Instead of drawing only the total drag curve on paper, draw both the induced drag curve and the form drag curve on the same graph.
From there think of your change of configuration/speed/weight etc and then move each of the two drag curves seperatly (according to the change) as required.
This should give you an understanding of how each curve moves.
Then draw the new total drag curve on the graph and compare to the old total drag curve.
e.g: Gear down will move the form drag curve up. So draw a slightly higher form drag curve on your graph. Now superimpose the total drag curve...and compare to the old drag curve.
Hope that helps.
In short think of it as two curves that interact, not one curve.
Last edited by Professional Amateur; 29th March 2011 at 02:43.
Reason: clarity