Keeping MAX quiet - Chevrons.
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I am sure you have seen the new LEAP engines that are fitted to the Boeing 737 MAX aircraft. If you have seen them I am also sure that you have seen that the engines looks "jagged" towards the back. These jagged dges are called CHEVRONS and I will be telling you the fascinating story behind them and many other wondrs of the modern Jet-engine in this video.
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A huge thank you to the channels which are featured in this video. Without your great content I would have a hard time explaining my points.
AIRBOYD
• Boeing 737 MAX Airshow...
/ @airboyd
Mathaderlie
• Wing Tip Vortices From...
/ @mat_in_texas
Boeing
• Boeing 787-10 Dreamlin...
/ @boeing
Stanford university school of engineering
• Effects of Chevrons on...
MiamiAirborne
• INSANELY LOUD!!!! 727 ...
This man explains things beautifully to non-technical aviation enthusiasts, like me. I have learned much from his videos.
Robert G Gee Boggs, Jr. I very much appreciate his ability to take complicated concepts and puts them in easy to understand descriptions. It’s an excellent skill and talent. 👍🏼
I like all his videos. I know a lot about Aviation and learn something new in all "MENTOUR PILOT" videos. Fun and Interesting facts. Don't forget the CREW :-)
Yeah, been watching this guy all weekend :)
I agree
Yeah I agree. If it weren't for this pilots TH-cam Videos I would most likely never feel safe on an international plane flight again.
The grounding keeps max also quiet !
MAXimum silence
the ultimate noise abatement
Kiwi hahaha
Sadly in 2 cases just after they hit the ground...
It makes them super fuel-efficient as well.
Max engines VERY quiet these days...
I barely hear them at all! 😅😅
Actually, it's all airplanes engines. They've all espoused that stealth paradigm I guess.
It's been 2months that i have heard of an airplane landing or taking off lately
It sounds as if they are Not even working
Very quiet 🤫😂
Yes... And now so silent
Also, the Delta 727 was so loud that when it took off from LGA that sometimes it shook the Windows, also whenever I think of a plane taking off I always remember the sound that the 727 made when it took off and flew over my house and made that turn, prolonging the noise, I freaking loved it.
Well explained as usual! As someone with an aerospace engineering degree, it is nice to hear someone who can explain these phenomena in a factual manner while making it understandable for all
And it’s awesome to hear that an aerospace engineer enjoys it! Great stuff!
Your hand motions really help me understand the subject matter
I live about 1 km from an airport. The US Navy has an offshore missile and bombing range just off the coast. Sometimes, if their F-18 Super Hornets are low on fuel returning from practice, they will land at our local airport for refueling. They use the afterburners on their engines to takeoff. THE NOISE IS STUPENDOUS. The sounds echo around the local hills and it feels like it will knock the glass out of the windows of our house.
Be happy the US Navy is not still using F-4. They would make the F--18's sound quiet.
This is due to supersonic wind speeds causing a air-based supersonic boom, along with an actual sonic boom once in a while.
@@benbraceletspurple9108 supersonic wind
I absolutely love your explanations. You make it simple enough to understand, but still scientifically accurate. Also, your English is impeccable and your accent is charming. I wish very much that I had learned a second language as a child. Sadly, it is not a priority in most American schools. It has improved a little over time in some areas. Both my sons learned a good bit of Spanish in school, and some of the other schools around are now teaching Mandarin Chinese starting in Kindergarten. Perhaps some day American children will not be so uneducated about the rest of the world and will graduate having at least learned a little bit of a second language.
Nice couch cushions, but they belong to a First Officer couch... you need to find some Captain cushions!
Hahaha!
Lol🤣
Good eyes.
Hahaha😂
As I am a small country east asian, I want to learn English from you captain. Thank you for sharing. I want to be like your English fluency.
I’m not a flyer but find these videos excellent! Keep up the great work!
At LAX I saw a 787-9 fly over on landing, the thing was whisper quiet. When we start up our 1971 Beechcraft Bonanza A36, it make more noise than a 100 ton beast.
I reckon the chevrons make the engines look better than any other engine type in the world. My favourite engines are the GeNx engines, love them!
As a former British Navy and Army Instructor Officer, I say with some authority, your instruction technique is of a very high order indeed. Thankyou.
Easy now...! Brexit = Potential war again.. Hope i'm joking!
