I'll take a stab at this...RMC, I think you may have it a bit backwards...
Lets consider the aircraft at FL 350, at 220 kcas. If it's climbing then one can expect the thrust vector to be canted up slightly, hence providing some force in the vertical direction. Therefore, for a steady climb, the wing will be producing less lift than if the aircraft were in level flight at the same speed, and thus the climbing aircraft is at a lower Coeff of lift, Cl
Hence, since a component of total drag includes induced drag (Di), and Di is roughly porportional to Cl squared, the aircraft described above will have less drag in the climb than in level flight.
So, this is in fact the exact opposite to what you were wondering. Further, a portion of induced drag is in fact from wing tip vortices, and thus the decrease in induced drag in the climb, (versus the same CAS at that FL in cruise), means that the wing tip vortices drag will also be less for the climb situation.
Caveats apply.
Is there any way to post a picture of this graph you have of the drag of the 737? Perhaps upload it to a site such as photobucket (
Image hosting, free photo sharing & video sharing at Photobucket), then link to there from a reply to this post?
Perhaps others (Mr Enicalyth?) will take glee in shooting down my analysis, or can take a stab at your second question.
TDV