How BIG can jet engines get?!
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- Äas pĆidĂĄn 22. 10. 2020
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Modern Jet engines are just getting bigger and bigger. The latest General Electric engine, the GE9X was certified last week and is the biggest one yet. Will the engines just keep getting bigger and bigger or is there some kind of limit to it?
In todays video we will discuss this from several different angles. We will talk about the origin of the jet engine, why they have been growing and what is likely to happen as we go forward.
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Below you will find the links to videos and sources used in this episode. Enjoy checking them out!
Topfelya: Boeing 737NG Go-arounds, 777 Crosswind landing
âą Aborted landing during...
âą Boeing 777 Crosswind l...
Boeing: 737MAX and 787 flying together
âą Boeing 787-10 Dreamlin...
Russel Croman: Shockwave on top of wing inflight
âą Shock Wave Formation i...
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Hey Mentour when you can would you mind showing us the 737 max mcas activation simulation.
@Aston Ding he doesnt care he just wants money
mount engines on rear again , not on wings
Correction - you said Mach 0.8 is 8% of speed of sound, but in reality Mach 0.8 is 80% of the speed of sound. By that logic Mach 1.0 would be 10% the speed of sound, not 100%.
If they want even bigger engines, why wouldnât they just use the wing position and angles of a TU-225? (Iâm not sure how itâs called but some planes have the wings above the frame like the Cessna or TU-225, and some have the wings angled down rather than up)
Iâm doing school presentation on you in French class, we had to pick a person we admire đ
Hope he sees this!!
Same here wtf
Oh, I used my pet rock.
My man is fighting for that scholarship lol
That's a hell of a compliment.
I'm surprised you did not mention that, as the diameter of the fan disk increases, the tips approach the speed of sound, causing internal shock waves and greatly increased drag- the reason for the upcoming GTF- the Geared Turbo Fan, which uses a planetary gear system to reduce the rotational velocity of the disk- this would enable even larger diameter engines (probably for high wing designs). Looking forward to a video on those!
Absolutely, the primary limit on fan size is tip speed (IIRC some reach mach 1.2-ish at full tilt at sea level - hence the rake in fan tips on big engines, like a swept wing, but below 1 is best for that first disc - in the compressor stages increased temperature elevates the speed of sound, so its less of a problem deeper into the engine). The GTF doesn't allow bigger fans, but rather higher LP rotational speed, thus efficiency (its all about the money). The amount of bypass air pumped by the fan is always limited by the tip speed; a smaller faster fan at approx M1 can produce as much thrust as a bigger slower fan also at M1 (without the weight penalty mentioned in the clip), so the gear ratio is set accordingly rather than just making ever bigger fans.
Why not use variable fan speed? Speed of sound depending of air density and it vary due altitude.
@@jarikinnunen1718 Easy; that would require complex gearing, which is just too unreliable (or if reliable, too heavy). GTF's are hard enough to get a single ratio thats runs for thousands of hours transmitting a few hundred kilo newtons of force. Basic gas turbines (99% of those in service) just had a shaft - no moving parts, so not much to go wrong (provided it doesn't fracture). Helicopters have gearboxes, but tend not to transmit bigger forces, require extensive maintenance, and are still the weak point in the whole system.
Which is why we are now seeing geared turbofan designs from all the major manufactures to keep the speed of the blade tips subsonic.
@@andyowens5494 I wounder if anyone tried putting several fans side to side, driven from one turbine through a shaft?
Somewhere, an engine designer is looking at that thumbnail and thinking "Maybe...?".
He probably also has a landing gear designer who is trying to talk him out of it.
Haha!
I hope (s)he doesn't work for Boeing...
Engineer here. Sorry to disappoint, my first thought wasn't... really engineering related đ
Some sort of software can surely counter possible issues.
@@5Andysalive lol i see what you did there đ
Mentor pilot is the Aviation Legend of youtube
Thank you so much! đ
@@MentourPilot your an awesome pilot!! Keep up the great content I love learning from you
@@MentourPilot As a former USAF jet engine tech, I enjoy your videos a great deal. Plus your mini Golden doodle is a handsome fellow and he matches your hair. Does he have his pilot's license yet? They are great dogs! I raise standard size Bernedoodles.
The principal of Mass Airflow you missed is that to double the thrust by increasing velocity requires four times the energy. Acceleration is a square rule function. To double the thrust by increasing mass only requires doubling the energy. So Mass Airflow is more efficient. I was in the business 26 years when I read a paper on Mass Airflow. I realized I knew "everything about aerodynamics" but I never understood what I knew.
I logged on just to comment this lol
I'm sure you're correct, but I'd love to ask why. I assume it's because of aerodynamic effects, because intuitively
F = m * a -> a = F/m
v = a * t -> v = F/m * t
So, if we take an arbitrary t, I would only have to double the acceleration force to double the velocity. And double the velocity should equal double the force.
But I'm sure I'm missing something obvious - I'm not calling you out, just trying to understand where I'm wrong!
@@MeMe-gm9di Acceleration is a square rule function It takes four times the energy to double the velocity of a mass. There is a self published paper "Mass Airflow" That paper explains this very well as it applies to ducted fans. I no longer have a copy of the paper. It used to be $35 with postage.
@@MeMe-gm9di There are to many listings for mass airflow and ducted fan to find the paper. I do not remember the college it came from. The basics are you can double the thrust by doubling the mass or doubling the velocity of the mass. Doubling the velocity uses four time the energy. That is why helicopters have long blades turning in the range of150 rpm.
LOL! WRONGES! velocity is MAGNUMTUBE and directionnes UNUIT VECTORS. Plese try agen!
Each of those new 777 engines costs (in todays dollars) about the same as an entire original 707.
In 1955, a 707 cost $4.3mm - about $41mm in current dollars. List price on a GE9X is around $42mm. You pretty much nailed it.
@@Taranaki66 Milimetres and dollars are not compatible
@@WELLINGTON20 yeah, it should be either âŹmm of $inch
@@WELLINGTON20 It stands for 'million moneys.'
And the diameter of the 777 engine is bigger than the diameter of the 707 fuselage!
CZcams: wanna know why airplane engines are so big at 4AM?
me: Well...I should probably be asleep right now
My brain: I DONT NEED SLEEP I NEED ANSWERS
Same lol
Thank you very much for the shout out! It really means a lot coming from the best pilot/teacher/mentour in the world :)
By the way, seeing this video in minute 17:05, I finally understood seeing that wake of air over the wing that I used to see over the wing. This wake was always easy to see on a 747-400 when flying overseas. You see I was in the bicycle industry and must have flown around the world more than 50 times starting in the late 70s till I semi-retired in 2016. I had the privilege to fly just about every modern airliner ever made and had several close calls too. I never get bored, flying, I love every minute of it.
Minutephysics has a video on this topic titled "Why Are Airplane Engines So Big?", he estimates the optimal engine diameter is about 4m, over that the drag of the engine itself negates the gain in efficiency.
You are a wealth of knowledge, and one of the nicest people on the planet. Giving Ronnie a shoutout like that is beyond nice. Your kind heart shows in everything you do. Thank you for being who you are and doing what you do.
So nice to chill at home and learn about jet engines this evening! Thank's, mentour :)
You are more than welcome!
Glad you liked it!
I finally passed my PPL last August here in the UK. Your videos have been a big inspiration along my journey. Thanks for posting your videos.
Congratulations!
Thatâs so nice to hear
I work around the RR and GE engines for the 787. They are huuuuuge.
Indeed they are, excellent work of engineering!
Damn, such a cool job! Hope you can work around the 777X engines in the future as well!
@@cl63pbx its pretty neat but very intimidating. I help bring the engines into the final assembly building using a massive forklift. Carrying 22 million dollars worth of engine in between 500 million dollar airplanes is sure to cause some stress lol
@@MentourPilot the RR engines have the advantage of less weight for equal thrust.
@@amargoun But RR are less powerful than the GE90
Hi Petter, I really love your channel with its huge variety of themes and aspects of aviation explained in a great manner!
Many thanks for these latest two videos. Very interesting!
Some airplanes with top mounted engines: HondaJet, Beriev Be-200, Antonov An72/74, Antonov An32
Exactly it would have solved the 737 max problem as they could have fitted them where they liked.
@@womble321 Well yes but actually no.
Did you watch the video????
There was an aircraft called the VFW 614 which first flew in July, 1971 and had over-wing, pylon-mounted jet engines, But this was a 40-44 seat airliner with a gross weight of 19,958 Kg. and with twin engines each rated at 7,500 lbs. of thrust. These were small turbo-fan engines. A photo in the Wikipedia article shows the engine and pylon above the wing and it's not hard to imagine a seven ton engine and how substantial and sturdy, not to mention the weight of it, a pylon would need to be to withstand flight loadings. There would be no engineering compromise which would work; shorten the pylon to save weight and you cause greater aerodynamic disturbance and drag. Lengthen it to avoid these effects and you increase the weight. So much easier to suspend the engines on pylons below the wing and they just hang there on the fuse pins.
@@womble321 see my reply, about the VFW 614, in answer to the same comment, from Luis Ramirez.
I am 11 years old and I watch your videos and want to become a fighter pilot you have such good videos
Glad you like them my friend! Keep working hard in school!
I always wanted to be a pilot as a kid, and now I am! Not fighters or huge jets, but still aeroplanes! đ Donât give up, and you can become that fighter pilot one day!
Someone want to give this kid some real advice? Everyone told me to work hard at school. But school just crammed curriculum down my throat and never gave any hint how to achieve me dreams and so now the closest I ever managed was a 30min experience flight as a 32nd birthday present.
@@SwedishVFR du har ett jĂ€tteskönt land för att flyga över. Och kanske du flyger över Norge ocksĂ„? Oj, vad jag önskar jag kunde göra bĂ„da âșïž
(And now I hope you are Swedish because I just gambled because of your username hehe. And no it probably isnât fully grammatically correct but I am Dutch, studied Swedish for 1,5years and studied there with all my courses in Swedish (passed them in one take, woohoo) . However that was 20-21y ago so Iâm surprised this came out when without looking up, I just let it come from memory. Now I wonder how bad it was đ )
@@lukeorlando4814 I can relate! After several years of post graduate academia and massive student loan debt, I realized that âyou can do anything that put your mind to â is a crocload. No; actually not at all. I will never be a superstar athlete or win the Nobel for physics. It turns out that the only thing a bachelor degree in chemistry with no working experience is only good for getting additional education in chemistry. The problem with spending a decade obtaining education is, end the end, you still have no job experience.
I can listen to you all day. The way you explain things is first class
I've been an "armchair pilot" for years and I really enjoy your explanation of the technical details of the jet engine as well as your other videos. Thank you - and I will try to patronize your sponsors in return.
Mike
Iâve been an aircraft maintenance tech for major airline for 28 years and still love aviation so I enjoy watching your videos a lot. We have to learn how to work on all the aircraft in our fleet and the last 16 years Iâve been working pretty much composite repairs exclusively, so Iâve had to learn a lot about the newest aircraft weâve purchased the A-350 and A-220 (C100) lol. The A-220 having GTF Geared Turbo Fanâs. Fascinating. I knew Rolls was working on a large GTF which is neat but I had no idea the A-220 had GTF Prattâs until we started receiving them. The compressor and turbine is tiny with a normal looking Fan. With a gearbox driving the Fan you can run the fan at the perfect RPM to get the most thrust out of the blades. And the wonderful computer designs of the blade contours allows ever point on the blade to keep the air flowing over that section at an ideal speed. Rolls has a Three spool engine with the very aft Turbine shafted to the Fan and then the turbine section just fwd of that shafted to the N2 fan directly behind the Fan which guides air into the compressor then the fwd turbine section driving the compressor section. 3 spool can assure that each section can spin at an RPM that helps prevent turbulence as air flows through the engine. GE and Prattâs are two spool and on the older engines the N1 and N2 Fan and blades just aft of the fan were driven by the same shaft from the Aft turbine section. Which caused an issue. Either the N1 or the N2 was spinning to fast or to slow never in the Goldilocks zone. Now with the Geared Fans we can always make sure through design and gear size that at core engineâs can run at the perfect speed for fuel efficiency and the fan will produce the best thrust possible. So this seems to be the next evolution in engines. The GTF is a really neat engine to look at.
