Why Are Airplane Engines So Big?
ฝัง
- เผยแพร่เมื่อ 18 มิ.ย. 2024
- The physics behind the perfect size of a jet engine.
Thanks to www.audible.com/minutephysics for supporting this video - if you try the free 30-day trial, I recommend "Ender's Game" by Orson Scott Card
Thanks for everyone who supports MinutePhysics on Patreon! Link to Patreon supporters here: www.minutephysics.com/supporters.html
The answer to this question has everything to do with drag & kinetic energy vs momentum change (thrust) - ie, a bigger engine fan allows for a larger air mass to be accelerated a smaller amount to give the same thrust as you’d get from a smaller engine with larger acceleration. Any acceleration of air imparts energy to that air, which is in principle wasted energy, so ideally we minimize the acceleration of air while maintaining constant thrust, aka bigger engine fan. However, bigger fans have more drag, so there is an ultimate size limit.
REFERENCES:
A350 schematics - www.aerospaceweb.org/aircraft/...
747 schematics - www.aerospaceweb.org/aircraft/...
Music by Nathaniel Schroeder, / drschroeder
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Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!
Created by Henry Reich - วิทยาศาสตร์และเทคโนโลยี
That plane at the end looked adorable.
Look up the Boeing X Plane
That's the Stipa Caproni airliner edition.
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
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).
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
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.
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.
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.
Love these videos more please :D
agreed
Daddy Sakurai nerfed you, hihi!
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!
What a great intro to that Audible ad!
a rough estimation
XD XD XD
Mr_____ - dead asf
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.
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
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
By far one of the best "to-the-point" videos broken down to my simpleton level. Bravo minutephysics ;)
Thank you man I love explanation videos with these type of art
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
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
always love these short clips of actually interesting topics
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.
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.
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...
great video, short fun and with lot of information that I won't probably use in my life haha, good job!
Very clear explanation and illustration!
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
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
I really i fell in love with your channel. Thank you for doing such a great job by making these videos!
Awesome video, as always
Good Work Henry!
1:15
"then it starts to cause too much DREG"
+Kivtej Rakhra he says dreg
Dont do dregs
@@itskelvinn хюжэзмэжп
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.
excellent short explanation, thanks for that!
Great video, short and informative.
omg ENDERS GAME. I loved that book. Its what got me into space games.
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
Great explanation! well done
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!
Good explane-ation Planely the best video Jet!
Bah-dum-tss 😂
0:07 it's also because the 747 has 4 engines while the A350 only has 2.
+DoubleYouPee Henry unfortunately chose the wrong 747 model to use as a comparison. He should have used the -400, which is much older, to illustrate the difference in bypass ratio. Or better yet, the difference between the A320ceo and A320neo.
+totoritko It wouldn't have mattered for me...
watching stuff about stuff you already know in great detail and is in fact my career, yet still enjoyable to watch.
Very good - succinct and entertaining - must look at some more of these
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*
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
I just love your channel! You do the research (that i'm too lazy to do), and i get the answer. Keep it up!
I loved your clip I saw it more than hundred times Thank you
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
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
Those equations though!!! Took me back to my vehicle performance lectures. Oh how fun that was!
Thanks, that was VERY interesting.
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.
I kinda laughed a little bit at the point when he said "kinda like using a machine gun to propel your car"
Love your work man .....
Interesting because in spacecraft its all about high exhaust velocity, which means more efficiency...
Having air everywhere is such a valuable resource!
I never asked myself that question in my life
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?
Great video!
Awesome video!
the last plane looks cute for some reason lol
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.
Yes! More Minute Engineering!!
That very last drawing XD
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.
Very cognitive and interesting video. All shown and explained in understandable speech. Thank you for a nice video .
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?
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!
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 :)
If they ever made a plane like the last one you drew, I'd fly on that, no problem. So cool.
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.
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.
jets are really cool :)
Awesome Video
Liked for the Ender's Game plug. One of my favorite books for sure.
Very interesting.
I was wondering why commercial jet engines were getting fatter and fatter.
Now - apparently - I know why.
Thanks.
"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)...
Amazing content! explains a lot in small amount of time, other youtubers would lengthen the video to 10:00 just to get extra money
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.
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
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.
You make physics very interesting and don't hide the fact that it takes some brains to know the math. Thanks for making cool videos!
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.
Its not a 'modern jet engine' it is a turbo fan. There are also turbo prop and turbo jet engines
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.
1) "As you may have heard"
Very Concise.
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".
Thanks for the translation into Arabic .
That equation was great!!
I'm loving the aviation videos!! I want to be a pilot myself :)
Why are you asking me these questions?!
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.
Love your videos 💕💕💕
Nice short video!
LOL dat last airplane
plus the engines have gotten so reliable they can get away with 2 instead of 4
You said the word 'drag' there very funnily 😂 Love your videos!
Lol i don't know why it would pop up in my recommendations but it shed some light on recent Boeing design on Boeing Max 8. Thanks!
Ender's Game is amazing
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.
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.
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