Simulating Hypersonic Glide Vehicles

Making sense of hypersonic performance through open-source modelling.

Hypersonic weapons have attracted substantial attention and funding in recent years, particularly in the United States, Russia, and China. Much of this appeal rests on their ability to maneuver within the atmosphere in ways that distinguish them from more common ballistic missile designs. Both missile technologies typically fly at speeds in excess of five times the speed of sound, but while long-range ballistic systems follow largely predictable, arcing paths through outer space, hypersonic glide vehicles re-enter the atmosphere earlier in their trajectories and can then use aerodynamic forces to adjust course throughout flight.

This maneuverability is often highlighted as a major operational advantage. It could, in certain missions, allow a missile to avoid defended airspace or approach a target from an unexpected direction. But these benefits come with significant downsides: lower average velocity, longer flight times, and greater production costs relative to comparable ballistic missiles. The trade-offs involved are central to an informed assessment of hypersonic weapons acquisition and use, yet they are rarely quantified in public discourses.

Analyses in the open literature have tended to rely on general descriptions of these weapons and their purported advantages, rather than mission-specific technical evaluation. Claims about a nascent hypersonic “revolution” are rarely accompanied by empirical assessment of real-world performance. As a result, policy debates about these weapons often lack grounding in the fundamental physics of missile flight.

To help address this gap I, alongside colleagues at the Berkeley Risk and Security Lab (BRSL) and the Massachusetts Institute of Technology (MIT), have developed the Hypersonic Glide Vehicle Simulator, a web application that enables rapid, accessible modeling of hypersonic missile flight. Built on computational models developed by myself and co-author David Wright, the tool allows users without specialized technical training to explore the performance of glide vehicles under a range of conditions. The intent is not to provide precise engineering predictions, but rather to offer an approximate, transparent means of examining missile capabilities and limitations in realistic military scenarios. In a detailed manual, we provide instructions on the use of this tool and examples of its analytical applications.

​​Two use cases, described in more detail in the manual, demonstrate the value of this tool in assessment of the performance and utility of hypersonic missiles. The first concerns the threatened “footprint” of a glide vehicle, or the area within which a missile could maneuver to strike at a certain point in its flight. The resulting ambiguity in what a hypersonic missile is targeting can have important implications for crisis stability. For instance, if multiple states lie within the footprint, more than one may believe itself to be the intended target. Even within a single state, uncertainty about whether a missile is aimed at, for example, nuclear or conventional forces could complicate time-sensitive assessments of the appropriate response. The Hypersonic Glide Vehicle Simulator provides a means of mapping these footprints and their evolution over time, enabling clearer evaluation of such risks.

The second use case examines midcourse maneuvering of a missile. While maneuvers can have operational utility—such as avoiding overflight of neutral states or staying clear of missile defences and sensors—they also consume energy and reduce range. Quantitative modelling helps illustrate when maneuverability provides meaningful advantages and when its benefits are outweighed by performance penalties, providing a clearer picture of viable military roles for hypersonic weapons.

More broadly, the simulator supports mission-based analysis of hypersonic systems. Instead of assessing these weapons in abstract terms, analysts can examine how they perform in specific, militarily relevant operational contexts. Recent work by the Congressional Budget Office (CBO), based on the computational model David Wright and I developed, demonstrates the value of this approach. In analysis of hypothetical conflicts in the Baltics and the South China Sea, they found that hypersonic weapons offered limited advantages over less costly ballistic systems. Tools such as the Hypersonic Glide Vehicle Simulator make it easier for others to replicate, extend, and scrutinize such findings.

Hypersonic weapons are technically complex and often misunderstood. By making quantitative analysis more widely accessible, we aim to improve the quality of discussion about their capabilities, limitations, and security implications. An informed debate requires more than broad claims about speed, maneuverability, or technological revolutions; it requires an understanding of how these systems would perform in specific missions. This tool helps to support that effort.