Henry - Great video! One minor clarification: The core of the engine does actually produce a significant amount of thrust in a high-bypass turbofan - when at altitude. It's about 50/50. This is due to the density of the air being much lower at 30+ k feet, the fan is not drawing as much mass flow so it can't impart as much momentum. As such, the fan's power consumption isn't as high, which leaves more enthalpy available to convert to thrust coming out of the core nozzle (the turbine driving the fan doesn't need as much at cruise). At takeoff, though, you're trying to squeeze every last drop out of the fan and therefore there will be very little energy left over to make thrust out of the core. At this point, the fan absolutely does produce the majority of the thrust (~ 85/15).
Another reason for bigger engines is noise. Because the velocity of the air travaling through the engine is proportional to the sound produced by compression shocks inside the engine. If you want to build quiter engines, you have to reduce the velocity of the air, but in order to compensate for the reduction in thrust, you need a higher mass flow rate. This is archived by a bigger diametre of the engine. Another limitation for the size of airplane engines are the standard sizes of airport hangars, that one reason why in recent development for example, of the Trent 900, the casing for the air-intake is elliptical rather than round.
+Sinan Al-Khadra While not true, it should be noted that a surface with air moving different velocities on either side will generate induced drag as well as a lot of noise from the vortices.
There are also various tasks performed on the ground that get more difficult the higher up the main fuselage of the airplane is off the ground and engines mounted below the wings are the main factor influencing how high that has to be. Not to mention that the landing gear causes more drag and needs to be more sturdy if it is longer too.
Great example of the difference between momentum and kinetic energy! It's difficult to intuitively grasp why one has a linear increase with velocity and the other the square of the velocity; and there is not much on TH-cam. That would make another wonderful video. In any case, I consider myself so fortunate to be able to watch your videos; keep up the good work!
The large turbine is also referred to as a bypass fan. In addition to trust, it also helps to create a cushion around the jet exhaust, helping to reduce noise vs a regular jet engine.
Modern fighter jets have dropped turbojets in favor of turbofan engines, for the same reason as the commercial airlines. They just tack on afterburners for more thrust when needed.
Nope. Fighter Jets use Turbojets because using a Turbofan with an Afterburner will just defeat the purpose of the Afterburner, if you don’t know Afterburners are used to burn the remaining Oxygen that exits the engine so they can create more thrust. But only one Jet in history used a bypass system and that is the Lockheed SR-71 Blackbird where tubes connected to the 4th Stage Compressor took air and sent it directly into the Afterburner
I'm an aspiring MSc Aero Engineer and must say, I'm impressed. The video explains a complex topic very well in just 1 minute. Some minor "imprecisions", but very well done!
There are a LOT of reasons as to why engines are like they are, what I find funny though is he focused on the larger commercial planes, but had a tiny side note for ramjet and turboprop, but very little to none on the prop planes, the Boeing aircraft use large engines for efficiency and speed, while the Dash 8 Q400 and ATR72 have tiny little engines that are much smaller and slower, but have a bigger range then some airliners and have massive fuel savings as being the most fuel efficient aircraft available, all Boeing and Airbus make are aircraft to shove people into and get them from point A to point B quickly, and most engines on those aircraft are limited by wing-ground clearance not just limitations of the engines themselves
This system actually works in reverse when talking about things with high vacuum efficiency, since the faster the exhaust moves the higher the specific impulse (about 100s for every Km/s of exhaust velocity), since the energy wastes don’t matter when rockets don’t have fans.
Good video, but just 1 thing, modern fighter jets also use turbofan engines, mainly because you still want your fighter jets to be able to be able to fly for an appreciable amount of time. The main difference between a jet used for fighters and commercial jets is the bypass ratio. In general fighters use a lower bypass ratio because there is a bypass ratio limit after which after-burning (or reheating) becomes difficult to achieve.
Its all to do with bypass ratio. You can also increase thrust by producing an engine with a much smaller core but the same fan diameter. Assuming you can create a core that has the same power output
Interesting because in spacecraft its all about high exhaust velocity, which means more efficiency... Having air everywhere is such a valuable resource!
Additionally the size of the fan is limited by the centrifugal and rotational forces on fan blades (both normal stresses and bending stresses). Furthermore, longer fan blade tips can reach supersonic speeds at the tips, leading to shocks and flow separation. Of course innovations in blade materials and design can push these boundaries.
+Jonathantje / Bammerbom Drastically over simplifying, a machine gun is like a very inefficient rocket engine, but instead of shooting out hot fuel and oxidizer it shoots bullets. Due the recoil produced by most guns being rather small to a car it doesn't move the car much.
The A350 has two engines that are bigger because it is smaller. The 747 has four engines that are smaller, while producing more thrust, that first segment wasn’t necessary.
The interesting thing is that this is the exact opposite of how it works for rockets. With a rocket, you want the exhaust velocity to be as high as possible so that the propellant mass fraction can be minimized, hence why ion engines are so efficient.
It depends. He's actually not 100% correct. Jet engines these days don't shoot out their exhaust at high speeds. Most rocket engines shoot their propellants out nearly ten times faster. The reason they're efficient is that they use the air around them. Most Isp/effective exhaust velocity data for jets is actually skewed, since Isp is impulse per kg of propellant in the vehicle. Some of the airplane's propellant is outside of the vehicle.He's right about the energy issue, though. It takes more energy to shove a small amount of mass really fast than a lot of mass really slow. The math shows it.