Yes indeed. There's an unspoken convention that airline pilots are required to speak like Petter. It inspires tremendous confidence when one's pilot doesn't sound like a stoned surfer, Beavis, or Butthead. To wit:
"Yeah, like, we're, y'know, huh-huh... Cool! Dude, we were like BOOOOOM and the jet things were totally WHOA!!! So, anyhoooo, huh-huh, they cut this sorta HOLE stuff, no, I mean, like pinking shears, y'know? It was well radical 'cause... Um... OMG! I like totally screwed that up!!! Hey, everybody pose for a SELFIE!!! Yaaaaaay!!!"
Ahem. Quite. Thank you for flying Elli Airways...
@@EleanorPeterson that’s how some Southwest pilots sound like
Great video as always. Even though the answer to the initial question was obvious, I appreciate how you always walk us through the history and considerations underlying these design choices. It keeps the video information-dense, and I'm always surprised at how much I've learned by the end of each one. Keep up the good work.
I'm becoming an airplane expert little by little thanks to your videos, thanks a lot!
Great! I do what I can to help you along. :)
Same here. Iam collecting these vedio for my own flying lessons. Believe me iam going to use them as needed. In fact I am planning to enroll in pilot school.
some of info are not 100% sure, so be aware
I love these short videos. Explained very well from a technical point of view and pilot's point of view. I have learned so much from them. Thank you very much for making them. You promoted Cambly in this video for improving English, and I find your command of English very good, as I know it is not your first language. Just one thing I have noticed on several of these videos, that makes me smile with the irony here: 1 vortex. 2 (or more) vortices (pronounced: vor-ti-sees). But no points taken away for these excellent videos! Thank you again.
before even watching this video "or are they there to look cool"
I already know the answer is, no. Airospace designers don't design things just for looks.. ever. Everything has a purpose, regardless of how it looks :P Airline designers especially. I don't see air carriers giving two shits about how 'cool' the plane looks. They only care about how many people they can cram into it, and how much money they can make flying it. If something exists on it to make it more efficient, they will use it.
I've been on a 737-MAX, and when I realized I was getting on one, I was fucking giddy. The cabin is seriously amazing...
...and so are the engines. It's really cool to hear this huge difference in sound between these and the previous generation.
Lol, I’m ground crew and when on my first day I realised that we were preparing one to be ready to receive passengers and fly back out, I was profoundly glad that I was just there for when it’s on the ground and don’t have to be anywhere near it when it flies although it was re certified.
The 737 Max is nowadays is the most silent airplanes ever produced.
I agree with you. Don’t hear them at all!
And the most fuel efficient, they dont burn a drop of fuel....
They are also more invisible than the F35
Just had this topic in my technical knowledge class at my CPL course, excellent video!
I love the sound of jet engines in the morning.
I also love the smell of jet exhaust...am I a bit weird? Haha...
No you not weird i also like the exhaust smell
@@KaiZhao-nv5px Then we both are weirdos..haha
@@maricidevamega939 I love the taste of jet fuel in the morning.
@@kerbonautics5217 Just like the aroma of a double shot espresso...What a kick! : )
I’m so happy I’m from California because I know English as if it’s my first language and it can help me in the aviation career
That is a good thing.
5:33 Varig, Varig, Varig!
Mentour love your videos, I work at Safran Aerospace Composites (50-50 partner with GE for the LEAP Engine). I work in the US plant that builds the Fan Blades and Fan Cases, there is a lot of very impressive engineering going into these planes
Ahh, cool!
I feel that you forgot a really important aspect of the chevron design. Noice frequency and how humans perceive different frequencies. This in turns is affected by surface area. The noise from the engines are produced when high-velocity air hits slower velocity air and the air molecules "rub" against each other. The surface area is important with regards to sound pitch and frequencies. Whit the old engines there was a smaller surface area between the two airflows (engine exhaust gas and ambient air) compared to modern high bypass engines. In an effort to reduce the noise frequencies from engine exhaust they are increasing the surface area of the exhaust gas exit and ambient air by adding chevrons. The total surface area of the fan air and ambient air contact area can be increased without increasing the diameter of the fan air outlet by using chevrons. By doing this the manufacturer is able to lower the pitch of the sound produces. Since humans perceive high pitch noise as louder/more annoying a lower pitch is preferred.
If you look at the outflow valve on the B737 you can see the same design. Older models will have a straight edge opening while newer models will have a tooth-like design (chevrons), this was done to lower the pitch levels of the air rushing out from the valve to reduce high pitch noise levels in the aft cabin/galley.
