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Thrust reduction after Take Off


Attilio Cardone

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Attilio Cardone

Today I took off from EGLL, with QNH 1030 and temperature 0 degrees, TOW 180000.
The performance calculator gave me a value of wrong N2 (88.7) and TLA (24.5).
From the BRITISH AIRWAYS tables I have instead obtained TLA = 18.6 and N2 = 93.7
Despite these values, after takeoff, to keep 250 kts with this N2 I could not climb above 100 ft / min. Was it so difficult even in reality?

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Fraser Gale
5 hours ago, Attilio Cardone said:

Today I took off from EGLL, with QNH 1030 and temperature 0 degrees, TOW 180000.
The performance calculator gave me a value of wrong N2 (88.7) and TLA (24.5).
From the BRITISH AIRWAYS tables I have instead obtained TLA = 18.6 and N2 = 93.7
Despite these values, after takeoff, to keep 250 kts with this N2 I could not climb above 100 ft / min. Was it so difficult even in reality?

At that weight, yes!

Remember that the noise abatement procedure is designed to climb as high as possible on maximum power until over communities, at which point power was reduced to "minimum safe" that would allow minimal climb and minimum noise. 

The wing produced so much drag at 250kts at heavy weight that it was just a small climb that remained.  

Which runway was it?  I flew yesterday and it was on the "09's" which are the most noise sensitive and give the smallest climb gradient due to the right turn required.

Frazz

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Ray Proudfoot

Out of curiosity I looked at the data CPS-X produced for a recent EGLL-KJFK flight with 85 pax and 95T of fuel. The reheat time was 81s and TLA was -15.3. With 24.5 you would have found it impossible to climb I would have thought.

Do you use CPS-X?

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Attilio Cardone

Exactly the value 24.5 is totally wrong. Perhaps a bag of the calculator concorde-x.
I found the correct value from the performance manual british airways, which corresponds to 18.6 and I used that

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Ray Proudfoot
1 hour ago, Attilio Cardone said:

Perhaps a bag of the calculator concorde-x.

Don't understand that sentence, sorry. It might help to mention your OS and version of flight sim you're using. But the Performance Calculator should work correctly whatever they are.

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Fraser Gale
4 hours ago, Attilio Cardone said:

26L.

So it is normal to put a lot of time(100ft/m) to get up to 8000ft

There is no 26L at Heathrow....unless they've changed the magnetic variation again...

If you mean 27L what wind were you experiencing? As yesterday departures and arrivals were on westerlies (09L/R).

If you took off with a tail wind it would have affected the climb considerably.  When I "arrived" back at EGLL around 21:30 Zulu yesterday the wind was around 070/11kts. 

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