RB211 Fan Up Close - That Noise Explained

A closer look at the front fan of the RB211-22B and an explanation of the rattling noise.

[@HistoricAeroEngines]

The N1 fan tips are supersonic at high power, typically at about 1.4 relative Mach number. The shock waves from the tips propagate non-linearly to produce that characteristic whining. The other contemporary turbofans (PW JT9D-7 and GE CFM50) have different pitches due to small differences in the fan diameter, length of duct and acoustic properties of the duct. At medium power when the fan tips are subsonic, that whine stops noticeably,

[@DavidHill333]

Flew on that incredible L-1011 many times and remember being pulled into the seat during take off. As the L-1011 pounded down the runway the RB211's changed pitch. Some call this 'THE NOTE'. Out standing plane and jet engine configuration. Will never forget that. Thanks for your video post.

[@RussellD11]

perforations are for sound dampening, anti-iceing is internal of the shroud.

[@lopezwoodenboats8441]

Lol my father who worked on these for 4 years at Qantas just said the same

[@javacup912]

In this engine, as well as the CF6-80, the blades are loose this way. Fan blades are LRUs, and I replaced many of them right on the flight line, with the eventual vibration check engine run. It's when the blades do not move that's a problem, as when centrifugal force places the blades on the same area relative to each other but one or two are stuck, and at high power, you'd think you're going to loose the engine and wing because of the tremendous vibration. Good video.

[@GABRIEL-dz9mh]

All jet engines have loose fan blades, not just RB211 and CF6-80

[@mytmousemalibu]

Those thousands upon thousands of little holes in side the fan cowl aren't for ice, that's all for noise abatement/sound absorbtion. The very front lip, the big polished ring on the inlet is where the anti-ice is. The backside interior of that lip is blown with engine bleed air that's between 400-500*F plus in temp. It may have a tubular ring inside the front lip that has many holes drilled in it for the bleed air to jet out of called a Piccolo-tube which is also how wing leading edge anti-ice works on most jet aircraft. The fan blades are most definitely supposed to be loose fit in the mounting. The fan blades should have something close to a dove-tail mount. All of the compressor section also. Only the hot section turbine blades use a fir-tree type mounting, 99.9% of the time. The part of the blade that contacts the others is what is known as a "snubbered blade". That is the root cause of most of the noise heard which is 100% normal. They manufacture may use snubbered blades to control harmonics and vibration properties of the blades. My background, A&P, Jet mechanic ;)

[@tahirkamboh147]

Very Well Explained, Please tell me more about that noise filtration Holes in cowl, That how those holes can reduce noise ?

[@tahirkamboh147]

Jake Heke & where I can find Alexia

[@alext9067]

All so very interesting to us mere mortals. I don't think people realize how interesting it is.

[@ravindrasonawane5863]

mytmousemalibu nice sir

[@jerrywatt6813]

Yes I worked a burbank aeronautical years ago 'they built hush kits for jt3d3b engines '707 dc8 reworking the bi ducts inlet and bullet for noise reduction and this what they to the inlets! The anti ice is bleed air from 16 stage hpc ducted to the leading edge of the inlet thru a defused ring !

[@exceloutkasts8104]

I'm glad I saw this because when I got off a Thomas Cook plane this June the engine was making the exact same noise and now I know why. Thanks for the explanation 👍

[@davsaltego]

Incredible how close the tolerances are on that assembly

[@12345fowler]

The PW engines of the same era did the same rattling noise at shutdown, first time I heard this it freaked me out I tought the engine was breaking down. I was looking at a B747-300 taking his slot at the gate and was placed just in front of the landing gear at the stop sign. I worked during the week-end in an airport and was taking every occasion to go out the ramp, visit cockpits and touring airliners. Good times

[@shanemurphy8102]

Actually the perforations in the nose cowl are for noise attenuation, nothing to do with de-icing. De-icing is accomplished by a tube in the leading edge of the nose cowl. Also the spinner is de-iced using hot air from the compressor.This is an RB211-22B which powered the Tristar.RB211-535 powered the B757 and Tu204RB211-524 powered the B747 and B767

[@coriscotupi]

+Shane murphy Exactly. Not to mention that it would take such an enormous amount of hot air blowing into free-streaming, -50C, 500kt to bring it to above 0C that there would probably even not be any compressed air left for the engine to actually work!

