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JeffB
Topic Author
Posts: 91
Joined: Fri Oct 03, 2003 1:38 pm

(RR) Engine Sounds?

Sun Aug 08, 2004 3:38 am

Question: I have flown in several planes(most notably an L-1011 back in the early 90s that had RR engines) that produce an odd sound during take off all the way to cruise. While the engines are throttled up for take off and for a while after take off(until the plane gets up closer to cruise), the engines make a sound that I can only describe as the engines running without a muffler. I have heard this sound on:

1) An ATA L1011
2) A NW A319
3) A HP A320

Again, the sound goes away after we get high enough in the air. So, the question is.. WHAT IS causing that sound??? I know that the L1011 had RR engines on it and I think the other planes that have made this sound were RR equipped as well. Is it a design specific to RR? Does anyone else know what I am talking about? Can someone shed some light on this?
 
TWAMD-80
Posts: 962
Joined: Tue Oct 16, 2001 8:25 am

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 3:44 am

Hmmm.... I'm not really sure that I know what sound you are talking about, but I do recall hearing a kind of buzz sound that came from the engines on the 717 - which has similar engines to the A-320 (I think anyways).

TW
Two A-4's, left ten o'clock level continue left turn!
 
QANTAS747-438
Posts: 1739
Joined: Mon Jan 22, 2001 7:01 am

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 3:45 am

I'm not sure if this is the sound you are referring to, but during the takeoff and cruise stage, RR engines tend to sound like propeller planes. From what maintence crews tell me, it has to do with the blades spinning at a certain rate where the tips of the blades are going supersonic. Again, this is what is explained to me, but this sound is pretty much evident on RR engines.
My posts/replies are strictly my opinion and not that of any company, organization, or Southwest Airlines.
 
JeffB
Topic Author
Posts: 91
Joined: Fri Oct 03, 2003 1:38 pm

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 3:52 am

YES YES YES!!!!! A buzzing sound that is closer to the sound of a propeller engine! Exactly! Now, the question is... is it exclusive only to RR engines or are there other manufacturers that do the same thing?

 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 4:02 am

The sound you hear are the blade tips approaching supersonic, as far as I know they do not in fact break mach 1. The sound can be heard on just about any high by-pass engine at TO power though some mid-bypass fans do it also.
 
aamd11
Posts: 919
Joined: Sat Nov 17, 2001 11:54 am

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 4:47 am

RR powered 757s have quite a distinctive buzzing kinda noise when you hear them on TakeOff.
Once around LHR, I was lucky enough to be quite close to the airport, and you could see the planes taking off quite close (we were near the big BA offices (can't remember the name of them at the moment) and you could tell the BA 757s apart as soon as you heard them flying over.

I like it tho  Nuts
 
dl757md
Posts: 1483
Joined: Mon May 24, 2004 9:32 am

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 5:11 am

The sound you hear are the blade tips approaching supersonic, as far as I know they do not in fact break mach 1.

The fan blade tips do in fact exceed the speed of sound by a large margin.
I don't have the exact figures in front of me but I at one time calculated the tip rotational speed of the RB-211-524 to be in excess of 1100mph at max N1.
This causes the noise you have described which is sometimes referred to as a growl. Most if not all large turbofan engines experience the phenomena which produces this noise. A good example of the sound can found on the CVR audio of DL flight 191 at about 1:23 into the recording.
http://www.airdisaster.com/download2/dl191.shtml

Dl757md
757 Most beautiful airliner in the sky!
 
AA737-823
Posts: 5512
Joined: Wed Mar 01, 2000 11:10 am

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 5:21 am

Jeff,
The L-10 had Rolls engines, but the NW A320 series do not- they're GE/Snecma CFM56 engines, and they have nothing to do with rolls. Now, the IAE V2500 on the AmWest planes are partially designed by rolls... but I find those engines to sound quiet.

Incidentall, the 717 engines are NOT much like those V2500s on Airbusses. However, the MD-90 DOES use the V2500, exclusively.

That muddied things up a bit I guess.

R
 
User avatar
foxecho
Posts: 633
Joined: Tue Dec 12, 2000 12:43 pm

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 5:21 am

Oooh dont get me started on RR Engines spooling up  Smile/happy/getting dizzy

LOVED to hear it from the L-1011 First Class section, and upper Deck on SAA 747-400s out of JFK

Andrew
JFK/MEM/MCI
..uh, we'll need that to live......
 
je89_w
Posts: 2070
Joined: Fri Mar 01, 2002 1:29 pm

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 1:45 pm

RR engines are quite distinct in terms where sound is concerned. I also noticed a lower "growling" sound as Dl757md put it.

I have to agree with Foxecho, hearing RR engines spooling up sounds quite neat.
 
aamd11
Posts: 919
Joined: Sat Nov 17, 2001 11:54 am

RE: (RR) Engine Sounds?

Sun Aug 08, 2004 2:05 pm

could the RR engine sounds be attributed to the tripe-shaft design that all the RR engines since the RB211 (correct me if I'm wrong)?

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