How do Aircraft BRAKES work?!

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Have you ever thought about what the aircraft brakes are made of and how they work? What about how much energy an Airbus A380 excerpts during a Rejected takeoff at maximum takeoff weight?
In todays Video I will go all in about brakes, anti-skid, auto-brakes and all you never knew you needed to know about the brakes on the Boeing 737NG so stay tuned!!
---------------Video highlights👇---------------
00:00 Intro
01:58 Overview
03:36 Break Energy calculation:
05:27 B737 Brake system:
07:23 B737 Brake Materials:
12:52 Anti-skid system:
15:39 System Backup:
16:46 Auto-Brake system:
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Artwork in the studio 👉🏻 plakaty_lotnicz...
Below you will find the links to videos and sources used in this episode. Enjoy checking them out!
Airbus - A380 tests
• A380 from dream to rea...
Gmpanazzolo - A380 Brake test
• Airbus A380 brake test
Boeing - 747-8 RTO test
• Boeing 747-8 performs ...

[@MentourPilot]

Get 20% discount on the yearly subscription of Brilliant by using this code 👉🏻 brilliant.org/Mentourpilot/

[@aerodynamics_sweden]

Hej!

[@bobac1083]

i got a good one. What is that noise in the gear bay that is a low pitch tone followed by a higher tone beep? I think it has something to do with a systems test or resetting the FMS or something. I hear it from time to time while fueling the 737 NGs.

[@topform4665]

During a normal landing, under calm and dry conditions, typically what percentage of speed reduction can be attributed to: brakes vs spoilers vs reverse thrust ?

[@rjmac3095]

Exactly how bad is it to do 2 rejected landings 40 minutes apart? I was flying from Fiji to LA and apparently a fuel pump wasn't working. The pilot waited for a plane to land that was supposed to have a replacement, but it didn't, so he tried and failed to take off... Then waited for the another plane to arrive that also might have a spare pump, but the didn't, so 40 minutes after the first rejected take off, we had a second one... About 10 minutes later he said, 'Ok, lets just try that again...' Third time lucky I suppose - we got airborne! And had a completely uneventful flight to LA. Would a third rejected take off in an hour have been bad?

[@md.sheikhshaddathossain2790]

Mentour Pilot ( Wow !!!) SHEIKH MD. SHADDAT HOSSAIN .

[@parapotamus]

For those who wasn't struck by lightning: 2.2 GJ is approximately the explosive energy of half a ton of TNT.

[@Joeybagofdonuts76]

Who does that equal to a gigawatt?

[@parapotamus]

@@Joeybagofdonuts76 it's 0.61 megawatt-hour, if anyone is interested.

[@maxsz91]

@@Joeybagofdonuts76 If you release 2.2GJ in ~1.8s you get 1.21GW

[@Joeybagofdonuts76]

@@maxsz91 thanks

[@ex4787]

@@Joeybagofdonuts76 a Watt is defined as J/s, so the wattage depends on how much time it takes to convert that energy to heat. It took the 747-8 in the video about 20 seconds to stop so if we assume the A380 and 747 are similar, you're looking at 110 MW of brake power. To put this in perspective, if you could convert that to electricity, you could power about 65,000 households for those 20 seconds!

[@jjquinn2004]

When you were talking about failures in both braking systems, and the need to apply the brakes only once, it reminded me of the story of the B-17 bomber returning to its base in England during WWII. Its hydraulics were shot up and the pilot didn’t know if he even had one brake application. His choice was to either hope he had brakes and land back at base where their Christmas dinner would be waiting for them, or land at one of the bases with an ultra-long runway, but then spend Christmas Day in the back of a deuce and a half ton truck and miss dinner. The captain polled the crew and they all wanted Christmas dinner, so they landed at their base. Luckily, the backup system worked and they had that one application remaining.

[@lucabuckley5643]

Between you, captain joe, and 74 gear, I get all the different types of aviation content I need!

[@yukionna1649]

In regards to brakes being the primary well... Braking method on the aircraft that is exemplified best in the C-17. Such an enormous aircraft designed for short feild landings with huge amounts of weight on board, it uses 12 MASSIVE carbon fibre brake packs, in conjunction with spoilers covering 3/4 of the wing span to dump all of the lift, but the thing making it so much more extreme than other aircraft is that the thrust reversers direct all thrust upward, with no openings on the lower half. So all of the thrust is in effect pushing down on the brakes even harder, in effect making the aircraft even heavier to allow harder braking without locking at all. One hell of am impressive aircraft

[@roriquevernonii8439]

Good ol' Moose!

