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777 Spool Up  
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Posted (8 years 7 months 3 days 22 hours ago) and read 12882 times:

Been spotting at LGW a load of times and noticed the 777s have a really unique spool up sound. Have noticed the A330 does do it but not as much.

The CO and BA triple sevens, being GE90 powered, tend to make a more pronounced whine, quite loud and high pitched, and the Rolls-powered ones do as well but not so loudly. I'm not talking about the actual jet noise, but a howl that seems to start once full power is applied and can be heard over the jet noise.

Listen here: http://www.flightlevel350.com/viewer.php?id=5076

Anyone know what causes it? I'm guessing it is something to do with the fan diameter - ultra high bypass or whatever.

I know that some jets, 757s and DC10s particularly, tend to make a buzzsaw noise but this tends to be in-flight rather than at brakes off. I know this is the fanblade tips going supersonic - i know the 777 does this too - so we can discount this as the cause of the whine.

Its a very unique sound - could listen to it all day!  Smile


What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
36 replies: All unread, showing first 25:
 
User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 1, posted (8 years 7 months 3 days 21 hours ago) and read 12842 times:

Quoting CHRISBA777ER (Thread starter):
The CO and BA triple sevens, being GE90 powered, tend to make a more pronounced whine, quite loud and high pitched, and the Rolls-powered ones do as well but not so loudly. I'm not talking about the actual jet noise, but a howl that seems to start once full power is applied and can be heard over the jet noise.

I spotted this on a number of FL350 videos and asked about it in Tech/Ops but to no avail. It definately seems that theres a two stage spool up somewhere in the engine because the second whine is a lot faster and very late into the spool up, imho  Smile


User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 2, posted (8 years 7 months 3 days 21 hours ago) and read 12785 times:

Quoting RichardPrice (Reply 1):
Quoting CHRISBA777ER (Thread starter):
The CO and BA triple sevens, being GE90 powered, tend to make a more pronounced whine, quite loud and high pitched, and the Rolls-powered ones do as well but not so loudly. I'm not talking about the actual jet noise, but a howl that seems to start once full power is applied and can be heard over the jet noise.

I spotted this on a number of FL350 videos and asked about it in Tech/Ops but to no avail. It definately seems that theres a two stage spool up somewhere in the engine because the second whine is a lot faster and very late into the spool up, imho

My thoughts exactly - thats exactly what I am on about.

Heard the PW-powered 777s at LHR and they dont make it hardly at all. The Rolls powered ones do it but its more high pitched and gets lost in the jetblast noise quite quickly - you only hear it for a second or two - the Rolls A330s do it too but not as loudly. I wonder if the Rolls A340s do it?

The GE90s do it much louder and more pronounced. Its most noticable in the Peter Max @ MAN takeoff vid on there.

Still - its a beautiful sound.



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 3, posted (8 years 7 months 3 days 21 hours ago) and read 12770 times:

IIRC all the 777 powerplants are three stage designs - the roller is a triple shaft design, the GE and the Pratt are single shaft.

What happens in the second stage? Bleed air? Could it be the bleed air vents?



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineLY777 From France, joined Nov 2005, 2688 posts, RR: 2
Reply 4, posted (8 years 7 months 3 days 21 hours ago) and read 12758 times:

I love this sound, too


אמא, אני מתגעגע לך
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 5, posted (8 years 7 months 3 days 21 hours ago) and read 12736 times:

Ok so working on the hypothesis that the larger then fan diameter is, the more pronounced the noise is - presumably the 777-300ER/200LR will make it even louder?

Wonder if there's a video I can check this out?



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineDTW757 From United States of America, joined Oct 2003, 1567 posts, RR: 4
Reply 6, posted (8 years 7 months 3 days 19 hours ago) and read 12590 times:

Here are two great videos which show these sounds. The first is a Saudi 777 with GE engines and the second is a BA 757 with RR engines. I love these sounds as well particularly the growl of the RR engines. The third video is a JA 744 with Pratt/Whitney engines which doesn't make either of these sounds.

http://www.flightlevel350.com/viewer.php?id=1388

http://www.flightlevel350.com/viewer.php?id=2386

http://www.flightlevel350.com/viewer.php?id=4033

I have always the noise to be there on takeoff and disappear as power is pulled back for cruise flight.



