On 31/01/2011 14:31, Olin Lathrop wrote: > Let's say the atmosphere around the earth is uniform and perfectly still > before the plane flies thru it. The plane is flying at a steady speed, a= nd > such that it is neither climbing or falling from it's point of view of > flying thru the air. This is ever so slightly different from not climbin= g > of falling from the point of view with respect to the ground. The > difference would be probably not be measureable even with today's most > advanced instruments, yet it is there. Or, it might be easier to consider a fixed wind and a tethered kite. Put=20 a scale on the cord to measure the lift force A plane in still air is a slightly more complicated version. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .