Why did wingroot engines like with the comet go out of style? Or bottom of the plane installations ala the planned american Concorde competitor SST? In military planes they seem to work pretty well. Are there concerns with the available room for payloads or maybe regarding crashing?
Thank you ! This question seriously bugged me for some time, ha. I would see planes with the engines off the fuselage and wonder how there could be such a big difference in engineering between jets. I mean one would have to be the clear winner for performance, economy etc. I guess the answer is complex. It would seem to me that the foreign object damage issue you mentioned. Would make the back mounted engines a far superior design, except from potentially making stall situations worse. Hmmm. In any case I really appreciate the video. Awesome job
For regional and executive jets, the tail-mounted engines also means the aircraft doesn't need much ground clearance, which makes air stair design much simpler, and a useful feature for many of the smaller airports both types fly out of.
Hi, thanks for the video. However, there is a notable advantage of the rear-mounted design over the wing-mounted design that I wish to add. The wing design is much simpler, resulting in a stronger, lighter, and aerodynamically better wing. Even being small, the under-wing engine produces some aerodynamic interference on the wing at high angles of attack. In addition, part of the flaps are directly in the path of the engine blast, which makes complex its design. Also, the airflow under the wing must be slower than the airflow over it to be effective (as you know), and the engine blast makes the opposite effect on the part of the wing affected by its trajectory even at higher speeds, at lower is worse. Another undesirable effect of under wing engines is that they produce huge torsional forces in the wing structure during accelerations and decelerations, such as when using the reversers making even complex it design. Just observations, and sorry the long message. Thanks again.
wonder if that's why McDonnell Douglas successfully got away with never redesigning the DC9 wing and only making stretched variants, because the wings were apparently efficient as-is.
@@PlymouthNeon "got away with" sounds like they *should have* but didnt redesign them. but as you say, they didnt need to bc they had a decent design already.
@@mostafakarandi363 Hi… I wish! But I´m not... sorry for that. I´m an industrial designer specialized in the field of machinery construction... I have some experience in sugar cane harvesters and bikes manufacturing. However, airplane construction is my passion, so I spent my last 24 years trying to understand that. As result I was invited to do some 3D analysis about nose cowling aerodynamics, cabin structure and ergonomics in a light aircraft project designed by an aeronautical engineer friend of mine (A great opportunity for me). That aircraft is almost finished and waiting for final approvals to perform its maiden flight. For that project my friend was invited to Oshkosh Air Venture; quite an honor of course… It is my hope to be able to design and build my own light aircraft someday :)
You might mean this site to be a mentor for budding pilots but I am enjoying it immediately. I am a 72 year old retired train driver with an interest in aviation and I find the site to be extremely interesting.
he sometimes is racist with people who dont work or have the hobby of flying. We also like watching the videos you know? And i understand everything he says.
Al grayson You tell me! I just know im here to learn about aviation and really like Mentour Pilots videos, but sometimes he makes bad comments about us. (people who havent ever piloted a plane)
MT: based on what appears to be the intent of your comment, "racist" is probably not the correct term. "critical" might be more along the line of what you intended.
I'm a private pilot, so I cannot comment professionally on your video, but I will say, if I needed an instructor to explain what I need to know to about flying big planes, learning about their structures and operations, or even small ones for that matter....you, sir, would be the man. Very informative, and well done, even with the slight accent. Some of the people I have heard on the radio, with ATC, those people who have chosen not to, at least try, and learn how to say the words, should have licenses suspended until the choose to. I think you know you're stuff real well sir. Thank you. True professional.
I was incredibly nervous my first time flying alone. I happened to be sitting next to a pilot, who noticed I was nervous and decided to tell me about the physics of flight and gave me a general sense of the systems in place on a jet. One of the things he told me was that if the engines failed, planes with wing-mounted engines were very good at gliding, while planes with rear-mounted engines were not.
@@tedarcher9120 It is about their centre of gravity, and the location of their aero surfaces. A T-Tail plane has stabilisers way off the line of mass and so have an outsized torquing moment.
@@Sagan_Starborn how does that affect gliding though? Stabilisers are producing downward torque anyway to compensate lift, if anything T-tais have lower drag because they need smaller tails
Well there was a case of a tail engine Mcdonald Douglas that had the engines die of ice but also there was a A-10 pilot who went off range during training maybe to look at the fresh powder in the mountains because he was a avid skier who I therefore suspect might also have been a unfortunate victim of icing flaking off the wings. The Air Force blamed the kid, very sad.
The Russian IL-62 T-Tail aircraft had saw tooth leading edges to stop wing tip stall and therefore super stall. The wing tip functioned as a sort flying wing due to the sweep. The VC10 and iL62 were the only aircraft that did not enter into a super stall. This was primary due to adequate sweep providing a downward pitch, saw tooth leading edges and fences and a little from the stub wing effect of the rear engines. Rear engine aircraft also were prone to engine stall and often had 'autolight' for the engines.
As an automobile enthusiast all my life and having majored in engineering, it is also very, very interesting to read every comment in the great debate of the location of the engine on an aircraft as well. Especially, I love learning about the pros and cons for each location of the engines, in terms of rigidity and aerodynamic flow. Just to point out where exactly it was fun, a specific attack angle in a rear engine aircraft can leave the horizontal stabilizers with significantly less airflow blocked by the wings, which could end up in a super stall.
I am not a pilot, but I used to fly quite a lot as a passenger. I always felt that the DC9 and 727 had cleaner wings and handled low-level / low-speed turbulence and cross winds better than planes with wing mounted engines. I do miss the 727, I loved seeing the stacks of analog guages as I passed through to my seat.
@@fredhurst2528 That may be why the 727s discontinued. They did have quieter cabins than wing engine aircrafts, since the majority of the noise from engines are behind them when a plane is acceleratingforward. You probably may've noticed when lined up for take-off back in the 1980s that the 727 in front of you moving away from you during its runway acceleration, it always sounded louder than the 727 you were in sounded while you accelerated down the runway for take-off, the reason was that the majority of the noise was behind the engines. For the same reason, I'm sure you've noticed that the back section of wing engine planes are always louder than the front half. Anyway, the quiet cabins all the way through wss something good about the 727s, the jist of the noise staying behind the planes
Some planes had the rear engines like the DC9s and 727s, some had just wing engines like the 747s, 767s, and present day 777s A330s, and A350s. And some had both such as the DC10s and L1011s (no side rear-engines though, just center tail-engines). There were good things about the DC9s and 727s, and the quieter cabins due to all the engines being in back was a reason I liked them, see my above reply. I have wondered why no wide-bodied long distance aircrafts had the side rear-engines and no wing engines like the 727s
Fantastic! There is a reason why you consistently have huge numbers of viewers and thumbs up. You teach us about interesting things in a relaxed manner. Love your vids.
This pilot is really great. Love all his vids! Flying on the Boeing 717 is allot of fun as it brings back memories from years ago when flying on many DC-9 fan-jets!! Please keen these vids coming!!
1. With time, aircraft needed bigger fans to higher propulsion. But engines on the wings have limited space because of ground clearance. Hence, they either fitted more engines on the wings or fit a bigger engine at the back. 2. Engines on the wings help counter wings flutter/vibration. See 3:30 3. In case of a fire in the engines, an engine on mounted on the wings help since it is separated from the main body of the aircraft. 4. The most noise comes from the exhaust of the engine. Separating it from the main body helps you sleep well when you're in the main cabin. 5. In case one of the under-mounted engines failed, it will add a non-zero torque and try to spin the aircraft about its center of mass. Hence, a larger Rudder is required compared to a back-mounted engine plane. 6. See 6:20 for Thrust-Pitch correct to keep the altitude stable/constant. 7. Engines at the back also help in the noise correction for a quieter cabin. 8. Charter planes have back-mounted engines because their smaller size may cause the engine to suck foreign objects like little grain or stone or grass in the surroundings. 9. See 8:40, the aircraft can use back-mounted engines to pull itself back without needing a tractor. Boeing 717 is a classic example. It's risky since you don't have a rearview mirror. And it can also suck foreign objects from the surrounding. 10. For back-mounted engines, a stronger structure is required at the back because it is further away from the center of mass. And yes, more piping to pump the fuel to hit. 11. See 11:30, back-mounted engines require T-tail to avoid "super stall". Like Boeing 717. Thank you!
