HL-20 Flight Simulator
Download this exampleHL20Demo.zipFull project — Dyad model + Julia + data
A 6-DOF flight simulation of the NASA HL-20 lifting body, assembled from rigid-body quaternion dynamics, a 1976 Standard Atmosphere table lookup, a TM-4302 body-axis aerodynamic coefficient buildup, the pitch/roll/yaw/speed flight-control laws, and a seven-surface control-surface mixer with actuators. What makes it notable is provenance: the entire model — plant, controllers, and mixer — is generated from scratch by the Dyad Agent, working directly from the engineering spec (assets/shared/hl20_spec.md) and two prompts in scripts/, with no model code written by hand. The build is validated against a golden solution and the NASA TM-107580 Appendix F closed-loop pitch-pulse check case.
Note
This is a heavy, agent-generated demo. The aerodynamic core's Dyad source is shown below; the full closed-loop plant, controllers, and mixer are produced by running the Dyad Agent prompts inside the HL20Demo project — start there to reproduce the end-to-end pitch-pulse maneuver.
The model
HL20Demo.shared.HL20Aero is the pre-provided aerodynamic core of the vehicle: the full TM-4302 body-axis coefficient buildup that maps flight state and the seven control-surface deflections to the body-axis force and moment coefficients (CX, CY, CZ, Cl, Cm, Cn). It is the aerodynamic heart around which the agent builds the rest of the closed loop: