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Aeroplane 'vroops'
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milk23Offline
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PostPosted: 15-08-2013 16:33    Post subject: Reply with quote

quick update-

I heard a reverse vroop the other day whilst actually watching the aircraft in question
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Old_ShoeOffline
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PostPosted: 17-08-2013 19:54    Post subject: Reply with quote

I think I just heard a vroop a few minutes ago while standing in my driveway. I heard the odd sound effect and looked up to see a commercial airliner making his approach to IAH in Houston. He was several thousand feet up, gear up and flaps at the approach setting. I don't think the sound effect seemed to be caused by anything like thrust setting changes or anything else like that, but rather a weird relationship between the speed of the airplane and the speed of sound, so that as the plane moves over the ground low enough to be heard the sound level ahead of it, beneath it and behind it have different tones. I didn't notice any sound at all, then I first noticed a high pitched whine that morphed suddenly into a lower, louder kind of dull roar, as if he wasn't there at all and suddenly popped out of a wormhole or sumpin'. It IS a very strange sensation.
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Old_ShoeOffline
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PostPosted: 17-08-2013 20:04    Post subject: Reply with quote

On further reflection, I can relate that vroop, now, to something I remember from years ago, and the two observations both seem to fit my theory. I was stationed aboard a ship and we were down at Guantanamo Bay in Cuba for training exercises. One day we were underway and we were playing cat and mouse with a fighter jet. The jet would leave the area and then he'd try to sneak up on us. We watched the sky with radar and with lookouts and I was posted as a lookout on the 01 deck forward, just behind the 5" gun mount in the foc'sle. Our goal was to get the gun trained on the jet and ready to shoot before the jet could have a chance to shoot at us. I remember standing on that deck with a few other lookouts and we spotted the jet on our starboard beam coming in low and fast straight at us. He was near the speed of sound, but not above it. At first we only could hear a faint metallic ringing sound, then an incredible explosion as he passed over our heads low enough to blow our hats off. THAT was obviously a relationship between the speed of the jet and the speed of sound. I think the vroop is the same thing, but less pronounced.
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ds0rcoOffline
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PostPosted: 21-08-2013 14:52    Post subject: Reply with quote

Old_Shoe wrote:
I think I just heard a vroop a few minutes ago while standing in my driveway. I heard the odd sound effect and looked up to see a commercial airliner making his approach to IAH in Houston. He was several thousand feet up, gear up and flaps at the approach setting. I don't think the sound effect seemed to be caused by anything like thrust setting changes or anything else like that, but rather a weird relationship between the speed of the airplane and the speed of sound, so that as the plane moves over the ground low enough to be heard the sound level ahead of it, beneath it and behind it have different tones. I didn't notice any sound at all, then I first noticed a high pitched whine that morphed suddenly into a lower, louder kind of dull roar, as if he wasn't there at all and suddenly popped out of a wormhole or sumpin'. It IS a very strange sensation.


This is exactly as I would describe it as, it happens 2 or 3 times a month, I'm on the approach to Newcastle airport. I've often said to my wife "There's another Easyjet arrived from hyperspace" Very Happy
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IlikepencilsOffline
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PostPosted: 21-08-2013 21:45    Post subject: Reply with quote

It's Newcastle airport for me too and I hear it once every couple of days or so but not with every plane that goes over. I must live right under the most frequent place of hyperspace drop in Wink I remember when I first noticed it a few years ago I was convinced there was something wrong with the plane. It does sound strange.
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MythopoeikaOffline
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PostPosted: 22-08-2013 20:24    Post subject: Reply with quote

Can you record the sound and post it somewhere for us to hear? Thanks.
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Old_ShoeOffline
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PostPosted: 22-08-2013 20:29    Post subject: Reply with quote

I don't know if the sound is loud enough for unsophisticated recording device to pick up clearly without it being drowned out by ambient background noise. Also, it would be nearly impossible to predict when a vroop might happen. Unless, maybe, you could find a spot near the airport where you can observe the phenomenon regularly enough to set up shop with a camera to record it. It seems to be a rather random occurrence, like trying to snap a picture of lightning.
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milk23Offline
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PostPosted: 22-08-2013 20:32    Post subject: Reply with quote

I will endevour to get it captured on a device. Whenever I have heard it I've been round a quiet spot so with any luck the surrounding sounds will not intrude too much
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milk23Offline
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PostPosted: 06-05-2014 14:12    Post subject: Reply with quote

Just so you know, the vroops are back
I'm quite certain that it's an atmospheric phenomena.
Weather becomes warmer, vroops return

I now have a recording device and will endevour to capture this noise
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Old_ShoeOffline
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PostPosted: 10-05-2014 20:24    Post subject: Reply with quote

That's an interesting observation about warmer weather affecting it. The speed of sound through air is not constant and is affected by things like air temperature and air density. If the speed of sound is variable, then it stands to reason the relationship between the aircraft speed and the odd sound phenomenon would also be affected by these variables.
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OneWingedBirdOffline
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PostPosted: 10-05-2014 20:41    Post subject: Reply with quote

Can any of the 'airport people' tell me how far away from the airport they live?

I'm just thinking that I've lived on the flightpath to Leeds Bradford airport for 22 years now and have never heard this... probably I'm a bit too far out.
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Old_ShoeOffline
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PostPosted: 11-05-2014 15:08    Post subject: Reply with quote

I'm about 20 miles from the airport, give or take a little. I've noticed that when I do hear the vroop it's from an airplane that is not flying on a path that goes directly overhead, but maybe a mile off to the side.
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OneWingedBirdOffline
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PostPosted: 11-05-2014 16:26    Post subject: Reply with quote

Then maybe I'm a bit too far in. Laughing
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markrkingston1Offline
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PostPosted: 13-05-2014 12:29    Post subject: Reply with quote

Just found this thread...

I live in north west London (about 1.5 miles south of Staples Corner) under flight paths both towards and away from Heathrow (depending on weather conditions and on where aircraft are coming from or going to) and I have heard this "vroop" phenomenon on many occasions. I wouldn't say I hear it every day but it is certainly not uncommon.

I think that it is more common in warmer (warm, still) weather but I could not say for sure. However, I definitely do associate the noise only with aircraft that are going into Heathrow, i.e. that are near the end of their flight. I have never known an aircraft leaving Heathrow to generate this sort of sound.

I used to think that the sound was related to a rapid but brief descent but from observation I now know this that not to be true. Aircraft making this noise are mostly I think in a relatively shallow continuous descent whilst heading in a south-easterly direction over my home with the intention of joining the east-to-west queue for landing at Heathrow. Note that I am too far from Heathrow for the aircraft to have lowered their undercarriage.

With services like www.flightradar24.com it is now possible to accurately confirm the altitude, vertical acceleration, and speed of aircraft making this noise.

If and when I hear it again I'll report as much as I can on weather, aircraft type, and aircraft movement parameters.
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rynner2Offline
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PostPosted: 13-05-2014 13:00    Post subject: Reply with quote

markrkingston1 wrote:
I think that it is more common in warmer (warm, still) weather but I could not say for sure.

You'll get a chance to test this in the next few days, as a high pressure system is expected to settle over Britain, with light winds and warmer temperatures.
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