[@yukionna1649]

@@roriquevernonii8439 she's definitely a beast 😁

[@roriquevernonii8439]

@@yukionna1649 Don't know if it's just JBER, but she's called a moose up here.

[@yukionna1649]

@@roriquevernonii8439 i think we've all always known her as the moose. She's got the call after all 😁

[@roriquevernonii8439]

@@yukionna1649 love that sound!

[@GregSr]

Excellent explanation...as usual. My grandfather was an engineer at Boeing in the late 60's. He told me that he was on the development team for the 747. One of the stories he told was fascinating. The engineers had to calculate the maximum heat generated in a 747 during a rejected takeoff. To prevent the tires from bursting, they had to determine the pressure rise in the tire and then design a special plug in the wheel that will pop out (relieving pressure) just prior to the tire self-destructing. If a tire bursts, it can do severe damage to nearby components in the landing gear. A bursting tire also damages adjacent tires and can lead to a chain reaction in tire failures.

[@tsint]

Interesting, I'm expecting ground staff with leaf blowers like in F1 next time I fly 😀

[@matsv201]

I woundet how it work in like middle east where the runway can be really hot

[@douglasfaichnie6931]

Yeah, and others packing the inner wheels with dry ice.

[@mattsains]

Some airliners do have brake fans that the pilots can turn on to cool the brakes down after they get hot

[@abcpsc]

I thought of F1 when he talked about pump braking (aka cadence braking)...

[@filanfyretracker]

I have seen videos of aircraft brakes being hosed off on some island hopper routes.

[@freednighthawk]

Interestingly, the brakes are very similar to "race" clutches in a car, or clutch packs in an automatic transmission.

[@Slash1066]

Yes! very much like wet clutches on motorbikes also which use this "pack" method to be more space efficient, i'm surprised that cars still use a single plate, large diameter clutch actually, such are the benefits of a multi-plate friction system like this

[@Spinattitude]

I'd love to see an animation showing how the stator and rotor plates all get pushed together.

[@AntonioCunningham]

This is the kind of content that makes me glad I found this channel. Thank you Peter for producing great content:-)

[@MentourPilot]

So glad you like it my friend! Feel free to share it around

[@richardbutler9466]

FYI, his name is Petter not Peter.

[@AntonioCunningham]

@@richardbutler9466 Really!?! Are you that bothered by one single letter?

[@cieludbjrg4706]

@@AntonioCunningham Would you be happy if your name got written Antoni? Cuningham? His name is PeTTer, not PeTer. It matters to us Scandinavians! :)

[@AntonioCunningham]

@@cieludbjrg4706 Considering I get called Toni, Anthony, Tonio etc, no I don't mind. Not everyone speak and pronunciate in the same way. I find being such a grammar Nazi to be more offensive than calling me the N word. Seriously when someone does, this, there's vertically no reason to communicate further because instead of dealing with what's being said or conveyed, they're nic picking irrelevant crap.

[@peterihoy4908]

In fact, the brakes are more closely related to the multi-plate clutch on a motorcycle than a car disc brake ('though the clutch default is ON and the brake OFF of course).

[@kingaire165]

Early B-727 had nosewheel brakes. Due to reliability issues, a service bulletin (SB) was issued and they were removed. Later 727's were manufactured without them.

[@mittelwelle_531_khz]

_"The antiskid system in airplanes works like that in cars..."_ Historically speaking switching that around to _"in cars it works like in airplanes"_ would even be more "correct" as when the automobile industry began to adopt that system for cars in the 1970s it was already in use for airplanes.

[@Markle2k]

One more “what has NASA done to improve our lives here on Earth?” example.

[@godfreypoon5148]

Dunlop Maxaret, eh?

[@bobl78]

really as a fully electronic system like today ? In cars there were many ABS ish systems around also in the 60s and earlier but the challenge for a modern system as we know it today was that the electronic ECU is able to proccess all information and controll the actuators fast enough.. that was not possible before the invention of modern transistors, micro processsors and other hugh speed digical electronic components

[@mittelwelle_531_khz]

