Low drag orbital velocity is defined as the orbital velocity at the low drag altitude. Earth's low drag altitude for a typical spacecraft is one hundred and fifty kilometers and earth's orbital velocity at that altitude is seven thousand eight hundred meters per second. When the atmosphere is practically a vacuum, the low drag altitude is zero and the low drag orbital velocity is the ground orbital velocity. The orbital velocity around a gravitating body is inversely proportional to the square root of the distance from the center of that body. Given ground orbital, low drag altitude and radius, low drag orbital is calculated.

low drag orbital = ground orbital * sqrt( radius / ( radius + low drag altitude ) )
 

This is used in astropolis, atmospheric spacecraft, multi stage spacecraft, and spacecraft cost.
 
 

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