| Popis: |
Resistance to projectile flight in air decomposes into three main components. The first component is the nose drag due to the air pressure ahead of the body. The second is the skin friction drag component due to shear forces between the air layers. The third is the total base drag component due to disability of air stream lines to follow up the body shape specially at supersonic speeds. Herein, it is shown how different drag coefficients, and consequently total drag coefficient, can be predicted.Drag models can be empirical or semi-empirical. A combination of two drag models will be used herein in order to predict drag coefficients at Mach numbers ranging from 0 to 3.5 for different projectile shapes. These models are the semi-, empirical model introduced by Lebeqev and Chernobrovsky and the experimental.. data illustrated graphically by ESDU.Drag prediction of classical and modern projectile shapes with boat-tails is conducted for different initial firing conditions. Effect of changing projectile shape on range is discussed. It is concluded that the range is increased in case of projectiles having longer ogive and boat-tail, and boat-tail angle ranging from 3 to 5 degrees. |