@@bobl78 I studied EE in the mid 1970s and my Professor teaching "electronic circuit design" owned a company which had developed an ABS for a German car manufacturer. (ABS at that time was an "extra" you had to pay for and was typically only available for the more expensive line of models.) At that time transistors were available since more than a decade and electronic circuit designs had started to incorporate analog ICs (like simple OpAmps as the uA 741 or timers like the NE 555). Digital ICs were quickly growing out of providing just the most basic building blocks, as they had been the years before, which had given us the 7400 (4 x dual NAND) or the 7490 (4 flipflop chainable counter stage). Now we could also have ADCs and DACs, which formerly needed to be built from discrete components. While I concede car ABS then was far from the "stability control" we have today, which e.g. incorporates inputs from MEMS acceleration sensors that are processes in real time and can recognize a car starts to turning around its vertical axis. Such an advanced system as we have it today can give control back to the driver by asymmetric application of the brakes on all four wheels. A very basic ABS can be much simpler and still be effective: The key understanding is there a substantial difference between static friction and sliding friction of the tires on the asphalt. If all four wheels go from static to sliding at about the same moment in time (if the driver simply pushes the pedal as hard as he or she cab) the brakes are just less effective as they could be. Worse if the road is more slippery on one side of the car than on the other, because the asymmetry then creates a force that makes the car turn around its vertical axis, making it uncontrollable for the driver. (And when friction becomes stronger again all of a sudden the car would also be in danger to roll over "sideways".) Therefore experienced drivers at that time applied a technique called "Stotterbremse" in German, which means full force is applied intermittently only, giving you a shorter distance to a full stop as constantly applying the brake and risking the tires to block. Which explains the name ABS: It means *Anti Blocking System* and the goal is (or then was) to avoid the wheels to go into sliding friction in the first place. This actually can be achieved quite simple: the electronics would only have to determine whether a wheel still rotates and if NOT to cut the pressure in the break cylinders of that wheel until the wheel starts to turn again. Exactly that was what early ABS did in cars and you would well notice it if you e.g. pushed the brake hard on a snowy road: the rattling of the "stuttering breaks" could be easily heard (and felt too).

[@bobl78]

@@mittelwelle_531_khz very interesting, thank you. The first german electronic ABS I know of was introduced in the Mercedes W116 around 1978 or so .. most like a 2 or 3 cannel sytem... So what was the challenge to bring an electronic ABS into a car ? I started drivin in the 90`s and remember that back then the systems were great compared to non ABS cars but compared totoday´s systems react and pulse much faster and contain many many more functions .BTW is a modern ABS system able to adapt the way it works to speed and ground / friction levels? Does it work different on snow than on dry road ? I remember when my dad got his first W126 in 1982 with ABS as a super expensive option ...

[@KENARDO]

My dad used to build autobrake/anti-skid control modules for the 737 back in the 1990s. Great video as always, Petter!

[@ayowhat6139]

Didn't ask

[@tobiasjacobsen_dk]

It send chills down my spine when I see that Helios livery 😔

[@oystercatcher943]

I’m impressed that as well as being a pilot you know the physics and engineering very well. I hadn’t appreciated the brake cool time was even an issue before

[@supersnot4]

727 actually did have nose wheel brakes as an option, I believe for unimproved runways. Pretty sure some did exist but most 727s did not have the option added.

[@justing42]

Those were air brakes

[@thpxs0554]

Great explanation. I’m amazed that steel brakes can build and retain heat over a day on short haul as each subsequent flight at minus 30-50 degrees would “suck” the heat out of them. It’s like being in a very interesting engineering class

[@rainscratch]

Just goes to show the myriad of physics, aerodynamics, electrical, aircraft systems, and engineering topics pilots have to be familiar with.

[@captainzeppos]

That's just some absolutely fantastic material. It's great to get into so much technical detail without boring the audience one second. I'm only experiencing aviation via flight sims and after watching this video I kinda feel content that in sims brakes work 100% of the time in maximum efficiency.

[@InopGauge]

It's been a long time ago but I can remember 727 and DC 9 occasionally arriving at the gate with very hot brakes. If it was dark outside you can actually see a glow from them and we were always told that that was burning magnesium. When we would see hot brakes we were always told to never approach the gear from the side and to the only approach from the front or the back in case it was to explode and the split Rim separated said it would blow out to the side. You definitely never wanted to throw water onto a hot break or it would explode. Usually the fire department would put fans in front and behind the landing gear to try to cool them off slowly. Having helped our mechanics replace brakes before, it's is surprising how heavy those things are.

[@averageguy371]

You should never approach mains straight in. Aircraft wheels have thermal plugs that melt & deflate the tire if the brakes get too hot but you shouldn't bet on it. You really should never bet on anything an engineer designed.