Great info Sören!
You are a perfect educator !!!!
Hats off Captain
it really is amazing how much aircraft noise has gone down over the years. I live very close to an international airport in Michigan and I barely notice the jumbo jets overhead these days. Great video!
Yes, it’s impressive. Thank you, I’m glad you liked it.
When NASA was studying ways to reduce turbofan exhaust as well as wing trailing-edge vortex noise back in the 70s/80s they made a detailed profile of the feathers of “silent fliers” - primarily owls - and found that there were structural forms, both macro as well as micro, that contribute directly to “noise reduction”. These “chevrons” are an engineering translation of those principles.
Your videos are really great. Thanks for producing them
Congratulations on a quarter of a million subscribers! Great video as always.
6 decibels (6dBA) on a logarithmic scale (the one used to plot noise levels) are by far not negligible. Great and very instructive video Mentour Pilot.
Can’t wait for these 737-Max to join your airline soon! Great work Petter
The chevrons would look like rockets if they would paint flames along the edges.
I appreciate your very comprehensive explanation of the chevrons and other topics. Keep it up!
Hey, Mentour ,
Your cushions are runway-end threshold marking stripes !
(Nicknamed the piano keys)
Great Video Mentour
Thanks
Did not Know this😁😁😁😁😁
Yes Airplanes are getting more Advanced as Time goes by
I have been curious about those "Chevrons" (I call them scallops) ever since we got our new 747-8's. I work on the ramp for UPS at SDF. Thank you for that explanation.
Man, I love your show. Greetings from Argentina!
Thank you!
The irony of using the B-727 example is that years ago Eastern Airlines marketed their 727s as "WhisperJets" touting how quiet they were.
Great video as always Mentour! Keep up the good work!
I am old enough to remember the first flight in San Diego of the Convair 880. It had no bypass at all and four engines needing water injection both to suppress some of its sound, and add thrust at take-off. The 727 you reference was sold by Eastern Airlines as a "WhisperJet" but to its forward passengers, not to those below at take-off:)
I live near a noise restricted airport, and recall another scheme that worked well to quell the noise of a then new regional aircraft, the BAE 146 which with four smallish engines (derived from a helicopter engine, I think, and thus much higher bypass than the typical JT8D found in its Douglas and Boeing competitors). The trick , I was told, was that the two engines on each wing rotated opposite to each other with some cancellation of their vortices as a result. Probably a maintenance headache keeping an equal number of each engine on hand for replacements.
Great plane, great pillows and great video.Thank you 🤗
MAX is now very quiet .
They look absolutely awesome, the same as the new winglets.
Turbulence effect. Fighting noise with noise..
That's how noise-cancelling headphones work!
No, you got is wrong. If you were fighting noise with noise it would take more energy, not less.
Noise cancelling headphones roughly speaking use phase inversion.
Thanks, I enjoyed the explanation, so a slight loss in efficiency of the engine, is compensated by a reduction in sound insulation weight material on the aircraft, with an overall increase in efficiency and reduction in noise, sounds like a win, win.
Excellent vid, sir.
What a specific explanation Sir!
On a more basic level, these chevrons seem to work a lot like a suppressor on a gun: They release some particles of air into the open earlier than others instead of all at the same time, thereby reducing the noise.
Silencers work by slowing the velocity of the expanding high pressure gas.
ZE0XE0 yeah, therefore not allowing the gasses to escape all in one uncontrolled explosion, but rather in a more controlled and quieter release of gas
Yes, that's what I mean by "on a more basic level". The gun suppressor achieves it in a different way, but it still slows down the gas release.
awesome !
No. They, too, work by phase cancellation. Put simply, they drag out the sharp report over several cycles of the report's frequency. A properly designed silencer critically dampens the acoustic of the report. A plastic bottle overdampens it, capturing all the gasses and allowing them to escape slowly. The oil filter silencer kits do the same thing - overdampen. The chevrons on the engine create vortices which interrupt the rapid boundary layer "ripping" that occurs when the rapid exhaust gases meet the slower-moving surrounding air.
Thnx captain for learning about my planes!
great and informative video as always !
EXCELLENT VIDEO. VERY CLEAR EXPLANATION. CONGRATS!
Very interesting, and very well explained.
BTW..where did you get the name "Mentour", What does it mean? Why do you use it??
Craig Dillon I think it is a pun on “Mentor” a trusted advisor.
