Design and Aerodynamic Modeling of MetaMorpher: A Hybrid Rotary andFixed-Wing Morphing UAV

Anja Bosak; Dorian Erić; Ana Milas; Stjepan Bogdan

cs.ROMar 31, 2026

Design and Aerodynamic Modeling of MetaMorpher: A Hybrid Rotary andFixed-Wing Morphing UAV

Authors: Anja Bosak, Dorian Erić, Ana Milas, Stjepan Bogdan

Organizations: All authors are with the University of Zagreb, Faculty of Electrical Engineering and Computing, LARICS Laboratory for Robotics and Intelligent Control Systems, Unska 3, 10000 Zagreb, Croatia

Abstract

In this paper, we present a generalized, comprehensive nonlinear mathematical model and conceptual design for the MetaMorpher, a metamorphic Unmanned Aerial Vehicle (UAV) designed to bridge the gap between vertical takeoff and landing agility and fixed-wing cruising efficiency. Building on the successful design of the spincopter platform, this work introduces a simplified mechanical architecture using lightweight materials and a novel wing-folding strategy. Unlike traditional rigid-body approximations, we derive a nonlinear flight dynamics model that enables arbitrary force distributions across a segmented wing structure. This modularity allows for testing different airfoils, mass distributions, and chord lengths in a single environment. As part of this work, various flight modes were specifically tested and analyzed in the Simulink environment. The results show that the model behaves predictably under different structural configurations, demonstrating its reliability as a tool for rapid design evaluation.

Figures & tables

Symbol	Description	Symbol	Description
$\mathcal{F}_{P},\mathcal{F}_{S},\mathcal{F}_{B},\mathcal{F}_{W}$	Port, starboard, body and world frames	$L,D$	Lift and drag forces
$\mathbf{p}$	Position vector in $\mathcal{F}_{W}$	$\rho$	Air density
$\mathbf{v}$	Linear velocity vector in $\mathcal{F}_{B}$	$q$	Dynamic pressure
$\boldsymbol{\omega}$	Angular rate vector in $\mathcal{F}_{B}$	$i$	Segment index
$m_{uav}$	Total mass of the UAV	$A_{P}^{i},A_{S}^{i}$	Segment reference area
$\alpha$	Angle of attack	$b_{\text{seg}}$	Segment span

TABLE I : Nomenclature and symbol description.

Fig. 1 : MetaMorpher in the XFLR5 environment, used for quasi-static stability analysis and the generation of aerodynamic polars.

Fig. 2 : Reference frames for the hover and cruise mode with the body frame ( $\mathcal{F}_{B}$ ) and the frames of the $i$ -th segment of both the port and starboard wings.

Fig. 3 : Block diagram of the nonlinear aerodynamic model implemented in Simulink.

Fig. 4 : Wing segmentation used in the analysis, coloured segments shown according to the simulation graphs.

Fig. 5 : Hover mode with actuator control in

\mathcal{F}_{B}

Fig. 6 : Hover mode with actuator control showing the individual segment forces.

Fig. 7 : Hover mode with thruster control in

\mathcal{F}_{B}

Fig. 8 : Hover mode with thruster control showing the individual segment forces.

Fig. 9 : Cruise mode changing the roll angle with joint actuators in

\mathcal{F}_{B}

Fig. 10 : Cruise mode changing the roll angle with joint actuators shown on individual segments.

Fig. 11 : Cruise mode changing the yaw angle with thrusters in

\mathcal{F}_{B}

Fig. 12 : Cruise mode changing the yaw angle with thrusters shown on individual segments.

Aerial Robotics

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From Model to Prototype: Design and Motor-Flap Propulsion Control of a Twin-Wing Metamorphic UAV

Anja Bosak, Dorian Erić, Ana Milas, Stjepan Bogdan

University of Zagreb, Faculty of Electrical Engineering and Computing, LARICS Laboratory for Robotics and Intelligent Control Systems, Unska 3, 10000 Zagreb, Croatia

Aerial Robotics

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This paper presents the design and control strategy for MetaMorpher, a metamorphic Unmanned Aerial Vehicle (UAV), capable of both spinning-wing hover and fixed flying-wing cruise flight. Since control of the cruise configuration is comparatively well established in the literature, this paper focuses on control of the MetaMorpher in hover mode, building on the flight dynamics model and conceptual design validated in previous work. The control algorithm is implemented using one of two phase-synchronized strategies: motor propulsion, which pulses motor thrust in synchrony with the vehicle's rotation, or flap propulsion, a novel strategy that pulses the deflection of the wing-mounted elevons. We evaluate both strategies in simulation through different flight experiments. Simulation results confirm the mathematical model and show stable reference tracking, demonstrating flap propulsion as a lightweight, decoupled alternative for hover control. Experimental testing validated the vertical-dynamics propulsion model against the physical prototype, demonstrating very good steady-state agreement across different configurations.

Abstract

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