Re: [amsat-bb] Spacefraft Aerodynamics [was:Re:AO-40: Plans for April-June 2001]

[Douglas Braun & Nadia Papakonstantinou <doug@xxxxxxxxxxxxx>]

At the atmospheric pressures where the satellite is, the classic concepts
of "laminar" and turbulent" flow do not hold.  The reason is that the
gas molecules are able to travel a significant distance (several cm?) before
colliding with another gas molecule.  Thus, the aerodynamic forces on
the S/C can better be modeled by stream of individual particles than
by fluid flow.  I believe that the drag would be almost exactly
proportional to the frontal area (i.e. silhouette) of the S/C.

Perhaps somebody who has studied this subject more recently
than me (i.e. in the last decade or two) can give a more detailed
and accurate explanation.

Doug
NA1DB

At 06:58 PM 4/4/01 , Margaret Leber wrote:


>So when changing the ALON it may actually be easier to go in one direction than the other if it takes the +Z face though the low-pressure zone "behind" the bird where the dragginess of all the stuff on that side is less important.

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