Your first point is wrong. You can't fit bigger engines onto the rear of the plane, because they would be too heavy and take the centre of gravity too far back. Also, the structure of the plane couldn't take the weight.
Very interesting video, thanks. You missed a important point though: The body of airplanes with back mounted engines can be placed lower, so many of those planes have their own stair to enter at the front. This gives more flexibility at smaller airports or airports far off with no big infrastructure. The Boeing 737 had very small engines in earlier versions for the same reasons, and then they had big problems placing the new and bigger engines below the wing for the NG/MAX. That's why they are oval and not round at the front.
Lol. But he means for the final design. If designed right, you can put as big an engine you want under the wing. Not adding bigger engines after the fact. That's what Boeing did to the 737.
Excellent video!! I want to add that an advantage of rear mounted engines is a more clean wing, which is more efficient in terms of aerodynamics, resulting in a lower fuel consumption for the same engine placed in the wing.
even, the rear engine must has piping line fuel for get it. and it should be make the consumtion of engine higher than wing engine. cause need help a pumping system for distribute the fuel from wings to engine.
@The Green Bastard That could very well be because they have much smaller fans than today’s high bypass engines that would not fit on the fuselage - as explained in the video. Inefficiency somehow seems to be a conserved quantity.
A disadvantage of rear mounted engines is that in cold weather, an improperly deiced wing could cause ice to get ingested in the engines and damage them, like what happened to one SAS flight that crashed on takeoff a while back.
I’ve asked this question before and usually get “all planes handle differently” which is obvious but doesn’t actually answer the questions about engine position. Thanks for some great information.
I've always enjoyed the ride of a T-Tail over the traditional config. However, I never knew, or realized, that a stall can affect the T-Tail and lose control. Thank you.
The Delta wing can also blank out the air over a more traditional tail, not only a T-tail. The A-4 Skyhawk was such a jet. Get the AOA too high and you get into a Super Stall. Without enough altitude, it's impossible to recover from it.
@@AaronOfMpls He's not bad in this one, (apart from a little problem with mic levels,) perhaps because he's enthusiastic about it, but he has since learned to be really good. :)
Thanks so much for this video! It should be part of the Kerbal Space Program tutorials, as I finally understood why my little plane with back-mounted rocket engines tends to nose-dive :) Now it's all so much clearer! You are a great instructure !
Interesting note about low mounted intakes, the Soviet/Russian MiG-29 was designed with intake doors which block debris by dropping down to allow intake from the louvres above the nacelles, facilitating operation from rudimentary or potentially damaged fields.
I remember once reading a silly paragraph on Wikipedia about it. It said something like "Being attached to the tail gives fewer points of structural failure that could separate the engine from the aircraft. With wing mounted engines the wing can separate or the engine can separate. With tail mounted engines only the engine can separate." That is what convinced me to get an account to edit the wiki because seriously what pilot is going to be saying "oh no! My engine" when the whole wing fell off?
nope... the hardpoints that fasten the engine are the same on any position, its on a captured rail so it can be easily slide out to perform maintenance... funny they don't take into account the tail is actually less heavily built then the wings.. the wings hold the entire weight of the plane in the air.. tail just acts as a stabalizer, it creates no lift lol .. wikipedia for ya... me, I build aircraft hehe
For anyone who has ever seen how much material is in an engine pilon, or the structural members attaching the wing, it would be the least of my worries.
Antonomase Apophasis one slip of the tung earns a lecture from you? Even the penguins at my Catholic school would only give you a stern look, the first time.
Only thing I’ve ever flown is a glider. No engine positioning decisions there. My late father, though, was an instructor with BOAC and East African Airways. Both flew Comets which had turbojet engines mounted inside the wing roots. Made then particularly difficult to access for maintenance and practically guaranteed that any serious malfunction would result in structural damage. The exhausts had to be angled outwards to avoid sonic damage to rear fuselage and tail plane (old fashioned phrase.) Excellent explanations so thanks very much. I fly as a passenger several times a year so you’ve resolved a lot of queries.
Yes, your English is basically perfect. You’re Swedish, no? I don’t think you’ve ever actually told us where you’re from - or perhaps I just haven’t seen that.
Another issue with rear mounted engines is weight and balance. I used to prepare load plans and W&B for Air Aruba out of BWI on MD80s and MD90s. They would fly from BWI with a small number of passengers to Philadelphia where the majority of passengers would board for the flight to Aruba. For the trip BWI -PHL we often had to load all the BWI passengers in first class and their bags in the forward compartment to get the aircraft properly balanced. Sometimes there were not enough passengers so we needed to add ballast as well.
Nice video! You took it in a hotel on a layover? 1. One of the main reasons that engines are mounted to wings is that the weight of the engines tends to stabilize the wing. It doesn't so much stop it from bending as it simply adds mass which makes the effect of turbulence less on the structure, which in turn means it can be built lighter. This is the same reason that fuel is carried in the wings. On most aircraft with a center wing tank, the wings are filled first and then the center tank is filled. The reason is that fuel in the center tank does NOT stabilize the wing and in fact causes greater center section flex, so it is detrimental. 2. Rear mounted engines have their weight attached to the fuselage. Just like center tank fuel, this engine weight contributes to center section spar stress during turbulence or maneuvering. Airplanes with rear mounted engines have to have stronger, heavier wings as a result. 3. Rear mounted engines give the wing a very clean profile, which greatly contributes to performance. The Boeing 727 was known to be the second fastest airliner ever built after Concorde, yet it's landing speeds were no faster than some turboprops. The rear engine design allowed barn-door sized triple slotted flaps yet the 37 degree sweep and clean design allowed cruise at .90 mach for some models. 4. Airplanes with rear mounted engines have shorter landing gear, which makes integral air stairs more practical. This is one reason why most private jets have this design. 5. Airplanes with rear mounted engines look less impressive. Since private jets are typically owned by public corporations, the "cheaper look" is easier to get past shareholders..... 6. Sure you can mount high bypass ratio engines to the rear of an airplane. Dee Howard had a design to re-engine 727's with two CFM-56's and delete the center engine. Problems? Yes: First of all, this would be a seriously expensive modification to airframes already basically worth their scrap value. But second...The heavy weight of the high bypass engines would make it very difficult to keep the center of gravity within the proper range. This is the reason no manufacturer did this; It is difficult to keep the CG correct and this ruins usability. 7. Rear mounted engines have very quiet cabins, in comparison the rear end of a 737, which is screaming loud.... Keep up the good work!
"Dee Howard", that name brings back some memories. I used to work in those big orange hangars in San Antonio (Of course, by then it was SAA. VT Aerospace now...)
I need to say that it accidently answered so many of my childhood questions on differences in built and proportions of planes. Wow. Just like that everything became clear now that I'm almost 42.
In the F-104, at some point of High AOA, the stubby wings, would start to shunt the airflow to the T-Tail. a departure becomes imminent, and hence the shaker.
Something I’ve thought about (working as a refueler). Quite interesting. I always thought it was style based and never really considered the pros and cons. Thanks.
I really liked your detailed explanation about the aircraft engine, and your explaination was so simple and clear and it was perfect and you made me understand in a single video. Thank you. Keep going...
9:30 "the reverses would throw loads of gravel and shit from the ground" 😀 Mentour Pilot, you are the best! I had to play this 5x just to make sure you really said that. LOL But seriously, you rock, man. I love the way you explain stuff.
Haha. "Shit" (or the swedish equivalent: "skit") is much less of a taboo word in Sweden. It almost doesn't even count as a bad word so that's why he said it so casually.
Rear mounted engine planes also have the advantage of having a lower clearance height from the ground...making boarding and loading cargo less complicated and available with cheaper equipment...”Oh but the 737 has that goal as well” But they had to flatten the nacelle to make it less complicated. However, flying one of those is totally different from a wing mounted engine plane, as you have bigger torque arm acting on the longitudinal axis of the plane.
loading cargo really does not need much equipment and wing mount engines are really not any significant factor, but it is PITA for maintenance and that matters a lot.
Ground clearance of the engine nacelle wasn't an issue until they started mounting high bypass engines on it, the 100 and 200 had no issues at all with that.
I guess harder access to maintenance and also they didn't used turbofans for the Comet, they require a much larger mouth to fit the fan, so you would also lose usable wing area if you replace the sleek intakes with a big fan.
When working for Boeing in 1966 I asked why the engines we moved on the wing 737. The plane could be lighter because it would be a counterbalance since the wing holds the weight of the total airplane.
Did he just say "shit", when talking about sucking things up from the ground in reverse thrust for the under wing engines? That's hilarious, i dont know why, just unexpected i guess. lol. Love Mentour!
In most germanic languages (including apparently aviation English), 'shit,' 'Scheisse,' what ever is a very mild expletive, like merde in French. In English it's stronger.
Excellent explanation. Of all the aircraft I've flown in as a passenger, my fondest memories from a performance standpoint has been the MD-80. Loved the immediate throttle response and the clean swept look of the wing.
Zan0s Congratulations! Getting my PPL was one of the funnest, most rewarding things I've ever done. How about you? Terrifying, to have that final check-ride, especially when you realize in the air that your instructor forgot to train you in one particular maneuver and now you're being tested on it. In my case I had to do a full slip down to the 500' markers and come within tolerances. Managed to do it though on my first try. I told my check-ride lady that I hadn't been trained on that before I did it too! She looked nervous and she squirmed right before I straightened her back out, but I'm pretty sure that helped me with the PPL at the end. :)
I think airplanes with rear-mounted engines look better. They sit lower on the ground and the T-style stabilizer looks so cool. The 727 and the Tu-154 are beautiful airplanes.
Back in the '60s, at least one airline (Delta or Eastern) called their DC-9s and 727s 'WhisperJets', making the cabin quietness of the rear-mounted engines a feature. Rear-mounted engines also allowed for simpler, less expensive wing structure.
Maximizing the necessary weight directly to the lifting surfaces HAS to make good structural sense, you don't need as much extra structure to transmit load to lift area.
Interesting! T-Tail aircraft look great, but wing mounted engines appear to produce a safer, more stable, more predictable aircraft. ( I am not a pilot.)
Hi Captain Mentour, i am a french person but i learn a lot of thing with your explanation althought i have a poor school english level. Great job captain !
I really have no idea about airplanes nor do I do anything related to airplanes, I stumbled upon a video by chance and it is so nicely explained that I understood everything even if in my life I had nothing to do with airplanes except in the case of travel. Every cast to the explained. Good luck
Even for Google, the state-of-the-art speak-to-text model they use is very funny and unreliable. Sometimes it is even funnier and write inappropriate obscenity.
Im not a pilot, and i dont train to be one. Im actually a computer science major but i just love airplanes and love your videos. I found this channel a week ago.
btw boeing 747 had that flattering problem in its original design. That happens when the natural frequency of the structure is equal with the flow induced vibrations on that structure.
In light of the recent grounding of the Boeing 737 MAX, pilots are saying that the airplane tends ti pitch down because of the center of gravity being unusual for a lower mounted engine, since the landing gear is short, they had to put the engines up and forward a little bit. Based on what you have explained, it seems like it could be behaving like a tail mounted engine. In your opinion, is the design of the 737 MAX flawed, or can it be solved with improved software without having to re-design the airplane?
Interesting topic: I have flown both of the discussed enginge mountings. I do not want to go into more handling details, but one thing you did not really mention: Mounting the engines at the back make an airplane MUCH heavier than if mounted on wings. I found out about it when flying a subcharter for Britannia Airways with a BALAIR MD-80 out of Korfu. As long as you have southerly winds there there will be no problem with take-off performance. But there will be with northerly winds due to a road and obstacles just north of the departure end of the runway. So my dispatch did not realize that when accepting the operation of a flight from Korfu to Birmingham I think it was. On the empty flight from Zurich to Korfu we went into the books to check and became aware of the problem. JUST GO ON READING - I WILL COME TO THE ENGINE-MOUNT PROBLEM SOON. So we hoped there would be southerly winds. But it turned out the other way - northerly winds and take-off towards the north. After take-off calculations I informed my homebase, that we had to make an intermediate landing, preferrably in ZRH, as the crew would then have to be changed due to maximum duty time, and of course for refuelling, which brings us to the point. I could only take fuel to just make ZRH with altn BSL. While, standing beside me, a Britannia 737, with same engines and passenger capacity !! would still be making the flight as scheduled directly to England. So I was wondering why and went to the cockpitcrew of that 737 and we compared our calculations. I am citing here round figures as it is long time ago, but just to give you an idea. With full load of 150 pax and their luggage the 737 was almoast 7000kg, 7 tons lighter than the MD-80, same engines and payload, without fuel. So could take some 7t more fuel, which gives you at the end of a flight about 90 mins. more trip (cruise) distance. Or in other words, they were about the same weight on take-off as we, but for the UK and we only for ZRH. After thinking for a while I came to the conclusion that this must be due to the engine mount. You mentioned already some negative points regarding the mounts in the back, but I think you forgot some very important ones: First of all the engines on the wings are carried by the strong wing-struts and their own cowling aerodynamicaly, while the ones in the aft add to the empty weight of the cell (in flight) and the aft-fuselage must be built much stronger than on 737-like planes in order to carry them and also to transmit the power/force. So in other words, the empty cell of a 737 (300 I guess it was) was about 29 tons while the MD-80 weighed almost 36 tons, almost 7 tons that you had to carry more on every flight. So more fuel consumption in same cruise conditions while less fuel could be carried along in certain cases like this one. Very disadvantageous for the operation then (in the 80's) If you came this far reading I sure do hope I did not bore you too much with this.
Like you said, the wing are the main lifting force and the main drag producer. Having the heaviest part and the trust at the same place make the structure simpler.
As much as I love DC-10s and MD-11s and the like, I've always wondered what the hell they were thinking. "...but we don't quite need an extra 2 engines." "Just one then, 3?" "3". "Okay, done. We just have to figure out where to put this high-powered volatile device with a massive fan blade that could blow up at any time..." "Okay, how about we stick it right in the middle of one of the most vulnerable sections of the plane. Yeah, that sticky-up bit at the back that the plane absolutely cant fly without should it be torn off." "Genius. Do it."
MPAH1981 3 engined widebody jets like the DC-10/MD-11 and L-1011 were really kind of a stopgap before ETOPs was a thing. 4 engines were too many for a smaller wide body but 2 engines weren’t enough without ETOPs. So they used 3 engines to save on fuel and still be able to fly over oceans unimpeded. It wasn’t an ideal configuration but at the time the DC-10 and L-1011 came out it was the only way to have a widebody that didn’t need 4 engines fly over oceans without limitations. In all honesty though, where else could they have put the 3rd engine that would have been better?
There is at least one MD-11 aircrew that can vouch for tails being overrated. During the Iraq war a MD-11 freighter was hit in the center engine by a surface to air missile over Baghdad, despite losing elevator, rudder, most of the hydraulics and the center engine they were able to successfully turn around and land the plane with no loss of life.
