New aircraft feasibility study

Currently, most SAI modeling assumes deployment at altitudes above 20 km — for instance, the ARISE-SAI scenario (a widely used set of model simulations of SAI deployment) involves injections at roughly 22 km. However, aircraft capable of reaching these altitudes with a useful payload do not currently exist.

Initial studies indicate that off-the-shelf aircraft would need substantial modifications to reach the stratosphere at mid-latitudes, and that a newly developed aircraft able to reach higher altitudes would offer clear advantages. These studies suggest a purpose-designed aircraft could achieve at least 18–20 km, but they lack the engineering depth to provide adequate confidence. A new aircraft would need to balance operating costs, deployment altitude, and payload size, and an un-crewed design would offer additional cost and safety advantages.

This activity conducts a feasibility study of a clean-sheet aircraft that can fly at 20 km altitude with a payload of at least 5 tonnes (larger payloads mean fewer flights and fewer aircraft), with system cost reasonably optimized across flights per day, fuel burn, and runway requirements. The study will determine the rough timeline and costs of an aircraft designed specifically for high-altitude SAI deployment. This will allow decision makers to compare two pathways: developing a new aircraft that enables deployment at lower latitudes and higher altitudes, or modifying currently available aircraft, which restricts operations to higher latitudes. The design will be developed to sufficient maturity to support that comparison with confidence.