Bomb Nose Case Study

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H. Bomb Nose The normal coefficient for the bomb nose has been taken as[2] Where CNN is the normal coefficient for the nose, σ, the cone semi-vertex angle is given by Where lN is the length of the bomb nose. The derivative, (CNα)N is given by[2] The center of pressure of the nose is given as[2] Where P is the pressure coefficient given by,[2] To facilitate the calculation of the pressure coefficient P, the ogive semi-vertex angle is given by,[2] I. Bomb Body The calculations for bomb body are,[3] The value of the center of pressure for the body alone is given by, Where, CNB is the normal coefficient for the body, (CNα)B is the derivative of the normal coefficient, lB is the body lenght and XACB is the body center of …show more content…

Boattail The calculations for the boattail are,[4] Where (CNα)BT is the normal derivative for the boattail, Abt and dbt are the area of cross section and the diameter of the boattail section. Aref and dref are the area of cross section and diameter of the reference area. For small angles of attack, The value of center of pressure for the Boattail is given as,[5] K. Center of Pressure for the Bomb Body The center of pressure of the entire bomb body is calculated from firure 2 as Thus, the value of center of pressure for the bomb body has been calculated for various boattail lengths and angles of attack. L. Tail Area Sizing As the nose provides the maximum lift for the body alone, the tails must be sized to provide static stability. The tail contribution to pitching moment stability, provided by the tail normal force effectiveness (CNα)T(ST/SRef) times its moment arm to the center of gravity must balance the contributions to pitching moment from the nose and body. The equation to be followed for the purpose of tail area sizing at a particular angle of attack is given as[3] Where ST is the optimum tail area required to balance the …show more content…

the top five tails with the least difference with the optimum tail area for neutral stability. The values of cone half angle (θ) and fin sweep angle (δ) were then adjusted to obtain the best result. The differences from the actual tail dimensions are vast. This means that the center of pressure of the bomb will be behind the center of gravity, which is desirable. To maximise the static margin, the best five tails were chosen based on maximum sweep angle δ based on subsonic leading edge to avoid drag divergence. Of these possible designs, the ones of 6, 7 and 8 degree boattail angles were chosen for further analysis. This was done to obviate the problems of too long a bomb (5°) and the possible problems of flow separation due to too short a boattail (9 and

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