First. This person knows what he is saying. Explanations make good sense. I grew up in the 60s 70s not 2 miles from the western end of GLA, right under the flight path. The turbo JETs were unbelievably noisy on take off. Prevailing wind for Glasgow came from the west. So 90% of aircraft going out under full thrust, right over head! The noise rattled windows and brickwork. The Turbo fan was a god send. Years later I apprenticed with the BAA. British Airports Authority. As an electronic and electrical engineer. Spent a lot of time out on the air strips. There are a full crew that just looks to make sure the strip is clean. Even small bits of grit and shit can be devastating to a big engine. One thing our pilot might think about, is where the noise actually comes from. At Aberdeen airport, where most traffic is helicopters servicing North Sea oil. There is an old US model. 2 Blades. when the leading blade is, in the direction of travel, the tip just breaks the sound barrier. It's common name there is "The Thumper". You can hear the thump long before the chopper is in sight. I think the roar of a jet is more to do with the fins constantly smashing the sound barrier than the eject thrust. In the early days it was that very speed that blew most of the prototypes apart. When you are near the runway, even 'tubo fan engines" WHINE up. They are FFin loud! The only engine built that the thrust creates the real noise is a rocket. Not sure you can call that an engine? More a "hopefully controlled explosion". Pilot or not, your information is interesting. Your 'Merchandise' makes me laugh heaps. Who in their right mind would pay 40 bucks for a T-shirt?? Only in the USA! Bet it says "made in China on the label."
Something I've always wondered about. Pretty much every jet engine creates a "buzzing" sound at high/full power. If you haven't already, could you please explain what causes that buzzing noise? Thanks in advance!
4:43 makes sense the same applies for car engines when they open the exhaust valvue durring the 4th step of the Otto or aspon cycle because the presure in the cylinder is still at 4bar
I kind of miss the airliners with engines on the tail. They were unique and different, like trijets or superjumbos. Nowadays, every airliner looks the same, with a wide-body and twin engines mounted under a slightly swept wing. It may be efficient, but I miss the old and quirky designs.
Another advantage of wing-mounted / disadvantage of rear mount: Tail size and drag. Rear-mounting makes the tail stabilizers much closer to the CG, so they have to be larger to compensate for the loss of leverage. That means lower speed and fuel efficiency. Additionally, the longer fuselage ahead of the CG works as an anti-tail, making the plane want to weathervane and swap ends, going backwards. That means the tail has to be even BIGGER, meaning even more drag slowing the plane and burning even more fuel.
Another downside of the fusulage mounted engines is the risk of getting ice from the wing sucked into the engine thus risking it to be destroyed. Its a very famous Swedish accident whom happen a couple of decades back whom you probebly heard about. A follow on question might be why no one has the pods mounted over the wings rather than under them? There are probebly good reasons for this but it would be interesting to hear about. Johan.
The German VFW-Fokker 614 had the engines mounted on top of the wings. I think the reason you don´t see this configuration very much is because it caused some airflow issues over the top of the wing, as well as engine maintenance was quite a hassle since you had to climb the wing to get to them.
I'm no expert, but to my understanding majority of the pressure change that produces lift happens on the upper surface of the wing, so an object of such size would reduce the overall lift much more than one positioned below it. That's probably the reason the spoilers are located on top of the wing too, because they are much more effective there, instead on the lower part of the wing.
HondaJet has jet engines _in pods_ over the wings. Others have had engines mounted _on top_ of the wing, but AFAIK Honda is the only one with jet engine nacelle pods mounted over the wings.
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And why are some Boeings have the engines in the wrong place and they fall down from the sky last 3 years😀
Which did you prefer to fly?
Why did wingroot engines like with the comet go out of style? Or bottom of the plane installations ala the planned american Concorde competitor SST?
In military planes they seem to work pretty well. Are there concerns with the available room for payloads or maybe regarding crashing?
Thank you ! This question seriously bugged me for some time, ha. I would see planes with the engines off the fuselage and wonder how there could be such a big difference in engineering between jets. I mean one would have to be the clear winner for performance, economy etc. I guess the answer is complex. It would seem to me that the foreign object damage issue you mentioned. Would make the back mounted engines a far superior design, except from potentially making stall situations worse. Hmmm. In any case I really appreciate the video. Awesome job
I hear home. Are ye a bit Irish?
For regional and executive jets, the tail-mounted engines also means the aircraft doesn't need much ground clearance, which makes air stair design much simpler, and a useful feature for many of the smaller airports both types fly out of.
plus a smaller (thus lighter) gear assy
Hi, thanks for the video. However, there is a notable advantage of the rear-mounted design over the wing-mounted design that I wish to add. The wing design is much simpler, resulting in a stronger, lighter, and aerodynamically better wing. Even being small, the under-wing engine produces some aerodynamic interference on the wing at high angles of attack. In addition, part of the flaps are directly in the path of the engine blast, which makes complex its design. Also, the airflow under the wing must be slower than the airflow over it to be effective (as you know), and the engine blast makes the opposite effect on the part of the wing affected by its trajectory even at higher speeds, at lower is worse. Another undesirable effect of under wing engines is that they produce huge torsional forces in the wing structure during accelerations and decelerations, such as when using the reversers making even complex it design. Just observations, and sorry the long message. Thanks again.
wonder if that's why McDonnell Douglas successfully got away with never redesigning the DC9 wing and only making stretched variants, because the wings were apparently efficient as-is.
@@PlymouthNeon "got away with" sounds like they *should have* but didnt redesign them. but as you say, they didnt need to bc they had a decent design already.
Edgar you are supposed to be an aviation designer or something similar very nice comments you had . thank you
@@mostafakarandi363 Hi… I wish! But I´m not... sorry for that. I´m an industrial designer specialized in the field of machinery construction... I have some experience in sugar cane harvesters and bikes manufacturing. However, airplane construction is my passion, so I spent my last 24 years trying to understand that. As result I was invited to do some 3D analysis about nose cowling aerodynamics, cabin structure and ergonomics in a light aircraft project designed by an aeronautical engineer friend of mine (A great opportunity for me). That aircraft is almost finished and waiting for final approvals to perform its maiden flight. For that project my friend was invited to Oshkosh Air Venture; quite an honor of course… It is my hope to be able to design and build my own light aircraft someday :)
Dunno about lighter. Without the engine counteracting aerodynamic forces, the wing is, in fact, stiffer and heavier.
"The reversers could throw up loads of gravel and S-H-I-T from the ground" Is that a pilot technical term? lol
Sierra Hotel India Tango
DARYL MT Socialmedia Hating Inclean language in Teaching
@@taxfraudpro Sierra Hotel India Trivago
@@vehicleboi5598 SMHILIT?
HAHAHAHAHAHHAA
You might mean this site to be a mentor for budding pilots but I am enjoying it immediately. I am a 72 year old retired train driver with an interest in aviation and I find the site to be extremely interesting.
Great to hear!! Welcome to the channel!
he sometimes is racist with people who dont work or have the hobby of flying. We also like watching the videos you know? And i understand everything he says.
Major Tom - What does racism have to do with technical interest?
Al grayson You tell me! I just know im here to learn about aviation and really like Mentour Pilots videos, but sometimes he makes bad comments about us. (people who havent ever piloted a plane)
MT: based on what appears to be the intent of your comment, "racist" is probably not the correct term. "critical" might be more along the line of what you intended.
I'm a private pilot, so I cannot comment professionally on your video, but I will say, if I needed an instructor to explain what I need to know to about flying big planes, learning about their structures and operations, or even small ones for that matter....you, sir, would be the man.
Very informative, and well done, even with the slight accent. Some of the people I have heard on the radio, with ATC, those people who have chosen not to, at least try, and learn how to say the words, should have licenses suspended until the choose to.
I think you know you're stuff real well sir. Thank you. True professional.
I was incredibly nervous my first time flying alone. I happened to be sitting next to a pilot, who noticed I was nervous and decided to tell me about the physics of flight and gave me a general sense of the systems in place on a jet. One of the things he told me was that if the engines failed, planes with wing-mounted engines were very good at gliding, while planes with rear-mounted engines were not.
Those aboard BA009 in 1982 can attest to this.
That doesn't make sense. Tail engined aircraft have a cleaner wing
@@tedarcher9120 It is about their centre of gravity, and the location of their aero surfaces. A T-Tail plane has stabilisers way off the line of mass and so have an outsized torquing moment.