[@engineerinnewyork]

Dear Petter, I love your channel. MentourPilot, BlancoLirio and VASAviation (all with a Spanish connection!) are my go-to sites for all things aviation. But I do have one BIG criticism to make: Your programs, barring those to do with sad events, are not the same without your adorable pooches, they never fail to bring a smile to my face!

[@MentourPilot]

They will be back. Molly has just given birth and Patxi is keeping my mother-in-law company after she lost her little dog.

[@treschlet]

huh, interesting. I didn't figure the brakes would be a clutch-pack, makes a lot of sense

[@michaelmurray7199]

I’ve read that Concorde was one of the first airliners to make use of Carbon Ceramic brakes, not only for the weight savings, but also because of the higher takeoff and landing speeds she had compared to her subsonic counterparts. She also had brake cooling fans to help keep the brake temperatures in check during taxi and after landing.

[@wernerhannefeld2636]

I would never even think of a fact that brake discs actually don't have the time to cool down during A WHOLE FLIGHT, although a short one. Amazing as always, thank you!

[@liammay7756]

I want 22" rims with low profile tiers on my 737

[@skyhawk_4526]

22" rims would actually be pretty small on the main wheels. 😉

[@danielaramburo7648]

With spinners.

[@mikes-b6009]

I’ll loan you the 22’s on my vehicle. Don’t trash them because I’ll need them back!!! 🤣🤣🤣

[@cliffwheeler7357]

American: Tires. British: Tyres. Definitely not Tiers.

[@marymonson2187]

Love the two pictures behind you. Someone has great taste! Oh yeah, love watching you, I learn a lot from your clips.

[@MentourPilot]

The link to the artist is in the description. Check him out! instagram.com/plakaty_lotnicze?igshid=yltik8pqq8mt

[@martinmillar8447]

Hey! New house?

[@tnutz569]

"1.21 Jigawatts!!! (Gigawatts)" -Doc Brown

[@zapfanzapfan]

If the A380 stopped in about 2 seconds, than yes :-)

[@edmondhung6097]

@@zapfanzapfan That call a crash, my friend

[@allmycircuits8850]

It's as much as lightning strike!

[@beachboy1234]

I love these tech videos. The A-6 Intruder I was married to for fifteen years had a problematic (unreliable) anti-skid system and it was not unheard of to blow tires or have brake fires after an aggressive brake application. BTW, we disarmed the anti-skid system and increased tire pressure for aircraft carrier operations. The latter could make for an exciting arrival when flying off the boat to a shore base.

[@chomp54321]

I thought: "Brakes? What's there to talk about?" Boy, was I wrong!! Thanks for a very interesting video.

[@aztec0112]

Ditto that!

[@kreiseltower]

What I use to picture what 2,2 Gigajoule of energy means is: This would be sufficient energy to bring 6579 liters of water from 20° to 100° (not including evaporating it). Everyone who has been waiting in front of his noodle pod with a few liters water to finally start boiling now can imagine, that you use a lot of energy for 6579 liters.

[@rainscratch]

Excellent analogy. If you can imagine a 1000 liter water tank and its mass (1 tonne) multiplied by 6.579 - that's a lot of water and mass to heat up! Interesting to know how long it would take to reach 100 deg boiling point.

[@maxsz91]

Release this energy in less than ~1.8s and you have enough power to power the flux capacitor and jump back to the future

[@rainscratch]

@@maxsz91 As long as your speed is 88mph = 76.5kn. The Flux Capacitor is very reliable.

[@maxsz91]

@@rainscratch Minimum speed requirement goes without saying - it's basic knowledge

[@rainscratch]

@@maxsz91 Only genius mad scientists can design the system though.

[@sheahoffman3218]

I’ve heard of some of the 727s having the nose wheel breaks but got removed

[@moi01887]

Years later, sadly, the 727s got removed. ;^)

[@jimcaufman2328]

Back in the 70s and 80s I worked for PSA in San Diego maintenance on the B-727. All our 727s had nose brakes which were only activated during heavy braking. They were required to operate out of airports with shorter runways to assure stopping during a rejected take-off at higher weights. More passengers were carried with operative nose brakes. We were required to remove the brakes after so many months because they were never used and send them out for overhaul basically to remove the rust.

[@peter2346]

We commissioned an induction heater for company which makes carbon brake discs. One of many stages is to cook them in an induction heater for hours. Process is quite interesting but messy (everything is covered with a fine graphite dust). Advantage of using induction for any conductive material is that heat generates in the workpiece so it does not need to conduct to it from hotter heater. in short terms indction heater is a transformer with shorted secondary winding (workpiece).

[@billbeyatte]

Fascinating, especially the physics of the kinetic energy calculation.

[@grahamnash9794]

Your animated 737 is spookily like Helios to look at.

[@speedbird9313]

It is from the Helios video so...🤭

[@grahamnash9794]

@@speedbird9313 Oh right, I should have had my glasses on. LOL. Thanks for that.

[@IcthioVelocipede]

MiG-21bis has brakes on the nose gear as well, with a handle on the instrument panel to enable for takeoff and landing, and disable for taxi. Its brakes are pneumatic and operate off stored pressure, which gets interesting if you use it all up.

[@ChiDraconis]

Ah yes but the beloved Frog Foot?

[@andretheterribe3751]

Love the technical videos! It was fun trying out a rejected takeoff with the brakes set to RTO in my sim. I normally set them to RTO but I had no idea how it would actually feel rejecting the takeoff after 80kts.

[@chriholt]

Fascinating info Petter, I love these technical videos!

[@CKOD]

If doing multiple short legs on a busy day, would pilots ever go gear-down early on approach to cool the brakes more if ground cooling fans arent available? Obviously the pilot would have enough temp 'reserve' to land if they were good for a take-off, but to prevent delays on the next departure? Would that be a company procedural thing? I.e. bean-counters determined that the increased fuel-burn was cheaper than 10-20 minute delay waiting on brakes for whatever reason, so gear down x miles further out from touchdown then they normally would be?

[@kreshnik1710]

They would delay landing gear retraction on take offs ...

[@antoniomaglione4101]

Great explanation. A very felt THANK YOU! Happy new year, Mentour Pilot ..

[@CMDRSweeper]

The DeHavilland DHC-7 "Dash 7" had an option to have brakes fitted on the nose wheel as well. However, very few aircraft got that option as it turned out the benefit, even in a STOL market as it was made for, the difference in stopping distance was minimal, but maintenance complexity was increased.

[@marcmcreynolds2827]

I think it's fair to say that in most airliner operations, required takeoff field length is greater than for landing? Perhaps another reason why a bit less stopping distance wasn't worth it.

[@benpatana3256]

My understanding is that some early model variants of the 727 200 had nosewheel brakes to supplement the main brakes. However, I believe they were ultimately removed due to ineffectiveness and relibility issues.

[@AB-yt4hd]

I remember having seen the brakes of my parents car glowing red hot (had to stop on the side of the road) going down a mountain when I was a kit. Also, when you turn off your car, you don't have hydraulic assistance anymore. If you need to brake, you also have to brake with one push on the pedal. Otherwise you will loose any braking assistance, like Peter explained for the plane.

[@F-Man]

The brakes on a car will still work even with no engine power, the pedal just gets very hard and you have to apply a lot of pressure. If you ever driven a old car or a race car, same story with them. 🤷🏼‍♂️

[@K0nst4nt1n96]

On most cars you have pneumatic brake boost. The brakes work with hydraulic fluid and work if the car is on or off and are divided in 2 seperate circles if one fails.

[@dewiz9596]

The pnuematic boost will work ONCE after the engine is turned off. . . until vacuum is lost.

[@chitlitlah]

I experienced something like that once. I was driving down the Rockies traveling west from Denver. Anyone who's driven there knows the freeway has steep descents for miles. I decided to put it in neutral and see how fast it would go just coasting. (My engine was choking in that high altitude, so I didn't do it just to see what would happen.) Well it ended up exceeding my car's speed limiter at 109 mph. I figured that would do nothing while the car was in neutral, but no, it still cut ignition and the engine just died. I lost power brakes and power steering while descending a hill and going around a curve. Then I had to slow the car down to get it to start up again. Losing power assist wasn't as bad as regaining it and having the steering suddenly become soft. I ended up rolling down the mountain and dying. It was a bad day.

[@WarrenGarabrandt]

A guy stole a car and proceeded to flee from the police on my town a little while back. The car was abandoned in the street in front of my alley, and my surveillance system caught the whole thing. The guy didn't even bother putting it in park it looked like. Those brakes were glowing so hot in the footage you couldn't see the tire rim any more. It was just white hot on the screen. Absolutely nuts.

[@jarod997]

I used to work for a company who manufactured wheel speed sensors for a number of aircraft, it's actually really interesting how the anti-skid system works. Depending on the aircraft, they can be a single or dual channel system, and there's a system in place to detect a broken wire even if the brakes are not being used.

