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-   -   B738 average burn (https://www.pprune.org/tech-log/242654-b738-average-burn.html)

oceancrosser 6th Sep 2006 19:29

B738 average burn
 
I would like to ask any 737-800 guys out there what the average burn pr. hr. is on an average 3-4 hr. sector. I remember from my 737 classic days that is would burn 2,2-2,4 tons pr. hr.

tks.

o/c

stator vane 7th Sep 2006 11:01

from QRH
 
long range cruise control: p. PI.11.2

weight 65,000 kg FL 370 FF/ENG=1231 KG/HR
FL 350 FF/ENG=1218
FL 330 FF/ENG=1239
FL 310 FF/ENG=1252
so multipy by two (if both engs working)

another QRH chart gives:
air distance: let's use 1000 NM
FL 310=4600KG FL330=4400KG FL350=4300KG FL370=4200KG

for "shooting from the hip" estimates-some use 40KG minute for hold, some use 50kg minute.

another rough guide=200KG per hour each 1000 feet below flight plan level.

i am sure you will get quite a range of differences.

oceancrosser 8th Sep 2006 13:44

thanks stator vane, appreciate it

captjns 8th Sep 2006 14:18

Average of 41 kilos per minute from takeoff to landing works out pretty well too.

alexban 8th Sep 2006 18:17

is there a difference between winglets and without winglets ones? How much?

captjns 8th Sep 2006 21:17


Originally Posted by alexban (Post 2833643)
is there a difference between winglets and without winglets ones? How much?

The winglets produce less drag which results in higher optimum operating altitudes which will result in slightly better fuel efficiency.

stator vane 10th Sep 2006 11:38

with winglets
 
Same Weight=65,000 KG LONG RANGE CRUISE
FL 370=1162
FL 350=1166 Kg/hr/eng
FL 330=1180
FL 290=1186

1000NM

FL 310=4900
FL 330=4700
FL 350=4600
FL 370=4500

did a double check for the 1000NM and that is what the book shows. fuel higher for the winglets but the times are shorter!

without winglets 1000 nm
FL 290=4700KG 2:45
FL 310=4600KG 2:42
FL 330=4400KG 2:37
FL 350=4300KG 2:32

with winglets 1000 nm
FL 290=5100KG 2:38
FL 310=4900KG 2:33
FL 330=4700KG 2:28
FL 350=4600KG 2:24

i must admit that i get bored very quickly doing these type of activities. perhaps later i will look into the subject further. but that is what the QRH book gives for the winglets and wingletless aircraft at ryanair.

anyhow, with a new flight crew notice that requires us to maintain at least a 1.45G manuever margin, we are always at least 2000 feet lower than usual. so the fuel savings forecast by the winglet sales department is seldom approached.

but regardless of fuel factors-- they do look good and we all know how important good looks are!


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