In other news, wake turbulence liberates tile(s); car damaged, expert called in
Avoid imitations
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I saw quite a surprising demo of this at Old Warden (Shuttleworth Collection) just a couple of weeks back.
As part of a "Flying Evening" they had a balloon bursting event. Small helium balloons were released into the path of light aircraft, including a Miles Magister, which came past at about 150 feet. The Magister pilot missed a rising balloon which got entrained in the slipstream vortex. The vortex caused the balloon to rotate very rapidly, around a radius of about two feet. It pulled it all the way to the ground.
As part of a "Flying Evening" they had a balloon bursting event. Small helium balloons were released into the path of light aircraft, including a Miles Magister, which came past at about 150 feet. The Magister pilot missed a rising balloon which got entrained in the slipstream vortex. The vortex caused the balloon to rotate very rapidly, around a radius of about two feet. It pulled it all the way to the ground.
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Y_D_F_D possibly needs to supply more detail as the grey matter is getting quite congealed these days.
Was I exceeding Vne on short finals, or did I infringe the airspace around an orange house on the hill on approach to R03?
=^.*.^=
Was I exceeding Vne on short finals, or did I infringe the airspace around an orange house on the hill on approach to R03?
=^.*.^=
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Sitting down by the lagoon at Kerkira(Corfu) whenever a B757 landed you could always see the water being disturbed as it left
large vortix trails and you could hear it as a swishing sound, very strange but impressive
Golf India Bravo
large vortix trails and you could hear it as a swishing sound, very strange but impressive
Golf India Bravo
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Broadreach- look at it like this. Take cross section areas of the vortex a little behind the aeroplane, and say a kilometer and compare. The first will be narrow and rotating very rapidly. The second will be wider and rotating far slower. There will be a slight loss of energy due to friction with the surrounding air. If you remember the ballet dancer theory, the rotational velocity will be reduced on the second, so as the vortex expands, it loses speed. Why does it expand? Haven't a clue! Sucking in free air?
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Back to the topic, Zurich "Unique" Airport is spending millions of Swiss Francs to clip tiles on the roof of houses standing under the newly opened southern airpath to the airport.
The airport is even diverting funds from an anti-noise fund to do so. I guess that if it does so, it means there is a real problem with turbulences on the southern approach.
The airport is even diverting funds from an anti-noise fund to do so. I guess that if it does so, it means there is a real problem with turbulences on the southern approach.
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Probably been posted before but have a look at the CX 747 here (at the bottom of the page). Loose tiles would be fair game, I'd say.
And yes, Maho Beach (SXM) is great entertainment watching the tourists watching the planes. Most learn quickly that a departing heavy will blow their towels, belongings and even small pets into the sea. Takes them a bit longer to understand WIHIH after a 757 lands
.
*Edited to add video link http://www.storeitonline.nl/funny/re...-depart-09.mpg
And yes, Maho Beach (SXM) is great entertainment watching the tourists watching the planes. Most learn quickly that a departing heavy will blow their towels, belongings and even small pets into the sea. Takes them a bit longer to understand WIHIH after a 757 lands
.*Edited to add video link http://www.storeitonline.nl/funny/re...-depart-09.mpg
Last edited by PaperTiger; 1st Jun 2004 at 20:45.
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hectorus rex
You were observed (through the smoke haze at Warbirds) on at least one occasion to pause between "Rouble Dum"s to debate the merit/futility of providing wake turbulence separation behind the "Dak" with a certain Senior ATCO.
Many hours later an agreement was reached...................
................ to disagree.
supply more detail as the grey matter is getting quite congealed these days
You were observed (through the smoke haze at Warbirds) on at least one occasion to pause between "Rouble Dum"s to debate the merit/futility of providing wake turbulence separation behind the "Dak" with a certain Senior ATCO.
Many hours later an agreement was reached...................
................ to disagree.
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Not many paid a whole lot of attention to wake turbulence until many years ago a DC9 (crew trainer) was turned upside down by a previously landing DC10 at the old Greater Southwest airport in Fort Worth, Texas.
Fatal to all on the DC9.
As for flying rather low and damaging roof tiles, some years ago a TriStar operated by AirLanka, during crew training, was completing circling approaches at the old Colombo airport, and blew the roof completely off a house.
Now for those that have actually been to SriLanka, will realize that houses there can be rather ah...flimsy.
Fatal to all on the DC9.
As for flying rather low and damaging roof tiles, some years ago a TriStar operated by AirLanka, during crew training, was completing circling approaches at the old Colombo airport, and blew the roof completely off a house.
