Windriver,
How early do you want to go? The very earliest aircraft could only just stay aloft - even rough air would bring them down. So we could say that their thrust was not much different from their drag. With a figure for weight and a guess at L/D ratio you would have some sort of answer.
I think I recall from Rolls Royce legend that the 1000lb static thrust Whittle engine was accepted for development on the basis that 1000lb was about the thrust a Merlin was giving at operational height
Dick