Cory6188
Topic Author
Posts: 2609
Joined: Mon Feb 02, 2004 12:29 am

Lawn Mower Noise On Takeoff?

Mon May 24, 2004 10:38 am

I noticed an odd sound coming from the engines of the CO 738 and 752 that I was on going to and from PVR, respectively.

Right after takeoff, a noise that could only be described as similar to a lawn mower began in the engines, and it did not quit until we were at crusing altitude. Could anyone explain to me what it is that I was hearing? I noticed this noise to be especially prominent when we flew on B6 last year, but I heard it for the first time on CO in April.

Thanks for the info!
 
goboeing
Posts: 2429
Joined: Mon Jun 05, 2000 5:31 am

RE: Lawn Mower Noise On Takeoff?

Mon May 24, 2004 11:31 am

Search for "buzz saw" and "engine noise" in the tech/ops archives. There have been some discussions of this before. It depends on the type of engine. I have heard it on SWA planes as well as others.

Nick
 
YWG
Posts: 1055
Joined: Wed Feb 07, 2001 11:29 am

RE: Lawn Mower Noise On Takeoff?

Tue May 25, 2004 6:08 am

I believe the engine sounds have to do with where exactly you sit in comparison to the engines position. I took 'the dopler effect' in gr12 physics last semester...and I believe this has a small part in it.

It's just the way the sound waves are compressed and meet with your head.

Blair
Contact Winnipeg center now on 134.4, good day.
 
avioniker
Posts: 1099
Joined: Tue Jan 01, 2002 5:38 am

RE: Lawn Mower Noise On Takeoff?

Tue May 25, 2004 6:37 am

You gotta love "cut-and-paste"

The noise to which you refer is most likely the sound generated by the blade tips of the engine fan at high rpm with a relatively low impact airspeed as the plane accelerates. The sound fades as the plane reaches cruise speed and the throttles are pulled back.

And to all you high techies that is an extremely oversimplified explanation and was intentionally so...
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
TomFoolery
Posts: 423
Joined: Tue Jan 06, 2004 9:10 am

RE: Lawn Mower Noise On Takeoff?

Wed May 26, 2004 3:08 am

That is the sound of innocent air particles being beat into submission by the fans.



TF
Paper makes an airplane fly

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