Cashing in on the 2 minute videos which 1/4 consist of a sponsor message. GREAT! If any other type of channel did this they would be hated on to no end.
Yup, we usually refer to that as "Bypass Ratio." The amount of air driven by the fan relative to the amount driven by the core. High bypass engines (sometimes as high as 10:1) are much more fuel efficient and quieter, while low bypass engines (nothing really uses a pure-jet anymore, but jet fighters can have bypass ratios as low as 0.3:1) generally have a better thrust to weight ratio, making the more suitable for applications where performance trumps economy and range.
One of best minute physics videos in a while, really interesting, well explained and concise. But most importantly it was on a topic that isn't known about very widely.
Wow, I came to this channel to boost my understanding of just how quantum mechanics plays into our everyday lives, and what it means for the future of technology. This channel is highly educational and I recommend watching every video.
Yay! Another Ender's Game fan. This like my favourite book of all time. Some random quotes off the top of my head: "I’ve watched through his eyes, I’ve listened through his ears, and I tell you he’s the one. Or as close to the one as we're going to get." “I'm putting you in Dink Meeker's toon. From now on, as far as you're concerned, Dink Meeker is God." "Then who are you?" "The personnel officer who hired God.” “He could see Bonzo's anger growing hot. Hot anger was bad. Ender's anger was cold, and he could use it. Bonzo's was hot, and so it used him. ” "For Ender, I burn candles on his birthday, but for Peter, I fulfill his dreams" "Salaam" "Alas it is not to be" “I also remembered that you were beautiful." "Memory does play tricks on us." "No. Your face is the same, but I don't remember what beautiful means anymore.” "Sometimes lies were more dependable than the truth." "Early to bed and early to rise makes a man stupid and blind in the eyes" "I've lived so long with pain, I wouldn't know what to do without it" "You don't understand" he said "Yes i do" "No you don't. I don't want to beat Peter" "Then what do you want?" "I want him to love me”
I want to point out that the Airbus A350 only has 2 engines while the Boeing 747 has 4. This is why the A350 has bigger engines than the new 747. If the A350 is powered by 4 engines, like the A340, it will have smaller engines than the 747.
Guys I can attest to that ad. If there is one book you should read in your whole life it should probably be a physics book but if there is another book it should really be Ender's Game. It's the best Sci-Fi in town and I've read Hubbard, Asimov, Clarke, Heinlein, Wells, Orwell and Gibson and Dick.... and .... and ... While you're at it read his fantasy too. The lost gate is the best accounting of any mythology I've ever heard. And if you're into audio books go into this forgetting any other audio you've ever heard. This is ten times better. Top tier.
Also you forgot to mention the bigger the engine the bigger the propeller, and the bigger the propeller the faster the tip of the propeller will spin up to a point it will reach a sonic boom which is very detrimental.
+Miguel lopez airlines already fly with fuel consumption in mind the winglets on b737 reduce fuel about 4% per flight but a massive cost reduction. They use cost index to determine speed zero means save fuel while 300 means burn alot because we are experciencing strong winds.
The larger engines (high bypass turbofans) are also quieter, not just more efficient. The mixing of cooler air from the bypass duct with the hot exhaust from the engine core outlet helps to keep sound down by eliminating the harsh blending of varying temperature parcels of air (ambient air in the surrounding atmosphere and hot exhaust). Add some chevrons on the back of the nacelle (like the Boeing 787 and 747-8) and it blends even more and makes it quieter.
+Ag8MrE A jet engine typically has a compressor to compress ambient air as oxidizer, as opposed to pre-compressed oxidizer. The compressor is generally driven by a turbine connected to the exhaust, only without a fan that bypasses the combustion chamber (as in a turbofan). Even fighter jets these days generally use turbofan engines, albeit much more biased towards the jet than the fan compared to airliners.
Fighters use low-bypass, high-pressure turbofans, because the high fan pressure makes them suitable for use with afterburners, allowing very high thrust for their size and weight, but still allowing good fuel economy below the speed of sound when not afterburning. Passenger jets use high bypass, low-pressure engines because of their very high fuel efficiency. Per passenger, modern-day airliners burn about the same amount of fuel per unit of distance traveled as a subcompact economy car--and they do it while travelling 8 to 10 times as fast!
4 metres is only optimal at a certain rotational speed. In the general case larger, slower rotating propellors produce less turbulence and are more energy efficient. I think the treatment here is specifically to do with jet turbines, which prefer to turn fast. It doesn't apply to other motors.
1:23 being a senior in AP physics, I understood about 40% of that, but thanks for including the math! I hate it when people go "I'll spare you the math..." lol
The same physics explains lift. We could point a small fast propeller upwards to generate lift, but the downward stream of fast-moving air wastes energy. Or we can have very large wings that nudge a lot of air downwards very slowly, very efficiently like a glider.
As an aviator, I agree with video. In fact, airplanes are products of design compromise between four contradictory quantities: lift, thrust. weight, and range. You can have the highest aspec ratio wings that are ultra efficient, but are equally fragile. You have the biggest engine that can allow to move your plane at phenomenal speeds, but it will big, heavy, and will guzzle fuel like no other.