@@Sagan_Starborn how does that affect gliding though? Stabilisers are producing downward torque anyway to compensate lift, if anything T-tais have lower drag because they need smaller tails
@@tedarcher9120 It’s about weight distribution.
Also, high mounted engines coast better in water landings and can be destroyed by ice coming off the wings.
Well there was a case of a tail engine Mcdonald Douglas that had the engines die of ice but also there was a A-10 pilot who went off range during training maybe to look at the fresh powder in the mountains because he was a avid skier who I therefore suspect might also have been a unfortunate victim of icing flaking off the wings. The Air Force blamed the kid, very sad.
@@Schtuperfly finish the story!
@@Schtuperfly not enough detail lol
Probably safer for emergency landings on land where the landing gear failed as well
But you lose water propulsion ability
The Russian IL-62 T-Tail aircraft had saw tooth leading edges to stop wing tip stall and therefore super stall. The wing tip functioned as a sort flying wing due to the sweep. The VC10 and iL62 were the only aircraft that did not enter into a super stall. This was primary due to adequate sweep providing a downward pitch, saw tooth leading edges and fences and a little from the stub wing effect of the rear engines. Rear engine aircraft also were prone to engine stall and often had 'autolight' for the engines.
"gravel and shit from the ground" LOL I laughed
Made me look, lol.
Haha, yeah, because this guy seems too refined to say "shit," huh? LOL!
I had to play that back a couple of times to make sure
That shit would definitely hit the fan
I was going to write the same!
Great podcast, Mentour Pilot! Very concise, comprehensive and engaging. I could not have explained this better myself. See you in the next one!
As an automobile enthusiast all my life and having majored in engineering, it is also very, very interesting to read every comment in the great debate of the location of the engine on an aircraft as well. Especially, I love learning about the pros and cons for each location of the engines, in terms of rigidity and aerodynamic flow. Just to point out where exactly it was fun, a specific attack angle in a rear engine aircraft can leave the horizontal stabilizers with significantly less airflow blocked by the wings, which could end up in a super stall.
I am not a pilot, but I used to fly quite a lot as a passenger. I always felt that the DC9 and 727 had cleaner wings and handled low-level / low-speed turbulence and cross winds better than planes with wing mounted engines. I do miss the 727, I loved seeing the stacks of analog guages as I passed through to my seat.
I was told that the 727 engine configuration is very inefficient, I doubt we will ever see anything like that again.
@@fredhurst2528 That may be why the 727s discontinued. They did have quieter cabins than wing engine aircrafts, since the majority of the noise from engines are behind them when a plane is acceleratingforward. You probably may've noticed when lined up for take-off back in the 1980s that the 727 in front of you moving away from you during its runway acceleration, it always sounded louder than the 727 you were in sounded while you accelerated down the runway for take-off, the reason was that the majority of the noise was behind the engines. For the same reason, I'm sure you've noticed that the back section of wing engine planes are always louder than the front half. Anyway, the quiet cabins all the way through wss something good about the 727s, the jist of the noise staying behind the planes
Some planes had the rear engines like the DC9s and 727s, some had just wing engines like the 747s, 767s, and present day 777s A330s, and A350s. And some had both such as the DC10s and L1011s (no side rear-engines though, just center tail-engines).
There were good things about the DC9s and 727s, and the quieter cabins due to all the engines being in back was a reason I liked them, see my above reply. I have wondered why no wide-bodied long distance aircrafts had the side rear-engines and no wing engines like the 727s
Fantastic! There is a reason why you consistently have huge numbers of viewers and thumbs up. You teach us about interesting things in a relaxed manner. Love your vids.
This pilot is really great. Love all his vids! Flying on the Boeing 717 is allot of fun as it brings back memories from years ago when flying on many DC-9 fan-jets!! Please keen these vids coming!!
1. With time, aircraft needed bigger fans to higher propulsion. But engines on the wings have limited space because of ground clearance. Hence, they either fitted more engines on the wings or fit a bigger engine at the back.
2. Engines on the wings help counter wings flutter/vibration. See 3:30
3. In case of a fire in the engines, an engine on mounted on the wings help since it is separated from the main body of the aircraft.
4. The most noise comes from the exhaust of the engine. Separating it from the main body helps you sleep well when you're in the main cabin.
5. In case one of the under-mounted engines failed, it will add a non-zero torque and try to spin the aircraft about its center of mass. Hence, a larger Rudder is required compared to a back-mounted engine plane.
6. See 6:20 for Thrust-Pitch correct to keep the altitude stable/constant.
7. Engines at the back also help in the noise correction for a quieter cabin.
8. Charter planes have back-mounted engines because their smaller size may cause the engine to suck foreign objects like little grain or stone or grass in the surroundings.
9. See 8:40, the aircraft can use back-mounted engines to pull itself back without needing a tractor. Boeing 717 is a classic example. It's risky since you don't have a rearview mirror. And it can also suck foreign objects from the surrounding.
10. For back-mounted engines, a stronger structure is required at the back because it is further away from the center of mass. And yes, more piping to pump the fuel to hit.
11. See 11:30, back-mounted engines require T-tail to avoid "super stall". Like Boeing 717.
Thank you!
Your first point is wrong. You can't fit bigger engines onto the rear of the plane, because they would be too heavy and take the centre of gravity too far back. Also, the structure of the plane couldn't take the weight.
Very interesting video, thanks. You missed a important point though: The body of airplanes with back mounted engines can be placed lower, so many of those planes have their own stair to enter at the front. This gives more flexibility at smaller airports or airports far off with no big infrastructure. The Boeing 737 had very small engines in earlier versions for the same reasons, and then they had big problems placing the new and bigger engines below the wing for the NG/MAX. That's why they are oval and not round at the front.
Gv
The 737 engines could also be serviced by a technician standing next to the engine.
Sounds like you've been watching a lot of youtube. In fact, doesn't this guy have another video explaining exactly this?
Cannot be placed lower than wing mounted. He has covered your topics
@thebase and @william he has a video exactly stating that...
welcome to the Mentour Channel
"you can mount larger engines under the wing"
737: Am I a joke to you?
*MAX 8 intensifies*
@@NeonBeeCat OMFG. 🤣
LOL
Yep then came the MAX 8.. we all know what happened after that
Lol. But he means for the final design. If designed right, you can put as big an engine you want under the wing. Not adding bigger engines after the fact. That's what Boeing did to the 737.
Excellent video!! I want to add that an advantage of rear mounted engines is a more clean wing, which is more efficient in terms of aerodynamics, resulting in a lower fuel consumption for the same engine placed in the wing.
are you have to research about this before ? cause in this video doesnt discuss about the advantages from fuel consumption.
even, the rear engine must has piping line fuel for get it. and it should be make the consumtion of engine higher than wing engine. cause need help a pumping system for distribute the fuel from wings to engine.
The wing without engines mounted on them are more aerodynamically efficient BUT the MD80 to MD88 series of jets are serious gas guzzlers!
@The Green Bastard That could very well be because they have much smaller fans than today’s high bypass engines that would not fit on the fuselage - as explained in the video. Inefficiency somehow seems to be a conserved quantity.
A disadvantage of rear mounted engines is that in cold weather, an improperly deiced wing could cause ice to get ingested in the engines and damage them, like what happened to one SAS flight that crashed on takeoff a while back.
The Gottröra disaster on flight 751, 1991.
I’ve asked this question before and usually get “all planes handle differently” which is obvious but doesn’t actually answer the questions about engine position. Thanks for some great information.
I've always enjoyed the ride of a T-Tail over the traditional config. However, I never knew, or realized, that a stall can affect the T-Tail and lose control. Thank you.
The Delta wing can also blank out the air over a more traditional tail, not only a T-tail. The A-4 Skyhawk was such a jet. Get the AOA too high and you get into a Super Stall. Without enough altitude, it's impossible to recover from it.