I wondered when Mentour was going to get to geared fans but he never did.
I guess fans getting bigger and slower, and turboprops steadily acquiring more and curvier blades, are an example of convergent evolution ;)
11:59 Little doggo makes a safe and comfy landing. đ
This video was very enlightening, I love learning about aviation stuff and the engineering that goes into these amazing machines.
I just found your channel and find it very interesting. You do a great job explaining things.đđ»
Thank you! It was so interesting I didn't even notice that 20 minutes passed!
Awesome!!
Another point to consider regarding the difficulties of having large jet engines on top of the wing vs. under slung is the shifting of mass in relation to the aircraftâs cg. Basically, having that weight above the cg results in less stability; engines under the wing (mass under the cg) actually improves stability.
I can't tell you how good you are at explaining aerodynamics for dummies. I really appreciate it. Thanks.
This is the only channel I watch without browsing the comments.More than enough info to keep me occupied!
(even though I've been flying jets for 20 years)đ
At about 14 minutes, you could have mentioned the VFW 614 with overwing engines, and explained why that was a failure. But still an excellent video, well done.
Great video as always đ
Thanks
Hey I love your videos. Your explanation is awesome. Great work.
Thanks for your excellent videos - always informative. Just one quibble on this one : it is the velocity of the working fluid that increases during combustion, not the pressure.
I walk by the 777X engines every morning on my way to my work station (767 pylons). These engines are freaking HUGE! I still look in amazement as I pass by them.
8:20 Damn those ailerons are working hard!
Great vid. Explanations of the reason behind bypass fans, and of transonic airflow particularly good.
That's Ceramic Matrix Composites, been working on devoping the parts for the 9x for 7 years. Retired last week, YAY!!!
Great channel, keep up the good work!
Hey Mr. Mentour, thank you for uploading a video explaining how jet engines work just as I requested in a previous comment (though you may have seen it) and explaining how and why a greater bypass generally means greater fuel efficiency. I would like to add something though. The fan may act like a propeller in the sense that it sucks air in and blows it backwards like an un-ducted turboprop but the reaction force on the fan is little to none, so the fan produces virtually no net thrust of its own by blowing air like a propeller. Iâve talked with numerous people who work for Pratt & Whitney along with RR Trent and theyâve all told me the same thing. They told me that the fan in a high bypass jet engine is more of a compressor than anything else, the fan blows air through the ever narrowing bypass duct as this air squeezes through a tighter and tighter space. The energy that the fan puts into partially compressing the bypass flow cancels out nearly all the thrust produced by the fan acting like a prop so the fanâs net thrust is
Another thing I noticed is that he said in this video that planes can and are even designed to exceed their critical Mach number where in his video about how fast a place can fly, he said planes arenât designed to do that and thus never ever do. He contradicted himself in those two videos though his second explanation was more accurate which makes me hope that he learned a thing or two about airplane speed since that other podcast.
Interesting video. But poor doggy...heard it all in rehearsals, clearly! Hehe
17:15] Compressibility, the formation of a shock wave! I love it.
Great video. I remember the small engines of the older 737's. Good explanation.
The VFW-Fokker 614 and the HondaJet do have the engines on top of the wing.
The VFW 614 had higher maintenance costs than a conventionally build small jet-airliner. This eats up the economical benefits of its good fuel efficiency and the excellent take of and landing performance even on unprepared dirt runways. VFW underestimated the maintenance problem of "standing" engines, so the 614 was no commercial success.
If we see more top-mounted wings, in the form of the AN124, for example, that would add a lot of engine space without landing gear weight or compromised aerodynamics.
What about rear-mounted engines? Like on the Boeing 727, Vickers VC 10, Cessna Citation, Lockheed Tristar, IL-62?
@@garycard1456 balance is an issue with rear mounted engines. There is a reason that the md-80 family has the wing box relatively far back in the fuselage. It is because the engines are heavy. This limits the weight of rear mounted engines.
Amazing info, great work! Thanks!
that dog has a funny character lol just like our bunny,cracks me up every time
I hope the dog is taking all this in...
Plot Twist: Mentour Dog is the true brains of the operation.