Now for those that have actually been to SriLanka, will realize that houses there can be rather ah...flimsy.
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Thanks for the memory jog, Y_D_F_D.
It surely was needed as I have neither smoked nor Rouble Dum'ed for nearly 10 years
Not in jest wake turbulence can really spoil one's day in the wrong circumstances.
In conclusion, was I for or against, or neither?
It surely was needed as I have neither smoked nor Rouble Dum'ed for nearly 10 years
Not in jest wake turbulence can really spoil one's day in the wrong circumstances.
In conclusion, was I for or against, or neither?
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Believe it.
Depends a lot on the stability of the atmosphere at the time as to how fast they dissapate. Presence of an inversion may be a factor, such as early morning.
Fly across your own, it is like a speed bump.
Fly along your own in ground effect and you will experience sudden uncommanded roll.
Seem worse if the aircraft is dirty, my own worst experience involved running into one where the previous spray run involved a sudden/steep pull up with flap. So it persisted at least long enough to get the aircraft back to nearly the same spot.
Can be quite embarrasing to hit one approaching an overhead obstacle...
Nothing theoretical here - only what I have seen myself.
Depends a lot on the stability of the atmosphere at the time as to how fast they dissapate. Presence of an inversion may be a factor, such as early morning.
Fly across your own, it is like a speed bump.
Fly along your own in ground effect and you will experience sudden uncommanded roll.
Seem worse if the aircraft is dirty, my own worst experience involved running into one where the previous spray run involved a sudden/steep pull up with flap. So it persisted at least long enough to get the aircraft back to nearly the same spot.
Can be quite embarrasing to hit one approaching an overhead obstacle...
Nothing theoretical here - only what I have seen myself.
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HectorusRex
You were most indignant that your precious DC3 was accused of producing wake turbulence and quite insistent that said wake turbulence was not of any great consequence to other traffic.
I think the Dak had been doing circuits on a Sunday afternoon and the Wake turbulence separation of 2 to 3 minutes was creating huge delays to those who didn't know they could ask for their own separation.
As an aside here, some pilots don't seem to realise that the wake turbulence delay to a subsequent departing aircraft is 1 minute longer from an inset position than from the full length holding point, therefore, it is sometimes quicker to taxi further when wake turbulence is a factor.
Just as well you've quit. Look what they've done to your memory. 
[edited for typos]
was I for or against, or neither?
I think the Dak had been doing circuits on a Sunday afternoon and the Wake turbulence separation of 2 to 3 minutes was creating huge delays to those who didn't know they could ask for their own separation.
As an aside here, some pilots don't seem to realise that the wake turbulence delay to a subsequent departing aircraft is 1 minute longer from an inset position than from the full length holding point, therefore, it is sometimes quicker to taxi further when wake turbulence is a factor.
I have neither smoked nor Rouble Dum'ed for nearly 10 years
[edited for typos]
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Perhaps if that had been explained initially, Y_D_F_D there would have been no need to resort to emphasis.
IF I recall it correctly the DC-3 was accused of delaying the departure of waiting aircraft because of wake turbulence separations being applied, when the said DC-3 was making a full stop landing?
Perhaps you can convince me and others, that wake turbulence, in the form of wing tip vortices, does not cease on touch down?
I have always been well aware of the effects of wake turbulence on other aircraft, so I doubt if I was making any such assertion.
The effect of wake turbulence was brought home to me very early on when I had the misfortune when solo flying a "Devon" and encountered the wake of a Vampire ahead which had not made a normal power-off approach, and when the jet wash hit one wing the Devon nearly became inverted at a precariously low altitude.
The "Checkers Van" Controller got nearly as bad a fright as I did.
You are quite correct that the DC-3/C-47 was, and still is, a most precious aircraft, and probably no more than in those days being commemorated at Normandy this weekend.
IF I recall it correctly the DC-3 was accused of delaying the departure of waiting aircraft because of wake turbulence separations being applied, when the said DC-3 was making a full stop landing?
Perhaps you can convince me and others, that wake turbulence, in the form of wing tip vortices, does not cease on touch down?
I have always been well aware of the effects of wake turbulence on other aircraft, so I doubt if I was making any such assertion.
The effect of wake turbulence was brought home to me very early on when I had the misfortune when solo flying a "Devon" and encountered the wake of a Vampire ahead which had not made a normal power-off approach, and when the jet wash hit one wing the Devon nearly became inverted at a precariously low altitude.
The "Checkers Van" Controller got nearly as bad a fright as I did.
You are quite correct that the DC-3/C-47 was, and still is, a most precious aircraft, and probably no more than in those days being commemorated at Normandy this weekend.