[@charlestaylor6898]

The 524 B4-02 was also use in the Tristar L1011.

[@christopherwilson6527]

They are for de icing in some engines. Hot air is usually fed from the ip8 to the anti ive valve then to the intake cowl where it does come out of the perforations.

[@phillaynejr5676]

Our 767s at American have CF6 engines.

[@american0153]

corisco tupi have you ever heard of bleed air? When a plane is flying 36,000 feet, how cold do think it is? Way below zero. And ice would form on the cowling and spinner

[@edwardcalvert]

The Lockheed L-1011 was my favorite airplane and thank you for sharing this video as I got to learn a little something about the engines on it. There were somethings that I already knew about jet engines and this was very helpful.

[@bobgreene2892]

Blade snubbers and their loose contact with adjacent blades probably explains the buzzing sound we hear at takeoff, but it is still hard to imagine snubbers producing the loud buzzing of a fan jet at full power. Thanks for the video.

[@johnnym4400]

It's just amazing how something that looks so fragile, can fly something that's like six hundred thousand pounds through the sky at 600 miles an hour.. when you think about it, it really blows your mind...

[@jjsifo1]

Finally !!! I asked that same question to an Eastern Airlines mechanic back in 1979 and he could not come up with a good explanation,their L1011's used the early RB211 engine.Thanks !!

[@SWAFanPilot]

My grandpa, Les Cobb, worked on the design of the L-1011 TriStar. What an amazing plane, I wish I got to fly on one.

[@12345fowler]

Thanks for the explanation of the shut down noise. I can all too remember standing in front of the Swissair SR110 B743 arriving to stand in Geneva (prior jetway era) stoping nose almost over me and I was almost panicked when I heard the same noise but from 4 engines fans shutting down at the same time. What a noise it made !!!

[@worldofai-games1036]

Some RB211s had wide chord fan blades too. The -524G and -524H for the 747-400 had those and I think the -535E for the 757 had those too. Rolls was the first to use wide chord blades because they allow a larger fan and a larger spinner to fan connection, making the fan blade stronger. Rolls was able to do away with the clappers. GE and PW didn't go to wide chord blades until the 777 came along in 1995.

[@UKAviationMovies]

I remember the first time I heard that noise, it was a C-5 on static display at a Mildenhall Air Fete when I was about 12. Fascinating noise.

[@SupraBdub]

Thank you for clearing up at people's who DO not know how these work sir

[@joepatroni8777]

I think I could have explained this in less than 30 seconds. Here is the blade look. Listen what happens when I spin it. Its normal. Thanks for watching...

[@FredtheDorfDorfman1985]

Well said!

[@derekwall82]

from what ive seen thru a few videos on here these engines are relatively easy to disassemble and clean and/or replace any parts if needed. the front fan however, that's the easiest part to assemble, and why they clatter is because they're pieced together on the shaft cone by sliding on the blades side by side and then securing them to the shaft with that conical looking piece

[@maesakonstruksiprima8423]

Thanks for the explanation. For many times i've been thinking that the engines were cracking everytime we landed...:-D

[@alivewithpassion]

I love that buzz saw sound that the RB211!

[@thethirdman225]

I love that sound in all large turbofan engines.

