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-   -   B737 NG De-rated Climb (https://www.pprune.org/tech-log/418850-b737-ng-de-rated-climb.html)

Boneman 21st Jun 2010 14:15

B737 NG De-rated Climb
 
Does a de-rated climb increase fuel burn during the climb?

(Please discuss in excruciating detail :bored:)

BOAC 21st Jun 2010 14:28

Yes

I will not:)

Pugilistic Animus 21st Jun 2010 14:31

more time at non-optimum level ,also more time in high drag configuration and more time in the climb---derates are nice for engine reliability:)

if this thread gets worse I'm outta here:\

de facto 21st Jun 2010 14:32

Stoneman:eek:

Use derate will increase your fuel burn as it will take longer to reach your cruising/opt level.

To save fuel,no derate(not as good for engines though) and use NDP2(3-4% fule save compare to other ndp1).

Sorry i wont get into details, especially without the magic word:E

Pugilistic Animus 21st Jun 2010 14:36


especially without the magic word
---------Vm:oh:
:}

Boneman 21st Jun 2010 14:59


Originally Posted by de facto
Sorry i wont get into details, especially without the magic word

But I said please.:{

de facto 21st Jun 2010 15:09

you did indeed.:8
Still,easiest is to believe us,burning more fuel by using less thrust,hence a longer time to reach higher level.

Derate is better in many ways...there are many threads concerning this...only bad thing is the fuel burn which is increased.

drive73 21st Jun 2010 15:15

It wouldn't burn much more fuel as climb power switches at 15k feet. The savings to the engine would be way more valuable than the small fuel savings through 15k. Please correct me if I am wrong.

BOAC 21st Jun 2010 15:42

Oh, since you've been so polite :)

Take it 'ab absurdo' - reduce power to just above cruise and look at the fuel burn when you are still at 10000ft 200 miles after take-off. As above, the quicker you get up there the less you burn. Generally climbing above 35000ft 'ish when the air is about as cold as it gets will not make so much difference

bumpyflight 21st Jun 2010 16:44

I dont really know on a 737, but I got some info that might helpmax take off weight = 144,500–187,700 lb (65,500–85,100 kg)take off field length = 8,000–8,300 ft (2,400–2,500 m)above is for 737 800 aircraft

Boneman 21st Jun 2010 16:46

OK, now I'm going to throw in a cost index; 5 vs. 50. Any takers?
:ugh:
Please?

BOAC 21st Jun 2010 16:56

Thank you. It depends on which climb speed 5 or 50 give. Whichever is nearer to the best r of climb speed will win.

I also suspect we are being trolled (no, boneman, not you:))

VH-ABC 28th Jun 2010 07:35

BOAC,

Whatever you put in as the TOC wind will also change your climb speed will it not?

citizensun 7th Jul 2010 17:40

two more question for you guys~~ thanks
 
:)i am flying 737NG ,and i have couple questions. as the manual says, the take-off thrust has a 5 minutes limit, could anyone tell me where is this limit come from, the reason for this and why it`s still a limit in de-rate and assume-temp take-off when the engines are not in full power. thanks~


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