I'm not disputing the general conclusion/consensus, I just didn't agree with the statement that equal velocity equals ZERO thrust and that this is the same as switching off the engine, that's all.
Yes - matched speed = zero thrust.
Efficiency improves as you approach matched speed but mass flow must be increased to maintain thrust levels. At a matched speed the mass flow required is infinity so clearly not feasible.
The Formula bigleagueslider posted, is the equation for specific thrust not the general thrust equation, that's why I ask which one was used in the discussion.
As they state if ve=vo then their is no NET forward thrust, which basically says no acceleration, but this should not be interpreted as NO thrust - IMHO (normally specific thrust is denoted Fs, not Fn)
I agree that the fuel mass is small compared to the air mass, but small and zero is not the same - at least in my book.
As seen in the other thread, this at times can lead to some wrong conclusions and reasoning - infinitesimal small is not zero either.
The force generated by the fuel massflow is perhaps not as small as you may think it is.
Consider the velocity of the fuel mass before and after it passed the engine?
Edited by TC3000, 12 July 2013 - 14:15.