getting to grips with fuel economy(35)

曝光台 注意防骗 网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者

The A320 family shows a completely different set of characteristics as shown in the  graph on the next page.
The variation of different techniques is very weight sensitive. However it is still the clean configuration at green dot speed that gives the lowest fuel flow. This picture is typical of all the A320 family.

Finally the A340-500/600 has another set of configuration/speed combinations and the following graph shows its different characteristics, but the basic concept that the clean configuration and green dot is the best combination still remains true.
 
 

There is also altitude to be considered, although it is often not the operator’s decision what flight level to hold at. Altitude has different effects on the fuel flow, depending on the airframe/engine combination. However, whatever the altitude effect, it generally affects all techniques equally; generally the higher the hold altitude the lower the fuel flow. This however is true only up to a certain altitude and this varies with each type.
 
The following table shows this altitude effect for a hold in the clean configuration at green dot speed. The holding fuel flow is compared with the lowest for the flight levels considered for each type, and the difference expressed as a percentage.
 
Flight Level
 50
 100
 150
 200
 250
 300
 350
 400
 
A300B4-605R
 4
 2
 1
 0
 3
 8
 16
 
 
A310-324
 11
 5
 2
 0
 0
 5
 9
 23
 
A318-111
 13
 8
 4
 2
 1
 0
 0
 5
 
A319-112
 19
 11
 3
 1
 0
 1
 0
 4
 
A320-214
 13
 5
 3
 1
 1
 1
 0
 2
 
A320-232
 7
 5
 5
 5
 2
 0
 4
 11
 
A321-211
 14
 11
 8
 3
 0
 1
 5
 
 
A330-203
 2
 1
 0
 0
 2
 4
 8
 18
 
A330-223
 9
 9
 5
 2
 0
 6
 14
 
A340-343
 10
 5
 1
 0
 0
 2
　
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