721,2,732,3,4,5,G,8,9,741,2,3,4,752,3,762,3,4,772,3,788,D93,5,M80,D10,M11,L10,100,AB6,319,20,21,332,3,388,146,CR2,7,ERJ,
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 7, posted (8 years 7 months 3 days 19 hours ago) and read 12525 times:

Wow that SV triple seven got off in about 4,000 ft of runway - Really fast rotation - she must have been nearly empty! Thats the noise though - definately. Cool vid BTW - cheers.


What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 8, posted (8 years 7 months 3 days 19 hours ago) and read 12462 times:

Wow that JAL 744 got off just as fast and that was going twice as far!


What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineTinkerBelle From , joined Dec 1969, posts, RR:
Reply 9, posted (8 years 7 months 3 days 19 hours ago) and read 12454 times:

Quoting CHRISBA777ER (Reply 8):
Wow that JAL 744 got off just as fast and that was going twice as far!

I was just thinking about that.

Quoting CHRISBA777ER (Thread starter):
Listen here:

Is that the new 772LR that was @ MAN last Saturday?


User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 10, posted (8 years 7 months 3 days 18 hours ago) and read 12394 times:

Quoting TinkerBelle (Reply 9):
Quoting CHRISBA777ER (Thread starter):
Listen here:

Is that the new 772LR that was @ MAN last Saturday

No mate - thats the normal 92b-powered 200ER.



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineManzoori From UK - England, joined Sep 2002, 1516 posts, RR: 34
Reply 11, posted (8 years 7 months 3 days 18 hours ago) and read 12286 times:

Quoting CHRISBA777ER (Reply 3):
IIRC all the 777 powerplants are three stage designs - the roller is a triple shaft design, the GE and the Pratt are single shaft.

What exactly do you mean by stage Chris?

The Rolls-Royce large civil engines are as you say three shaft, and therefore have a low pressure compressor and turbine (the LP compressor being the fan), an intermediate pressure compressor and turbine and a high pressure compressor and turbine.

P&W and GE are both make two shaft engines and have High and low pressure compressors and turbines.

Cheers!

Rez
 Big grin



Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 12, posted (8 years 7 months 3 days 18 hours ago) and read 12271 times:

Quoting Manzoori (Reply 11):
Quoting CHRISBA777ER (Reply 3):
IIRC all the 777 powerplants are three stage designs - the roller is a triple shaft design, the GE and the Pratt are single shaft.

What exactly do you mean by stage Chris?

The Rolls-Royce large civil engines are as you say three shaft, and therefore have a low pressure compressor and turbine (the LP compressor being the fan), an intermediate pressure compressor and turbine and a high pressure compressor and turbine.

P&W and GE are both make two shaft engines and have High and low pressure compressors and turbines.

Cheers!

Rez

Thanks for clearing this up fella.

I think stage and shaft are the same thing now you've explained it.



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineJetstar From United States of America, joined May 2003, 1648 posts, RR: 10
Reply 13, posted (8 years 7 months 3 days 17 hours ago) and read 12211 times:
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The noise is from the pneumatic air starters on the engines. Years ago on the Mohawk airlines BAC-111’s, (I am dating myself) which were RR Spey powered, you could hear when the starter engages and starts turning from across the airport. The noise started at a low pitch and as the engine spools up the noise would get higher and you could hear it when the starter disengages and winds down. AA’s BAC111’s had a different model Spey engine and the Gulfstream G2’s and G3’3 also with the Spey engine, you could not hear their air starters.


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At the airport that I was working as an A&P for a small FBO on the airport, Mohawk Airlines served the airport with their BAC-111’s. Sometimes the electric starter engage solenoid would fail and prevent the starter from operating. On the solenoid manual override button, when held in it would allow the starter to engage and start the engine. I was usually called out for this after being checked out by their maintenance people on how to manually override the solenoid. The procedure was simply to open the bottom cowling, hold the button in, give the pilot who was sticking his head out of the window the thumbs up signal and he would then start the engine and the starter would disengage normally after startup. After engine start I would then go into the cockpit and sign off the logbook. I also checked out some of our other mechanics on how to start the engine. I would do this at least a few times a month until they finally came up with a fix to the problem. I heard it was moisture getting in the solenoid.

