Conceptual aircraft design of a Homeland Defense Interceptor (HDI) vehicle under the request for proposal released by the American Institute of Aeronautics and Astronautics (AIAA) Design Competition. The MQ-25 Horsefly is a remotely-piloted, supersonic interceptor designed to meet the growing demands of a changing threat landscape in the domestic United States. The MQ-25 Horsefly's cost-effective, force-compatible design enables it to complete defensive counter-air patrol, single point defense, and intercept-escort missions.