3D photophoretic aircraft made from ultralight porous materials can carry kg-scale payloads in the mesosphere

TL;DR

This paper proposes 3D photophoretic aircraft designs using ultralight porous materials, capable of carrying kilogram-scale payloads in the mesosphere by optimizing geometry and airflow for high-altitude flight.

Contribution

It introduces a theoretical model for 3D photophoretic aircraft lift, validated with simulations, and identifies optimal geometries and materials for high-altitude, high-payload applications.

Findings

Minimum operational altitude of 55 km.

Payload capacity of 1 kg at 80 km altitude.

Ultralight porous materials are essential for sidewall density constraints.

Abstract

We show that photophoretic aircraft would greatly benefit from a three-dimensional (3D) hollow geometry that pumps ambient air through sidewalls to create a high-speed jet. To identify optimal geometries, we developed a theoretical expression for the lift force based on both Stokes (low-Re) and momentum (high-Re) theory and validated it using finite-element fluid-dynamics simulations. We then systematically varied geometric parameters, including Knudsen pump porosity, to minimize the operating altitude or maximize the payload. Assuming that the large vehicles can be made from previously demonstrated nanocardboard material, the minimum altitude is 55 km while the payload can reach 1 kilogram for 3D structures with 10-meter diameter at 80 km altitude. In all cases, the maximum areal density of the sidewalls cannot exceed a few grams per square meter, demonstrating the need for ultralight porous materials.