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767333ER
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Posts: 670
Joined: Wed Jun 15, 2016 5:14 am

CSeries Interesting Noise

Mon Sep 11, 2017 3:08 am

In the linked video there is what seems to be the sound of an electric hydraulic pump which isn't anything out of the ordinary, but what I find strange is how the rpm of the machinery seems to follow what the engines do which is strange for such a piece of equipment and I haven't noticed any other aircraft do that. To anyone who knows, what is going on here? http://www.youtube.com/watch?v=V0K15a4jnCY&t=3m50s
Been on: 732 733 734 73G 738 752 763 A319 A320 A321 CRJ CR7 CRA/CR9 E145 E175 E190 F28 MD-82 MD-83 C172R C172S P2006T
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

Re: CSeries Interesting Noise

Mon Sep 11, 2017 3:46 am

To be honest I can't hear hydraulics going in the video. It just sounds like harmonics from the engines.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Woodreau
Posts: 1442
Joined: Mon Sep 24, 2001 6:44 am

Re: CSeries Interesting Noise

Mon Sep 11, 2017 2:15 pm

If you've never heard a GTF engine before - it doesn't sound like a normal engine. I guess the way I'd describe it it's more like wind howling between buildings in a downtown metropolis or down a mountain pass - a low pitch howl rather than a high pitched turbine whine of a gas turbine engine.

That's what that noise in the video sounded like in the few sections I listened to.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
YankeeTech
Posts: 2
Joined: Mon Sep 11, 2017 12:14 am

Re: CSeries Interesting Noise

Mon Sep 11, 2017 7:01 pm

The C series uses a next generation engine that has a 3:1 gearbox for the fan. This enables the core to be much smaller in relation to the fan, increasing efficiency 20%.
The engines bypass ratio is 12:1. (12 times the volume of air moves through the fan than the core) Consequently, the core turns at higher speeds. The fan blades also have higher pitch (greater angles to the air pulled in).
All of this changes the sound vs current airliners. As a comparison, A PW2037 on a 757 has approx 6:1 bypass ratio.

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