Position of Elevators at T/O - A-320
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ss41
But that's the thing - FCOM does not mention elevator deflection, it says half down or full down sidestick deflection, and as we have seen that's not the same thing at all.
DNR may have the answer three posts back - but we should not encourage anyone to deviate from SOP's... please leave the engine display on the lower ECAM, it really is not that important, but your customers' safety is.
quite confident that you can hold the elevators half down and full down; just as the FCOM recommends.
DNR may have the answer three posts back - but we should not encourage anyone to deviate from SOP's... please leave the engine display on the lower ECAM, it really is not that important, but your customers' safety is.
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Different reasons
It looks to me that nobody has really adressed your question. Here's my go:
I think the idea of full stick input is there in each case for different reasons:
In a significant xw T/O, there is more need of NGW assistance before 80kt IAS, for obvious reasons.
In the case of a pure tailwind component, there wouldn't be more need of assistance, only that whatever assistance is needed would be obtained, say, 10kt GS later, even more when comparing to a headwind component T/O. Higher GS, the AC veers off CL quicker for a given angle of misalignment. So, the elevator assistance is needed "sooner" (IAS-wise), hence the call for full downstick.
I have no idea how stick pos and elev deflection are mapped to each other over different speeds during the roll (it is said to be in direct proportion but that doesn't mean the proportion is constant for different speeds), but it makes sense to assume that AB just wrapped both wind conditions in one case and called for full down stick from the get go, just to keep it simple.
As for the second part of your question, I don't know. I wouldn't be surprised if, for certain thrust x TOW x CG conditions, the NGW became VERY light in the begining of the T/O.
I think the idea of full stick input is there in each case for different reasons:
In a significant xw T/O, there is more need of NGW assistance before 80kt IAS, for obvious reasons.
In the case of a pure tailwind component, there wouldn't be more need of assistance, only that whatever assistance is needed would be obtained, say, 10kt GS later, even more when comparing to a headwind component T/O. Higher GS, the AC veers off CL quicker for a given angle of misalignment. So, the elevator assistance is needed "sooner" (IAS-wise), hence the call for full downstick.
I have no idea how stick pos and elev deflection are mapped to each other over different speeds during the roll (it is said to be in direct proportion but that doesn't mean the proportion is constant for different speeds), but it makes sense to assume that AB just wrapped both wind conditions in one case and called for full down stick from the get go, just to keep it simple.
As for the second part of your question, I don't know. I wouldn't be surprised if, for certain thrust x TOW x CG conditions, the NGW became VERY light in the begining of the T/O.
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FlightDetent
Correct, it's in the FCTM;
XPM
My observation shows that when you input half forward stick as observed on PFD you get full down deflection of the elevator on F/CTL page. I had tried to locate a reference in the manuals but did not find it.
XPM
Only half a speed-brake
Sure it can. The questions left unanswered:
- what is the position of elev when SD indicates "full down" (i.e. atop the stop band, achieved with half stick forward) - see last pictures
- what is the position of elev when SD indicates "end stop" (i.e. in the middle of the the stop band, achieved with more than half stick forward) - see last pictures
- what is the behaviour of elev during TO roll if the stick is held half way forward up to 80 kt
- what is the behaviour of elev during TO roll if the stick is full forward up to 80 kt
- what difference do the two techniques provide
- why does Airbus require different techique for each case depending on wind component.
XPM: Sometimes the old manuals have more information that gets removed later on to prevent confusion amongst the "common users". In order to make the essentials more visible the nice-to-know and beyond skin deep is deleted. Or of course, sometimes because it is plain wrong. I have a copy of "Instructor Support" dated 2001 which I thought was predecessor of FCTM until seeing the header you posted.
This book is much richer than the present day FCTM although some procedures are now explained and/or done differently. Still it has no reference to the witnessed elev behaviour unlike your (older) manual. It took 45+ posts to get the question right and yield some clever ideas but no answers, I love it, thanks for your inputs so far.
FD (the un-real)
- what is the position of elev when SD indicates "full down" (i.e. atop the stop band, achieved with half stick forward) - see last pictures
- what is the position of elev when SD indicates "end stop" (i.e. in the middle of the the stop band, achieved with more than half stick forward) - see last pictures
- what is the behaviour of elev during TO roll if the stick is held half way forward up to 80 kt
- what is the behaviour of elev during TO roll if the stick is full forward up to 80 kt
- what difference do the two techniques provide
- why does Airbus require different techique for each case depending on wind component.
XPM: Sometimes the old manuals have more information that gets removed later on to prevent confusion amongst the "common users". In order to make the essentials more visible the nice-to-know and beyond skin deep is deleted. Or of course, sometimes because it is plain wrong. I have a copy of "Instructor Support" dated 2001 which I thought was predecessor of FCTM until seeing the header you posted.
This book is much richer than the present day FCTM although some procedures are now explained and/or done differently. Still it has no reference to the witnessed elev behaviour unlike your (older) manual. It took 45+ posts to get the question right and yield some clever ideas but no answers, I love it, thanks for your inputs so far.FD (the un-real)
