Michel Jullian wrote: > But the air propelled downwards by the ion has a mass (hidden in the ion > mobility parameter), that's what's matters, just like the mass of a > helicopter's propeller is irrelevant. If one can speak of thrust for a > helicopter, one can speak of thrust for a lifter.
Ok. I presumed the phrase "ion mass is irrelevant" meant "ion mass is physically irrelevant". > BTW the momentum of the discharged+ejected ions is negligible compared to that > of the neutrals they drag along, because their concentration is very small. > > BTW2 the derivation is elegant but admittedly it could be a little more > rigorous wrt distinguishing between scalars and vectors. > > Michel Harry