[@alexstrazza4068]

Loved the video, great explanation and good demos. I hope to see more of these!!

[@arthurlejawka6392]

Does RTO also arm spoilers for rejected takeoff ?

[@MentourPilot]

Yes, but it’s a different system that activates it

[@puma.will.pounce7590]

Partly. You arm the spoilers to deploy automatically by (1) selecting RTO on the Autobrakes dial as Mentour showed and (2) move the spoiler handle to the "ARMED" position. Moving the spoiler handle to the ARMED detent will also cause the ground spoilers to automatically deploy during not only a rejected takeoff but during landing as well.

[@neilsuri]

Love the animations! These technical videos are the best!

[@sharoncassell9358]

The c141 had anti skid system . We had to change 8 wheels after hard landing. They all blew out. A person approaching the plane from the side got hit with the wheel rim in the chest and died. The wheels can be very hot and dangerous. They are rather heavy.

[@neitasfuneralhomeltd]

Loving These Technical Videos

[@wavseeker]

loved the technicality of this video and i loved the images and videos used! keep up the great content!

[@rickochet6569]

Thank you so much! I really enjoyed this, I love systems videos, really interesting!

[@t1geres544]

Thanks for the great content!

[@bertblankenstein3738]

Thank you Petter! This was very informative.

[@johnmaclellan2589]

Excellent teaching about aircraft braking. Thank you for your wonderful videos.

[@sheriflashin]

Hey mentour pilot love your videos:) would love to see a video about aircraft maintenance and what goes around in the hangers.

[@alkhibrah]

Hi. This is interesting. As introduction, it'll be interesting to mention that airplane breaking is constitute by: aero brakes, tires brakes, and thrust reverse. Thank you.

[@shakeit6898]

Thank you for using Helios LIvery in the video!

[@david14Herbie]

Timed so well! I was literally wondering that this week

[@AllanEvansOfficial]

Can you do a video on why airplanes don’t fly in a straight line even to short destinations?

[@gabrielsimon7944]

Ahhh you got a heart I think that might mean a video is coming ...

[@oldman975]

I’d like know that,,too. Great suggestion!

[@AllanEvansOfficial]

@@gabrielsimon7944 I hope so! It’s been a dying itch to understand this! Especially between short flights. For example, San Diego CA - Las Vegas NV. Only a 45 minute flight but seems like it could be shorter if they would just fly straight!

[@williamhaynes7089]

my guess is the world is round...

[@user-fn1xm3pq6t]

Usually it's because of airways.

[@ajssimmer2922]

Love your content😄🤗

[@raoulsantos1522]

I enjoy your very informative videos, your are not only a pilot, but your are a very good teacher

[@murraystewartj]

Petter, any semi truck driver who deals with long down hill runs know this. That's why they gear down and use engine (jake) brakes rather than rely on friction brakes. Brake fade is a thing, and if a trucker overheats their brakes - well that's what runaway lanes are for. I can't imagine anything more terrifying than having a brake failure as a pilot, trucker or, in my case, in my POS car.

[@matsv201]

That is really a case for hybrid trucks

[@kpn574]

Whenever I read or see a video on brakes or braking, I remember Swiss Air 306. The Caravelle crashed because of overheated brakes stowed after takeoff resulting in fire and destruction of hydraulic systems. 80 lives perished. Morbid, I know.

[@Dirk-van-den-Berg]

That is a good story about breaking. During all the flights I took,, on landing there was a regular descelerating movement. Just grab your seat bars and everything was fine. On one landing in Washington DC. from Europe the plane was descelerating so heavily I was pushed forward strongly, I had to grab the backseat in front of me so not to get slammed against it.

[@marcmcreynolds2827]

I once got to experience max braking while standing up (in the cockpit, behind the captain during an accelerate/stop test). I was hanging on for dear life to the column of a temporary equipment rack behind me. Even back in my lean/40-pushups days, it was all I could do to stay out of the captain's lap.

[@jeremykeba6428]

Thanks again for videos like this. Love the technical videos. Every video i learn just how amazing aviation is.

[@ivayloivanov9277]

The most useful channel I have ever found. It makes my life easier . Thank you👏🏻

[@dewiz9596]

Well, that was a lot more interesting than I thought it would be.

[@martinmillar8447]

These always are

[@nigelburgess9946]

Concorde had breaks on the nose wheel, but only to stop the wheel spinning when it was being retracted

[@puma.will.pounce7590]

Concorde had wheel brake fans in its rear bogies.

