Aero Force Balance

The big one. A strain-gauge load cell, an HX711 amplifier, a printed kinematic mount, a hard stop to protect the sensor, and a honeycomb of drinking straws to smooth the airflow.

Target: coefficient of variation under 4%. That's what buys the right to claim a 10% difference from five trials. The surprising part is that the expensive 24-bit sensor turns out to be the smallest source of error — the biggest one is how carefully I put the wing back on.