I am private pilot myself and besides the highly interesting videos contentents, I enjoy watching those two dogs too.... The brown one looks very much like the 7 year old poddle that we have at home. !!!
The dog is thinking âheâs talking to himself again! â
The dog taught mentour everything he knows
This was an interesting installation, and it is, of course, a very complicated subject. However, there were two potential solutions that you did not cover: 1) high mounted wings; 2) tail mounted engines. Both configurations have fewer constrictions on the engine diameter. (I am a B-24 enthusiast, so high wings are always in the back of my mind.)
good point.
Or engines mounted inside the wings/as part of the body.
VERY interesting and informative video! Thank you Peter.
Another great video, thought you might have mentioned the geared bypass fan
I finally remembered to not turn the volume up loud enough to hear you until AFTER the âtheme song â
And Iâve reduced the volume, just for you! I always think of you when I edit that part.
Aww I liked it loud!
@@alanguile8945 Agreed that I don't need my subwoofer tested every time I watch a video. I think these are edited often on laptop or wimpy computer speakers, so the editor is unaware of the decibel level in the 100 Hz range, and/or assuming everyone else has wimpy speakers. Those of watching on the big screen in 5.1 surround get a bit more 'experience' than the author intended.
@@gg5115 Yes I'm watching on an old MacBook pro so 100Hz doesn't exist for me!
Thank you.
Realistically only slightly bigger than the GE9X. The drag increase will eventually make it a losing battle.
na mate just add afterburners and hope the thing doesn't melt anything important
Kun Feng HBPR turbofans act on the opposite end of thrust production than an afterburner. One increase the amount of slow moving air and the other increase the small amount of fast moving air. You donât want both.
Probably one of my favorite videos you have done! I really enjoyed this one...and we both said: "Ahh, NO" at the same time. LOL!!! Soon to be a Patreon member!!!!
Hi, Mentour. Thank you for sharing your _MASSIVE_ accumulation of wisdom with all of us. I am in awe of it. Also, had I _even_ one teacher in high school with your skill at making difficult concepts relatable to the untrained mind, I woulda really kicked ass in physics! You are the BEST, sir!! Gotta go, the fasten seatbelt sign just lit up! \m/
Maybe I'm "old fashioned" or something, but, my favorite planes are the old trijets. I just like them.
Petter, something you forgot to mention was the jet engines have become much quiet as they kept increasing the fan bypass ratios
Extremely quiet. If you're near heathrow you notice the A380s because they're a "hole" in the background noise in the sky
This is an important advantage of high bypass engines - moving more gas at lower speed is innately less noisy. The higher the bypass ratio the quieter (assuming the fan blade tips are kept subsonic). Noise at takeoff is a major problem in designing a supersonic airliner, because you can't use high bypass engines supersonically (again, fan blade tip speed ...).
I love your dog who keeps next to you as you talk :)
Although I am not a pilot (i like to fly though), I very often watch your videos; they are great!! Very well explained, very good English, very interesting stuff. Thanks!
This was cool! My understanding was that turbo-prop engines have even larger bypass ratios, but at the cruising speed of commercial airliners turbo-fans become more efficient. Could you also do a video that compares turbo-prop vs turbo-fan Please?
This is true, which is why you see short hop routes often use turbo-props, for instance Horizon's fleet of Dash 8s. They cruise at a lower altitude, and a lower speed, but with far greater efficiency. For short hops they can be a similar gate to gate time, but cost a lot less.
Hello, thank you for your super interesting Channel!
I was wondering: engine layout such as the one of A400M or an Antonov AN-124 could ease the accomodation of big engines below the wings, since the wings are implemented on the top of the aircarft fuselage. Why such architecture is not applied to commercial aircarfts?
NICE VIDEO THANKS FOR POSTING
Nice vids and cute dog! đ
One limiting factor of engine size will also be when one of these failed engines creates so much drag in flight that ETOPS will not be guaranteed anymore, and as we've seen with the two UAL fan blade failures, this can happen, and the amount of drag induced in such cases. Another limiting factor will be the vibrations caused by an unbalanced fan blade as shown in UAL 1175.
Maybe the solution to this will be that the pilot can eject the complete engine from the wing, but I suspect airlines will not like it too much if the plane suddenly loses a 8 million USD engine in the ocean because it failed.