[@aih1013]

Thank you for the video. Superb explanation.

[@paulwinter9672]

A natural teacher, love it.🙂

[@pilotavery]

Drop the landing gear for a few seconds at a couple thousand feet altitude to cool it off

[@lordw9609]

Haha I thought the same thing. Wouldn't that be a drag? 😆

[@pilotavery]

@@lordw9609 Well the extra fuel might be less than the extra revenue from reduced loading times. It's a cost-benefit. This is a joke OFC

[@froggymicb]

I'm sure there is a procedure to do this.

[@ChiDraconis]

@@froggymicb Yes; Look it up in the manual *before* attempting the approach!

[@ChiDraconis]

@@pilotavery Whatever OFC denotes I had a girl friend whom held an MBA and obtained work at ( major carrier ) I can assure you is is no joke to them: If some person in that position reads this they might just do the calc's ~ the person expressed wonderment at how 2 major airframe had reported being under 1 mile separation - all the computing power we have nowadays can be brought to bear saving 0.000051 / seat-mile → Many do not realize the commercial carriers operate on thin margins

[@michellepowell1956]

the early 727s had an option for nose brakes.

[@Leminge42]

The saab gripen has also nosebreaks. They really nake a diffenerce in combination with the canards pushing down

[@hairyairey]

@@Leminge42 Was at Farnborough many years ago with a Saab pilot showing off the nosewheel brake whilst spooling up the engine. Then off he went! They don't let you that close now.

[@aiestef]

I love your technical videos too!

[@danielbustos]

I have one year flying the b737. Really helpful, thank you so much. Greetings from Mexico

[@dennishanlon4856]

Small point, but I recall Boeing once offered nose wheel brakes as an option on its high gross 727-200 ADV’s.

[@puma.will.pounce7590]

2:45 - You left out the part that the brakes are certified to be able to stop an MTOW aircraft WITHOUT the use of thrust reversers.

[@tunnelrat6809]

I really love these more technical videos sir! Thank you!

[@macentropist1301]

Always love your cogent explanation Pettar

[@musicnotenshi]

Thank you for a new highly detailed video! Quite a lot new things to know. The question on the autobrake (especially on the RTO braking). As i understand the manual brake application disengage the autobrake system. But, as i understand the captain are mandated to manually apply near full manual braking at the rejected takeoff above 80 knots, so RTO just saves about a second or so and serves as failsafe for human error basically? Is that correct?

[@cedricromano7354]

I guess there was a version of a B727 that had nose wheel brakes in an attempt to reduce even more landing distances, but it was abandoned due to weight and not achieve the desired objective.

[@christinecalafatis7683]

What a great explanation! Your videos are so great, thank you for the work and effort you put into these!

[@stevedowler2366]

Great technical video, thanks. I've only been through a rejected takeoff once, as a passenger of course since I'm not a pilot just always interested in how things happen with aircraft. It was in a Shorts turbo prop (or fan, don't recall) on a short runway at a relatively small airport (SBA). Passengers experienced that situation of hanging on our seatbelts during maximum braking but nobody panicked and we were at full stop with room to spare remaining ahead on the runway. I recall it turned out to be a false warning indicator that caused the rejected TO. It was tested, resolved and we proceeded back out to takeoff with nothing further of note. After initial concern, it became an interesting diversion from normal operation, at least for myself. Cheers and stay safe.

[@kelvinmwalili5609]

You good mentour,,, your vedios are just good,🤗

[@nfjrb]

You can use the heat energy to warm up your coffee system.

[@cieludbjrg4706]

Damn. I always thought that reverse thrust was the best way to stop (or at least brake) an airplane. Now I've learned something! 😄

[@rainscratch]

The brakes information was excellent.

[@albucristian7861]

The third brake is the wall of the airport:))

[@Markle2k]

The “brake pad” would be the cockpit and crew.

[@mikeschmidt2695]

i love watching your video's from the United states very intresting and great information and entertaining hope all is well with you and the family thank you

[@MentourPilot]

Great to hear that

[@Paul1958R]

Petter/Mentour - fantastic video thank you! God bless Paul (in MA USA)

[@ismaelbs4815]

A big thank you Petter for these technical podcasts you have been doing. Besides of being very interesting, they are helpful to complement the atpl theory for example.