Take my word for it, being near the air starter as the starter engages and hearing the starter close up was awesome, even with my Mickey Mouse hearing protectors on.

On one airplane at every stop they had to have a mechanic manually start the engine until their maintenance people could replace it, they even carried the solenoid on board with them hoping they could find someone on the road who could change it.

The old DC-8’s with the P&W engines also had a loud starter, you could hear them from across the ramp. Also ever hear a large diesel truck start, they also use pneumatic starters.


User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 14, posted (8 years 7 months 3 days 17 hours ago) and read 12152 times:

But the engines got started long time prior to the noise - The noise only comes when TOGA/FLEX is applied.

Do you mean they keep the starter running?



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 15, posted (8 years 7 months 3 days 17 hours ago) and read 12141 times:

Quoting Jetstar (Reply 13):

Wicked post though - thanks mate. Very informative.



What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineTristarsteve From Sweden, joined Nov 2005, 4016 posts, RR: 34
Reply 16, posted (8 years 7 months 3 days 17 hours ago) and read 12088 times:

Quoting Jetstar (Reply 13):
AA’s BAC111’s had a different model Spey engine and the Gulfstream G2’s and G3’3 also with the Spey engine, you could not hear their air starters.

The Spey engine on the Trident and the Gulfstreams had an ordinary air turbine starter.
On the BAC111 the starter was combined with the CSD. The CSD had an air driven constant speed device, not oil like every other one i've ever seen. This air rotor was driven by APU bleed air to start the engine. It was called a CSDS. I agree the noise when it started was unique. You could hear it from the other side of the airport. Wonder why no other manufacturer ever tried this design. It worked OK. But it was a large bit of kit and very heavy to replace.


User currently offlineJetstar From United States of America, joined May 2003, 1648 posts, RR: 10
Reply 17, posted (8 years 7 months 3 days 16 hours ago) and read 11924 times:
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Quoting Tristarsteve (Reply 16):
The Spey engine on the Trident and the Gulfstreams had an ordinary air turbine starter.
On the BAC111 the starter was combined with the CSD. The CSD had an air driven constant speed device, not oil like every other one i've ever seen. This air rotor was driven by APU bleed air to start the engine. It was called a CSDS. I agree the noise when it started was unique. You could hear it from the other side of the airport. Wonder why no other manufacturer ever tried this design. It worked OK. But it was a large bit of kit and very heavy to replace.

Thanks Tristarsteve, very interesting.

As I mentioned on AA’s BAC-111’s, you could not hear the starter and I know they had a different model Spey engine, I think it had more thrust so I assume they had the standard air starter like on the Gulfstream 2’s and the Fokker F-28’s. I worked on G-2’s and the Spey engines and I remember they had constant speed drives on the engines, but I can’t remember where the starter was mounted on, the CSD or gearbox.

Airframe manufactures can build up the same engine differently for their needs, so the very popular Spey engine has quite a few engine buildups


User currently offlineDTW757 From United States of America, joined Oct 2003, 1567 posts, RR: 4
Reply 18, posted (8 years 7 months 3 days 16 hours ago) and read 11902 times:

The starter wouldn't be engaged at takeoff power would it?....I'm going to guess that the shape of the fans have something to do with the sound they produce.


721,2,732,3,4,5,G,8,9,741,2,3,4,752,3,762,3,4,772,3,788,D93,5,M80,D10,M11,L10,100,AB6,319,20,21,332,3,388,146,CR2,7,ERJ,
User currently offlineCHRISBA777ER From UK - England, joined Mar 2001, 5964 posts, RR: 62
Reply 19, posted (8 years 7 months 3 days 16 hours ago) and read 11884 times:

Is it the fans making the noise though - or is it the air being sucked and pushed into the core?


What do you mean you dont have any bourbon? Do you know how far it is to Houston? What kind of airline is this???
User currently offlineAA777223 From United States of America, joined Feb 2006, 1246 posts, RR: 6
Reply 20, posted (8 years 7 months 3 days 16 hours ago) and read 11824 times:

Awesome post! Love listening to the sounds of those massive T7 engines. I am especially fond of the GE90's and RR 892's.