One of the simpler answers to this question is that newer engines use a greater amount of bypass air to achieve greater thrust. A large amount of air bypasses the combustion chamber and is re-introduced into the combustion exhaust. This air expands and accelerates in the hot exhaust and delivers more thrust. The engines must be bigger to allow for the bypass air. (BTW: Read Ender's Game about 6 times and enjoyed it every time).
Xenro66 I think you'll enjoy Audible if you don't like reading! It's great for me since I commute, and you can listen while doing menial work eg washing up/driving, so don't need to set any time aside for reading alone. Currently I'm reading a book called "the power of habit" which is really relevant in my life right now so I enjoy it - you just need to find a book you'll enjoy, really. It is, however, £8/month...
Kishan Chandrakumar Only issue is there's nowhere in the day that I can comfortably sit down and listen to an audio book. I don't commute for long, I can't exactly listen while in classes, and at home, I have youtube! xD. But ouch, 8 quid a month, that's damn well expensive. razveck Hmm, it's not that simple for me. I rely heavily on visuals to get immersed in a story.
+Cryp Tic Yeah, fluid dynamics is really complicated, especially when you're talking about compressible fluids like air. Almost any calculation you perform would involve making some assumptions that simplify the problem from the real world solution. The fact that the calculations even fit on a single frame of the video means this is a very simple and rough estimate with a lot of assumptions. The trick is knowing the right assumptions to make the calculation manageable while still being accurate. That, or knowing the right computer software to model the problem, which in itself takes a good deal of experience. Really, that's true for a lot of physics and engineering sciences in general.
I dont like the new style of not physically timelapse drawing like you used to. im sure this is easier and more efficient and ill always watch but im just not a huge fan.
I really liked the derivation of the formula at the end. I assume that this is a well known equation within the aeronautics field? Can you recommend any other video or textbook where the design of an engine in terms of efficiency is discussed in greater detail?
Compare a A350 with a B747 was really a bad example.... Firstly, the B747 is marginally larger. Looking at the 747-400 compared to the A350-900, the Airbus actually got larger wing span and its only 4 meters shorter.. so yes, the 747 is larger, but only just. The A350 is actually a huge plane And the uppcoming A350-1000 will actually be longer than the 747-400. (of cause the 747-i8 is longer still, but its the 747-400 in the picture.) The issue is that B747 have 4 engines and the A350 have only 2. The thurst of the A350 engines is maximum 350kN, but for the B747-400 only 280kN. Actually the engines of the A350 is even stronger than the one of the A380. There is one additional error in the video. its over theoretical compared to the actual reality of aircraft engines. All (or almost all?) turbofan engines is direct drive engines. Because the fanblade have a maximum speed the rotation velocity most be keeped. This make it so the turbine engine have to have huge torque. The compromise to this is that the turbine engines is a loot larger than it need to be, and the fan ist still smaler than is optimal. This is why engine manufacture dont make the fan at optimal size. Because then the torque would be to much. The solution to this is of cause to introduce gearing. And there are some prototypes under development. This not only makes it so the fan can be any size (that is the optimal size for every given aircraft, but it also make it so the turbine engine can be the optimal size to.. that is a lot smaller. This will decrease the fuel consumpsion more than making the fan bigger. But the comibnation will cut the fuel consumption quite a bit.
jibeneyto Well.. i would still think they should compare two aircraft of similar size. Say a A330 and a 787. Also i think the issue about geard and ungeard turbine is to important to just skip over..... .... i would think this is more a matter of that the videomakes know the theoretical background, but not the current limitations of the engines that is in service. There is a glaring whole in the video. If they know the optimal size (and it been known since the 1900-century)... why don´t they just makes the engines optimal size... This is a question that is unanswered.....And the answer is quite simple.. there is no gearing.... so they cant.
You're right as before, but gearing in turbofans has not really been implemented in any aircraft. Maybe in the future it will. I don't think it's important to consider such a "new" concept in a 2-minute video.
I find it interesting how we can define physics using mathematical equations and then use those equations to optimize technology in intuitive but not immediately recognizable ways. Neat
"As I might have heard?" Only like seventeen billion times. I love Audible. I use their product, in fact I have been a subscriber for years. I also love the fact that they pay for much of my online content through their advertisement. But comes to a point where I am soooooo friggin sick of hearing the same ad time and time again. And what if I DO what to support this youtube channel or podcast? I can't follow their merchant link to sign up, because I already am signed up. And if I wasnt, I would still be only able to support one of the dozens of creators that I like that are supported by Audible. I dont know if there is a solution, maybe audible is the only one willing to support creators, or maybe they just are the only ones with really good taste (aka same as mine)...
Efficiency is certainly the main reason size has been increasing but it's not the only reason, larger engines are quieter because they can generate the needed thrust by moving a larger volume of air but at a slower exhaust velocity. That's also the reason behind putting larger fans on higher end computers - it keeps the noise down while still providing the cooling needed.
A clear explanation of the commercial air place compared to military fighter plane. Now, I am curious to learn how these two compare to a rocket engine as used in the space shuttle.
0:17, describes a turbofan jet engine which has all the 'bypass' air going around the jet core as opposed to a turbojet in which all of the air goes through the jet core and turbine itself.
+Timothy McLean Probably much more difficult to make. The tolerances need to be very small to reduce vibrations. The bigger the engine, the more difficult to produce with small tolerances.
