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> At 17:14 3/2/2006, you wrote: From: Frode Lindgjerdet <Fr-Lind@Online.No> Date: 6:45 PM 3/1/06 Subject: The "Cuzaux-effect" And The 1930's Bomber-paradigm > >are you sure that it is the air flow that is the key? What was new in the 1930s was probably not firing a rifled gun into strong wind, but firing it from an object moving at such speed. Shouldn't the forward energy of the plane be transferred into a side-way movement of the projectile? As when you drop a bomb, it does not fall straight down, it follows the direction of the moving object from which it was dropped, until it loses its forward momentum. To be frank, I have to say that this sounds like 16th century physics -- before Galileo. I am a former designer of airplanes and weapons and can assure you that Galilean-Newtonian physics really works a very great deal better for such purposes. In the Newtonian scheme of things, it is necessary to choose one frame of reference and stick to it, unless an explicit coordinate transformation is made. If one chooses a reference frame centered on the bomber then the bomber has no kinetic energy, since it is at rest with respect to the coordinate system whose origin it defines. This is the simplest situation to describe and to grasp in a naïve way. From the standpoint of an observer standing in the bomber, there is a great wind blowing outside. If he drops a bomb he is not surprised to see it appear to curve downwind -- backward with respect to the direction of flight -- under the influence of this wind. Similarly, if he fires a projectile out to the side he sees that it too curves downwind, but not very greatly. If one wants to shift to an airmass-centered coordinate system then the aircraft has kinetic energy but there is no airflow -- only airplane movement through unmoving air. From this point of view the bomb is not so much dropped as launched into the air with an initial velocity vector equal in magnitude and direction to that of the aircraft. It is accelerated by both gravity and drag, and in consequence progressively gains velocity downward (up to some limit) and loses velocity forward (up to the point at which it has lost all forward velocity and is falling vertically). Viewed from the side its trajectory appears very roughly parabolic and its velocity vector rotates in the downward direction as the vertical component increases and the forward component decreases. (This is a great deal clearer with diagrams, which e-mail unfortunately does not accommodate.) Similarly, the projectile fired to the side has an initial velocity vector that is the vector sum of the aircraft velocity and the normal initial velocity associated with the gun firing at rest. In this case the dynamics are a little more complicated to describe verbally -- more than I think is manageable here. But their net effect is for the trajectory to start in a direction aligned with the initial velocity vector and the curve slightly back with respect to the direction of flight. In short, when one talks of aircraft energy of motion and also airflow in the same breath then one is talking physical nonsense and should not be surprised at any seeming paradoxes that emerge. This will be obvious if one recalls that it is not possible to stand both in the aircraft and in a balloon floating in the air at the same time. Will O'Neil "William D. O'neil" <W.D.Oneil@Pobox.Com> ----- For subscription help, go to: http://www.h-net.org/lists/help/ To change your subscription settings, go to http://h-net.msu.edu/cgi-bin/wa?SUBED1=h-war -----
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