PARAMETERS.md

Parameters: values and where they come from

"Guess" means the value still has to be identified. As of 10 Oct 2026 the aircraft is still the Aerosonde placeholder; the Strix model has been requested from the lab.

Aircraft (aerosonde() in fixed_wing/airplane/parameters.py)

Parameter	Value	Source
Mass, inertia, wing geometry, air density, 28 aerodynamic coefficients	see parameters.py	Beard & McLain, Small Unmanned Aircraft, appendix E (Aerosonde)
Maximum thrust thrust_max	40 N	Guess
Actuator time constants	0.05 s (surfaces), 0.2 s (throttle)	Guess
Surface limits, throttle range	±30°, [0, 1]	Same as the lab NMPC (Bobbili et al. 2026, Table I)

Simulation

Parameter	Value	Source
Control period integration.dt	0.01 s (100 Hz)	Same as L2F; external actuator commands to PX4 are limited to < ~50 Hz (Bobbili et al. 2026)
Substeps integration.n_substeps	1	Choice (L2F N_SUBSTEPS)
Command latency latency.action_steps	0	Unknown; asked to the lab
Thermals	off; w* = 2.56 m/s, z_i = 1401 m when used	Allen 2006, AIAA 2006-1510, table 1 (yearly mean); shape constants from its appendix B code
Turbulence	off; presets such as σ = 1.06, 1.06, 0.7 m/s, L = 200, 200, 50 m	Beard & McLain, table 4.1 (MIL-F-8785C), light turbulence at 50 m

Strix: what is known

Quantity	Value	Source
Mass, wing span	4 kg, 1.7 m	Lim & Loianno 2026, arXiv 2607.15863
Best-glide airspeed, sink rate	~12 m/s, 1.51 m/s	Morando et al. 2026, arXiv 2605.15619
Level-flight throttle	0.376 at ~12 m/s	Morando et al. 2026
Trim	throttle 0.60, elevator 8°	Bobbili et al. 2026, arXiv 2608.20655
Climb / descent rate at 15 m/s	4.6 / 2.26 m/s in flight	Lim & Loianno 2026
Aero coefficients, inertia, wing area, T_max	not published	requested

Placeholder vs Strix (examples/validate.py)

Quantity	Strix	Aerosonde model
Best-glide airspeed	12.0 m/s	16.6 m/s
Sink rate at best glide	1.51 m/s	1.06 m/s
Best glide ratio	7.9	15.7
Level-flight throttle at 12 m/s	0.376	0.287
Climb rate at 15 m/s, full throttle	4.6 m/s	3.25 m/s
Descent rate at 15 m/s, throttle off	2.26 m/s	0.97 m/s

The Strix has about twice the drag of the placeholder. calibrate_drag_polar will fit its polar once the wing area is known.

Simulation speed (examples/benchmark.py)

About 335 steps/s on one core for one airplane in pure Python, so 1 M steps take ~50 min. Batching (NumPy) or the C++ port (RLtools) comes later.