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SKIPS2

MISSING THAT GE STARTUP HUM

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Hi Guys.

Just bought the v3...but I was a little disappointed in not having that start up "hum" that the GE's dish out.

https://www.youtube.com/watch?v=K_yA456Q6B0 

Listen @ 0.04-0.10

I'm a ramp officer & if i'm inside the office once I hear this "hum", I know that my flight just pushback without even looking. 

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12 hours ago, SKIPS2 said:

Just bought the v3...but I was a little disappointed in not having that start up "hum" that the GE's dish out.

It's definitely in there. The video you've linked to shows more of a 'beat' than the GE hum. Anything out of sync in frequency will throw out a beat pattern, which is more of what you're hearing in the video. Pratts on 772s do it all the time, particularly on final for some reason (perhaps it's simply most evident there). My old high school is under the approaches to IAD's 1s, so I'd hear it all the time back when IAD had a ton of 777s.

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Think Kyle is bang on - it's that slightly out of sync sound I can hear there.  Two hums together?

Cheers,

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4 hours ago, VHOJT said:

Think Kyle is bang on - it's that slightly out of sync sound I can hear there.  Two hums together?

Cheers,

Pure physics, when two sound waves close together in frequency are summed, or detected by the ear, you get the frequency and the difference frequency usually a much lower rump rump rump sound.  When the two frequencies are slowly varying the difference frequency will speed up and slow down, it can be very annoying. Fly a twin prop and you quickly learn how to synchronize the props just by ear, but if you let them go you're likely to get very unhappy looks from your copilot.

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Watching that video during the takeoff roll always reminds me of how the real simulator is different from the jet in that it really doesn't replicate well the bouncing and jostling around you do in your seat on takeoff and landing with the nose gear behind you by about 8 feet. It feels like you are in a washing machine, nice video...

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I hear this on my starts almost every time.  Not sure why you wouldn't

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2 hours ago, SKIPS2 said:

hhmmm....probably so subtle i can't even hear it.

Thx for response guys.

Try starting two engines at once

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1 minute ago, VHOJT said:

Try starting two engines at once

That's the thing.

I tried this already...no joy

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3 hours ago, SKIPS2 said:

That's the thing.

I tried this already...no joy

Maybe your speakers just aren't broadcasting the sound?  My speakers are pretty bassy and turned up loud. It rattles the wall sometimes and I suspect my neighbors can hear it lol.  They probably wonder what's going on at 11 PM at night.  Hard to say but it's there for me. 

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We're talking about separate issues here. Bassy is one thing. There is inherent vibration in sound, which is how sound actually works. Bass uses larger waves (Ryan will probably kill me for my amateurish explanation, but whatever - haha), which will usually cause things to vibrate a lot easier than higher sounds. That isn't the issue though.

The video shows a different concept called beat interference. There are two waves whose frequencies are close together, but slightly different. When this happens, you get varying level of beat interference, depending on how different the frequencies are. For anyone who has taken multi-engine training, you are very familiar with this when it comes to syncing up your props. If they're not in sync, you'll get a bunch of beat interference, which will manifest as a "wah wah wah wah" sound, and the speed of that will be dependent on how different the frequencies are.

You hear it a lot on engine start because the two engines are usually started closely enough together that the frequencies are close together, but one engine is slightly ahead/behind. This difference in frequency will cause beat interference and give you that rather quick "wahwahwahwahwah" that you hear at about 0:05 in the video. Note that it is a lot less prominent on the second set of engines starting at about 0:45, simply because they were started, and spun, a little more in sync (and there's already noise from the other two spinning).

I'm not sure how supportive the whole sound environment is for something like this. That's a question for Ryan and Armen.

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There is a big difference using a subwoofer.  A great set at a reasonable price are the Klipsch ProMedia THX Certified 2.1 PC Speakers.  Poor Klipsch when through a hard time with poor ownership but they bought themselves and are back to creating very good speaker systems.  I still use a set of Klipsch Cornwalls in my home system that I've had since 1978.

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It's definitely there. I'm using a good pair of headphones and can hear it all the time when starting the GE engines.

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Yep, it's definitely there. 

As a slight side note - I didn't realise the 747's engines were quite so audible idling and taxiing as they are in the cockpit!

Cheers,

Rudy

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On 27/04/2017 at 5:49 PM, Captain_Al said:

Watching that video during the takeoff roll always reminds me of how the real simulator is different from the jet in that it really doesn't replicate well the bouncing and jostling around you do in your seat on takeoff and landing with the nose gear behind you by about 8 feet. It feels like you are in a washing machine, nice video...

It pretty much depends on the Real Sim brand/type and tuning actually, and also whether or not it has a Roughness setting (most of the newer ones have, but usually set on the smooth side), but I agree that it's not the norm. I once flew a rather old one of the A330 and looked so realistic, compared to the majority of them, to me.

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21 hours ago, PhugoidEffect said:

It pretty much depends on the Real Sim brand/type and tuning actually, and also whether or not it has a Roughness setting (most of the newer ones have, but usually set on the smooth side), but I agree that it's not the norm. I once flew a rather old one of the A330 and looked so realistic, compared to the majority of them, to me.

Good point, because I am guilty of not cranking up the Roughness Setting for the sake of realism, most of us keep the roughness on the smooth side for training, but once you are in the airplane, the jostling around after landing becomes the norm.

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