What about mounting the engines at rear like the MD 80 ?
It's an option weight is still a major issue as big heavy engines on a tail moves the center of gravity aft. Too big and you could never push the nose down and will stall once you get airborne.
@@garrnk Which is why the wings are set so far back. Like he said, it's all about compromises or, more accurately, tradeoffs.
@@TonyRule exactly
@@garrnk The C of G is not at all an issue. It is just a matter of putting the wings further back. What probably is an issue is that the wings will need to be stronger since their weight is now bearing down on the middle of the aircraft rather than directly from the wings, which means heavier wings. Once would of course need to see if maybe that increase in weight of the wings is still offset by the increased efficiency that might be achieved, which could well be the case.
@@garrnk moving the horizontal stabilizer to the front can help with that
Perfectly fascinating details on aerodynamics and engines, thanks much, Petter. My engineering hat was on and I completely (well mostly) understand the issues with over-wing engine placement. I hadn't thought about top airflow moving at speeds closer to Mach 1 before so that was nice. Cheers.
Thanks for this Vid Peter! I listen to your vids every night as I brush my teethđ
So I am a few months late, I know, but when you talk about engine above or below the wing, I get that there is an aerodynamic issue to be dealt with. So lets not put the engine on top of the wing.
But, how about raising the wing like on the Antonovs? Or placing the engines at the back, like the MD90? The An 225 has six engines, but couldn't it in theory have two enormous ones hanging from the wings that are already high up on the plane body?
Congrats on the thumbnail! It's hilarious.
Yes, my graphic designer is a genius! â€ïž
Thank you!
Superb man with excellent explanation..
Very informative, thankyou.
@Mentour Pilot - one question, what about "top wing aircraft"? Theoretically, can they lift a bigger turbofan engines? Or maybe there are other factors precluding the creation of this type of structure? Nice to watch you, great job, regards from Poland!
Antonov An-124 and An-225. My idea also. Big engines, high wing, short landing gear. Et voila.
As I now see, Piotrek and Kaptein Superskoot have already asked my question, Petter. These points are worthy of further discussion on your channel.
What about high wing configuration mounted on the upper fuselage, like on the Antonov An-225? That would make a lot of room to fit larger engines.
Was that solution demoted due to handling reasons?
Could also be a passenger safety issue? You'd have the engines with a direct line of sight to the cabin, maybe that would be a bit too loud? On the AN-225 they don't need to worry about deafening the cargo :) I can also imagine that in the case of an engine fire, you'd want to keep shrapnel away from the fuselage (placing the engines below the fuselage puts a conveniently placed reinforced barrier between the passengers and the engines, and also makes it harder for passengers to see an engine fire).
from the construction point of view it's easier to lift the load than to have the load hanging below the wings so this is probably one of the main reasons why we see that it's so common with the low mounted wing designs on bigger aircraft.
@@polcho most purpose built cargo planes have a high wing design though
Absolute information, thank you.
Great video, great explanation of the scientific problems of bigger engines enjoied it a lot
2:48 the pressure doesn't actually increase across the combustion chamber; the volume (and thus velocity) increases. AgentJayZ has a great video about this.
Thanks for pointing this out. You are correct. The highest pressure in a jet engine is at the exit of the compressor. If the burner pressure was higher than the compressor pressure, the combustion gasses would flow backwards, towards the lower pressure in the compressor. The heat of the burners add volume and velocity but not greater pressure. The exhaust gasses flow out the rear, to the relatively low pressure of the atmosphere. Along the way, the fast flowing hot gasses drive turbines which power the compressor and the fan.
Yes, containing pressure after after the compressor does nothing, releasing it creates thrust.
I canât stop laughing at that thumbnail!
It is the Kerbal version. MOAR THRUST!!
Great video Mentour I enjoyed watching it
Thank you for this explaination. I am from Holland and i'm not good in Englisch, but when you're talking, i can understand more! So, thank you and i did immediatly subscribe your schannel! Greets from Holland, the Netherlands.
So why canât they configure the wings at the top like the Boeing C-17 Globemaster III?
the c17 is a cargo plane with no windows on the side of the fuselage if thats a hint.
