D and X
I originally posted this on the Flight Testing Forum, I had one response from Sycamore and he suggested cross posting to here because some of you guys frequently discuss obscure perf. data and seem to have long memories about the subject and origins. Any info would be appreciated
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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. (I think X is V1/Vr ratio but what on earth (in real terms) is D?)
A quick summary (or some useful references) would be much appreciated
Thanks