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Funny how the louder the voices got, the harder it was to hear what was being said.
The aircraft might stop creating a wake at touchdown, but the trail behind it doesn't instantly dissolve. My understanding is that the wake turbulence is at its greatest immediately prior to touchdown. So, if the Dak touched down by the Waitemata taxiway and vacated at the end, it is conceivable that a C172 departing from full length could get airborne into what was left of the Wake Turbulence. Of course, if the C172 held it on the runway until the Waitemata taxiway, he would be clear of the risk. That would be his decision to make.
The standards required to be applied can be downloaded at:
NZAIP - Wake Turbulence
It's a PDF file
The table gives the example of a MEDIUM ARRIVAL followed by a LIGHT DEPARTURE and the required separation is 2 minutes.
Then further on:
This was probably pointed out to you at the time. Like many things, the pilot is entitled to decide that the situation is safe, the Controller mustn't assume that it is.
Now, here's a question to get you thinking. Does all the Wake Turbulence cease at the moment the mains are on the runway? Or does the tailwheel have to be on the ground as well?
Perhaps you can convince me and others, that wake turbulence, in the form of wing tip vortices, does not cease on touch down?
The standards required to be applied can be downloaded at:
NZAIP - Wake Turbulence
It's a PDF file
Between Arriving and Departing Flights
1.4.4 The minimum time separations applied between arriving and
departing aircraft, if the flight path of the following aircraft will cross the
projected flight path of the leading aircraft (e.g. when an arriving aircraft is
operating onto a runway with a reduced landing threshold) are provided in
Table AD 1.6-4.
Sourced from www.aip.net.nz
1.4.4 The minimum time separations applied between arriving and
departing aircraft, if the flight path of the following aircraft will cross the
projected flight path of the leading aircraft (e.g. when an arriving aircraft is
operating onto a runway with a reduced landing threshold) are provided in
Table AD 1.6-4.
Sourced from www.aip.net.nz
Then further on:
1.5.3 Notwithstanding the wake turbulence separation standards
previously outlined, if pilots consider that the effect of wake turbulence can
be nullified by ensuring that flight profiles do not cross, they may request
and be granted exemption from these separations. ATC will advise the
category or type of the other aircraft where that aircraft is a HEAVY weight
category or is a B757 aircraft.
Sourced from www.aip.net.nz
previously outlined, if pilots consider that the effect of wake turbulence can
be nullified by ensuring that flight profiles do not cross, they may request
and be granted exemption from these separations. ATC will advise the
category or type of the other aircraft where that aircraft is a HEAVY weight
category or is a B757 aircraft.
Sourced from www.aip.net.nz
Now, here's a question to get you thinking. Does all the Wake Turbulence cease at the moment the mains are on the runway? Or does the tailwheel have to be on the ground as well?
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Thanks for all the chapter and verse, Y_D_F_D.
I'm not sure what the relevance of all this is, some nearly 10 years hence.
Strange as it may seem, Ardmore, still the busiest airport in NZ based on aircraft movements, manages to continue operating safely without the assistance of ATC.
In conclusion I understand that wing tip vortices cease with the unloading of the wings at touch down.
I do not think that the fact that an aircraft is a tricycle or tail wheel type makes any difference to this.
I'm not sure what the relevance of all this is, some nearly 10 years hence.
Strange as it may seem, Ardmore, still the busiest airport in NZ based on aircraft movements, manages to continue operating safely without the assistance of ATC.
In conclusion I understand that wing tip vortices cease with the unloading of the wings at touch down.
I do not think that the fact that an aircraft is a tricycle or tail wheel type makes any difference to this.
Per Ardua ad Astraeus
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To be pedantic, vortex turbulence (which is what I think you are all talking about, not 'wake' which is behind every moving body at all times) is produced by a surface when that surface is producing lift. In the case of a tailwheeler, the wing is still at a positive incidence during the landing run, so there will be some (small) vortex generation along with some lift generation. With a nosewheeler, the roll-out incidence is minimal as is the vortex and lift.
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In the case of a tailwheeler, the wing is still at a positive incidence during the landing run, so there will be some (small) vortex generation along with some lift generation. With a nosewheeler, the roll-out incidence is minimal as is the vortex and lift.
Anyway, Bill, I knew you'd take the bait.
Late-night rambling perhaps but I find it difficult to believe that any taildragger could generate vortices threatening to anything larger than an ultralight on. Speed surely has a bearing on it, i.e. the faster the speed the faster the vortices spin so the longer the cone.