Aircraft have better handling when the wings are below the fuselage, because of this most commercial aircraft have the wings mounted at the bottom of the fuselage.
A major acceptation to this is are antonov aircrafts which are designed for pure cargo capacity, this is why there flown by some of the best cargo pilots in the world.
It's not impossible but the extra efficiency of the engines would have to overcome the extra drag from bulges to accomodate landing gear etc. the engines getting larger would make it more difficult to work on to for maintenance - again could be overcome if the maintenance requirements and reliability were low enough. currently though engine efficiency is right at the edge of what can currently be done (IMHO this is why we've seen a few failures over the past few years) perhaps witha bit more technology you might be able to get past this.
@Jason Bowman They could use B52 style undercarriage.
@@drewpknutz1410 I don't get the hint. Check out the BA146. It has lots of windows.
The future they just ganna go ham on the engine and then build around it
Great post. thank you very much.
fantastic... thank you so much for this education!
Mentour: You can't put jet engines on top of the wing of an aircraft!!!
Russian Beriev Be-200: Am i a joke to you?
You can! It just wonât be as effective
@@MentourPilot yeah they actually did it just because it's amphibious aircraft and they had no other choice
I submit for your review the HondaJet.
@@MentourPilot I guess it might be a thing of the future. They could build engine mounts that protrude from the wing backwards and just slightly up as opposed to forwards-downwards as it is now common. This should have some benefits like better ground clearance, better visibility from inside the cabin in case of engine failure, reduced thrust vectoring caused by better geometry and better lift and low-velocity capabilities (by sucking in air from above the wing). Meanwhile it would keep advantages of the contemporary design like dampening wing vibration and good accessibility to the engine. Maybe i am totally mistaken by missing some important detail but one sometimes wonders how long it took mankind to implement technologies that are kinda obvious. The basic structure of jet airliners was introduced with the first operational jet-fighter the Me262, it had a long and heavy nose, front gear, engines mounted under the wings and a broadened wing root and is really more a predecessor to airliners instead of fighters structurally. And since then, its all tweaking the same basic form...
With these engines sitting above high-mounted wings as on the Dornier X or the Martin P6M, these are of course limited in thrust due to bad thrust-vectoring, but they did it to get away from spray water. But I am thinking about high-mounted engines on low-mounted wings.
@@A.Lifecraft Honda does that
What about attaching the wing higher?
@Guillaume Huet what about the anthonov
A very successful aircraft with this is the BAe 146. I don't see any reason why this couldn't be scaled up but i'm no expert.
Just a great learning video!!!
Straight and to the point
I remember seeing jet aircraft with three (3) jet engines mounted too the tail, keeping them out of wing-effect aerodynamic consideration could such a system lend itself more to giant-engine-attach-kerbal-style?
I don't see why not. A projet has been drawn with one unique fan and turbine at the end of the plane.
they come with their own issues. Podded engines on the wings as as counterweights for wing flutter and the pylons act as vortillons blocking spanwise flow under the wing (as do the flap track fairing canoes, they're that big for this reason, not for the mechanicals inside)
On top of that, fuselage mounted engines are a pain in the rear to do the daily stuff on == higher costs
Fun fact: the theoretical limit of an engine diameter is about 4 meters, industry is reaching the limits.
What limits the diameter?
@@currentriver4951 Drag
@@PaliVCiernom How so?
Is it only diminishing returns on the efficiency?
@@almerindaromeira8352 frankly, I don't know enough to explain in detail.
This video is awesome and easy to understand
Excellent explanation, thank you.,
That may be the funniest thumbnail yet. What a dangling pair
Wouldn't want to snag them on treetops.
VIDEO PODCAST!
From the days of the breakthrough RB211 to the upcoming GE9X, I notice that the fan is getting bigger while the core is getting smaller. Add exotic materials, new manufacturing process and advanced electronics control to that, you got an engine that is fascinating to study as a system. What an insight into the development of jet engine and its relation to other part of an aircraft that dictate its design. Thanks.
Very interesting! Thanks!
"The way to [prevent the engines from scraping the runway] is with bigger landing gear."
The C-5 Galaxy disagrees.
