The panel on propulsion aerodynamics

Sources of discrepancies noted between propulsion aerodynamic characteristics as predicted from wind tunnel tests and as measured in flight are discussed. The variable Reynolds capability of the National Transonic Facility will provide a tool for understanding and quantifying uncertainties involved in extrapolating the corrected wind tunnel data from tunnel conditions to full scale flight conditions

Invariance of coarse median spaces under relative hyperbolicity

We show that, for finitely generated groups, the property of admitting a coarse median structure is preserved under relative hyperbolicity

Boundaries of strongly accessible hyperbolic groups

We consider splittings of groups over finite and two-ended subgroups. We study the combinatorics of such splittings using generalisations of Whitehead graphs. In the case of hyperbolic groups, we relate this to the topology of the boundary. In particular, we give a proof that the boundary of a one-ended strongly accessible hyperbolic group has no global cut point.Comment: 47 pages. Published copy, also available at http://www.maths.warwick.ac.uk/gt/GTMon1/paper3.abs.htm

Peripheral splittings of groups

We define the notion of a "peripheral splitting" of a group. This is essentially a representation of the group as the fundamental group of a bipartite graph of groups, where all the vertex groups of one colour are held fixed - the "peripheral subgroups". We develop the theory of such splittings and prove an accessibility result. The theory mainly applies to relatively hyperbolic groups with connected boundary, where the peripheral subgroups are precisely the maximal parabolic subgroups. We show that if such a group admits a non-trivial peripheral splitting, then its boundary has a global cut point. Moreover, the non-peripheral vertex groups of such a splitting are themselves relatively hyperbolic. These results, together with results from elsewhere, show that under modest constraints on the peripheral subgroups, the boundary of a relatively hyperbolic group is locally connected if it is connected. In retrospect, one further deduces that the set of global cut points in such a boundary has a simplicial treelike structure

Some design considerations for supersonic cruise mixed compression inlets

A mixed compression inlet designed for supersonic cruise has very demanding requirements for high total pressure recovery and low bleed and cowl drag. However, since the optimum inlet for supersonic cruise performance may have other undesirable characteristics, it is necessary to establish trade-offs between inlet performance and other inlet characteristics. Some of these trade-offs between the amount of internal compression, aerodynamic performance and angle-of-attack tolerance are reviewed. Techniques for analysis of boundary layer control and subsonic diffuser flow are discussed

The curve complex and covers via hyperbolic 3-manifolds

Rafi and Schleimer recently proved that the natural relation between curve complexes induced by a covering map between two surfaces is a quasi-isometric embedding. We offer another proof of this result using a distance estimate via hyperbolic 3-manifolds.Comment: 5 page