High-speed STOL UAV — Enoch M. Kund

The carbon-fibre UAV resting on asphalt in low sun, seen from above and behind the left wing. A single carbon tube runs from the wing to the tail surfaces; a two-blade propeller sits at the nose. — The assembled airframe on the ground.

Lighter airframe, with required safety factors heldDesign result from analysis: 12%
SolidWorks parts, assemblies and GD&T fabrication drawings: 40+

Objective

Design a composite fixed-wing UAV for short takeoff and landing, with high speed as a design goal, and carry it from concept through fabricated hardware to prototype assembly and flight testing.

Constraints

The airframe had to get lighter without dropping below its required safety factors.
A composite structure and a retractable landing-gear mechanism both had to be integrated into the same airframe.

My role

I led the mechanical design. That meant owning the CAD, drawing release and manufacturability decisions from concept to fabricated parts, and running the structural and aerodynamic analysis that drove design changes.

Prototype assembly and flight testing were team efforts across a five-person multidisciplinary group; I supported both, and wrote bills of materials and technical documentation for the build.

Approach

The fuselage was developed in SolidWorks as a lofted body and then shelled, leaving a thin skin supported by internal ring bulkheads. A mould block was modelled around the fuselage profile for the composite parts. In total I produced more than 40 parts, assemblies and GD&T-annotated fabrication drawings.

Testing and analysis

Aerodynamics. Lift and drag were evaluated in XFLR5 using NACA 0012 (symmetric) and NACA 4412 (cambered) sections.
Structure. Structural FEA in SolidWorks Simulation checked stress against the required safety factors at each design iteration.

Outcomes

The FEA-driven iterations reduced airframe weight by 12% while holding the required safety factors. This is a design result from analysis, not a measured flight-test figure.
The released drawings took the design through to fabricated, assembled hardware, shown in the photographs on this page.

SolidWorks screen showing a shelled fuselage body, open along one side to reveal a series of internal ring bulkheads. — Fuselage modelled as a thin shell with internal bulkheads in SolidWorks.

Mould block modelled around the fuselage profile.

Workbench covered in plastic sheeting; two people work on the opened fuselage, with the carbon tail boom and a carbon tail surface laid out beside it. — Team assembly on the bench, with the tail boom and a tail surface laid out.

The fuselage held open by two people, showing servos, wiring, a battery and connectors packed inside the carbon shell, with the wheels attached. — Inside the fuselage — servos, wiring and power distribution.

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