projects / 10

WatArrow RC Aircraft

competition SAE Aero East 2025 (Micro Class) structure Balsa Ribs + Carbon Fiber Layup award 3rd Place Mission Points avionics Custom Flight Computer + Telemetry

A competition-grade radio-controlled aircraft engineered for maximum payload-to-empty-weight ratio in the SAE Aero Design East Micro Class. Features modular interchangeable balsa wings, wet-layup carbon fiber landing gear, and high-reliability servo wiring harnesses.

How: Prototyped foam-cut control surfaces and fabricated CNC-cut balsa wing ribs with heat-shrink laminate. Drafted electrical schematics and wired servos to the flight computer with banana-plug harnesses. Debugged a flap-creep issue during the competition, helping team to secure 3rd-place in mission points.

• Carbon Fibre Layup [1st Attempt]: Protoyped rear landing gear using carbon fibre layup with wide design.

• Flight Computer Connector: Crimped flight computer wiring for easy electronic swaps and troubleshooting.

[01/08] How: Prototyped foam-cut control surfaces and fabricated CNC-cut balsa wing ribs with heat-shrink laminate. Drafted electrical schematics and wired servos to the flight computer with banana-plug harnesses. Debugged a flap-creep issue during the competition, helping team to secure 3rd-place in mission points.

Manufactured modular CNC-cut balsa wings and performed custom vacuum-bagged carbon fiber wet layup for high-impact landing gear.
Wired and routed modular flight computer harness with crimped strain-relieved connections, eliminating in-flight voltage dips.
Diagnosed and resolved an in-field flight computer firmware glitch during competition, securing 3rd Place in Mission Points.

01Mechanical Design & CAD Assembly

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

01.1 Full Aircraft 3D CAD & Aerodynamics

Complete SolidWorks parametric assembly of the micro-class RC aircraft with dual vertical stabilizers and modular high wing.

Aerodynamic Propulsion CAD: Assembly model showing front brushless outrunner motor, tractor propeller, carbon landing gear, and twin vertical tails.

[01/02] Full Assembly: CAD model of the RC aircraft, designed for modularity to interchange wing configurations and structural payloads.

01.2 Internal Avionics & Component Packaging

Spatial layout and weight distribution optimization for flight controller, servos, LiPo battery, and telemetry receiver.

Avionics Packaging: CAD model detailing internal servo bays, battery compartment tray, and ESC airflow ducting.

Center-of-Gravity (CG) Optimization: Component layout balanced to maintain stability margin across varying payload weights.

Empennage Control CAD: Pushrod linkage geometry and elevator/rudder micro-servo torque transfer mounts.

[01/03] Avionics Packaging: CAD model detailing internal servo bays, battery compartment tray, and ESC airflow ducting.

01.3 Wiring Schematics & Cable Routing CAD

Detailed electrical assembly drawings callouts for signal lines, power distribution, and modular wing disconnect plugs.

Wing Disconnect Callouts: Modular quick-disconnect harness pinouts allowing field removal of outer wing panels without rewiring.

[01/02] Electrical Routing Drawing: Assembly schematic showing servo wiring harnesses, ESC motor phases, and flight computer power bus.

02Prototyping, Manufacturing & Flight Testing

Hands-on fabrication: carbon fiber wet layup, CNC balsa trusses, hot-wire airfoil slicing, Monokote skinning, and flight validation.

02.1 Carbon-Fiber Landing Gear Layup

Vacuum-bagged compression molding of high-strength, lightweight carbon fiber landing gear arches to absorb hard competition landings.

3D Printed Compression Tooling: Dual-part male/female mold prepared for carbon fiber wet layup and clamp compression.

Epoxy Infusion & Cure: Multi-ply bidirectional carbon weave saturated with low-viscosity epoxy resin under uniform pressure.

Demolding & Trim: Cured composite landing gear arched spring demolded before edge cleanup and axle hole machining.

Finished Carbon Component: High-gloss, zero-void carbon fiber spring strut ready for airframe mounting with foam wheels.

[01/04] 3D Printed Compression Tooling: Dual-part male/female mold prepared for carbon fiber wet layup and clamp compression.

02.2 Hot-Wire Foam Wing Core Cutting

Fabrication of low-drag symmetrical and cambered airfoil cores using a custom gravity-fed nichrome hot-wire bow.

Hot-Wire Cutting Rig: Nichrome wire bow with adjustable spring tensioning and variable DC current supply.

Precision Root/Tip Airfoil Templates: Laser-cut sheet templates clamped to EPS foam blank for synchronized sweep cutting.

Core Slicing Pass: Smooth hot-wire traversal maintaining constant velocity along template curves to avoid ridges.

