Although data are not available for many shapes in the transonic region, the table clearly suggests that either the Von Kármán shape, or power series shape with n = 1/2, would be preferable to the popular conical or ogive shapes, for this purpose.Did you know that human beings have different nose shapes? Take a closer look, and you’ll realize people have different ones. In many nose cone designs, the greatest concern is flight performance in the transonic region from Mach 0.8 to Mach 1.2. Rankings are: superior (1), good (2), fair (3), inferior (4). This chart generally agrees with more detailed, but less comprehensive data found in other references (most notably the USAF Datcom).Ĭomparison of drag characteristics of various nose cone shapes in the transonic to low-mach regions. The chart shown here seems to be the most comprehensive and useful compilation of data for the flight regime of greatest interest. Many references on nose cone design contain empirical data comparing the drag characteristics of various nose shapes in different flight regimes. Influence of the general shape Closeup view of a nose cone on a Boeing 737 The factors influencing the pressure drag are the general shape of the nose cone, its fineness ratio, and its bluffness ratio. In the transonic region and beyond, where the pressure drag increases dramatically, the effect of nose shape on drag becomes highly significant. For example, in strictly subsonic rockets a short, blunt, smooth elliptical shape is usually best. The major significant factor is friction drag, which is largely dependent upon the wetted area, the surface smoothness of that area, and the presence of any discontinuities in the shape. 8, the nose pressure drag is essentially zero for all shapes. The aerospike creates a detached shock ahead of the body, thus reducing the drag acting on the aircraft.įor aircraft and rockets, below Mach. Main article: Drag-reducing aerospike An aerospike on the UGM-96 Trident IĪn aerospike can be used to reduce the forebody pressure acting on supersonic aircraft. Special values of C (as described above) include: īi-conic nose cone render and profile with parameters shown.Ī bi-conic nose cone shape is simply a cone with length L 1 stacked on top of a frustum of a cone (commonly known as a conical transition section shape) with length L 2, where the base of the upper cone is equal in radius R 1 to the top radius of the smaller frustum with base radius R 2. While the equations describe the 'perfect' shape, practical nose cones are often blunted or truncated for manufacturing, aerodynamic, or thermodynamic reasons. The full body of revolution of the nose cone is formed by rotating the profile around the centerline C⁄ L. The equations define the two-dimensional profile of the nose shape. y is the radius at any point x, as x varies from 0, at the tip of the nose cone, to L. In all of the following nose cone shape equations, L is the overall length of the nose cone and R is the radius of the base of the nose cone. Nose cone shapes and equations General dimensions For many applications, such a task requires the definition of a solid of revolution shape that experiences minimal resistance to rapid motion through such a fluid medium. Given the problem of the aerodynamic design of the nose cone section of any vehicle or body meant to travel through a compressible fluid medium (such as a rocket or aircraft, missile, shell or bullet), an important problem is the determination of the nose cone geometrical shape for optimum performance. General parameters used for constructing nose cone profiles. ( July 2018) ( Learn how and when to remove this template message) Please help to improve this article by introducing more precise citations. This article includes a list of general references, but it lacks sufficient corresponding inline citations.
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