[@michaelpierrynowski7253]

Got to take off a fan blade on one of these at school! We didnt have the tool to hold all the fan blades in place when moving them all forward slowly so we had to have two people on either side make sure the blades wouldnt fall out after the fir tree's were about 6" out, I was even able to keep some of the print outs for the fan blade removal! was lots of fun, love these older turbo fans

[@thewtf]

I stand corrected, there is an acoustic lining in the nose cowl in addition to de-icing air. There is also de-icing air through the spinner that I forgot to mention.

[@DaylightDigital]

Cool video, but I am fairly sure that the wall perforations are for acoustics, not de-icing purposes...

[@dreaded_pegasus6578]

DaylightDigital you would be correct, their name is actually called acoustic panels

[@TheUtuber999]

Dreaded_Pegasus Just a fancy name for muffler.

[@BrickNewton]

DaylightDigital 8

[@tahirkamboh147]

Please Tell me that how those panel work, means acoustic filtration. Thanks

[@pauljackson8261]

I love the clatter of the older turbo fans😀

[@FBWFTW]

Just awesome that you got the RB.211 running! RR is the best engine maker-GE's move to be the sole provider for the 773ER shows how scared they are of the geniuses of Darby! long live the RB.211 and it's trent descendants!

[@calvinrovinescu6166]

How can GE choose to have no competition? Boeing could have convinced RR to make a new engine of they could have tried themselves,

[@ronjon7942]

I love how there are like 5 moving parts, will run forever on anything and are essentially bulletproof. A little less complicated than a 4360. Or a lawnmower.

[@cupcar94]

That is the Part Span Shroud. That is also what produces the grinding motor sound at power.

[@craigw1379]

Love it, some one who has in-depth knowledge explaining it to the couch potatoes.

[@buckotte1414]

Air loads when running twist this rattly clearance to none, the wrap up rests the clapstrip on each othe to stiffen the assembly. When fanning under power, there is no longer any clearance between the brace ring segments.

[@cupcar94]

The old JT9D would sometimes lock and cause vibrations resulting in shutdown. We would don ear protection, and hit with a rubber mallet. when it broke free, it was as loud as a firecracker. It was routine maintenance on the GE CF6's to pull all blades and lube on overnights. Todays blades are composite and along with tech, those issues are gone.

[@planenutok]

The perforated metal on the inner surface of the inlet is strictly for noise suppression only not anti ice. Behind the perforations is an acoustical deadening material. Only the lip of the inlet cowl is heated with bleed air for ice prevention.

[@johnm400uk]

When i worked on these engines we used to have a competition to see who could stand the longest in front of the fan with the engine running at full power. I never tried it but the lads who did never turned up for work ever again.

[@thewtf]

This is something that has been the subject of many a forum. I believe it's got to do with the combustion chamber/turbine assembly resonating as it speeds up. The 22B was particularly noted for it's sound at start-up.

[@jaketoth8052]

where the hell do you get a turbo fan engine to play with

[@Quasihamster]

jake toth Craigslist.

[@woolmeister4265]

jake toth

[@MarksTournaments]

Jake Heke backpages is no more, rip

[@seanwatts8342]

Dark Web.... it's a real place.

[@seanwatts8342]

You misspelled 'vagene.'

[@grahamj9101]

When the engine is rotating under power, the fan blades untwist. This brings the abutment faces of the clappers (R-R Derby nomenclature) or snubbers (R-R Bristol nomenclature) into contact to provide a friction damping effect. The blade roots also load outwards into the disc firtree slots. BTW, if anyone tells you that it is centrifugal force causing them to untwist and load outwards, then please be informed (as I was as a 1st year mech eng undergraduate) that there is no such thing as centrifugal force: centripetal force, yes, but centrifugal force, no!

[@donaldasayers]

Anyone who says that centrifugal force does not exist needs putting in a centrifuge, sorry centripede and centripeded til they stop being so silly. Inertial forces are real and according to general relativity indistinguishable from gravitational and other forces.

[@TonyP9279]

It's inertia - the resistance to change in motion. Centrifugal force is just a term applied to a special case when inertial counters centripetal force.

