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American 757 Engines  
User currently offlineQANTAS747-438 From United States of America, joined Jan 2001, 1924 posts, RR: 2
Posted (12 years 2 months 1 day 4 hours ago) and read 3169 times:

Today I was hanging out at LAX, and I noticed that only the AA 757-200's with the engines like in the picture below, sounded like actual propeller planes when they took off. DL 757s, UA 757s, US 757s all sounded like normal roars of engines, but AA's 757s sounded like propeller planes. Why is that?


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My posts/replies are strictly my opinion and not that of any company, organization, or Southwest Airlines.
12 replies: All unread, jump to last
 
User currently offlineSxmarbury33 From United States of America, joined Oct 2000, 445 posts, RR: 0
Reply 1, posted (12 years 2 months 1 day 4 hours ago) and read 3141 times:

Well they are RB-211 engiens which are known some what for that sound. It may have something to do with the triple spool?

User currently offlineDuncan From United States of America, joined Apr 2002, 131 posts, RR: 0
Reply 2, posted (12 years 2 months 1 day 2 hours ago) and read 3115 times:

Delta and United both use the PW2037 on their 757's, though US Airways use the RB211-535E4 so that shouldn't sound any different from the AAL RB211's. A lot may have to do on where in the flight profile they are (i.e. take off, climb, descent and approach etc,....)

Duncan


User currently offlineWilcharl From United States of America, joined Jun 2000, 1166 posts, RR: 3
Reply 3, posted (12 years 2 months 1 day 2 hours ago) and read 3107 times:

the P&W engines have a more distinct buzz saw sound on talke off then the RB's

User currently offlineQANTAS747-438 From United States of America, joined Jan 2001, 1924 posts, RR: 2
Reply 4, posted (12 years 2 months 1 day 1 hour ago) and read 3103 times:

I seemed to hear the opposite of what Wilcharl says... the RB's had the buzz saw sound while the PW's of United and Delta were huge roars. All of these happened upon takeoff off of 25L.

Also, what does the triple spool mean or do?



My posts/replies are strictly my opinion and not that of any company, organization, or Southwest Airlines.
User currently offlineATA L1011 From United States of America, joined Feb 2001, 1378 posts, RR: 6
Reply 5, posted (12 years 2 months 1 day 1 hour ago) and read 3094 times:

Yes the RR on the 757 is a lot more buzzy than the PW, you know a RR 757 on takeoff. The PW on the 757 makes that sound that all large turbofans make at near or full power but to a lesser extent than the RR on the 757.


Treat others as you expect to be treated!
User currently offlineWilcharl From United States of America, joined Jun 2000, 1166 posts, RR: 3
Reply 6, posted (12 years 2 months 1 day ago) and read 3078 times:

hmmph i didnt get it as much on the RR powered ones but i noticed it today on a P&W powered one i was on...

User currently offlineAmerican 767 From United States of America, joined May 1999, 3735 posts, RR: 12
Reply 7, posted (12 years 1 month 3 weeks 2 days 6 hours ago) and read 2876 times:
AIRLINERS.NET CREW
FORUM MODERATOR

Triple spool means that the engine is designed with three different stages of compressor blades, intake air is compressed in three successive steps before mixing with fuel in the combustion chamber. Yes, it is true that RR-RB211 engines are noisy compared to PW-2037 engines, they have a lower bypass ratio but they deliver more thrust. RR engines, in the case of the Boeing 757 which is the aircraft related to the scope of this topic, deliver 43000 lbs of thrust each, while PW engines deliver only 37000 or 38000 lbs of thrust. I have flown on both RR and PW powered 757's and I do feel there is such a difference. On RR powered 757's, during climb at full power, you almost feel like you are travelling on a rocket!

American, British Airways, Continental and US Airways operate the 757's with RR engines. Eastern had RR engines on 757's too. Delta, Northwest and United chose instead the PW engine on 757's. That doesn't surprise me because Northwest and United always had a special relationship with Pratt & Whitney. TWA's 757's had PW engines, that's why you'll see sometimes American 757's with PW engines. It's easy to spot a PW engine on a 757. The PW engine has a larger cowling surrounding the largest fan to increase the bypass ratio, the RR engine dosn't have that. The cowling on the RR engine surrounds the whole machinery, there is a nozzle but you don't see it. That's how I can tell an American 757 comes from TWA.

Ben Soriano
Brussels Belgium



Ben Soriano
User currently offlineMlsrar From United States of America, joined Mar 2000, 1417 posts, RR: 8
Reply 8, posted (12 years 1 month 3 weeks 1 day 11 hours ago) and read 2814 times:

Most Charter operators have chosen the 535E4/535E4B as well for a simple matter of the power mentioned above. The wingtime reliability of the RR has proven itself, and its efficiency is spoken for by preference.

However, the PW does offer both a 2037 and a 2040 for the 757. Delta and United both have a mixed bag of 37s and 40s, UPS chose the 40 for their higher MTOWs.



I mean, for the right price I’ll fight a lion. - Mike Tyson
User currently offlineDuncan From United States of America, joined Apr 2002, 131 posts, RR: 0
Reply 9, posted (12 years 1 month 3 weeks 1 day 10 hours ago) and read 2803 times:

UPS also operate the 757 with R-R power, I think along with AA, they are the only operators to fly a mixed PW/RR fleet.

Duncan


User currently offlineAlphazulu From United States of America, joined Mar 2002, 266 posts, RR: 19
Reply 10, posted (12 years 1 month 2 weeks 6 days 1 hour ago) and read 2725 times:
AIRLINERS.NET CREW
HEAD SCREENER

WHATEVER WAY YOU PUT IT, I LOVE THE SOUND OF THE AA 757'S RB211's, IT GIVES ME A WARM FEELING INSIDE Big thumbs up

User currently offlineA330 From Belgium, joined May 1999, 649 posts, RR: 7
Reply 11, posted (12 years 1 month 2 weeks 3 days 20 hours ago) and read 2659 times:

OK, just to be exact, the RR RB211 engine actually produces LESS sound than her american concurrent, thanks to the mixed exhaust system. The exhaust of the by-pass and turbine air are mixed at the end, instead as kept seperated, which reduces the exhaust noice. The compressor noice is however bigger on the RR engine, indeed due to the somewhat lower by-pass. It is still a high by-pass engine though, and the RB211 is known as being the best develloped engine in the industry!!



Shiek!
User currently offlineGeotrash From United States of America, joined Jun 2001, 326 posts, RR: 0
Reply 12, posted (12 years 1 month 1 week 6 days 4 hours ago) and read 2578 times:

If memory serves, the distict buzz-saw sound is actually the tips of the fan blades exceeding the sound barrier.

-Geo


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