Rates of Climb

The power required to climb at a given flight path angle, y, can be determined by using the charts of Chapter 3 just as for level flight but modifying the flat plate

area to account for the rearward component of gross weight along the flight path:

r r G. W. sin у

/climb — /

Figure 4.48 shows the results of the calculations for the example helicopter at rates of climb from zero to 3,000 ft/min at sea level conditions. A cross-plot at the various ratings gives corresponding rates of climb as a function of forward speed in the lower part of the figure. Carrying out the same analysis at several altitudes allows us to find the maximum rates of climb as a function of altitude, as in Figure 4.49.