Question from MrSottobanco2 years ago
Why don't all projectiles use a Sears-Haack body (to a practical extent)? Specifically, why do even highly aerodynamic projectiles( i.e. boat-tails) not taper to a point as opposed to have a heel? [Berger hybrids use two different functions as opposed to Sears-Haack] The efficient application of "Force" doesn't seem to demand a boat-tail. The controlled expansion of gases from burning gunpowder generates pressure (force/area). The area here is the base of the bullet (equivalent to diameter of barrel) and is a constant. Therefore, the energy transmitted to the bullet (with a given mass) will depend upon mass times force times the time interval over which the force is applied. (Source: http://library.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNBLST.html)
Rex: Great question, sir! Its good to see you guys are thinking! Most practical applications of small arms fire do not call for the prioritization the aerodynamic efficiency of the projectiles being selected, there are other characteristics that are being considered here; the proportions of the bullet's volume and mass and how they displace limited case capacities is important, cost of production / manufacture is a big one, and the flow dynamics of erosive gases are how they are distributed behind the bullet while firing are also a biggy when considering long term bore erosion. To make a long story short, projectile design has been perhaps one of the biggest investments of the military industrial complex for hundreds of years now, and countless teams of the worlds' top engineers, physicists, ballisticians and tacticians have burnt up a lot of time and money refining all classes of projectiles - the end design stabilizing on the current general profile for about 100 years now. Its a very complex science with many different criteria dictating the end design. :-)