Preliminary Conceptual Design of a Closed-Wing High-Altitude Pseudo-Satellite

The Italian Aerospace Research Centre (CIRA) is developing an unmanned stratospheric platform for Earth observation and telecommunications, commonly known as a high-altitude pseudo-satellite (HAPS). This airship combines the advantages of both terrestrial and satellite communications for long-endurance broadband relay missions. This paper presents the conceptual design of a closed-wing HAPS configuration that generates lift through both aerodynamic and aerostatic forces. The design process is divided into two stages. In the first stage, a reference wing is defined based on input parameters such as cruise speed, altitude, airfoil profile, and payload mass. Subsystem masses, aerodynamic coefficients, and structural dimensions are estimated using semi-empirical formulas. In the second stage, the wing is modified into a closed-wing configuration (PrandtlPlane). For a cruise altitude of 18–20 km, a speed of 16 m/s, and a payload of 10 kg, the E186 airfoil is selected. A lift–drag curve is obtained from 3D Reynolds-Averaged Navier–Stokes (RANS) analysis using the 𝑘 –𝜔 SST turbulence model in OpenFOAM. Static stability analysis shows that buoyancy generates a nose-down moment, reducing the trim angle of attack. The quasi-elliptical upper wing also contributes to lateral instability.