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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?
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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.
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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.
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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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