飞机怎么会短路呢? Anas Maaz 的回答火了

2020-11-27 00:22

How can airplanes on short JfR世界播

飞机怎么会短路呢?JfR世界播


Answered by: Anas Maaz,Airline pilot. Airbus A320/A321. JfR世界播

回答者:阿纳斯·马兹(Anas Maaz),航空公司飞行员。空中客车A320/A321JfR世界播


I will start with a real life example from a pilot's point of view. Two days back, I did a 55 minute flight in the Airbus A320. With the weights and the flight plan inserted, the flight management system calculated an optimum altitude of 38000 ft. JfR世界播

我将从飞行员的角度从一个真实的例子开始。两天前,我乘坐空客A320进行了55分钟的飞行。在输入重量和飞行计划后,飞行管理系统计算出最佳高度为38000英尺。JfR世界播


Because we felt that climb to an altitude of 38000 ft is too high for such short a flight, we decided to climb to an altitude of 36000 ft. You will get almost the same efficiency as at the optimum altitude as long as you are within plus or minus 2000 ft of the optimum. So, we were quite happy to climb to 36000 ft. JfR世界播

因为我们觉得爬到38000英尺的高度对这么短的飞行来说太高了,所以我们决定爬到36000英尺的高度。只要你在距离最佳高度正负2000英尺的范围内,你就能获得与最佳高度几乎相同的效率。所以,我们很高兴能爬到36000英尺的高度。JfR世界播


We took off as planned and climbed to 30000 ft as per the initial ATC clearance. After a while, we requested to climb to our planned 36000 ft. Unfortunately we got denied further climb and we had to continue our flight at 30000 ft. Our cruise was only about seven minutes, but because we cruised at 30000 ft, we burnt 300 kg of fuel more than we should have. JfR世界播

我们按计划起飞,根据最初的空中交通管制许可爬升到30000英尺。过了一会儿,我们要求爬到我们计划的36000英尺。不幸的是,我们被拒绝进一步攀登,我们不得不继续在30000英尺的高度飞行。我们的巡航时间只有7分钟左右,但由于我们在30000英尺的高空巡航,我们多烧了300公斤燃料。JfR世界播


How much is 300 kilos, you say? Well, the A320 burns 2.4 tonnes every hour. So, 300 kilos is about eight minutes of fuel. With Jet-A fuel prices in our country, that costs about 400 dollars. JfR世界播

你说300公斤是多少钱?嗯,A320每小时燃烧2.4吨。所以,300公斤大约是8分钟的燃料。考虑到Jet-A在我国的燃油价格,这一价格约为400美元。JfR世界播


I think this example says a lot. Jet engines are very inefficient at low altitudes where the temperatures and air density is higher. The longer you cruise at lower levels, the more you will burn. With higher altitudes the compressibility effect also increases. This creates something called the ram effect which increases the pressure ratio through the compressor stages. This increases engine efficiency. JfR世界播

我认为这个例子说明了很多问题。喷气发动机在温度和空气密度较高的低海拔地区效率很低。你在较低的高度巡航的时间越长,你燃烧的就越多。海拔越高,压缩效应也越大。这就产生了一种叫做柱塞效应的东西,它增加了通过压气机级的压力比。这提高了发动机效率。JfR世界播


Higher altitudes also increase the True air speed (TAS) of the aircraft. This is particularly important to increase the range, or in layman terms, the fuel mileage of the aircraft. The higher the TAS at a given engine thrust and Indicated air speed (cockpit indicated speed), the better will be the range of the aircraft. It is also worthwhile to note, that the airplane calculates a best economical cruise speed based on pilot entered cost index, weight, present wind conditions, temperature and the altitude. JfR世界播

更高的高度也会增加飞机的真实空速(TAS)。这对于增加飞机的航程,或者用外行人的话来说,增加燃油里程尤其重要。在给定的发动机推力和指示空速(驾驶舱指示速度)下,TAS越高,飞机的航程就越好。值得一提的是,飞机根据飞行员输入的成本指数、重量、当前风况、温度和高度计算最佳经济巡航速度。JfR世界播


The lower you cruise, the lower will be this economical speed. Hence, it will have negative effect on your trip time. Long story short, it is far better to spend most of the times climbing in a short flight in a high flying jet rather than leveling off at a low altitude. JfR世界播

你的航速越低,这个经济速度就越低。因此,它会对你的出行时间产生负面影响。长话短说,大部分时间都是乘坐高空喷气式飞机在短时间内爬升,而不是在低空保持平稳。JfR世界播


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Jet engines are most efficient at high altitudes, where the temperatures are low and RPM is high while burning less fuel. JfR世界播

喷气发动机在高海拔地区效率最高,那里温度低,转速高,燃料消耗少。JfR世界播

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