This paper investigates the trajectory prediction and dispersion for unguided fin stabilized artillery rocket in order to explain the importance of the rocket production accuracy and the benefit of using guided rockets. The total dispersion results mainly from three effects. The first is the dispersion due to rocket production inaccuracy, which includes propellant mass, composition inaccuracy, rocket total mass, axial and lateral moments of inertia and resultant center of gravity. The second dispersion during boosting phase which includes launcher deflection, missile tip-off from the launcher, thrust and fin misalignments, and atmospheric disturbances such as tail wind, cross wind, and gusts. While the third is the dispersion during free-flight phase that is due to the fluctuations in wind profile. In this study, a trajectory calculation using a 6-DOF model was developed and applied for a typical artillery rocket, the 122 mm artillery rocket, at different mass and flight properties to predict the trajectory parameters and dispersion.
This paper investigates the dispersion for unguided spinning projectile in order to explain the importance of the projectile production accuracy and the benefit of using guided projectiles. The total dispersion results mainly from the production inaccuracy of: (1) gun tube which can be shown in projectile's launching problems (muzzle angle, and muzzle pitching and yawing rates), (2) propellant which can be shown in projectile's muzzle velocity and muzzle spinning rate and projectile which is the projectile total mass, axial and lateral moments of inertia, and resultant center of gravity. The other causes are occurred due to free flight portion of projectile's trajectory which may be divided to: launching problems (vibration of launch tube), wind velocity and direction (wind profile). In this study, a trajectory calculation using a 6-DOF model was developed and applied for 155 mm M107 projectiles at different projectile and flight properties.
SUMMARYThe Bergan-Wang approach for the transverse shear inclusion in thin and moderately thick plate deformation has led to an energy expression which is a function of the only lateral deflection. The corresponding Euler equation is an eighth-order partial differential equation. A variety of examples has been analysed. Analytical solutions have been presented for different thickness to span ratios under different boundary conditions. Results show very close resemblance to solutions based on Reissner plate theory.
The centrifugal pump performance depends to great extent upon the flow pattern in the impeller passages. When the pump operates at small flow rates, the problem of circulation due to vortex formation in the impeller passages is found. A new method is introduced to control and reduce the size of generated vortices in the impeller passages. Slots are opened in the impeller vanes to allow fluid to flow from the pressure side to the suction side of the vane. The bleeding fluid could reduce the size of the vortices. It is found to depend mainly upon the length and the position of the slot. In the present work, the flow field is solved in the radial impeller passages using the stream function and the primitive variable approaches, to solve the flow equations. The flow pattern is used to compare the vortex size and the pump head for both cases with and without slotted impeller vanes at different slot sizes and at different positions. The slot position that produces the highest pump head, the slot length has been changed until the smallest vortex size is achieved. The numerical solution is introduced in a code program form, which is written in the Microsoft Visual C++ 6 language. Finally the optimum position and length of the slot is obtained at Rs/R2 = 0.4981, and with L /(R2-R1)= 0.2291. The model has been validated by comparison to a published experimental result of the same pump (for the same research program).
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