What are you bus drivers doing over my house ?
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Hi Landroger,
When we leave the Biggin hold we are normally at / around 7000ft at 220kts (Airbus 320 that is). We are then turned northwest briefly before turning back on ourselves heading East. We reduce speed from 220kts to 180kts generally between after leaving Biggin and before turning onto final approach. We need to use Slats + Flaps to reduce our speed below 200kts (ish!) hence when we are asked to fly 180kts we need to use the slats + flaps which is most likely what you would hear. Generally people wouldn't need speedbrake on the A320 in that area, it's more needed once turning onto final approach if the aircraft is very light.
When we leave the Biggin hold we are normally at / around 7000ft at 220kts (Airbus 320 that is). We are then turned northwest briefly before turning back on ourselves heading East. We reduce speed from 220kts to 180kts generally between after leaving Biggin and before turning onto final approach. We need to use Slats + Flaps to reduce our speed below 200kts (ish!) hence when we are asked to fly 180kts we need to use the slats + flaps which is most likely what you would hear. Generally people wouldn't need speedbrake on the A320 in that area, it's more needed once turning onto final approach if the aircraft is very light.
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There you go Wheelie, thank you. That puts some real numbers on my rather fast guesses, but my altitudes are about right! 
Which also highlights that some of the configuration changes to your aeroplane would be happening roughly overhead SW16. 
As a field engineer, sounds are part of my stock in trade and for me there is rarely 'just a noise' - I can't help analysing them to figure out what makes them. I'm a Land Rover driver, so I'm very used to trying to work out what's going to break next!
Roger.
Which also highlights that some of the configuration changes to your aeroplane would be happening roughly overhead SW16. As a field engineer, sounds are part of my stock in trade and for me there is rarely 'just a noise' - I can't help analysing them to figure out what makes them. I'm a Land Rover driver, so I'm very used to trying to work out what's going to break next!
Roger.
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dean4689
Bleed air valves.
I can guess what bleed valves are, but what, where and roughly when? And, given how much - relative - noise the engines are making, would it be possible to hear one or more opening/closing/oscillating?
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Landroger,
The air for the air conditioning, pressurization, anti-ice etc is supplied from the compressor sections of the engine. On the type of engine that I am familiar with, the air during pressure normal power settings comes from the IP (intermediate pressure) section. However, during low power operations such as descent, there is not enough bleed air available so it is augmented with air from the HP (high pressure) section.
During operations in the terminal area where you may be carrying out step climbs or descents, as the thrust is varied, the HP bleed air valves will be opening and closing to make sure that sufficient air is available.
I think it is this that is making the strange noises.
Rgds,
Dean
The air for the air conditioning, pressurization, anti-ice etc is supplied from the compressor sections of the engine. On the type of engine that I am familiar with, the air during pressure normal power settings comes from the IP (intermediate pressure) section. However, during low power operations such as descent, there is not enough bleed air available so it is augmented with air from the HP (high pressure) section.
During operations in the terminal area where you may be carrying out step climbs or descents, as the thrust is varied, the HP bleed air valves will be opening and closing to make sure that sufficient air is available.
I think it is this that is making the strange noises.
Rgds,
Dean
It is certainly the sound of speed brakes being extended. The sound is very caracteristic and much louder than any other sound produced by the aircraft.
It can be heard on the ground while the aircraft is as high as 20000 ft.
The arrival routes for EDDH are coded -HAM-LBE-FAP but the actual distance flown is a direct to final, much shorter. So many pilots end up being much to high and have to use the speed brakes.
I flew the A320 for years, when my parents moved to a town 30 NM south of EDDH. When I sat in their garten for the first time I was nearly shocked what an extreme amount of noise those speedbrakes produce. Nearly 2/3 of all arriving Airbus end up deploying them more or less over our house, and while no aircraft noise is heard inside the house normally the sound of A320 speedbrakes being extended is clearly noticable.
It can be heard on the ground while the aircraft is as high as 20000 ft.
The arrival routes for EDDH are coded -HAM-LBE-FAP but the actual distance flown is a direct to final, much shorter. So many pilots end up being much to high and have to use the speed brakes.
I flew the A320 for years, when my parents moved to a town 30 NM south of EDDH. When I sat in their garten for the first time I was nearly shocked what an extreme amount of noise those speedbrakes produce. Nearly 2/3 of all arriving Airbus end up deploying them more or less over our house, and while no aircraft noise is heard inside the house normally the sound of A320 speedbrakes being extended is clearly noticable.
Last edited by safelife; 6th Sep 2012 at 21:17.
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Check out this flex leading edge from DLR...put that on the howler (A320)...
Page 29 - DLR_Magazin_130-GB
Page 29 - DLR_Magazin_130-GB
The more modern efficient jet engines do sound a bit like lawn mowers or fly-mos but usually at take off or at full thrust. This sounds quite different to the older noisier jets on take off but on the landing approach at low thrust would have a more pronounced whine than the more modern types.
