B737NG retractable landing light drag.
Join Date: Mar 2006
Location: USA
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Take off performance:
Drag at 160 kt = 190 N
10 nm = 18520 m
Energy = 3,518,800 Joules per light.
3,518,800 J / 9.8 / 75,000 kg = 4.79 m per light.
2 x 4.79 x 3.281 = 17 ft
So after 10 nm the aircraft would be 17 ft lower than it would have been if the lights were retracted.
Rough numbers I know but it give you an idea.
Drag at 160 kt = 190 N
10 nm = 18520 m
Energy = 3,518,800 Joules per light.
3,518,800 J / 9.8 / 75,000 kg = 4.79 m per light.
2 x 4.79 x 3.281 = 17 ft
So after 10 nm the aircraft would be 17 ft lower than it would have been if the lights were retracted.
Rough numbers I know but it give you an idea.
Join Date: May 2007
Location: Western Pacific
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Our MEL has the following penalties for operating the B737-800 with the retractable landing lights extended -
1. Reduce the enroute climb limited weight by 681kg per light
2. Increase the fuel burn by 1% for each light.
There is further information in the introduction section of the CDL, discussing the enroute climb weight penalties & providing factoring figures for various speeds. These factoring figures range from 1.5 to 6.4.
The interesting thing is that the CDL for operating with retractable landing lights in the extended position states that the enroute climb penalty is negligible, along with the takeoff & landing weight penalty.
1. Reduce the enroute climb limited weight by 681kg per light
2. Increase the fuel burn by 1% for each light.
There is further information in the introduction section of the CDL, discussing the enroute climb weight penalties & providing factoring figures for various speeds. These factoring figures range from 1.5 to 6.4.
The interesting thing is that the CDL for operating with retractable landing lights in the extended position states that the enroute climb penalty is negligible, along with the takeoff & landing weight penalty.
