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chiswick72

Engine Power Setting

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Hi guys,Ive set the aircraft and all systems ready for takeoff, but I cant seem to find the calculated engine %N1 for takeoff power.It seems the first time I know what my TOGA N1% is, is when I select it for take off on the throttle and it appears on display, but I need to know before I initiate the takeoff sequence.Best regards.Armen at EGLLwww.veryquiet.com


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Armen L Cholakian
PMDG Sound Engineer

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Guest vrandar

Why particularly do you need to know this before the takeoff roll? It will show up on the ECAM as soon as you move the thrust levers to TOGA but I can't see a benefit by knowing it earlier, or a problem by not knowing it. Let the FADEC do it's job.

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"Why particularly do you need to know this before the takeoff roll?"Well, to me its VERY important to know what power your engines are set at before trying to takeoff.Say, a pilot made an incorrect input into the FMS then what? hurtling down the runway at 80 knots you realise oh N1 is set at 60% !! Lovely!Doesnt sound safe to me... is this lack of functionality a PSS thing or and Airbus thing ????Armen at EGLLwww.veryquiet.com


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Armen L Cholakian
PMDG Sound Engineer

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Guest vrandar

There will be a difference in N1%/EPR, even with TOGA thrust, depending temperature and altitude. But with TOGA it's not going to be anything like the reduction you mention. Even with Flex on a hot and high takeoff the thrust will not go down that far. I have just tried a Flex TO Temp at the maximum figure of -99, at an altitude of 75 feet and a temp of 0 degrees C - so a cold day at near sea level at Hamburg - and N1% only went down to 82.3% (TOGA thrust 97.7%). For a hot and high from Johannesburg at flex -99, altitude 5400 ft and temp 22 deg C: the N1% was 84.2% (TOGA thrust was 103%).The main error that might occur is to input a drastically incorrect Flex TO Temp which might cause a problem like running out of runway, but it would of course have no effect if you were using a TOGA thrust setting for takeoff. Entering incorrect vspeeds is also not a good idea.Airbus pilots have runway charts with temps, thrust and vspeed figures. But in the absence of those (although a vspeeds chart is available from the speedbirdonline site in my address) what you can do is that when you are holding for takeoff, while holding on the brakes quickly press the + key to go to TOGA or Flex (whichever thrust you are using) and watch the top right of the upper ECAM which will display the thrust almost instantly. Then reduce thrust again to idle. This should all be done very quickly. If the thrust didn't seem to be wrong then you can line up and takeoff. If it doesn't seem right then you can investigate why.PS - with flex don't forget that PSS got the programming wrong and you should be entering the flex figures as a minus. If you enter a positive figure or leave it at the default of 42 degrees C you will see hardly any difference between Flex and TOGA. Entering Flex as a minus gives you the correct difference in thrust and I am currently trying to turn various temp, alt and flex combinations into a usuable chart.Sorry, a longer answer than I intended and than you probably wanted.

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Hi Rob,Many thanks for your reply again, what you say makes good sense, but I would still expect the calculated thrust rating on the ECAM to appear visibly somewhere in the cockpit before TOGA selection. It seems strange to me that it isnt, but oh well.The figure I used in my initial post was purely a hypothetical one, and was only intented to show that the calculated thrust at given temp and pressure should be shown to the pilot before the take off roll, otherwise one might not notice an error until it is too late.All the best. :)Armen at EGLLwww.veryquiet.com


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Armen L Cholakian
PMDG Sound Engineer

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Guest S Hilmerby

In the real Airbus, this information is shown as soon as the first engine is running. TOGA N1 if you don

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Guest vrandar

The trouble is Stellan that most of us can't afford a real one so we have to work with what PSS gives us :) Now if they would sell me the code ....

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Thanks for your comments gentlemen.Oh well I will have to do without.Armen at EGLLwww.veryquiet.com


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Armen L Cholakian
PMDG Sound Engineer

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