The effect of wake turbulence is likely to be strongest behind...
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Can anyone explain why PPLCruiser think something different to the exam board on this? Which answer is right and why?
I've actually just found a thread discussing a similar topic on here. However, it's seven years old so would be interesting to see if there have been any changes or anyone has a new perspective.
I've actually just found a thread discussing a similar topic on here. However, it's seven years old so would be interesting to see if there have been any changes or anyone has a new perspective.
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Not read the other thread yet. But according to FAA AC 90-23G, answer B is correct because:
Makes sense to me.
The greatest vortex strength occurs when the generating aircraft is heavy-slow-clean since the turbulence from a “dirty” aircraft configuration hastens wake decay.
Makes sense to me.
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A safe answer such as "I don't care, because I'm not going anywhere near either of them" will keep you alive but, quite unreasonably, won't get you the marks.
Don't forget the reason for deploying flaps when landing is...
1. To reduce the stalling speed, so that aircraft can be flown slower.
2. Move the stalling area of the wing to the root section. The wing-tip will be at a reduced AoA, so that it is not likely to tip stall and cause a spin. The wing-tip will therefore create less vortex.
The question says each aircraft is flying slowly, but maybe the first one will be flying slower that the clean aircraft.
1. To reduce the stalling speed, so that aircraft can be flown slower.
2. Move the stalling area of the wing to the root section. The wing-tip will be at a reduced AoA, so that it is not likely to tip stall and cause a spin. The wing-tip will therefore create less vortex.
The question says each aircraft is flying slowly, but maybe the first one will be flying slower that the clean aircraft.
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Thanks oggers, Gertrude, scifi.
GBEBZ, the basics physics laws don't change very often, but the application of them in this CAA question apparently has. CAA have had two opposing answers to this question in different exam papers.
GBEBZ, the basics physics laws don't change very often, but the application of them in this CAA question apparently has. CAA have had two opposing answers to this question in different exam papers.
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Heavy Slow Clean has and always will (should) be the right answer.
If you are questioning the CAA now, you wait until you sit the 14 ATPL Exams, where currently you have to answer questions with the incorrect answer in order to get the question right... or like me you get the exact same question TWICE in the same exam, but both questions have totally different answers to chose from...
If you are questioning the CAA now, you wait until you sit the 14 ATPL Exams, where currently you have to answer questions with the incorrect answer in order to get the question right... or like me you get the exact same question TWICE in the same exam, but both questions have totally different answers to chose from...
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Not very PC but when I was having difficulty remembering when wake turbulence was at it worst my instructor said to me in a moment of frustration "look just think of a fat moron getting out the shower he's going to be heavy slow and clean". No trouble remembering it after that.
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As has been said, anything that demands a higher angle of attack to generate lift will increase wake turbulence, as that is essentially where it comes from.
Flying fast, adding flap (increasing wing camber and possibly increasing wing surface area) and being light all assist with lift (or reduce the need for it) and allow for a lower AoA which therefore reduces wake turbulence.
Light winds are normally cited as the worst scenario as the wake vortices can drift back onto the centreline (as opposed to dissipating left and right in calm conditions or being 'destroyed' by strong winds).
The given answer seems correct enough to me.
Flying fast, adding flap (increasing wing camber and possibly increasing wing surface area) and being light all assist with lift (or reduce the need for it) and allow for a lower AoA which therefore reduces wake turbulence.
Light winds are normally cited as the worst scenario as the wake vortices can drift back onto the centreline (as opposed to dissipating left and right in calm conditions or being 'destroyed' by strong winds).
The given answer seems correct enough to me.
Estimation of Wake Vortex Advection and Decay Using Meteorological Sensors and Aircraft Data supports the FAA line mentioned by oggers.
