aircraft. As bombs are generally well streamlined and have high density, this effect is much smaller in magnitude than the effects of the wind on the aircraft itself. For instance, consider a bomber at altitude dropping a stick of AN-M65 500 lb general-purpose bombs. These bombs will take approximately 37 seconds to reach the ground. In a wind the bomb will move about due to the wind's effect on the aircraft's ground speed. In comparison, the effect of the wind after leaving the aircraft would be only . Basic mechanism Opening the adjacent diagram in a separate window will greatly ease the understanding of the following description. At the rear of the CSBS is a large compass with a slip ring carrying a rotating compass rose known as the bearing plate. The bearing plate has lines on it that are used to represent the wind direction during manual calculations. The top of the bearing plate was designed to be drawn on with a chinagraph pencil so it could serve as a general navigation calculator as well. On early models, rotating the compass face also rotated a shaft that ran forward under the main body of the bombsight and through a metal tube running out the lower front of the main housing. On later models, a large knob known as the milled head was placed directly behind the compass and drove this shaft independently of the compass face, allowing calculations to be carried out without changing the bombsight settings. The rotating shaft ran to the wind bar located in front of the body of the gunsight. The rotation of this bar to the selected angle mechanically represented the wind vector relative to the aircraft. At the end of the wind bar is the wind screw knob, which is used to set the wind speed. As the knob is rotated, a plate inside the wind bar moves fore and aft along the direction of the bar. Connected to and extending from the front of the main bombsight housing is the drift bar, normally forming over half the overall length of the device. The drift bar is pivoted at its base, just in front of the compass area, allowing it to rotate to the left or right. On top of the wind bar, connecting the wind bar to the drift bar, is the ground speed slider. A pin passing vertically through the wind