[@MRyzlot]

I knew that but it's GREAT to see the detail on video - thanks JR

[@geomo44094]

Thanks for explaining the hot-air anti-ice. The P&W JT-5 on the older Cessna Citations used to make a similar racket when windmilling in a breeze. Great video. Thanks.

[@yrreb_xela]

It must be extremely cool to examine one of these engines.

[@bobgreene2892]

Those of us coming to this video without having heard the "broken bearing" noise (that brought comments from viewers) were left puzzled by narrator's references to the sound. It would be helpful to place that noisy spin-down sequence at the start of the video. Otherwise, a very helpful video to understand the anatomy of the compressor.

[@jodde73]

What a beauty! A true piece of art.

[@alexh5257]

I remember hearing this noise while boarding an American Trans Air L1011 via the air stairs in Puerto Vallarta Mexico back in 1999..glad to know it was normal!

[@zinc20L]

+Alex H I worked for ATA at that time. completely normal.

[@thspamed]

when the fan is spinning the centrifugal load on the blade makes the fir tree hold them in place nice and snug. The clappers support the blade behind it as the blade wants to flex as power increases.

[@florin604]

The friction factor on this baby is outstanding.

[@allwinds3786]

Thanks that was most enlightening

[@joeschneider67]

Notice the min 3:30, the blade has a small wear out. Pause video and take a closer look. Not good at all. Need to be replace to prevent what happen with southwestern Airlines April 2018.

[@squirt.mcgirt]

That's normal. Fan blades and propeller blades get chipped from ingesting foreign objects, this is absolutely unavoidable operating an aircraft in the real world. Instead of throwing it away, the mechanic will file down the damage until it's smooth, then file down the opposite blade so there's no imbalance. A fan or a propeller can be filed many times before it needs to be replaced.

[@visionist7]

@@squirt.mcgirt can this operation be performed without removing the blade from its housing?

[@JohnSmith-be5py]

Felice Graziano, just curious, why do you ask?

[@redturtletraining4692]

damn that was weird those blades clang like a bunch of dishes in a sink. Its amazing how we have advanced in technology comparing this to the new engines of today. I remember flying on an L1011. Had a lot of power for such a large plane (in those days).

[@dalehorne9316]

The part you refer to as the clapper is actually the mid span and the bottom of the blade that sits in the hub is called the root.

[@xaviarston3022]

thanks I really appreciate u taking the time to explain. what part of the engine makes it sound like a pissed off refrigerator typically at or throttle down during takeoff ?

[@L1011trijet]

It's definitely an RB211 although one that's no longer in service. If you look at the other videos there's a big sticker on the side that says "Rolls Royce", if you look even closer there's a serial number plate with the words "RB211-22B, Made in Derby, England"

[@zinc20L]

They make one hell of a noise bouncing off the hangar floor when the fall from the S-duct of an L1011. A guy dropped one. CCCCLLLAAANNNNGGGGGGGGG. Followed by many curse words.

[@kayemilson0108]

trust me, his is correct, its funny how people with no real knowledge or understaning of the workings of a jet. are so sure their correct and dismiss the answers they are given. keep up the good work and look after that RB211.

[@clarkie005]

The perforations are for noise attenuation. Source... I make them for a well known U.K. Nacelle manufacturer.

[@teenagerinsac]

Short Bros. Northern Ireland- correct?

[@teenagerinsac]

Short Bros. builds them for GE for the CF-34 series powerplant

[@Trump145]

I love jet engines and the way they sound I wish I could have saw your 1st video

[@IOWPCV]

Great was wondering what the noise was , saw an engine spinning in the wind on a stationary dc10 (I think it was )making the same noise . Enjoyed the start up vid .

[@shug831]

I worked in RR in the 80's & 90's and mostly on Rb211/535 or 524d4d and they all sound like a bag of spanners when they are cold.

