Hetfield, can you help me with reading the graph you posted, is this example right?
For zero wind, slats 15, at a speed of 250 kias or .55 IMN whichever comes first, at 130 tons weight, "optimum" altitude for maximum range is FL 280, minimum drag at FL 260, if flight at FL230 at 250/.55 then 4% loss in specific range .
But if 20 kts tailwind, then no loss in specific range for flight at FL 230.
But...what does the "maximum altitude" line represent?