Cant this also stall the turbines?
Easy solution. Dont stall
4 years after publication, it’s absolutely fantastic how much you have improved your presence and storytelling on video. What a pilot! ❤
And yet even then, he still wasn't bad. 😎
@@AaronOfMpls He's not bad in this one, (apart from a little problem with mic levels,) perhaps because he's enthusiastic about it, but he has since learned to be really good. :)
Thanks so much for this video! It should be part of the Kerbal Space Program tutorials, as I finally understood why my little plane with back-mounted rocket engines tends to nose-dive :) Now it's all so much clearer! You are a great instructure !
13:21 "over-explanation"?! ... that's the very reason why we are on your channel!
Interesting note about low mounted intakes, the Soviet/Russian MiG-29 was designed with intake doors which block debris by dropping down to allow intake from the louvres above the nacelles, facilitating operation from rudimentary or potentially damaged fields.
Your videos are so interesting. You made me interested in aviation, before Seeing this channel I didn’t care at all.
Just wanted to tell you that I have loved airplanes and flight all my life and greatly appreciate all the information you share in your videos.
Some shake your stick
Others push your stick away
Airbus just unplugs your stick and tells you to go sit in the corner.
Lol
*.*
* *.* *
"Why are you calling me, mum?"
"Your plane asked me to"
Lol
after a really bad turbulence I found your channel... excellent content Sir, you got a subscriber.
I remember once reading a silly paragraph on Wikipedia about it. It said something like "Being attached to the tail gives fewer points of structural failure that could separate the engine from the aircraft. With wing mounted engines the wing can separate or the engine can separate. With tail mounted engines only the engine can separate."
That is what convinced me to get an account to edit the wiki because seriously what pilot is going to be saying "oh no! My engine" when the whole wing fell off?
EpicSpaceTroll 139 You’re fucked either way if your wing or tail breaks off 👀
nope... the hardpoints that fasten the engine are the same on any position, its on a captured rail so it can be easily slide out to perform maintenance... funny they don't take into account the tail is actually less heavily built then the wings.. the wings hold the entire weight of the plane in the air.. tail just acts as a stabalizer, it creates no lift lol .. wikipedia for ya... me, I build aircraft hehe
Yep. That's part of why I thought the paragraph on Wikipedia was so ridiculous. :P
For anyone who has ever seen how much material is in an engine pilon, or the structural members attaching the wing, it would be the least of my worries.
Awesome video Petter, hope your week in Stansted has been going *fantastic*
In English, the word “shit” is beneath the quality of the language you normally use here.
“Stuff” works.
Christ a week at Stansted, can't think of a worse form of torture. I guess Luton
Using occasional profanity makes a person more likable and makes a message more personal. It's good to say shit like that sometimes.
I can beat that. How about a week in Glasgow, not only the same depressing Travelodge, but a depressing city overall
Antonomase Apophasis one slip of the tung earns a lecture from you? Even the penguins at my Catholic school would only give you a stern look, the first time.
Only thing I’ve ever flown is a glider. No engine positioning decisions there. My late father, though, was an instructor with BOAC and East African Airways. Both flew Comets which had turbojet engines mounted inside the wing roots. Made then particularly difficult to access for maintenance and practically guaranteed that any serious malfunction would result in structural damage. The exhausts had to be angled outwards to avoid sonic damage to rear fuselage and tail plane (old fashioned phrase.) Excellent explanations so thanks very much. I fly as a passenger several times a year so you’ve resolved a lot of queries.
GingerPilot talks to me like I’m intelligent. Bless his heart.
🤣🤣🤣🤣🤣
Very educational video and your English is excellent by the way !
Thank you! I do my best!
Yes it really is
May learn to use word FUSELAGE one day too.
I thought he was a native English speaker. 😲
Yes, your English is basically perfect. You’re Swedish, no? I don’t think you’ve ever actually told us where you’re from - or perhaps I just haven’t seen that.
Another issue with rear mounted engines is weight and balance. I used to prepare load plans and W&B for Air Aruba out of BWI on MD80s and MD90s. They would fly from BWI with a small number of passengers to Philadelphia where the majority of passengers would board for the flight to Aruba. For the trip BWI -PHL we often had to load all the BWI passengers in first class and their bags in the forward compartment to get the aircraft properly balanced. Sometimes there were not enough passengers so we needed to add ballast as well.
Thank you for making these videos ! They are always informative and entertaining. Also, very educational ! 👍
Its not an Like an aticathera mechanism they use topel the aircraft. Come on!
Nice video! You took it in a hotel on a layover?
1. One of the main reasons that engines are mounted to wings is that the weight of the engines tends to stabilize the wing. It doesn't so much stop it from bending as it simply adds mass which makes the effect of turbulence less on the structure, which in turn means it can be built lighter. This is the same reason that fuel is carried in the wings. On most aircraft with a center wing tank, the wings are filled first and then the center tank is filled. The reason is that fuel in the center tank does NOT stabilize the wing and in fact causes greater center section flex, so it is detrimental.
2. Rear mounted engines have their weight attached to the fuselage. Just like center tank fuel, this engine weight contributes to center section spar stress during turbulence or maneuvering. Airplanes with rear mounted engines have to have stronger, heavier wings as a result.
3. Rear mounted engines give the wing a very clean profile, which greatly contributes to performance. The Boeing 727 was known to be the second fastest airliner ever built after Concorde, yet it's landing speeds were no faster than some turboprops. The rear engine design allowed barn-door sized triple slotted flaps yet the 37 degree sweep and clean design allowed cruise at .90 mach for some models.
4. Airplanes with rear mounted engines have shorter landing gear, which makes integral air stairs more practical. This is one reason why most private jets have this design.
5. Airplanes with rear mounted engines look less impressive. Since private jets are typically owned by public corporations, the "cheaper look" is easier to get past shareholders.....
6. Sure you can mount high bypass ratio engines to the rear of an airplane. Dee Howard had a design to re-engine 727's with two CFM-56's and delete the center engine. Problems? Yes: First of all, this would be a seriously expensive modification to airframes already basically worth their scrap value. But second...The heavy weight of the high bypass engines would make it very difficult to keep the center of gravity within the proper range. This is the reason no manufacturer did this; It is difficult to keep the CG correct and this ruins usability.
7. Rear mounted engines have very quiet cabins, in comparison the rear end of a 737, which is screaming loud....
Keep up the good work!
"Dee Howard", that name brings back some memories. I used to work in those big orange hangars in San Antonio (Of course, by then it was SAA. VT Aerospace now...)
I need to say that it accidently answered so many of my childhood questions on differences in built and proportions of planes. Wow. Just like that everything became clear now that I'm almost 42.
I loved the stick pusher info on T-tailed planes. Made me remember that even the F-104 fighter (a t-tailed plane) also had a stick pusher.
Every large aircraft has a stick pusher
In the F-104, at some point of High AOA, the stubby wings, would start to shunt the
airflow to the T-Tail. a departure becomes imminent, and hence the shaker.
Mentour: large fans on the 737
GE9X: A 737 fuselage can fit inside inside of me and so can the engine!
3:58 that’s the old Tacoma Narrows Bridge that fell in the 1940s. I frequently drive on the new one
I learn valuable info from this video. thank you soooooooo much for sharing your knowledge.
Something I’ve thought about (working as a refueler). Quite interesting. I always thought it was style based and never really considered the pros and cons. Thanks.
I really liked your detailed explanation about the aircraft engine, and your explaination was so simple and clear and it was perfect and you made me understand in a single video. Thank you. Keep going...
9:30 "the reverses would throw loads of gravel and shit from the ground" 😀 Mentour Pilot, you are the best! I had to play this 5x just to make sure you really said that. LOL But seriously, you rock, man. I love the way you explain stuff.
Haha. "Shit" (or the swedish equivalent: "skit") is much less of a taboo word in Sweden. It almost doesn't even count as a bad word so that's why he said it so casually.
