What is CUPID?
CUPID (Composite Unmanned Photovoltaic Innovative Drone) is a research project developed at the University of Padua in collaboration with Team LiftUp. Its goal is to investigate and test new solutions for energy autonomy in unmanned aerial vehicles.
Launched in 2024, CUPID aims to design a drone built from composite materials and equipped with integrated photovoltaic panels, capable of drastically extending flight endurance compared to traditional electric UAVs.
CUPID is not linked to any competition. Instead, it was conceived as a modular experimental platform: a research environment where we can test materials, energy configurations, solar-cell integration techniques and energy-management strategies. The project lays the groundwork for future applications, potentially supporting environmental monitoring, civil-protection operations, wildfire detection with IR sensors and, more broadly, any mission that requires a lightweight, autonomous, long-endurance aerial platform.
Final Goal
The long-term goal of CUPID is to develop a fully autonomous and energetically self-sustaining aircraft, capable of flying for extended periods without any external recharging.
To reach this target, the drone is being designed to:
– Fly fully autonomously, thanks to an advanced autopilot;
– Generate and manage its own energy through high-efficiency solar cells integrated into the wing structure;
– Support long-duration missions, far exceeding the typical endurance of electric UAVs;
– Carry different sensor payloads, acting as a flexible modular platform for future applications.
Developing an aircraft capable of remaining airborne for many hours opens the door to a wide range of missions: infrared monitoring for wildfire detection, environmental surveying, LiDAR mapping, and research instrumentation.
CUPID is therefore conceived as a technology demonstrator, enabling us to explore innovative approaches to energy, aerodynamics, and flight control while moving toward a truly self-sufficient drone.
Short-Term Objective
In the short term, CUPID’s goal is to build a first test prototype dedicated to studying the behaviour of solar cells in flight.
At this stage, aerodynamic perfection is not the priority: we first need a stable structure able to host the photovoltaic panels and allow us to analyse:
– The real efficiency of the cells during flight,
– Their performance under different lighting conditions,
– The impact of the added weight on the aircraft’s dynamics,
– The energy balance between production and consumption.
The operational target for this phase is to reach around six hours of endurance using a battery that would normally provide only one hour of flight.
Achieving this will represent a key step toward full energetic self-sufficiency and will validate the preliminary configuration of the solar array, energy-management system, and propulsion setup.
Technical Challenges
Developing CUPID involves a series of complex engineering challenges. Each design choice influences the others, and the system must be optimised as a balance between weight, efficiency, aerodynamics and reliability.
Optimising the Number of Solar Cells
Determining how many photovoltaic cells can realistically be integrated is one of the most delicate aspects of the project. The SunPower 12.5 mm cells offer excellent efficiency, but they also introduce weight and require surface area. The trade-offs are significant:
more cells → more power generated,
more cells → increased mass and aerodynamic drag,
more mass → higher energy demand to stay airborne.
The system must reach the point where the energy produced exceeds the energy required to compensate for the added weight. Our initial estimate is around 40 cells, with the final number to be refined after prototype testing.
Selecting the Motor and Propeller
The propulsion system is critical for achieving long endurance.
The motor must:
guarantee stable flight at the lowest possible energy cost,
remain lightweight,
operate efficiently with the selected propeller,
fit within the voltage range supplied by the solar + battery system.
Propeller choice heavily affects efficiency: diameter, pitch and material define the optimal operating regime. A propeller optimised for low RPM and high aerodynamic efficiency is essential for maximising flight duration.
Integrating the MPPT
The photovoltaic system requires a Maximum Power Point Tracker (MPPT) capable of extracting the maximum available power at all times, despite changing conditions such as:
aircraft inclination during flight,
shadows, clouds or lighting variations,
cell temperature.
The current candidate is the Genasun GV5, a compact, high-efficiency MPPT ideal for low-voltage systems. The final choice will depend on the confirmed number and configuration of solar cells.
Balancing Weight and Structural Design
For the first prototypes we plan to use:
a polystyrene core,
a fiberglass skin.
This structure allows fast iterations and modifications while offering a good strength-to-weight ratio.
In later stages, we will evaluate a transition to carbon fibre, aiming to reduce weight further while maintaining rigidity and structural safety.
Material choice directly affects:
solar-cell placement,
weight distribution,
resistance to aerodynamic loads,
capacity to integrate electronics and future sensors.
Integrating Future Payloads
CUPID is designed as a scalable experimental platform, capable of hosting different types of sensors.
The first planned payload is an infrared camera, chosen for its simplicity and low integration cost.
Every new payload introduces engineering challenges involving:
energy consumption,
added mass,
centre-of-gravity balancing,
electromagnetic interference,
aerodynamic impact.
For this reason, the airframe must be designed from the beginning to be scalable, enabling future upgrades without requiring complete redesigns.
What's Next?
In the coming months, CUPID will enter its most decisive phase: the definition and validation of the first prototype. The process begins with the digital modelling of the aircraft, which will allow us to analyse the available surface for solar-cell integration, define the preliminary wing geometry, and organise the internal layout of the components. The CAD model will be essential for balancing structure, battery placement and aerodynamic behaviour, with the goal of completing it by summer 2026.
The next stage will be the construction of the first physical prototype, built with a polystyrene core and a fiberglass skin—an approach that is lightweight, easy to modify and ideal for rapid iterations. This initial platform will host the first set of solar cells, the MPPT, the propulsion unit and avionics, together with the first experimental payload, an infrared camera. Prototype construction is scheduled for autumn 2026.
The first experimental flight, planned for October 2026, will provide crucial data on aerodynamic stability, real energy production during flight, power consumption, MPPT efficiency and battery behaviour. The objective is to reach around six hours of endurance using a battery typically designed for one hour, allowing us to assess the true potential of the photovoltaic system.
After this initial test cycle, CUPID will enter a phase of continuous iteration: refining the number and placement of solar cells, optimising the MPPT, evaluating carbon-fibre structures, testing alternative motors and propellers, and integrating more advanced sensors. This steady improvement process will progressively bring CUPID closer to its final goal: a truly autonomous and self-sustaining drone.
Timeline
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2024 — Project Launch
CUPID is initiated as an internal LiftUp research platform, aimed at testing solutions for long-endurance electric drones powered by integrated photovoltaic panels.
The first conceptual ideas begin to take shape.
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2025 — Preliminary Study and Initial Purchases
The team begins analysing wing surfaces, studying potential solar configurations and developing the first CAD model, which will define geometry, internal volumes and component layout.
The first electronic components are also purchased to perform early tests.
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2026 Q2 — CAD Completed
The digital design of the first prototype is finalised.
This phase validates preliminary choices regarding solar-cell placement, electronic layout, weight distribution and aerodynamic compatibility.
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2026 Q3 — Prototype Construction
Construction of the first airframe begins, using a polystyrene core with a fiberglass outer skin.
Solar panels, the MPPT, the BMS, the battery, the flight controller and the propulsion unit are installed.
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2026 Q4 — First Experimental Flight
The prototype is tested in flight for the first time.
The aim is to gather real data on solar-energy production, verify aerodynamic behaviour and measure potential endurance.
The target is to achieve around six hours of flight.
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After 2026 — Continuous Iteration
Based on the collected data, CUPID enters a cycle of ongoing refinement: updating solar-surface layouts, optimising the MPPT, evaluating carbon-fibre structures, testing new motors and propellers, integrating additional sensors and improving overall endurance.