Closed-Loop Gust Loads Analysis of a Supersonic Fighter Aircraft

Kurzfassung

Military supersonic fighter configurations, due to their high maneuverability requirements, are usually sized by maneuver loads. This work investigates if gusts can exert higher loads on the primary structure in terms of section loads and structural dynamic accelerations. The aeroelastic models of the free-flying aircraft are extended by a longitudinal flight control system for disturbance suppression, which is mandatory for meaningful gust analyses of longitudinally unstable aircraft. The closed-loop system is simulated in the time domain based on the aerodynamic panel methods VLM and ZONA51, applied in the subsonic and the supersonic regime, respectively. Mission profiles, certification requirements, and current research outcomes are assessed, followed by a comprehensive gust load campaign. The results suggest that the quasi-steady Pratt method is not able to accurately predict the gust loads acting on a supersonic combat aircraft, significantly falling short of the dynamic gust loads. Still, most of the gust loads stayed well within the maneuver loads envelope. However, very high accelerations (up to ≈100g) due to short gust impacts are observed on the wing tips, so that mounting payloads in these areas would be difficult.