Rear mounted engine planes also have the advantage of having a lower clearance height from the ground...making boarding and loading cargo less complicated and available with cheaper equipment...”Oh but the 737 has that goal as well” But they had to flatten the nacelle to make it less complicated. However, flying one of those is totally different from a wing mounted engine plane, as you have bigger torque arm acting on the longitudinal axis of the plane.
Correct! I knew I forgot something!!
Also since the aircraft is lower the main gear and nose gear will be shorter thus reducing weight.
loading cargo really does not need much equipment and wing mount engines are really not any significant factor, but it is PITA for maintenance and that matters a lot.
Ground clearance of the engine nacelle wasn't an issue until they started mounting high bypass engines on it, the 100 and 200 had no issues at all with that.
The 717 F100 airframes are pretty inefficient for lift when operating at high ambient temp compared to 737 A320.
Oh, thank God. This is one of those things that I have wondered about for years but kept forgetting to look up. Thank you.
Your videos are very informative and interesting. I love them. Please keep up the amazing work.
Is ground clearance a factor? For a small aeroplane low to the ground you might not have room for engines under the wing?
Absolutely correct.
I was thinking about it too, it would be impractical for jets with low ground clearance to have wing mounted engines,
Why not have wing-top engines? Back in the 1950's the DeHavilland Comet actually had its engines inside the wing.
Yeah, all of the RAF's V bombers also had the engines in the wing root. Wing root engines only work with turbo jets, not turbo fans though.
I guess harder access to maintenance and also they didn't used turbofans for the Comet, they require a much larger mouth to fit the fan, so you would also lose usable wing area if you replace the sleek intakes with a big fan.
When working for Boeing in 1966 I asked why the engines we moved on the wing 737. The plane could be lighter because it would be a counterbalance since the wing holds the weight of the total airplane.
Did he just say "shit", when talking about sucking things up from the ground in reverse thrust for the under wing engines? That's hilarious, i dont know why, just unexpected i guess. lol. Love Mentour!
Haha! Glad I could bring a laugh to you.
He said sheeeet 😂😂😂😂
It was a "slip" of the tongue! Off the tarmac, on a hot day, after a bad meal!
In most germanic languages (including apparently aviation English), 'shit,' 'Scheisse,' what ever is a very mild expletive, like merde in French. In English it's stronger.
That 'shit' caught me off guard and made me repeat and laugh. Love these videos. :D
Fascinating explanation and so clearly expressed.
Glad you liked it!
Excellent explanation. Of all the aircraft I've flown in as a passenger, my fondest memories from a performance standpoint has been the MD-80. Loved the immediate throttle response and the clean swept look of the wing.
1:55 boeing has left the chat
dosmastrify 😂😂😂🤣
X Plane mobile Channel umm your channel is infinite flight not x plane mobile ( •_•)
I passed my PPL today! :D
Congratulations!! Welcome up in the sky as commander!
Mentour Pilot Thank you so much. I love your videos.
Zan0s Congratulations! Getting my PPL was one of the funnest, most rewarding things I've ever done. How about you? Terrifying, to have that final check-ride, especially when you realize in the air that your instructor forgot to train you in one particular maneuver and now you're being tested on it. In my case I had to do a full slip down to the 500' markers and come within tolerances. Managed to do it though on my first try. I told my check-ride lady that I hadn't been trained on that before I did it too! She looked nervous and she squirmed right before I straightened her back out, but I'm pretty sure that helped me with the PPL at the end. :)
All the best
Wish you luck for your flight with captain!
I love u r podcasts the way you explain the things is very great I simply make complex topics into very simpler form
4:19 "thats not good"
is it just me or is that a bit of an understatement
He kinda left off the part that the fire was engulfing the fuel tank!
Thank you! Was thinking why isn't anybody commenting on that?!
I think airplanes with rear-mounted engines look better. They sit lower on the ground and the T-style stabilizer looks so cool. The 727 and the Tu-154 are beautiful airplanes.
If at all possible I will never set a foot inside a plane with rear mounted engines ever again :/
Lembas mit Spinat-Kuerbis Creme yeah, when that engine explodes and takes out the hydraulic lines to the tail, your gonna have a bad day.
As an engineer with 36+ years in aircraft propulsion, I found this video a good review. Thank you.
Back in the '60s, at least one airline (Delta or Eastern) called their DC-9s and 727s 'WhisperJets', making the cabin quietness of the rear-mounted engines a feature. Rear-mounted engines also allowed for simpler, less expensive wing structure.
That was the name Eastern Airlines used for their 727s
Меги обсди ми се наблюдава
That was eastern airlines but it called it for Lockheed tristar L1011 not for 727 or DC9
Ashish Anand L1011 was a sweet flier.
I was remembering that too.
Maximizing the necessary weight directly to the lifting surfaces HAS to make good structural sense, you don't need as much extra structure to transmit load to lift area.
Good video. The value of your videos is superior than flightchannel's where nothing is spoken.
‘Shit from the ground’ 😂😂😂 funny af!
True though
The joys of unedited content lol 😂
Why is it funny? That’s just reality
I was looking for this comment, that moment got me laughing - gotta love Mentour!
Truth can be funny. Absolutely!
Tail mounting requires heavier structure in the tail. Wing mounting takes advantage of the existing wing structure.
Well explained 👍🏾
9:35 I swear I thought you were going to say "this is why you can see people flying into the engine". 😂
Interesting! T-Tail aircraft look great, but wing mounted engines appear to produce a safer, more stable, more predictable aircraft. ( I am not a pilot.)
Thanks! I've watched most of your newer stuff, so this was a great find.
*Aaaaaabsoluuutely Fantaaastic*
I learn something in every one of these videos.
Hi Captain Mentour,
i am a french person but i learn a lot of thing with your explanation althought i have a poor school english level.
Great job captain !
1:47 as opposed to changing the spark plugs at 30,000 feet.
Excellent video, good explanation.....you are a great pro.
I really have no idea about airplanes nor do I do anything related to airplanes, I stumbled upon a video by chance and it is so nicely explained that I understood everything even if in my life I had nothing to do with airplanes except in the case of travel. Every cast to the explained. Good luck
Pilot you are very brilliant man
"4 engines"
*youtube subtitles: 4 indians*
I saw that lol
They are race obsessed after all.
Even for Google, the state-of-the-art speak-to-text model they use is very funny and unreliable.
Sometimes it is even funnier and write inappropriate obscenity.
in the engine
@@和平和平-c4i I really feel for people depending on them due to disability, it must be a really wtf situation sometimes.
Im not a pilot, and i dont train to be one. Im actually a computer science major but i just love airplanes and love your videos. I found this channel a week ago.
8:47 "they're getting clearance from the ground"
*van drives past
*
me: shocked pikachu face
i just seen WTF lol WoW!
The main reason for the tail mounted design is to reduce ground clearance. This makes boarding easier when a jet bridge isn't available.
Super interesting and informative, explained in a way a ley person can easily understand.
btw boeing 747 had that flattering problem in its original design. That happens when the natural frequency of the structure is equal with the flow induced vibrations on that structure.
manos, I think you've been drinking too much. Big aircraft have a computer to control flutter problems.
Robert Lee in the 1970s ?
747 dates before the invention of the microprocessor.
If I remember correctly, didn't the Me 262 (first jet fighter) have a similar problem?
In light of the recent grounding of the Boeing 737 MAX, pilots are saying that the airplane tends ti pitch down because of the center of gravity being unusual for a lower mounted engine, since the landing gear is short, they had to put the engines up and forward a little bit. Based on what you have explained, it seems like it could be behaving like a tail mounted engine. In your opinion, is the design of the 737 MAX flawed, or can it be solved with improved software without having to re-design the airplane?