[@aubreyaub]

Grab a book. " Not much of an Engineer". Autobiography, Stanley Hooker. Bloody good reading.

[@Dino0469]

My all-time favorite engine and one of the reasons I used to intentionally book flights on L1011's instead of taking flights on other aircraft to the same destination..I loved L1011's and the sound these engines made back then so my question is this: what causes this type engine to make that long distinctive vibrating hum on startup which could even be heard inside the terminal?!! also the moaning sound heard once power is applied and of course the choppy growling "whir" heard at takeoff power?

[@zaveexixterteen3841]

For a second I thought it was Red Bull. 😆 searched it up, and I knoe its Rolls Royce.

[@Shuriver]

the whistling noise the engine makes is just like the way how you whistle

[@Termixx1234]

Nope...It's important that they are able to expand. Not only the fan blades are loose, also the compressor and turbine blades. They must be able to expand under high temperatures. If they would be fixed, stress would cause and than they would "rip themselves apart".

[@thewtf]

I guess you might see some minor effects if the OAT was very cold i.e. -50 Degrees C and the other atmospherics right.

[@sasasimic75]

Man,you have Rolls Royce parked in front of your house :)

[@deeremeyer1749]

-50 F is far too cold for "icing" to be a concern and there's no reason for those "clappers" to be rattling "back and forth" as the engine winds down unless there is a serious balance issue. There are also other bearings in that engine that can fail or run dry and cause that kind of rattling. It's also pretty obvious that "RB211" isn't from a 747.

[@mrkongsimr]

I have often wondered about that . Thanks

[@bgandy1980]

Well that does explain the noise. Just curious as to why the blades are designed that way. It seems like it would cause excessive wear.

[@mistere02]

The RR RB211 is a cute little machine, I've run one of those... My favorite though is my GE 7FA+e DLN2.6 eats 211's for breakfast...

[@MrSwampy442]

It is indeed air resonance, if you listen to the CFM 56 that makes a good howl.

[@thewtf]

I doubt the de-icing air would make much difference to the noise reduction. There is an acoustic lining surrounding the fan and the cold-stream air itself is supposed to provide a degree of noise suppression from the core.....so they say!

[@thewtf]

Oh yes very noticeable, in fact it was standard practice to use anti-rotation sticks to stop the fan rotating in the breeze while on the ground.

[@peterharrington-cressman6635]

I would love to know the story of how you came to acquire this engine...since it's a 22B, it's an early production engine...what is the serial number of this engine? Can you post some history on how you came to own it?

[@MarksTournaments]

Peter Harrington-Cressman he borrowed it from Bush.......

[@MRyzlot]

It's Trump's spare

[@rabarwan2900]

I was enjoying watching your videos. Just a quick question why the blades were kept lose in the sense you can hear a friction sounds?

[@Felevr]

this is very educative

[@jonnyueland7790]

There called midspan shrouds on the CFM engines, never heard the name clappers before.

[@ethansaviation2672]

Thats not a cfm that's an RB2 11

[@adammccarthy2157]

No the perforations are not anti ice they are noise suppression, they are acoustic liners ..

[@scottdearmond4804]

thank you for the explanation. had no idea that that the blades moved ,they must push against each other?

[@AdventuresofanoldSeadog]

Interesting stuff.

[@ChrissonatorOFL]

Why do you have such a large engine in your backyard? O.o

[@Dadito1201]

why not?

[@ChrissonatorOFL]

Dadito1201 I just don't see what having such a large turbofan engine in one's backyard would accomplish...

[@Dadito1201]

nothing at all, but it's nice to have such big toy on backyard :D

[@ChrissonatorOFL]

Dadito1201 An expensive big toy.

[@FredtheDorfDorfman1985]

They make great leaf blowers.

[@jimthompson129]

Very interesting! Thank you!

[@Twobarpsi]

That explains why!

[@MrSwampy442]

You'll find the opposing blade will also have a piece missing, or cropped as its called.