[@kilianortmann9979]

A brake is basically just a type of clutch, that happens to connect the wheels to the frame. These brakes are actually quite similar to a multi plate clutch. That being said, there are few things faster and heavier, than a landing airplane, lots and lots of heat.

[@AlessandroGenTLe]

Exactly what I was thinking: they reminds me a lot my motorcycle clutch, just working the other way around (not to transfer motion to the wheel but to stop the wheel to spin, a bit like shifting down).

[@phillee2814]

Railway trains can be much heavier and have far less grip - steel wheel on steel rail is what makes them efficient, but also means they are unable to stop hard. Of course, failure to strap down the self-loading cargo is also a limiting factor. Ships are vastly heavier, although much slower, but again - very limited grip so emergency stops are not a thing in naval architecture.

[@unvergebeneid]

There are different kinds of brakes though. You are talking about friction brakes but there are induction and regenerative brakes, too, that are used on high-speed trains.

[@phillee2814]

@@unvergebeneid They are still limited to the grip of the wheel on its running surface. The only exceptions are those used on a few mountain railways and tramways which grip the rail itself, but they are limited in usefulness due to the inability to deal seamlessly with points and crossings. Regenerative braking is also used on EVs.

[@Kedvespatikus]

I have a question: can frequent use of the anti-skid system wear off carbon brakes quickly?

[@roriquevernonii8439]

I wouldn't say quickly, it would be quicker than if you didn't use anti-skid, but the wear rate is according to design. The issue with this is that you wear down and destroy the tires when the wheels lock up.

[@marcmcreynolds2827]

@Jim Mork Friction coefficient (with A/S) is around 0.75 for airliner tires on dry pavement (varies a bit with speed). A wet runway knocks that down to more like 0.4 depending on the particulars, and then ice or hydroplaning closer to 0.1 or less. So reversers don't typically matter much for average stops on a dry runway, but are crucial when runway friction is severely degraded.

[@marcmcreynolds2827]

​@Jim Mork In my answers I like to throw in numbers perhaps not readily available on the internet, for whomever might be curious, but the bottom line is antiskid systems work on contaminated runways as well. What changes as surface friction degrades is how the plot of brake pressure vs time looks. On a dry runway, the antiskid-enabled brake pressure is a flat-ish line with just small ripples from the antiskid's pressure dumps. The lower the runway friction, the deeper and wider those pressure drops get.

[@vinylrevolutions9718]

Thanks for an interesting video Mentour. Yes, I really enjoy the technical videos.

[@richtrost2676]

Very interesting video. I do enjoy the more technical aspects of aircraft design. Thanks!

[@Draavo]

Very early! Can tell this will be great! :)

[@Halli50]

If you think airliner braking is a complicated issue, you should try operating smaller turboprops with no anti-skid and perhaps badly designed brakes. They can be a nightmare! Some of those aircraft (Cessnas C406 & C441 and the DHC-6 Twin Otter) have nicely designed no-antiskid systems where the brake pedal force directly translates to brake effect, just like an ancient car with no ABS. There was one aircraft I have flown that has astonishingly difficult brakes, the Do228 Dornier. after landing, you applied brake pedal and nothing happened. Then you carefully applied some more pedal pressure and very little happened. THEN, if you had to, you applied just a little more pedal pressure and the wheels would lock up! A flat spot on the main tires SERIOUSLY damages them, an expensive occurrence. Fortunately the Do228 has a touchdown speed well below 100 knots and being a Garret-powered high-wing aircraft has MAGNIFICENT reverse capabilities. Wheel braking was rarely needed for anything more than taxying.

[@balajisharathkumar9753]

absolutely fantastic video

[@CaptainKevin]

Just to add to what you said about the rejected take-off test, when they do this, the test is done with the brakes degraded to the point where an airline would normally be required to replace them. Once they stop the plane, the plane has to sit for five minutes without catching on fire to simulate the time it would take the fire crew to get there. As far as nose wheel brakes, the Boeing 727 had added in at some point, but they were later removed after it was determined that they didn't really have much of an effect when it came to stopping the plane.

[@MartinY1234.]

Haven’t seen this vid yet but know it’s good I’ve smashed the like first

[@accountalreadyinuse]

There are also brake fans that are supposed to cool brakes after landing. At least in some airbus a320 family. Funny thing about those is that you have to make sure no one is standing next to main landing gear when those fans are applied because it blows out carbon fibre dust which can be extremely harmfull to your lungs.

[@robertpearse6472]

As a Aussie very chuffed to see the big Qantas baby in you video. More than that love these technical videos. Well don from Down under!