Straight forward, plain language explanations. Thanks
Excellent. Thank you. (subscribed)
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Interesting topic: I have flown both of the discussed enginge mountings. I do not want to go into more handling details, but one thing you did not really mention: Mounting the engines at the back make an airplane MUCH heavier than if mounted on wings. I found out about it when flying a subcharter for Britannia Airways with a BALAIR MD-80 out of Korfu. As long as you have southerly winds there there will be no problem with take-off performance. But there will be with northerly winds due to a road and obstacles just north of the departure end of the runway. So my dispatch did not realize that when accepting the operation of a flight from Korfu to Birmingham I think it was. On the empty flight from Zurich to Korfu we went into the books to check and became aware of the problem. JUST GO ON READING - I WILL COME TO THE ENGINE-MOUNT PROBLEM SOON. So we hoped there would be southerly winds. But it turned out the other way - northerly winds and take-off towards the north. After take-off calculations I informed my homebase, that we had to make an intermediate landing, preferrably in ZRH, as the crew would then have to be changed due to maximum duty time, and of course for refuelling, which brings us to the point. I could only take fuel to just make ZRH with altn BSL. While, standing beside me, a Britannia 737, with same engines and passenger capacity !! would still be making the flight as scheduled directly to England. So I was wondering why and went to the cockpitcrew of that 737 and we compared our calculations. I am citing here round figures as it is long time ago, but just to give you an idea. With full load of 150 pax and their luggage the 737 was almoast 7000kg, 7 tons lighter than the MD-80, same engines and payload, without fuel. So could take some 7t more fuel, which gives you at the end of a flight about 90 mins. more trip (cruise) distance. Or in other words, they were about the same weight on take-off as we, but for the UK and we only for ZRH. After thinking for a while I came to the conclusion that this must be due to the engine mount. You mentioned already some negative points regarding the mounts in the back, but I think you forgot some very important ones: First of all the engines on the wings are carried by the strong wing-struts and their own cowling aerodynamicaly, while the ones in the aft add to the empty weight of the cell (in flight) and the aft-fuselage must be built much stronger than on 737-like planes in order to carry them and also to transmit the power/force. So in other words, the empty cell of a 737 (300 I guess it was) was about 29 tons while the MD-80 weighed almost 36 tons, almost 7 tons that you had to carry more on every flight. So more fuel consumption in same cruise conditions while less fuel could be carried along in certain cases like this one. Very disadvantageous for the operation then (in the 80's) If you came this far reading I sure do hope I did not bore you too much with this.
Like you said, the wing are the main lifting force and the main drag producer. Having the heaviest part and the trust at the same place make the structure simpler.
your explanations are really wonderful for curious and interested guys thanks a lot captain 🙏🙏🙏🙏🙏
As much as I love DC-10s and MD-11s and the like, I've always wondered what the hell they were thinking.
"...but we don't quite need an extra 2 engines."
"Just one then, 3?"
"3".
"Okay, done. We just have to figure out where to put this high-powered volatile device with a massive fan blade that could blow up at any time..."
"Okay, how about we stick it right in the middle of one of the most vulnerable sections of the plane. Yeah, that sticky-up bit at the back that the plane absolutely cant fly without should it be torn off."
"Genius. Do it."
as if turbine disc failures for under-wing engines have not resulted in disasters...
You missed the point, and at no time did I say they hadn't. But thank you Mr. Asif.
MPAH1981 3 engined widebody jets like the DC-10/MD-11 and L-1011 were really kind of a stopgap before ETOPs was a thing. 4 engines were too many for a smaller wide body but 2 engines weren’t enough without ETOPs. So they used 3 engines to save on fuel and still be able to fly over oceans unimpeded. It wasn’t an ideal configuration but at the time the DC-10 and L-1011 came out it was the only way to have a widebody that didn’t need 4 engines fly over oceans without limitations. In all honesty though, where else could they have put the 3rd engine that would have been better?
There is at least one MD-11 aircrew that can vouch for tails being overrated. During the Iraq war a MD-11 freighter was hit in the center engine by a surface to air missile over Baghdad, despite losing elevator, rudder, most of the hydraulics and the center engine they were able to successfully turn around and land the plane with no loss of life.
KentB27 Under the body, F-16 style? 😜👍
3:28 Well, that's rather terrifying...
The plane is farting. Relax
First. This person knows what he is saying. Explanations make good sense. I grew up in the 60s 70s not 2 miles from the western end of GLA, right under the flight path. The turbo JETs were unbelievably noisy on take off. Prevailing wind for Glasgow came from the west. So 90% of aircraft going out under full thrust, right over head! The noise rattled windows and brickwork. The Turbo fan was a god send. Years later I apprenticed with the BAA. British Airports Authority. As an electronic and electrical engineer. Spent a lot of time out on the air strips. There are a full crew that just looks to make sure the strip is clean. Even small bits of grit and shit can be devastating to a big engine. One thing our pilot might think about, is where the noise actually comes from.
At Aberdeen airport, where most traffic is helicopters servicing North Sea oil. There is an old US model. 2 Blades. when the leading blade is, in the direction of travel, the tip just breaks the sound barrier. It's common name there is "The Thumper". You can hear the thump long before the chopper is in sight.
I think the roar of a jet is more to do with the fins constantly smashing the sound barrier than the eject thrust. In the early days it was that very speed that blew most of the prototypes apart.
When you are near the runway, even 'tubo fan engines" WHINE up. They are FFin loud!
The only engine built that the thrust creates the real noise is a rocket. Not sure you can call that an engine? More a "hopefully controlled explosion".
Pilot or not, your information is interesting. Your 'Merchandise' makes me laugh heaps. Who in their right mind would pay 40 bucks for a T-shirt?? Only in the USA! Bet it says "made in China on the label."
So, is the "stick pusher" essentially the first iteration of of MCAS?
The MCAS emulates previous iterations of the B737 so training and rating could be done fast and cheap.
Something I've always wondered about. Pretty much every jet engine creates a "buzzing" sound at high/full power. If you haven't already, could you please explain what causes that buzzing noise? Thanks in advance!
4:43 makes sense the same applies for car engines when they open the exhaust valvue durring the 4th step of the Otto or aspon cycle because the presure in the cylinder is still at 4bar
I kind of miss the airliners with engines on the tail. They were unique and different, like trijets or superjumbos. Nowadays, every airliner looks the same, with a wide-body and twin engines mounted under a slightly swept wing. It may be efficient, but I miss the old and quirky designs.
Were you a fan of the trislander?
This is very informative.... I sleep though all my flights 😂
Another advantage of wing-mounted / disadvantage of rear mount:
Tail size and drag. Rear-mounting makes the tail stabilizers much closer to the CG, so they have to be larger to compensate for the loss of leverage. That means lower speed and fuel efficiency.
Additionally, the longer fuselage ahead of the CG works as an anti-tail, making the plane want to weathervane and swap ends, going backwards. That means the tail has to be even BIGGER, meaning even more drag slowing the plane and burning even more fuel.
Very enlightening. Thanks
Another downside of the fusulage mounted engines is the risk of getting ice from the wing sucked into the engine thus risking it to be destroyed. Its a very famous Swedish accident whom happen a couple of decades back whom you probebly heard about. A follow on question might be why no one has the pods mounted over the wings rather than under them? There are probebly good reasons for this but it would be interesting to hear about. Johan.
Yes, great point.
The German VFW-Fokker 614 had the engines mounted on top of the wings. I think the reason you don´t see this configuration very much is because it caused some airflow issues over the top of the wing, as well as engine maintenance was quite a hassle since you had to climb the wing to get to them.
I'm no expert, but to my understanding majority of the pressure change that produces lift happens on the upper surface of the wing, so an object of such size would reduce the overall lift much more than one positioned below it.
That's probably the reason the spoilers are located on top of the wing too, because they are much more effective there, instead on the lower part of the wing.
Johan Månsson honda jet
HondaJet has jet engines _in pods_ over the wings. Others have had engines mounted _on top_ of the wing, but AFAIK Honda is the only one with jet engine nacelle pods mounted over the wings.
9:30 - "Gravel and shit..." made me chuckle
I'm afraid my attention to what he was saying was done after he said "gravel and shit". That's made my morning. He's priceless