D and X
Is anybody familiar with the "D" and "X" method of take-off performance prediction and if so can you explain what the "D and X" values actually represent?
I understand that it is a reasonably old method of take off prediction not widely used nowadays but I have failed to find any references either on the web or in text books. I am happy with using the method to predict the take-off performance but I don't have a physical understanding of what the parameters D and X actually represent.
A quick summary (or some useful references) would be much appreciated
Thanks