It looks like your math assumes that the area causing drag is just the frontal area of the engine. I don't think that's right: it's the frontal area of the *whole plane* that causes drag, of which the engine is only a small part. Also, since the engine is moving air *through* itself, I don't think you can model its drag as if it's a flat disk with Cd=1.
nice, I was curious about that as well, cuz jet fighters always have small engines with like 1/7 as much dry thrust as a GE90 (~500kN), but they both have similar fuel consumption
QuakyJunior Whenever I'm on the computer and it's late at night, I make really stupid mistakes. However, you are wrong. It's pi*(r^2) ,this is area, not circumference. I was also wrong, but you were, too. 12.5, divide by pi, take square root, get radius. Multiply by 2, get 3.9894228040143267793994605993438. Pretty close, I'd say.
That plane at the end looked adorable.
Look up the Boeing X Plane
That's the Stipa Caproni airliner edition.
Henry - Great video! One minor clarification: The core of the engine does actually produce a significant amount of thrust in a high-bypass turbofan - when at altitude. It's about 50/50. This is due to the density of the air being much lower at 30+ k feet, the fan is not drawing as much mass flow so it can't impart as much momentum. As such, the fan's power consumption isn't as high, which leaves more enthalpy available to convert to thrust coming out of the core nozzle (the turbine driving the fan doesn't need as much at cruise). At takeoff, though, you're trying to squeeze every last drop out of the fan and therefore there will be very little energy left over to make thrust out of the core. At this point, the fan absolutely does produce the majority of the thrust (~ 85/15).
I want the last plane.
Me too
+tver I came.
+kaczan3 i want some science on why that last plane wouldnt work.
+kaczan3 KSP
kerbals are always the answer
Another reason for bigger engines is noise. Because the velocity of the air travaling through the engine is proportional to the sound produced by compression shocks inside the engine. If you want to build quiter engines, you have to reduce the velocity of the air, but in order to compensate for the reduction in thrust, you need a higher mass flow rate. This is archived by a bigger diametre of the engine.
Another limitation for the size of airplane engines are the standard sizes of airport hangars, that one reason why in recent development for example, of the Trent 900, the casing for the air-intake is elliptical rather than round.
+Sinan Al-Khadra While not true, it should be noted that a surface with air moving different velocities on either side will generate induced drag as well as a lot of noise from the vortices.
does it applies to cats as well?
Sinan Al-Khadra what?
There are also various tasks performed on the ground that get more difficult the higher up the main fuselage of the airplane is off the ground and engines mounted below the wings are the main factor influencing how high that has to be. Not to mention that the landing gear causes more drag and needs to be more sturdy if it is longer too.
Great example of the difference between momentum and kinetic energy! It's difficult to intuitively grasp why one has a linear increase with velocity and the other the square of the velocity; and there is not much on TH-cam. That would make another wonderful video. In any case, I consider myself so fortunate to be able to watch your videos; keep up the good work!
1:31 I died XD:
R.I.P
Rest in RIP bro
+Simon Riley RIP in peace is better.
+Rafi Ahmed Chowdhury Ah yes, the Kirby 707 was a good attempt at aviation, but unfortunately it sucked too much.
+TaliesinMyrddin that was one of the better puns i've heard in a while. gg
The large turbine is also referred to as a bypass fan. In addition to trust, it also helps to create a cushion around the jet exhaust, helping to reduce noise vs a regular jet engine.
1:31 The last plane is so cute
+22BIKS I just want to comment that XD
+22BIKS There was a plane made in 1932 that if worked may have become the one he drew. its called the Stipa-Caproni.
JBTheMighty Thanks for letting me know XD
+Fallen Exe Oh yeah that is true. That plane isn't a airplane it is bird killer
***** It would never be as good as the planes today.
Modern fighter jets have dropped turbojets in favor of turbofan engines, for the same reason as the commercial airlines. They just tack on afterburners for more thrust when needed.
Low bypass turbofans
Nope. Fighter Jets use Turbojets because using a Turbofan with an Afterburner will just defeat the purpose of the Afterburner, if you don’t know Afterburners are used to burn the remaining Oxygen that exits the engine so they can create more thrust. But only one Jet in history used a bypass system and that is the Lockheed SR-71 Blackbird where tubes connected to the 4th Stage Compressor took air and sent it directly into the Afterburner
@@whoyoulookingatabs1028 nope
@@whoyoulookingatabs1028 Very wrong
But they have lower bypass ratio than airliners
By far one of the best "to-the-point" videos broken down to my simpleton level. Bravo minutephysics ;)
can that last plane carry me to Global Elite?
+AXE PIDY
Underrated comment.
silver 3
+AXE PIDY It would need a bigger engine
Fucking csgo tryhards
Melting Clocks I don't play cod, salty kid.
I'm an aspiring MSc Aero Engineer and must say, I'm impressed. The video explains a complex topic very well in just 1 minute. Some minor "imprecisions", but very well done!
There are a LOT of reasons as to why engines are like they are, what I find funny though is he focused on the larger commercial planes, but had a tiny side note for ramjet and turboprop, but very little to none on the prop planes, the Boeing aircraft use large engines for efficiency and speed, while the Dash 8 Q400 and ATR72 have tiny little engines that are much smaller and slower, but have a bigger range then some airliners and have massive fuel savings as being the most fuel efficient aircraft available, all Boeing and Airbus make are aircraft to shove people into and get them from point A to point B quickly, and most engines on those aircraft are limited by wing-ground clearance not just limitations of the engines themselves
This system actually works in reverse when talking about things with high vacuum efficiency, since the faster the exhaust moves the higher the specific impulse (about 100s for every Km/s of exhaust velocity), since the energy wastes don’t matter when rockets don’t have fans.
most people have no idea how incredible air planes really are.