? the Platypus Also, touring means traveling, which is fitting since aviation is in the travel industry. So it’s like a double pun.
Very interesting aviation technology and innovation! Thank you sir!
can you make a video on explaining thrust reversers, because i have seen there are many styles/kinds of thrust reversers
I can.
From the stand point of a ramp rat, I'd like to see something done about the noise from the APU. Nothing says fun like having to shout over one, or escorting an elderly passenger to the plane and listening to her hearing aid whistle in complaint. A Hawker pilot I dealt with simply left the #2 engine idling which was quieter than the APU.
Thanks!
That was fascinating info. Thanks!
Mentor hi... in the recent announcement from tim clark president of Emirates airlines said there might be no Windows in the future aircrafts or virtual Windows like in their business class of Boeing 777 thus to decrease the weight of the aircraft. What's your say on it or make up an video on it...
Thanks
Great video! The old 707 and DC-8 turbojets were even louder than the 727.
Great video - very interesting and well explained!
6 dB is about quarter the noise energy, that is much. I wonder if that is at full power, or also at approach (approaches are noisier on the ground - airplane is slow and close to ground).
That’s at takeoff thrust.
Great explanations love your videos mentour
7:00 Kloten! :-D
on the left Side you see our Village, Buchs ;-)
Awesome Video! Keep them coming, learning so much, THANKS !
Chevrons and vortexs, feeling in Stargate :-P
Here's a very good way to control the noise complaints from people living near airports...
Don't allow housing to be built close to an airport!
Every New airport that's built, it's just right away they start building houses all around it... then complaints start flying.... Form a no build boundary around it that allows for the planes to perform their takeoff and landings efficiently without molestation.
LEAP..takes forever to start n stabilize...must protect thermal..new technology..we gain some...we lose some...
Good stuff Capt Mentour.
AW AV in my opinion, the LEAP is only loss and no gain.
Excellent video. You are a really good teacher. By the way, the word would be "encapsulates" not "encapsules". Just FYI because I know you are very precise and accurate in every aspect of your presentations.
Question: Will other Boeing types be retrofitted with the chevrons?
Possibly, maybe with engine upgrades.
Thanks!
maybe the 777X but with the current look of the GE9X, maybe it wont.
The upgrade would also need to include the lighter soundproofing material to gain the benefits of the quieter engine, correct?
MaidenAirTM
Lmao
Never understood why some planes had them! I think the 747, at least the upgraded version had those ridges. Great video my man!
5:28 VARIG, we here in Brazil miss you A LOT
Not only that but now that the aircraft is lighter that loss of extra thrust isn’t that big a deal. Depending on how much weight is lost, the thrust to weight ratio is probably larger than the thrust to weight ratio of the original engine and aircraft weight.
Max 8 is the most silent plane today!
At times I thought I might have been watching Peter Windsor and Scarbs talking about the latest Red Bull winglets... It's all about the vorteces.
Hahaha!
1:06 Is this an operational takeoff or a high performance one for demonstration purposes? The climb rate seems very aggressive ...
Boeing pilots' demonstration of the then new MAX8 possibly at Oshkosh 2016 Air show.
Mentour, have you ever had the opportunity to visit the Boeing factory near Seattle, WA? I saw them building Dreamliners. It was the best tour I have ever taken.
This is how the wings of owls enable them to fly with virtually no sound.
Great vid as always. I read also that Boeing & GE removed the chevrons from the upcoming 777x engines.
DO THOSE CHEVRONS COME WITH TECHRON?
thanks , your videos are very very good, you have a good way to explain
AFAIK the primary reason for the high bypass ratio is fuel economy. You get a higher impulse for the same energy.
Of course, but now the topic was noise. :)
Thanks for the explanation about the engines, i thought it was a bit of a odd look and was wondering why this design, i like the new winglets.
You mean scimitar split winglets? They've been out for years
Yes, those split winglet, i like the look of it, I've been noticing them for a while.
I'm curious, I live in the flight path of Chicago O'Hare, and most of the planes are pretty reasonable, but there's a Korean Air Cargo 747-800 I can see on FightRadar24 and it's the loudest plane by far. I don't even have to look at FR24 to know it's flying overhead. It's a relatively young plane, so why is it so damned loud? None of the other 747s are even close to its level of noise.
Hard to say, it might be flying lower.
