Hypersonic boundary-layer transition can have dramatic effects on aeroheating and control authority, yet it remains very difficult to predict. Applications include missiles for time-critical strike, hypersonic cruise vehicles, reusable launch and re-entry vehicles, and missile-defence interceptors. Although researchers have been working toward mechanism-based prediction methods for several decades, designers are still using empirical methods, and there is a need to narrow the gap between the two groups. Transition is complex, as it can be caused by several different instability mechanisms, is affected by various freestream and surface perturbations, and can occur under a variety of flow conditions. Accordingly, the activities of the group were divided into multiple Subtasks. For each Subtask, several experts from various NATO nations embarked in cooperative research, each with their own financial support. These subtasks covered: (1) Second-mode transition on slender geometries in quiet and conventional ground based facilities, (2) Cross-flow transition on conical geometries at wind tunnel flow conditions, (3) Mechanism of windside forward transition on sharp and blunted cones at angle of attack, and (4) Mechanism of boundary layer transition on nonablating capsules and its sensitivities.     «

Hypersonic boundary-layer transition can have dramatic effects on aeroheating and control authority, yet it remains very difficult to predict. Applications include missiles for time-critical strike, hypersonic cruise vehicles, reusable launch and re-entry vehicles, and missile-defence interceptors. Although researchers have been working toward mechanism-based prediction methods for several decades, designers are still using empirical methods, and there is a need to narrow the gap between the two...     »