Sic 'em bears
User currently offlineDTWAGENT From United States of America, joined Jan 2006, 1283 posts, RR: 0
Reply 21, posted (8 years 7 months 3 days 15 hours ago) and read 11769 times:

I love the sound of the B777 when they start the take off roll.. Those engines had a great sound to them.......

User currently offlineMich From United States of America, joined Feb 2006, 36 posts, RR: 0
Reply 22, posted (8 years 7 months 3 days 15 hours ago) and read 11692 times:

Favorite sound second only to the buzzsaw.

Does sound like it simply increased in rps's though from the 500 rpm idle to about 1500 rpm then stepped up to 2500 rpm take off thrust. Core speed is shown at 6600 rpm at 500 rpm fan speed and 10,600 rpm core speed at take off 2500 fan speed rpm. This is for the GE90 version, models will vary.

www.ge.com


User currently offlineBigMac From Suriname, joined Nov 2003, 319 posts, RR: 9
Reply 23, posted (8 years 7 months 3 days 15 hours ago) and read 11673 times:

Here's another 777 RR Trent spool up, but from inside the cabin. You can clearly hear the whining (which gets my adrenaline pumping): http://www.flightlevel350.com/viewer.php?id=2279


To fly, or not to fly: that is the question
User currently offlineDTW757 From United States of America, joined Oct 2003, 1567 posts, RR: 4
Reply 24, posted (8 years 7 months 3 days 14 hours ago) and read 10991 times:

Quoting CHRISBA777ER (Reply 19):
Is it the fans making the noise though - or is it the air being sucked and pushed into the core?

My guess is it is the sound of the intake fan, a different shape fan makes a different sound. I think it's quite similar to larger vehicles that are equipped with fan clutches. We have several medium duty trucks and when that fan clutch engages and the fan is spinning at full rpm, it will make a sound quite similar to the "buzzsaw" sound.

On takeoff the fan on the jet engine is spinning close to maximum rpm, you would get the most noise out of it at that point. At cruise flight power is pulled back and the fan is not spinning nearly as fast as it was on takeoff so the noise pretty much disappears.



721,2,732,3,4,5,G,8,9,741,2,3,4,752,3,762,3,4,772,3,788,D93,5,M80,D10,M11,L10,100,AB6,319,20,21,332,3,388,146,CR2,7,ERJ,
25 FlyDreamliner : One might attribute the strange sound made by the GE90 to its fairly uniquely shaped intake fans. Even more strange are the intake fan designs for the
26 Tristarsteve : On the non BAC111 Speys, the starter was mounted on the gearbox. The CSD and the generator were monted on opposite sides of the gearbox, with the CSD
27 Positiverate : Almost, but not quite, as good as the RR growl on the L-1011's...
28 Post contains links and images RichardPrice : This video shows a wonderful example of what I think we are talking about http://flightlevel350.com/viewer.php?id=4392
29 EWROwznj00 : Great thread. I've always wondered about the different noises you hear from the engine. The best clip here I think is the AA 777 taking off. The spool
30 Jetstar : Tristarsteve, thanks again for the information,
31 Post contains images Ptharris : Umm.. no. At least not on the RR or GE engines. Perhaps on the old JT8's, but dunno. I'm surprised an A/P mechanic hasn't picked up on this thread. M
32 Post contains links KDTWFlyer : Listen to this A330-300 spool up noise from the inside... http://flightlevel350.com/viewer.php?id=1689
33 Bluewave 707 : Visually, the PWs spew some smoke as they spool up right before take-off. It's reminiscent of the old JT3s from back in the day. The UA and KE 772s he
34 FI642 : Nothing sounds like a RB211 powered 757..... except maybe "You've just won two hundred million dollars!"
35 Fbgdavidson : And if you need a comparison with a 747 I've got one here. This was a BA747 so I presume RR RB-211s...
36 AvFan4ever : Different parts of an engine contribute different sounds to the mix. You have transonic fan tip "buzz saw" sounds, turbomachinery whine from the compr
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