BAE 146 Question

[anotherglassofwine]

Hi,
I've recently had the need to fly in and out of London City and hence have been a pax on the 146 for the first time. On a recent flight I was sitting beside the wing and on our initial climb there was a very loud noise as the flaps were been raised. I've flown on many different aircraft but never heard this on anything other than the 146. So the question is - why is this flap system so noisy?? - what are the mechanics behind it that make it so different to other jets, such as 7xx or A3xx?

[mfaff]

It isn't the flaps per say.. its the changing airflow pattern as the flaps deploy which creates an acoustic 'signature', ie noise as differnet bits of airfrmae disturb the airflow etc etc.Onc eht eflpas are out the noise settles down.

You can hear it quite clearly from the ground as they turn finals to land at City.....

[anotherglassofwine]

not sure that airflow is solely responisble for the noise - certainly a factor, but it sounds more specifically like a type of motor? (I could be completely wrong!) I've never heard it on any of the props I've been on with similar type flaps - just wondering whether it might be a feature unique to the 146 - maybe a 146 driver out there could answer?:confused:

[spagiola]

This has already been discussed in detail:

146 'banshee howl' thread (http://www.pprune.org/forums/showthread.php?s=&threadid=138702&highlight=banshee)

[rhythm method]

mfaff is quite correct. It is the changing airflow which creates the characteristic 'roar'. The flaps are driven by standard hydraulic motors which themselves produce almost no noise as flaps are deployed. To prove this, you will have heard no noise as you taxied out and flaps were selected prior to take-off, and again as the were selected up as you taxied back in.

The audible noise is only experienced during the first stage of flap retraction, or flap extension (ie selecting flap 18 to flap 0 after take-off, or during the initial approach when flaps are moved from 0 to 18 degrees).

The 146 is a fantastic machine to fly and produces many clunks, bumps, screams and roars during flight!!! I like to think that it is such a quiet machine, that it announces our impending arrival! :D

I used to wind people up by saying the noise acted as a bird scare technique during the early and final stages of the flight! Unfortunately, I keep being told that we only ever get birdstrikes from behind! :}

RM

[anotherglassofwine]

Thanks guys - interesting stuff!

[Antoninus]

I flew the BaE 146 several times, usually between Nice and Geneva, or Nice and Biarritz and I liked it a lot.
First, it's cute. It looks like a scale model of a bigger one.
It's comfy --jets don't shake half as much as turboprops.
It has an impressive rate of climb --as far as I can tell. I was really amazed at the angle of ascent and the "push" on take off.
And yes, the flaps are noisy. But it never scared me. It actually sounds exactly like what it is: aerodynamic noises generated by extension/retraction of the flaps.
All in all this is what I call an healthy, cute little aircraft.:O

PS: for the fanatical flyers out here: I recommend the Nice/Geneva trip. Get a right side seat from Nice and a left side seat from Geneva. You'll be treated with a full view of the Alps and the plain of the Po river. Awesome.

[anotherglassofwine]

its a perfectly nice aircraft to fly on from a pax viewpoint - and the approach into LCY is particularly interesting with the steep approach angle. I didn't think the flap noise would be severe enough to alarm passengers or give people who didn't fly a scare, but it' quite a unique noise, I can't imagine it scaring anyone. I didn't think it sounded like an aerodynamic noise but on my flight next wednesday I will pay more attention!
Incidently - I have a work colleague who absolutely despises the 146 - he reckons everytime he flys on one he gets a headache and blurred vision - although I think that might be the complimentries more than anything else! :O

[Smokie]

Headaches, blurred vision probably due to the Air Conditiong in this aircraft. It's a well know problem especially amongst Flight crews and Cabin crews.:mad:

[Antoninus]

Maybe the noise has to do with the fact that it is a small high wing aircraft, which means that when your're sitting by the wing, you are only a few feet away from the flaps..
Maybe the 747 flaps (for instance) generate far more noise, only they're much further and below and thus you don't hear anything.

[pax britanica]

I didnt fly ona 146 until a couple of years ago after trying just about every other type out there. Its a nice plane from a pax point of view I thought ( no nasty oil fumes on the one I flew on-)

It does make a really starnge noise as the flaps retract tho ,as this thread discusses and I have often wondered exactly what caused it- airflow I assumed

As Antonius points out is it noticeable because its exceptionally loud (on a quiet aircraft) or is it a high wing phenomenum and is present on other a/c but shielded from being heard in the cabin by the wing which I think all agree is a pretty good noise suppressor. I live close to one of the LHR approaches -downwind to the Easterlies and hear a simialr noise from the smaller airbusses sometimes as they are descending and I guess at a point were they might be dropping first stages of flaps and of course I am well below the wing in that case -is it the same effect?

Just curious
PB

[JamesT73J]

One of my all time favourites as a passenger. The noise does get your attention.

My flat is under one of the departure tracks at Southampton, and the noise is so distinctive, I hope BE keep the Jumbolino around for a while.

[BOAC]

Thank you 'spagiola' for the link to the existing thread. It would seem sensible to divert you all to that one for continued discussion, so this one is closed..