Ikr
+TheXtremeunleashed ikr
ikr pdq kp lmfao tits
+TheXtremeunleashed Whenever I get in a plane I think about how incredible machines they are.
Shaheer Syed I know, it took me so long to learn about aerodynamics.
Good video, but just 1 thing, modern fighter jets also use turbofan engines, mainly because you still want your fighter jets to be able to be able to fly for an appreciable amount of time. The main difference between a jet used for fighters and commercial jets is the bypass ratio. In general fighters use a lower bypass ratio because there is a bypass ratio limit after which after-burning (or reheating) becomes difficult to achieve.
finally was able to understand equations at 1:25 when realizing |sec didn't mean LINE SECANT.. but ONE SECOND.. sigh..
Oof
Ideal engine diameter
What a great intro to that Audible ad!
a rough estimation
XD XD XD
Mr_____ - dead asf
Its all to do with bypass ratio. You can also increase thrust by producing an engine with a much smaller core but the same fan diameter. Assuming you can create a core that has the same power output
Love these videos more please :D
agreed
Daddy Sakurai nerfed you, hihi!
Interesting because in spacecraft its all about high exhaust velocity, which means more efficiency...
Having air everywhere is such a valuable resource!
1:20 yes, yes, I understand some of those characters...
All of these are mostly taught by the 8th grade
Source: Just passed 8th
@@TheBluePhoenix008 education ain't universal like that
Additionally the size of the fan is limited by the centrifugal and rotational forces on fan blades (both normal stresses and bending stresses). Furthermore, longer fan blade tips can reach supersonic speeds at the tips, leading to shocks and flow separation. Of course innovations in blade materials and design can push these boundaries.
I understood the machine-gun part! I'm smart!
+DimesTR I didn't.
+Jonathantje / Bammerbom XKCD Refrence? I'm not sure
+Jonathantje / Bammerbom Drastically over simplifying, a machine gun is like a very inefficient rocket engine, but instead of shooting out hot fuel and oxidizer it shoots bullets. Due the recoil produced by most guns being rather small to a car it doesn't move the car much.
I hope so
DimesTR no you're not
The A350 has two engines that are bigger because it is smaller. The 747 has four engines that are smaller, while producing more thrust, that first segment wasn’t necessary.
1:16 "dreg"
Goddamnit hahahaha
b-but now that you said that i can't unhear it ... before reading your coment i heard drag ... but now i hear dreg everytime .... WTF ?
NOOO it happened to me to
dreg dreg dreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dregdreg dreg
Greg
The interesting thing is that this is the exact opposite of how it works for rockets. With a rocket, you want the exhaust velocity to be as high as possible so that the propellant mass fraction can be minimized, hence why ion engines are so efficient.
It depends. He's actually not 100% correct. Jet engines these days don't shoot out their exhaust at high speeds. Most rocket engines shoot their propellants out nearly ten times faster. The reason they're efficient is that they use the air around them. Most Isp/effective exhaust velocity data for jets is actually skewed, since Isp is impulse per kg of propellant in the vehicle. Some of the airplane's propellant is outside of the vehicle.He's right about the energy issue, though. It takes more energy to shove a small amount of mass really fast than a lot of mass really slow. The math shows it.
1:15
"then it starts to cause too much DREG"
+Kivtej Rakhra he says dreg
Dont do dregs
@@itskelvinn хюжэзмэжп
I actually recently spent a week at GE Aviation with their new GE9X. 11 feet 2 inches in diameter at the blade tips! It was huge!
+Ethan Education No, however I do have some photos. If you're legitimately interested I can compile then and post them
+Ethan Education Sure thing. I'll forward what I'm allowed to.
omg ENDERS GAME. I loved that book. Its what got me into space games.
Cashing in on the 2 minute videos which 1/4 consist of a sponsor message. GREAT! If any other type of channel did this they would be hated on to no end.
Good explane-ation Planely the best video Jet!
Bah-dum-tss 😂
If they ever made a plane like the last one you drew, I'd fly on that, no problem. So cool.
1:24 thats a very rough estimate.
Ikr haha
well, it would take forever to write it out, and it not too big of an estimate anyway
It is, actually.
It has the Approximation symbol written within the actual equation. So.... ya...
1) "As you may have heard"
when in doubt though, remember to always add moar boosters.
+sbraz and if its too wobbly just smack a few more wings on it
+LeagueOfCakez And if it behaves like a wet noodle, add struts.
Fuck jet engines we have infinite fuel so we are gonna use rocket engines!
+Zuthal Soraniz Yup. Try simple planes today, I think you've got the basics down.
Yup, we usually refer to that as "Bypass Ratio." The amount of air driven by the fan relative to the amount driven by the core. High bypass engines (sometimes as high as 10:1) are much more fuel efficient and quieter, while low bypass engines (nothing really uses a pure-jet anymore, but jet fighters can have bypass ratios as low as 0.3:1) generally have a better thrust to weight ratio, making the more suitable for applications where performance trumps economy and range.
