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Airfoil Wind Tunnel

instrumentation Orthogonal 2-Axis Load Cells controller Raspberry Pi + HX711 24-bit ADC airflow Variable Speed Duct + Flow Straightener team WatArrow Student Design Team

A closed-jet aerodynamic test tunnel engineered for the WatArrow flight design team to measure lift and drag polars on experimental airfoils. Features modular load-cell instrumentation, automated angle-of-attack pitch control, and continuous data acquisition.

How: Modeled the wind tunnel in CAD, fabricated components via CNC and 3D printing, then integrated a stepper-motor drive, load cells, and wiring to a Raspberry Pi for data capture and analysis.

• 3D Printed Parts: Printed prototype PLA stepper motor mounts, load-cell brackets, and wind tunnel mounts.

• Precision Tolerancing: Applied ±0.1 mm tolerances to mounts, ensuring secure load-cell alignment.

• Soldering: Soldered load-cell PCB connections, including removable connector plugs for replaceability.

[01/08] How: Modeled the wind tunnel in CAD, fabricated components via CNC and 3D printing, then integrated a stepper-motor drive, load cells, and wiring to a Raspberry Pi for data capture and analysis.

Designed full wind tunnel assembly in SolidWorks with quick-disconnect modular airfoil mounts and orthogonal load-cell isolation.
Engineered a 2-axis force measurement rig capable of resolving aerodynamic forces down to 0.05 N using calibrated strain-gauge load cells.
Developed Python DAQ software with live plotting to log lift-to-drag curves across varying angles of attack.

01Mechanical Design & CAD Assembly

Comprehensive SolidWorks 3D CAD modeling, multi-body kinematics, tolerance stack-up analysis, and assembly architecture.

01.1 Wind Tunnel Aerodynamic Duct & Frame CAD

Full SolidWorks parametric CAD model of the open-circuit wind tunnel, engineered for modular airfoil mounting and streamlined flow.

[01/02] Full Assembly: CAD model of the wind tunnel, engineered for quick mounting and remote airfoil control.

01.2 2-Axis Force Sensor & Angle-of-Attack Drive CAD

Kinematic layout integrating dual orthogonal 90° load-cell mounts and a precision NEMA stepper motor drive for remote angle-of-attack pitch sweeping.

Electronics Integration: 90° load cell mounts for lift/drag measurements, stepper motor for airfoil control.

[01/03] Electronics Integration: 90° load cell mounts for lift/drag measurements, stepper motor for airfoil control.

01.3 Exploded Architecture & Component BOM

Exploded assembly view and detailed engineering drawing callouts detailing modular test section uprights, bearings, and load-cell brackets.

[01/02] Assembly Breakdown: Exploded view and assembly drawing with BOM callouts showing every component.

02Prototyping, 3D Printing & Fabrication

Rapid prototyping iterations, slicing optimization (Bambu Studio / PrusaSlicer), material selection (PLA / PETG / Carbon Fiber), and precision fit checks.

02.1 3D Printed Motor Mounts & Structural Brackets

Rapid prototyping of custom PLA stepper motor mounts, structural support brackets, and tunnel attachment brackets printed on tuned profiles.

[01/02] • 3D Printed Parts: Printed prototype PLA stepper motor mounts, load-cell brackets, and wind tunnel mounts.

02.2 Precision Toleranced Sensor Clamps (±0.1 mm)

Iterative fit checks maintaining ±0.1 mm tolerances to prevent binding and ensure orthogonal alignment across both lift and drag load cells.

[01/04] • Precision Tolerancing: Applied ±0.1 mm tolerances to mounts, ensuring secure load-cell alignment.

02.3 Chassis Integration & Anti-Slip Baseplate Assembly

High-friction clamping interfaces lined with sandpaper for zero-slip airfoil grip, fastening hardware, and solid mounting to the rigid baseplate.

• Parts Assembly: Lined side mounts with sandpaper for improved grip and installed electronics onto base.

[01/03] • Parts Assembly: Lined side mounts with sandpaper for improved grip and installed electronics onto base.

03Electrical, Firmware & Hardware Integration

Schematic capture, PCB routing, sensor interfacing, actuator control, and embedded firmware implementation.

03.1 Strain-Gauge Sensor Soldering & Quick-Disconnects

Precision soldering of sensitive load-cell Wheatstone bridge leads with removable keyed connectors for rapid replacement and calibration.

[01/02] • Soldering: Soldered load-cell PCB connections, including removable connector plugs for replaceability.

03.2 Stepper Driver & Raspberry Pi DAQ Interface

Interfacing stepper motor driver and dual HX711 24-bit ADC amplifiers to Raspberry Pi GPIO for real-time aerodynamic data acquisition.

[01/02] • Embedded Electronics: Wired stepper motor and load cells to a Raspberry Pi for data collection.

03.3 Baseplate Harness Management & Strain Relief

Clean chassis cable routing along structural rails with protective strain-relief anchor points to prevent mechanical vibration interference.

[01/02] • Mounting & Wiring: Secured PCBs and components to the base, then routed cables neatly along the base.