Can someone give me a clear explanation on how to calculate the landing distance of the Douglas DC-4 with the following graph? And why is the Temperature variable not in the graph, because temperature also has an influence on the LDR? Thanks in advance.
Follow the arrows in the graph.
You start with the gross weight on the right X-axis and move straight upward until you intersect the correct field elevation. In the graph the line starts at 58,000 lbs and moves up to a field elevation of approx. 1700 ft.
From there move left into the left side of the graph. There, the X-axis is the effective headwind speed. Note the remark above the graph: This is 50% of the reported speed when the data for this graph was collected. Now you need to find the intersection of the line from the right half with the line vertically up from the headwind. Where both cross you take an interpolation of the landing distance lines. In the example the headwind is 18 knots, so the landing distance becomes 2000 ft.
Yes, temperature would have an effect, but for the landing distance that effect is small. A colder air is denser and reduces all speeds, so a shorter landing distance will be possible in colder air. But compared to a take-off where air density has a much stronger influence on engine performance, this effect can be neglected for a landing chart.