I had the same thought. Why do cargo planes like the C-5, C-130 etc have top mounted wings vs passenger planes generally mount the wings on the bottom of the fuselage? I suspect that the military aircraft need more engine ground clearance to operate on dirt runways, and shorter landing gear can be made stronger. But is there an efficiency argument for bottom mounted wings?
@@liampedersen You fuselage needs extra struts to support a high wing, thus there are weight concerns. The military also has different requirement than fuel efficiency. Dirt clearance, as you mentioned, is an important factor because military aircrafts has to be able to land on unpaved runways.
@@deep.space.12 Thank you for your reply. But I fail to see why a top mounted wing needs struts when a bottom mounted one does not. The C-130 (which I have ridden in a lot) does not have them. My guess is that airlines avoid the top mounted wings because of cabin noise (engines right next to windows) and difficulties entailed by stowing all the landing gear in the fuselage rather than the wings.
@@liampedersen Think about the body of the fuselage.
On the ground, the body has to carry the extra weight of a top-mounted wing, hence heavier components. In comparison, the fuselage doesn't have to handle the weight of a bottom-mounted wing. The force is a compression force on the structure on both types.
In the air, the fuselage would hang down from a top-mounted wing, and the force is now tensile. So you structural element has to handle both compression and tensile forces, which probably translates to even more increased weight.
While for a bottom-mounted wing, the force is compression in both cases. Less requirement, less weight.
@@deep.space.12 Interesting point. Thanks again.
So having a giant passenger size âA-10â Warthog design aircraft would be a bad idea ??? It works pretty well for that aircraft?
In the warthog the engines are sitting behind and above the wings. You canât do that with huge engines since it would severely alter the weight and balance.
@@MentourPilot Nah, that could be balanced by huge gatling autocannon in front :)
Which could then e.g. launch fireworks to celebrate succesfull landing... what a briliant idea, i should patent this!
@@MentourPilot wouldn't placing the landing gear towards the rear also counter act that issue?
@@NenYim Your aircraft basically become unlandable
I like how how much QUIETER the turbo fans are vs turbo jet. We lived north of DFW airport years ago directly below a landing /takeoff corridor. Planes would generally take off toward the north in the winter and I noticed the reduced sound of turbo fan jets was clearly much less. American Airlines flew the old MD 80 models with turbo jet engines and the noise was incredibly noticeable.
Thank you, great explanation
Well, with a new build from scratch, I can see the possibility of mounting engines further from the fuselage. And also new builds with high wings. Like the C-5 for example. Or think outside of the box as Boeing did with the YC-14, and Antanov took that idea to produce the AN-72/74 types. All very interesting.
wide spaced engines == more yaw on engine out == bigger vertical stabiliser and rudder == more mass and more drag
OTOH, imagine re-engining the C5 with GE90s or PW1000s
Could the wings on top of the fuselage? Or have a gull wing design to raise the height of the wings to create more clearance? I'm sure engineers have considered this but I'd be interested to know why they don't do it (or if they do in some aircraft).
Yes, that's quite possible. Many small aircraft and some larger ones like the B-52 do exactly that. The thing is it has some downsides that make it less than ideal for passenger aircraft:
* It makes evacuations more dangerous because passengers can't walk out onto the wings and slide down, instead having to either be under the wings (which isn't possible or safe after many kinds of landings) or not be able to exit near the middle at all.
* It would likely expose passengers to more engine noise since there's just open space between the engines and fuselage instead of deflecting a lot of sound off the bottom of the wings.
* It again increases the noise passengers are exposed to by sending turbulent air down past their windows instead of having most of the turbulence below the aircraft.
* Other design factors could compensate, but it decreases the ground effect during takeoff and landing, potentially requiring higher speeds and/or making rough landings more likely.
@@MrNukealizer Maybe boeing could ask from mercedes s580 maybach engineers how to do proper noise dampening then ;)
I work at an MRO Facility, and i am involved with the GE90 Engine every day. its a great engine, and its huge. I have also been involved with getting our Facility ready for the 9X. Theres some great technological leaps in it with the CMC and additive manufactured hardware.
The 9X may be rated with less thrust than the GE90 115b, but don't forget is has tested to more than it on the beds, so there could be potential for a higher rated powerplant in the future.