== modification of the IonThruster page == 

 Hi Kev, 

 I wasn't aware of the Talks page, so thanks for the hint. However reading the Talk page relative to the IonThruster I have seen that somebody has posted the same remark as I did. I clearly think that the "Propulsive efficiency" paragraph in the Ion Thruster article is irrelevant because the equations used in that section are only valid within an athmosphere (the vehicule velocity is in fact the air velocity around the vehicule). Ion Thrusters are designed and are only used within a vacuum, therefore there is no obvious definition of vehicule velocity. 
 This section is therefore completely misleading.  
 Can I directly modify this page or do we have to wait for the author or somebody else to modify it?