the helicopter can climb vertically, so V$_{X}$ is zero. Wind direction and speed have an effect on climb  performance, but it is often misunderstood. Airspeed is  the speed at which the helicopter is moving through the  atmosphere and is unaffected by wind. Atmospheric wind  affects only the groundspeed, or speed at which the helicopter  is moving over the Earth’s surface. Thus, the only climb  performance affected by atmospheric wind is the angle of  climb and not the rate of climb. With this chart, first confirm that it is for a pressure altitude  of 8,000 feet with an OAT of 15°. Begin on the left side  at 80 knots indicated airspeed (point A) and move right to  maximum gross weight of 5,000 lb (point B). From that point,  proceed down to the torque reading for level flight, which  is 74 percent torque (point C). This torque setting is used  in the next problem to add or subtract cruise/descent torque  percentage from cruise flight. When planning for climb performance, it is first important to  plan for torque settings at level flight. Climb performance charts  show the change in torque, above or below torque, required  for level flight under the same gross weight and atmospheric  conditions to obtain a given rate of climb or descent. Determine torque setting for cruise or level flight using  Figure 7-7.  Use the following conditions: With this chart, first locate a 500-fpm rate of climb or descent  (point A), and then move to the right to a maximum gross  Determine climb/descent torque percentage using  Figure 7-8 .  Use the following conditions: Figure 7-8.  Climb/descent torque percentage chart. Figure 7-7.  Maximum rate-of-climb chart. 7-8 Pressure Altitude............................................... 8,000 feet Outside Air Temperature...................................... +15 °C A. Indicated Airspeed........................................80 knots B.  Maximum Gross Weight................................5,000 lb A. Rate of Climb or Descent .............. 500 fpm B.  Maximum Gross Weight ...............5,000 lb Sample Climb Problem Sample Cruise or Level Flight Problem Legend Maximum range Maximum rate of climb or maximum end Continuous torque Torque (%) Fuel flow (pounds per hour) 110 100 90 80 70 60 50 40 30 20 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 30 40 50 60 70 80 90 100 PRESSURE ALTITUDE = 8,000 FEET  Indicated airspeed (knots) True airspeed (knots) OAT 15°C 160  200  240  280  340 380 420 0 10 20 ∆Torque % Maximum torque available Transmission limit Maximum rate of climb  or maximum end Maximum range Continuous torque available 10 SO F1 AF 5500 3500 5000 4500 4000 3000 GW (LB) A C B Torque (%) 1,500 1,400 1,300 1,200 1,100 1,000 900 800 700 600 500 400 300 200 100 0 0 5 10 15 20 25 30 35 40 Rate of climb or descent (feet per minute) GROSS WEIGHT - (LB) 3000 3500 4000 4500 5000 5500 A C B