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Old November 5th 14, 11:21 PM posted to rec.aviation.soaring
Andy Blackburn[_3_]
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Default Where is the LX S80?

On Wednesday, November 5, 2014 3:10:29 PM UTC-8, jfitch wrote:

I think you need to recheck your math. 600 fpm is 10 fps. That would be around 20 ft at 1G with no other retarding forces and mass = weight. But in this case mass weight depending on the buoyancy, i.e., much less than 1G deceleration acting on it. When the density matches the surrounding air, the air bubble is weightless (A due to G = 0), and therefore will carry on forever absent another retarding force. Of course as it rises through an inversion of less dense air, it will lose buoyancy and G will begin to have some effect, also there are frictional effects of the surrounding atmosphere which I imagine are hard to calculate. Much for that 1.6 feet though.


Must've missed a decimal place, but even with that corrected, the inertial effects seem to be a lot less than the buoyancy effects, which is mostly driven by temperature profile in the atmosphere versus a dry adiabat. Humidity matters a little, but is the equivalent of a a fraction of a degree to maybe a couple of degrees of temperature variation - which is way less than the variations you see in a typical sounding. Temperature seems like more than an order of magnitude more important than humidity, which itself is roughly an order of magnitude more important than inertia effects.

Where's Dr Jack when I need him?

9B