, which fits the Operating Manual's charts and compares them against data/. It needs your own copy of the charts; they are not redistributable and are not in the repository.
Fixed

W/S BLEED AIR in its lower position read as off, so an airplane with all three bleed air anti-ice systems selected could show dashes instead of the anti-ice schedule. Either live detent of that switch now counts. The WING/ENGINE switches still have to be fully up — their lower detent is engine inlet heat with the wings cold, which is not the full configuration.
The manual documented the wrong switch for the anti-ice interlock, naming engine bleed where the device actually watches W/S BLEED AIR.
Documentation

Behaviour is now sourced from the flight manual supplement itself rather than from FlightSafety's training manual paraphrasing it, and the documentation notes the name the flight manual uses for the box.
data/PROVENANCE.md records an independent check of the schedules against Cessna's Operating Manual charts. They agree to about half a percent N1 — roughly what reading a printed graph supports, and coarser than the tables' own tenth, so the charts corroborate rather than supersede. The check does settle the two blocks previously flagged as carrying known uncertainty: at every cell where this repo departed from a printed community value, the manufacturer's curve is closer to the value adopted than to the one rejected.
docs/CONTRACTS.md records three schedules the charts publish that this device does not model: engine-only anti-ice, the environmental-bleed split, and (before this release) the hot-and-high trim.

Author

RISCfuture

Joined Nov 2020

Information

Release Date 30. Aug 2026

Downloads 7

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