From a hand sketch
The Swallow started as a pencil sketch: a 2.62 m, 9 kg V-tail survey aircraft. Before any CAD or simulation, it got a 32-page dimension check sheet — every measurement tagged and cross-checked over three editions until the paper aircraft and the real one agreed. The 3D mesh spinning above is lofted directly from those measured numbers.
A model with receipts
Every aerodynamic number is traceable to a source: geometry from the measuring tape, drag from a component build-up, stability derivatives from AVL. The textbook placeholder dataset was deleted the day real numbers existed.
Five modes, one warning
Linearizing the 6-DOF model finds all five classical flight modes — and a spiral that doubles in six seconds. The model says this aircraft cannot be flown hands-off, and the control laws are designed knowing it.
Control that respects cheap servos
The autopilot design includes what $12 servos actually do: lag, backlash, rate limits. That honesty caught two real problems on paper — a roll loop limited by the servo rather than the airframe, and a pushrod that buckles at top speed unless it's a 2.5 mm rod.
Flying the mission
The whole stack flies survey patterns in FlightGear: Simulink integrates the physics and streams state live to the visual. There's a keyboard-flyable mode too — practice the mission before the real aircraft ever leaves the bench.
Appendix — Figures & Plots
1 figure · click to enlargeSupporting imagery for this project — boards, plots, screenshots and build shots that did not make the narrative above. Click any figure to open it full-screen.