I'm not even directly in the flight path, but we get some really loud military planes (cargo) here in Hilo. Astonishingly loud actually. The rest of the traffic is fine... some of the helicopters and older jets are certainly noticeable, but nothing in comparison. I'll have to check flight radar/tracking and see if they are listed (thanks for that idea).
I used to live in a small town along a training flightpath from Travis AFB. Occasionally some dumbass would come over very low, including fighters just barely subsonic. I swear these cargo flights are actually louder.
Travis Collier • Your comment reminded me of the “old days” when Millington Naval Base just north of Memphis (long since shut down) would fly practice sorties over our vast farmlands along the Tennessee River bottoms. My husband loved it when they would “buzz” him as he drove his tractor. Sometimes he wouldn’t even see them but he jumped a mile as he heard them seconds later!
Funny, I live right at the end of the downwind leg of the Ottawa airport, and find the cargo flights are always louder. They do seem to be flying lower usually.
Always enjoy your videos. I am not a pilot but am interested in techology in general.
I wonder what aircraft are going to look like in 50 years. ✈️
EveryTypeOfVideo I imagine we'll see quiet supersonic aircraft that can produce lift from their fuselage(s) with or without a wing as we know it.
EveryTypeOfVideo extremely boring... how else? That is the direction they have been heading for the last 4 decades. Quiet, plastic twins.
Remember decibels are a logarithmic scale. So a 6 decibel reduction in noise is about a 75% reduction in noise energy.
Great video, will be great to see a detailed video with the differences between a B737NG and the B737NG SFP
Good idea
Awesome could see the area where I live on that map!
As always, a fascinating and informative presentation. Thank you.
Also, as a retired technical teacher, I'm very impressed that you can talk authoritatively for 12 minutes without notes or hesitation! {:-)
Yes, and that he uses SIMPLE LANGUAGE, _without losing content._
You will find that the more competent you are, the less jargon you use when addressing the public. It arises from confidence.
Comprehensive explanation!
Thank you! I hope you liked it!
Congratulations on 250k Captain 😍😍👍👍
Thank you!!
Congratulations!
Could you make a video about the different causes of delays and why these delays are increasing nowadays?
I have done a video on slot delays a while back. Check that out.
That is an endless list, a 5 minute delay due to ramp congestion (Aircraft pushing/taxying delaying your own pushback) on an aircraft's first flight can have a knock on effect of hours by the end of the day due to Air Traffic Control 'slots' (ie. You're time for the airport is 1525hrs) to ensure you can actually 1. Be handled in the air and on the ground and 2. To fit into landing/departing traffic.
Aircraft can have a tech issue and require engineers, this can take minutes or hours
A problem with baggage, a passenger may not have turned up and so needs their bag offloaded, this could be the first bag you see and it could be the 200th bag you see
Waiting for cleaning/toilet/water service if alots been used or passenger has been sick etc
The list can go on and on
Very nice and comprehensive podcast, Mentour Pilot. I did have a fantastic time just watching this!
That makes me happy to hear!
I always look at things (such as these spiffy new engines) and ask myself, "Why is it designed in that manner?"
Thank you for further educating me on this and a variety of interesting topics.
So, is this engine silencer "modification" causing these MAX to fall off the sky?
Don't be ridiculous.
No it's the MCAS system that's faulty
No
It was a faulty sensor, poorly designed software, and a lack of training for pilots on changes from previous 737 models
@@markmoreiras7649 it was caused by a faulty sensor that then showed incorrect data which then triggered the mcas system and the pilots couldn't ovarride it which led it into a steep nose dive straight into the ground
@@shannonflyer757
And all this things would not happen if engines did not mounted on "wrong"place casing too much pitch moment.
If engines could fit in normal position, MCAS would not be needed, no MCAS - no bad installation of MCAS, no problem. So yes, engine installation on B737MAX is root cause of the problem.
Great! Excellent explanation
Captain your the best. I am your beloved student from India.
Thank you!
Learning English isn't just good for being an airline pilot. English is now the language of the World. It's used for business, diplomacy, science, and everything else. If two non-English speakers need to communicate with each other, they will invariably use English as the common language. Taiwan has just announced that they will adopt English as an official language.
I remember in the 70’s to early 80’s seeing the first generation 707 and DC8 planes with engines that had a rocketlike daisy shaped thrust nozzle in an attempt at suppressing noise in the 1950’s to 60’s.
Ahh Yes, Hush-kits
Nozzle suppressors. Made a big difference on the turbojets of the old jets e.g. B707.