Never been so early in this channel
Same
+Shiben Chakravorty Same
+Shiben Chakravorty Agreed
+Shiben Chakravorty wow... and i just woke up too... early ftw
+Shiben Chakravorty Me 2
One of best minute physics videos in a while, really interesting, well explained and concise. But most importantly it was on a topic that isn't known about very widely.
It just dawned on me that this series was influenced by the Blue's Clues notebook segments. Just listen to that music.
+Anthony Pendley my god I just had that same realization as well xD
Piss.
Wow, I came to this channel to boost my understanding of just how quantum mechanics plays into our everyday lives, and what it means for the future of technology. This channel is highly educational and I recommend watching every video.
Bigger is better, up to a point. You don't want to tear her love place in two.
to 10000000000000000 decimal places.
+Raik That's what she said
@@yousorooo he*
Yay! Another Ender's Game fan. This like my favourite book of all time.
Some random quotes off the top of my head:
"I’ve watched through his eyes, I’ve listened through his ears, and I tell you he’s the one. Or as close to the one as we're going to get."
“I'm putting you in Dink Meeker's toon. From now on, as far as you're concerned, Dink Meeker is God."
"Then who are you?"
"The personnel officer who hired God.”
“He could see Bonzo's anger growing hot. Hot anger was bad. Ender's anger was cold, and he could use it. Bonzo's was hot, and so it used him. ”
"For Ender, I burn candles on his birthday, but for Peter, I fulfill his dreams"
"Salaam"
"Alas it is not to be"
“I also remembered that you were beautiful."
"Memory does play tricks on us."
"No. Your face is the same, but I don't remember what beautiful means anymore.”
"Sometimes lies were more dependable than the truth."
"Early to bed and early to rise makes a man stupid and blind in the eyes"
"I've lived so long with pain, I wouldn't know what to do without it"
"You don't understand" he said
"Yes i do"
"No you don't. I don't want to beat Peter"
"Then what do you want?"
"I want him to love me”
I want to point out that the Airbus A350 only has 2 engines while the Boeing 747 has 4. This is why the A350 has bigger engines than the new 747. If the A350 is powered by 4 engines, like the A340, it will have smaller engines than the 747.
Guys I can attest to that ad. If there is one book you should read in your whole life it should probably be a physics book but if there is another book it should really be Ender's Game. It's the best Sci-Fi in town and I've read Hubbard, Asimov, Clarke, Heinlein, Wells, Orwell and Gibson and Dick.... and .... and ...
While you're at it read his fantasy too. The lost gate is the best accounting of any mythology I've ever heard. And if you're into audio books go into this forgetting any other audio you've ever heard. This is ten times better. Top tier.
That image at 1:32 made me laugh for 2 minutes straight.
P.S. Why is audible sponsoring pretty much every TH-cam channel now?
Amazing content! explains a lot in small amount of time, other youtubers would lengthen the video to 10:00 just to get extra money
Also you forgot to mention the bigger the engine the bigger the propeller, and the bigger the propeller the faster the tip of the propeller will spin up to a point it will reach a sonic boom which is very detrimental.
+dontknowdontcare The fan blades already are supersonic at the tip I think. Thats what they told us at the university anyways -
they are already super sonic but a company just resent ly figured out how to have the fans run slower to reduce fuel consumption.
+Miguel lopez airlines already fly with fuel consumption in mind the winglets on b737 reduce fuel about 4% per flight but a massive cost reduction.
They use cost index to determine speed zero means save fuel while 300 means burn alot because we are experciencing strong winds.
Those equations though!!! Took me back to my vehicle performance lectures. Oh how fun that was!
jets are really cool :)
The larger engines (high bypass turbofans) are also quieter, not just more efficient. The mixing of cooler air from the bypass duct with the hot exhaust from the engine core outlet helps to keep sound down by eliminating the harsh blending of varying temperature parcels of air (ambient air in the surrounding atmosphere and hot exhaust). Add some chevrons on the back of the nacelle (like the Boeing 787 and 747-8) and it blends even more and makes it quieter.
How is a "pure jet engine" (as used for fighter jets) different from a rocket engine? Is the difference that rockets carry an oxidiser?
Basically, yes.
+Ag8MrE A jet engine typically has a compressor to compress ambient air as oxidizer, as opposed to pre-compressed oxidizer. The compressor is generally driven by a turbine connected to the exhaust, only without a fan that bypasses the combustion chamber (as in a turbofan).
Even fighter jets these days generally use turbofan engines, albeit much more biased towards the jet than the fan compared to airliners.
Typically, fighters use low-bypass turbofans, most likely due to size restrictions, while airliners use increasingly-higher-bypass turbofans.
Fighters use low-bypass, high-pressure turbofans, because the high fan pressure makes them suitable for use with afterburners, allowing very high thrust for their size and weight, but still allowing good fuel economy below the speed of sound when not afterburning.
Passenger jets use high bypass, low-pressure engines because of their very high fuel efficiency. Per passenger, modern-day airliners burn about the same amount of fuel per unit of distance traveled as a subcompact economy car--and they do it while travelling 8 to 10 times as fast!
watching stuff about stuff you already know in great detail and is in fact my career, yet still enjoyable to watch.
4 metres is only optimal at a certain rotational speed. In the general case larger, slower rotating propellors produce less turbulence and are more energy efficient. I think the treatment here is specifically to do with jet turbines, which prefer to turn fast. It doesn't apply to other motors.