[@williegillie5712]

Any kind of noise vibration I would think would translate to the corresponding part that caused it. I have seen these blades explode. Like a tire that needs balancing I would think these blades should be able to be designed for quiet thus long lasting, smoother, better running engines

[@maxwellbutler4184]

I hear Rolls has an opening in the engineering department.

[@williegillie5712]

Maxwell Butler what's the matter? They must not have anyone willing to tackle the hammering noise and vibration from those blades me thinks.

[@maxwellbutler4184]

Willie Gillie Clearly.

[@williegillie5712]

Ingleprop Noosegarm off to bed boy. No ice cream for you tonight

[@TheUtuber999]

Willie Gillie You're the boy in this story, though.

[@toddsky661]

Great work and many thanks for sharing the videos of your RB-211 project!! The -22B is and always will be my favorite turbofan\musical instrument. @1:55 Don't the perforations and mesh inside the inlet cowl also help with some noise cancellation.? Cheers.

[@Kevin19700]

Quite informative!

[@uploadJ]

Appreciate the explanation and the vids. A question - noticing the large amount of air expelled in the discharge path, what would be the effect if one were to 'cant' the engine up towards the clouds? Would it be possible to have any effect at 1,000 or 2,000 feet up? Would it be possible to have any significant meteorological effect like breaking a 'cap' (capping inversion or Cinh) on a clear day and initiate condensed water vapor (cloud material)? .

[@MackFire_Sets]

I love this engine

[@turbine6338]

Why didn't you explain why the blade are loose, all to do with the centrifugal rotating force of the engine. Should have hade a RR engineer to explain

[@justinwoolgar9853]

That info is on the video of it running

[@thspamed]

Yea the bleed air for nacelle anti ice is only at the front lip

[@nickjaxe]

Mmmmm very interesting...so when this engine was in service and say starting up or running down on an airfield apron would that rattle be noticeable, Such amazing things jet Engines. Nick.

[@awesomegamer2435]

I agree also I'm the fan blades go supersonic and it turns side to side and it vibrates like you said when goes to full thrust there's a rapid vibration do you agree English man?

[@awesomegamer2435]

yes i agree

[@matt18333]

I love that sound but always wondered what that groan was from but for now @Jdwoolgar1's reply answers it for me. Got plenty of videos of the RB211-524 (G-H and G/H-T) which are the groaner's on my channel.

[@bearbon2]

My concern was the long time it took to spin up the engine during start. If the apu doesn't put out enough volume it's like a hung start which could overtemp the turbine. No?

[@sephiroth1349]

This a great video but I must say that this engine is not a Rolls Royce RB211 it's a Pratt and Whitney PW 2037. The RB211 has only 22 blades and the blades don't move in their spots unlike the PW 2037 has 33 blades. I work with UPS 757-200's and they have both types of engines.

[@Felevr]

Imagine if those pito tube broken and got sucked during mid flight. But I never heard that happen.

[@dreaded_pegasus6578]

The perforations are not for deicing, and the engine gets so hot during operation that it won't freeze

[@micstonemic696stone]

will some explain the deep tone on starting the Rolls-Royce RB 2-11, PLEASE, my favourite gas-turbo-jet, 3 spool turbine shafts it sounds great, even CPT Eric Moody- speedbird 009 mentions it on a RB-211 747 after losing all 4 due to ash cloud, then he explains restart and this comforting deep tone,

[@GodLike-pe6kj]

that clearance though :)

[@helthuismartin]

The high sound is produced by the Rotations /minut.10000 RPM produces 10000 HZ.

[@geofflancaster8542]

It most certainly does not. Hertz is the frequency SI unit measured in cycles per second, which makes 10,000 rpm 166.66Hz. But anyway, I recall the 100% rotation speed of the RB211-524B4 LP assembly on the advanced TriStar-500 was 3600rpm = 60Hz