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直升機(jī)飛行手冊(cè) Helicopter Flying Handbook

時(shí)間：2014-11-09 12:30來源：FAA 作者：直升機(jī)翻譯 點(diǎn)擊：次

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Once you reach the remote location in the previous problem, you will need to hover OGE for some of the pictures. The pressure altitude at the remote site is 9,000 feet, and you will use 50 pounds of fuel getting there. (The new gross weight is now 1,200 pounds.) The temperature will remain at +15 °C. Using Figure 7-2, can you accomplish the mission?
Enter the chart at 9,000 feet (point A) and proceed to point B (+15 °C). From there, determine that the maximum gross weight to hover OGE is approximately 1,130 pounds (point C). Since your gross weight is higher than this value, you will not be able to hover in these conditions. To accomplish the mission, you will need to remove approximately 70 pounds before you begin the flight.
These two sample problems emphasize the importance of determining the gross weight and hover ceiling throughout the entire flight operation. Being able to hover at the takeoff location with a specific gross weight does not ensure the same performance at the landing point. If the destination point is at a higher density altitude because of higher elevation, temperature, and/or relative humidity, more power is required to hover there. You should be able to predict whether hovering power will be available at the destination by knowing the temperature and wind conditions, using the performance charts in the helicopter flight manual, and making certain power checks during hover and in flight prior to commencing the approach and landing.
For helicopters with dual engines, performance charts provide torque amounts for both engines.
Sample Hover Problem 3
Using Figure 7-3, determine what torque is required to hover. Use the following conditions:
A. Pressure Altitude . . . . . . . . . . . . . . . . . . . 9,500 feet
B. Outside Air Temperature . . . . 0 °C
C. Gross Weight. . . . . . . . . . . . . . . . . . . . . . . . . 4,250 lb
D. Desired Skid Height . . . . . . . . . . . . . . . . . . . . . . 5 feet
First, enter the chart at 9,500 feet pressure altitude, then move right to outside air temperature, 0 °C. From that point, move down to 4,250 pounds gross weight and then move left to 5 foot skid height. Drop down to read 66 percent torque required to hover.
Climb Performance
Most of the factors affecting hover and takeoff performance also affect climb performance. In addition, turbulent air, pilot techniques, and overall condition of the helicopter can cause climb performance to vary.
A helicopter flown at the best rate-of-climb speed (VY) obtains the greatest gain in altitude over a given period of time. This speed is normally used during the climb after all obstacles have been cleared and is usually maintained until reaching cruise altitude. Rate of climb must not be confused with angle of climb. Angle of climb is a function of altitude gained over a given distance. The VY results in the highest climb rate, but not the steepest climb angle, and may not be sufficient to clear obstructions. The best angle of climb speed (VX) depends upon the power available. If there is a surplus of power available, the helicopter can climb vertically, so VX 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.
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.
Sample Cruise or Level Flight Problem
Determine torque setting for cruise or level flight using Figure 7-4. Use the following conditions:

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