Finished Foam Core: Clean EPS wing panel with integrated carbon spar channel ready for trailing edge sheeting.

[01/04] Hot-Wire Cutting Rig: Nichrome wire bow with adjustable spring tensioning and variable DC current supply.

02.3 CNC Balsa Rib Skeleton & Truss Assembly

Precision laser-cut and CNC balsa truss architecture maximizing lift-to-weight ratio and torsional wing rigidity.

Assembly Jig Alignment: Ribs slotted into main carbon tube spar on a pinned building board to guarantee zero washout/twist.

Leading Edge Sheeting & Shear Webs: Balsa shear webbing glued between upper and lower spar caps creating a rigid D-box torque tube.

Completed Truss Structure: Ultralight skeleton ready for servo bay hatch installation and film skin covering.

[01/04] Lightened Balsa Ribs: CNC profile cuts with lightening pockets engineered to handle aerodynamic bending moments.

02.4 Monokote Film Covering & Wing Finishing

Heat-shrink polyester film covering applied with iron and heat gun for an airtight, aerodynamically smooth wing skin.

Tack Ironing: Monokote film tacked along wing root and spar lines under calibrated iron temperature.

Shrink & Tension: Heat gun sweep tensioning the film drum-tight across balsa bays to eliminate wrinkles.

Hinged Control Surfaces: Ailerons hinged with zero slop and color-coded bright yellow tips for visual orientation in flight.

Finished Modular Wing Panels: Two matched wing halves featuring smooth surface finish and pre-installed servo linkages.

[01/04] Tack Ironing: Monokote film tacked along wing root and spar lines under calibrated iron temperature.

02.5 Airframe Evolution & Prototype Iterations

Iterative design cycles refining fuselage mass, tail volume ratio, and empennage aerodynamic stability across three distinct builds.

Plane 1 (Short-Tail Prototype): Initial proof-of-concept airframe featuring box fuselage and conventional tail feathers.

Plane 2 (V-Tail Configuration): Explored ruddervator V-tail to minimize drag and reduce overall parts count in the empennage.

Plane 3 (Modular Carbon Backbone): Final competition configuration using a pultruded carbon fiber tail boom for maximum stiffness at minimum weight.

[01/03] Plane 1 (Short-Tail Prototype): Initial proof-of-concept airframe featuring box fuselage and conventional tail feathers.

02.6 Flight Testing & SAE Aero Competition

Extensive ground run-ups, short-field takeoff trials, and competition flights at SAE Aero Design East.

High-Altitude Climb: Flight testing measuring climb angle, stall characteristics, and roll response under full throttle.

Competition Takeoff Run: Aircraft lifting cleanly off the runway pavement carrying mission payload within designated takeoff distance.

Flight Line Ready: WatArrow team staging aircraft in the competition inspection pit prior to official scoring sortie.

3rd Place Podium Trophy: Official SAE Aero Design East award plaque celebrating 3rd Place overall for Micro Class mission performance.

[01/04] High-Altitude Climb: Flight testing measuring climb angle, stall characteristics, and roll response under full throttle.

03Electrical, Firmware & Hardware Integration

Avionics wiring harness, flight controller integration, crimped micro-connectors, and vibration-isolated RF hardware.

03.1 Flight Computer Wiring & Pin Crimping

SpeedyBee F405 flight controller integration with vibration dampeners and crimped micro JST-SH harnesses.

Flight Computer Pinout: Pin crimping and header soldering for telemetry, receiver, and sensor power rails.

Harness Assembly: Wire stripping and micro pin crimping ensuring gas-tight electrical connections under vibration.

Strain-Relief Terminations: Heat-shrink booted connectors for quick-disconnect field serviceability.

[01/03] Flight Computer Pinout: Pin crimping and header soldering for telemetry, receiver, and sensor power rails.

03.2 Servo Harness & Power Distribution

Custom power distribution bus providing isolated 5V rail to prevent servo back-EMF from browning out the flight controller.

Servo Signal Leads: Twisted servo lead pairs minimizing electromagnetic noise coupling from the high-current ESC.

Power Bus Distribution: Star ground and central power rail supplying high transient current to 4 analog micro-servos.

Continuity & Deflection Check: Verifying servo travel limits, centering trim, and failsafe holding torque.

[01/03] Servo Signal Leads: Twisted servo lead pairs minimizing electromagnetic noise coupling from the high-current ESC.

03.3 Airframe Harness Management & Routing

Clean wire management along the carbon fiber fuselage tube with conformal tie-downs and receiver antenna orientation.

Receiver Antenna Mount: 90° orthogonal antenna orientation for diversity reception and maximum RF link budget.

[01/02] Carbon Boom Wire Routing: Clean spiral routing along tail boom preventing snagging during assembly and payload loading.