+Ray Kent I would expect that this video oversimplifies things a bit :)
1:23 being a senior in AP physics, I understood about 40% of that, but thanks for including the math! I hate it when people go "I'll spare you the math..." lol
I kinda laughed a little bit at the point when he said "kinda like using a machine gun to propel your car"
The same physics explains lift. We could point a small fast propeller upwards to generate lift, but the downward stream of fast-moving air wastes energy. Or we can have very large wings that nudge a lot of air downwards very slowly, very efficiently like a glider.
That plane with an engine belly looks adorable. I'd have it as a pet in the future.
+Ninterd2 There was a real Italian plane before WWII that looked like that called the Stipa-Caproni. It wasn't jet powered though.
yes :3
As an aviator, I agree with video. In fact, airplanes are products of design compromise between four contradictory quantities: lift, thrust. weight, and range. You can have the highest aspec ratio wings that are ultra efficient, but are equally fragile. You have the biggest engine that can allow to move your plane at phenomenal speeds, but it will big, heavy, and will guzzle fuel like no other.
I never asked myself that question in my life
One of the simpler answers to this question is that newer engines use a greater amount of bypass air to achieve greater thrust. A large amount of air bypasses the combustion chamber and is re-introduced into the combustion exhaust. This air expands and accelerates in the hot exhaust and delivers more thrust. The engines must be bigger to allow for the bypass air. (BTW: Read Ender's Game about 6 times and enjoyed it every time).
TH-cam.
sponsored by audible.com
+roshan keni Glad I'm not the only one to have noticed! However, I've fallen victim to their marketing - currently on the Audible free trial xD
+Kishan Chandrakumar What's it actually like? I've never listen to an audio book, and I don't really like books in general. Is it even useful?
Xenro66 I think you'll enjoy Audible if you don't like reading! It's great for me since I commute, and you can listen while doing menial work eg washing up/driving, so don't need to set any time aside for reading alone.
Currently I'm reading a book called "the power of habit" which is really relevant in my life right now so I enjoy it - you just need to find a book you'll enjoy, really. It is, however, £8/month...
+Xenro66 Listen to this video but don't look at it. Just the audio. Did you like it? If so, you'll like audiobooks.
Kishan Chandrakumar Only issue is there's nowhere in the day that I can comfortably sit down and listen to an audio book. I don't commute for long, I can't exactly listen while in classes, and at home, I have youtube! xD. But ouch, 8 quid a month, that's damn well expensive.
razveck Hmm, it's not that simple for me. I rely heavily on visuals to get immersed in a story.
always love these short clips of actually interesting topics
Its not a 'modern jet engine' it is a turbo fan. There are also turbo prop and turbo jet engines
Awesome video, as always
Good Work Henry!
I think the last one with big "X" on the last slid might work! at 1:30
+Jianyue Tang Yeah, I see nothing wrong with that design.
+Da_NKP it might need a larger fuel tank
+Jianyue Tang entirely fair, as well as larger wings.
A jet fighter version of that already exists and has existed since 1946. Look up the Mig-9.
Basically, but it wasn't big enough. We're talking something around the size of, say, an AirBus 320.
I really i fell in love with your channel. Thank you for doing such a great job by making these videos!
That last plane looks like kirby eating something sorta kinda! :D
+Power Max New copy ability confirmed? :D
I had forgotten how awesome your channel was.
1:25 when physicists take a rough estimate
+Cryp Tic Yeah, fluid dynamics is really complicated, especially when you're talking about compressible fluids like air. Almost any calculation you perform would involve making some assumptions that simplify the problem from the real world solution. The fact that the calculations even fit on a single frame of the video means this is a very simple and rough estimate with a lot of assumptions. The trick is knowing the right assumptions to make the calculation manageable while still being accurate. That, or knowing the right computer software to model the problem, which in itself takes a good deal of experience. Really, that's true for a lot of physics and engineering sciences in general.
+Gary Ermann ^^^when physicists explain things in simple terms^^^
That's a rough estimate by any engineer's standards as well. And it's not complicated at all. You can learn all the basics for this in a day.
Physics.. Its usually like that
Liked for the Ender's Game plug. One of my favorite books for sure.
I dont like the new style of not physically timelapse drawing like you used to. im sure this is easier and more efficient and ill always watch but im just not a huge fan.
You may not be a huge fan, but what about a huge engine?
Jordan Johnson #roasted
+Jordan Johnson (Mighty Burger)
You just made my day.
Did you just make that ENTIRE comment for 1 shitty wordplay?
+Jhawk 163 If he did, he's in good company. Isaac Asimov wrote an entire short story just for a terrible pun. It's called "Shah Guido G".
I really liked the derivation of the formula at the end. I assume that this is a well known equation within the aeronautics field? Can you recommend any other video or textbook where the design of an engine in terms of efficiency is discussed in greater detail?
Compare a A350 with a B747 was really a bad example....
Firstly, the B747 is marginally larger. Looking at the 747-400 compared to the A350-900, the Airbus actually got larger wing span and its only 4 meters shorter.. so yes, the 747 is larger, but only just. The A350 is actually a huge plane And the uppcoming A350-1000 will actually be longer than the 747-400. (of cause the 747-i8 is longer still, but its the 747-400 in the picture.)
The issue is that B747 have 4 engines and the A350 have only 2. The thurst of the A350 engines is maximum 350kN, but for the B747-400 only 280kN. Actually the engines of the A350 is even stronger than the one of the A380.
