UAV SILM

Current professional reconnaissance UAV platforms are expensive, often subject to export or trade restrictions, and hard to produce or adapt quickly in the field. Small states and civil-defence organisations lack affordable, quickly-built, easily-maintained reconnaissance platforms that can be built and repeated locally.

The target group is Estonia's defence and security sector: the Defence Forces, Kaitseliit, and the Police and Border Guard Board, plus more broadly European defence development programmes. No engagement with these organisations has taken place yet; this is the intended long-term audience for the concept. It matters because:

• a low-cost, domestically-built airframe (target unit cost under $500) could put the platform within reach of organisations without a professional-system budget;
• long calculated endurance (~100 min target flight time) would enable genuine observation and reconnaissance work;
• a secure link concept (4G LTE / WireGuard MAVLink failsafe) is designed to keep data protected and the link operational even under GPS interference.

• Most hobby-grade fixed-wing UAVs aren't optimised for ISR use. SILM's endurance target, airfoil selection and airframe design come from CFD analysis aimed specifically at that purpose.
• It's designed to pair open-source flight control (ArduPilot-compatible) with an encrypted 4G/WireGuard backup link, an unusual combination for a student-scale build.
• The whole design process (XFLR5 CFD analysis, centre-of-gravity calculations, materials selection) is documented and repeatable, which is the point: a base that can be extended, corrected, or used for training.

Long-shaft fixed-wing pusher motor on a 4S LiPo pack, sized against the 1.6 kg all-up mass with margin for material or battery changes. Full component models are listed under Tools & materials below.

ArduPilot-compatible autopilot with GPS and digital airspeed sensing, capable of autonomous waypoint flight. Mission routes are planned on a map in ground-control software (e.g. Mission Planner or QGroundControl) and uploaded to the autopilot before launch, so the aircraft can fly a pre-set trajectory without continuous manual control. A 4G LTE module paired with an encrypted WireGuard link is planned as a MAVLink failsafe channel, intended to keep telemetry and control available under GPS interference or beyond normal radio-link range. The concept is borrowed from professional encrypted-link systems, adapted here to commodity hardware.

The nose cone is designed to screw on and off, so the same airframe can carry an ISR sensor payload or be reconfigured, without redesigning the fuselage. Swapping the wing set for a cheaper, higher-aspect-ratio pair is intended to trade cruise performance for lower-cost, lower-tempo missions. Because the modules attach at fixed stations, moving the centre of gravity is mostly a matter of choosing which modules are fitted.