Comment Re:Ooh, IONs (Score 1) 330
fyi you got your equations wrong -- you meant mass flow rate (aka m_dot) times exhaust velocity gives you thrust .. notice that the units on this end up correct (mass*distance/time^2) whereas the mv^2 gives us Joules (in metric) aka energy - infact, you might recognize 1/2 mv^2 from highschool physics.
Also - as far as light speed goes - yes, I guess your particle mass would approach infinity, but then so would your power requiremnent (its not just a voltage difference), wouldn't it? And even a nuclear reactor can't provide inifite power.
Also, generally ion engines have charged plates to accelerate the ionized fuel, these would wear out pretty quickly if you were bombarding them with infinitly massize particles moving at light speed .. even if they were made out of "unobtanium."
Finally, practically speaking ion engines CANNOT function in atmospheres - the ambient pressure of an atmosphere will "out push" the pressure produced at the mouth of the thruster by the thruster. With a nuclear reactor - I don't know - I do agree that it'd be nice if someone would cough up the cash for that...
Also - as far as light speed goes - yes, I guess your particle mass would approach infinity, but then so would your power requiremnent (its not just a voltage difference), wouldn't it? And even a nuclear reactor can't provide inifite power.
Also, generally ion engines have charged plates to accelerate the ionized fuel, these would wear out pretty quickly if you were bombarding them with infinitly massize particles moving at light speed
Finally, practically speaking ion engines CANNOT function in atmospheres - the ambient pressure of an atmosphere will "out push" the pressure produced at the mouth of the thruster by the thruster. With a nuclear reactor - I don't know - I do agree that it'd be nice if someone would cough up the cash for that...