There is one additional error in the video. its over theoretical compared to the actual reality of aircraft engines. All (or almost all?) turbofan engines is direct drive engines. Because the fanblade have a maximum speed the rotation velocity most be keeped. This make it so the turbine engine have to have huge torque.
The compromise to this is that the turbine engines is a loot larger than it need to be, and the fan ist still smaler than is optimal. This is why engine manufacture dont make the fan at optimal size. Because then the torque would be to much.
The solution to this is of cause to introduce gearing. And there are some prototypes under development. This not only makes it so the fan can be any size (that is the optimal size for every given aircraft, but it also make it so the turbine engine can be the optimal size to.. that is a lot smaller.
This will decrease the fuel consumpsion more than making the fan bigger. But the comibnation will cut the fuel consumption quite a bit.
+matsv201 You're right, but this is a video for laymen and in 2 minutes. I think they did a pretty good job.
jibeneyto Well.. i would still think they should compare two aircraft of similar size. Say a A330 and a 787.
Also i think the issue about geard and ungeard turbine is to important to just skip over.....
.... i would think this is more a matter of that the videomakes know the theoretical background, but not the current limitations of the engines that is in service.
There is a glaring whole in the video. If they know the optimal size (and it been known since the 1900-century)... why don´t they just makes the engines optimal size...
This is a question that is unanswered.....And the answer is quite simple.. there is no gearing.... so they cant.
You're right as before, but gearing in turbofans has not really been implemented in any aircraft. Maybe in the future it will. I don't think it's important to consider such a "new" concept in a 2-minute video.
jibeneyto No.. but it answers the question why the turbin gradaly grow, and why they don´t make it optimal from day one.
Uh explain 1:23
1:14
Is that a nod to xkcd?
what-if.xkcd.com/21/
(Scroll down to just above the end.)
+TheRancidMarshmallow -- I'd say yes, but guns have been used as rocket analogues far before XKCD.
I find it interesting how we can define physics using mathematical equations and then use those equations to optimize technology in intuitive but not immediately recognizable ways. Neat
"As I might have heard?" Only like seventeen billion times. I love Audible. I use their product, in fact I have been a subscriber for years. I also love the fact that they pay for much of my online content through their advertisement. But comes to a point where I am soooooo friggin sick of hearing the same ad time and time again. And what if I DO what to support this youtube channel or podcast? I can't follow their merchant link to sign up, because I already am signed up. And if I wasnt, I would still be only able to support one of the dozens of creators that I like that are supported by Audible. I dont know if there is a solution, maybe audible is the only one willing to support creators, or maybe they just are the only ones with really good taste (aka same as mine)...
Very clear explanation and illustration!
has anyone noticed that in this video there is no pen....!!
i
omg i didnt
+Tamara the Sloth
dont worry...
notice it next time...
+Vaibhav Jain ok
+Tamara the Sloth thumbs up....!!
;-);-);-)
wow. i didnt too
great video, short fun and with lot of information that I won't probably use in my life haha, good job!
Very interesting.
I was wondering why commercial jet engines were getting fatter and fatter.
Now - apparently - I know why.
Thanks.
Efficiency is certainly the main reason size has been increasing but it's not the only reason, larger engines are quieter because they can generate the needed thrust by moving a larger volume of air but at a slower exhaust velocity. That's also the reason behind putting larger fans on higher end computers - it keeps the noise down while still providing the cooling needed.
and the FAA (and agencies in other countries) have been passing more stringent rules when it comes to noise from civilian aircraft.
plus the engines have gotten so reliable they can get away with 2 instead of 4
Thank you man I love explanation videos with these type of art
the last plane looks cute for some reason lol
A clear explanation of the commercial air place compared to military fighter plane.
Now, I am curious to learn how these two compare to a rocket engine as used in the space shuttle.
That very last drawing XD
Very cognitive and interesting video. All shown and explained in understandable speech. Thank you for a nice video .
Why are you asking me these questions?!
Ender's Game is amazing
0:17, describes a turbofan jet engine which has all the 'bypass' air going around the jet core as opposed to a turbojet in which all of the air goes through the jet core and turbine itself.
Why didn't we start with 4-meter engines?
+Timothy McLean Probably much more difficult to make. The tolerances need to be very small to reduce vibrations. The bigger the engine, the more difficult to produce with small tolerances.
It looks like your math assumes that the area causing drag is just the frontal area of the engine. I don't think that's right: it's the frontal area of the *whole plane* that causes drag, of which the engine is only a small part. Also, since the engine is moving air *through* itself, I don't think you can model its drag as if it's a flat disk with Cd=1.
Like just for the Ender's Game reference.
nice, I was curious about that as well, cuz jet fighters always have small engines with like 1/7 as much dry thrust as a GE90 (~500kN), but they both have similar fuel consumption
1:23 A rough estimate...
Area of about 12.5 m^2, take the square root, it's about 3.53...
QuakyJunior Whenever I'm on the computer and it's late at night, I make really stupid mistakes.
However, you are wrong. It's pi*(r^2) ,this is area, not circumference. I was also wrong, but you were, too.
12.5, divide by pi, take square root, get radius. Multiply by 2, get 3.9894228040143267793994605993438.
Pretty close, I'd say.
I just love your channel! You do the research (that i'm too lazy to do), and i get the answer. Keep it up!
Thanks for the translation into Arabic .