Why do aircraft store fuel in the wings?
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- Опубликовано: 4 июн 2024
- Sponsor: brilliant.org/mentourpilot/
You probably know that aircraft store a lot of its fuel in the wings but do you know why?
In todays video I will explain exactly what the idea behind aircraft fuel tanks in the wings are and I will also give you some info regarding the fuel system of the Boeing 737NG.
If you have more aviation related questions I would ask you to please download the Free MENTOUR AVIATION APP using the links below.
Enjoy!
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A huge thank you to the following channel from where I have borrowed some material:
John Baxter
/ @johnbaxter8740
Ask Aero
/ @askaero7498
Flow Science
/ flowscience
I’m a fueler at BNA & lately have been working with Southwest which only flies 737s - watching your videos have given me such an appreciation for my job and I’ve literally enjoyed working there more knowing more about these planes than I received in our training. Keep up the good work. It’s so nice to be able to look at the dozens of 737s I see daily and understand why they are the way they are. Thanks :)!
BNA - good old Berry Field.
It’s channels like these that make me realize that I haven’t turned on my TV to watch cable in months! Thanks Mentor!
It certainly is more intelligent. Pbs is cool. This video group takes me away from t.v. and you can take it with you on your travels.
I had no idea aircraft wings were also fuel tanks. I'm bingeing your videos at the moment and learning such a lot. Your channel is excellent.
This man is contributing a lot to the public. Thanks a lot. Keep moving.
He is a conman liar, there is no fuel in wings, total BS. These planes run on compressed air, not fuel.
now that's funny
@@leonmacri2910
Elon Musk?
That you?
@Androya 13
Background info:
Elon musk proposed the idea of flying cars with cold thrusters.
Conspiracy theorist much?
Your videos have really helped me with my fear/anxiety of flying. I have had to fly twice in the last year alone and it is a terrifying ordeal for me. Being a gear-head myself, it is so reassuring to know how a plane actually works. Thanks!
lmao what are you going to do take your wrench outside at 35k feet doing 540mph and fix it if it has problems?
Agent 47 has no fears.
@@heyitsthatoneguy91 No hes saying he appreciates and is interested in on how planes work, and run.
I dont think you understand what a gear head is
It is also reassuring to know how much abuse an aircraft goes through during testing to ensure that it will manage in normal situations.
"The Wings was perfectly designed to flex"
Wings:
"Bruh, do you even lift?"
[The wings very hard, they flex so hard they flex themselves right out of the room]
yes.
Underrated coment
While killing time waiting for my flight, I noticed a working crew fueling a plane through the wing which got me curious. I'm glad I googled it and found this channel. Gave me a lot of insight on why.
In a documentary about airplanes, it was said there was so much space in the wings so the engineers decided to store fuel in there. It created more space in the fuselage for passengers and cargoes. Function followed by science.
You are a walking aeronautical encyclopedia. I am no pilot but enjoy learning how things work. Thanks for posting these videos..
And what did we learn in this episode?
Engineers are damn smart people. :)
lbs of fuel!
@@geraldboykin6159 * litres of fuel
@@shubhankardasgupta4777 En aviación se usa el PESO del combustible (ya sean lbs, Kg, etc) no se mide en lt. Eso sólo lohace el camión cisterna que los abastece... de ahí el problema que a veces sucede al convertir de lt. a PESO (lbs, Kg...)
more like genetically blessed.
i've always been fascinated by planes but wow this video shows just one element of the plane and how well constructed and well thought out this flying bus really is, keep the videos coming
I am a teacher. The way he explains the things just like a teacher. I used to think where the fuel is store in the aeroplane but my doubts are cleared today hats on sir
Hi
Excellent video. You just forgot to mention that for £ 12.89 Ryanair let you fly in a wing with your mouth just above the fuel level.
Hahaha
lmao
Lol
Funny
@@MentourPilot get roasted
I always thought that the fuel tanks were in the wings. It never occurred to me that the fuel tanks were the wings.
I thought the same until my 3rd year of college. I used to think that the wings and the center wing box held separate tanks.
@@mach6893
They do have separate tanks.
A B747 for instance has 2 main tanks in each wing plus a small reserve tank (and a vent tank), the center wing tank is a separate tank.
So 7 individual tanks in the wing.
@@johno9507 what about twa 800????
@@vincentiancare8361
What about it?
I'm learning so much from this channel, thank you so much. The Swedish accent is also very nostalgic for me , as my dad worked in Sweden in the 80s and 90s. 😊
I have been flying small aircraft for decades. I love to fly! I have just found this chanel and I find it extremely professional. Very clear scientific explanations served one bite at a time. Great chanel!
I felt like a center fuel tank being loaded with awesome information. Thank you Captain!
The holes in the ribs in the wings of the aircraft are called baffles. They act like seperators to prevent the fuel from sloshing around inside the fuel tank.
He said that, why are you repeating what he said what they do?
@@ollelarsson995 So that someone like you could point it out. Click bait?
They strengthen the wing section.
One interesting thing I learned flying with my dad is as you fuel up the wings, they actually sag a significant amount. His plane has a 30' wingspan, the wings would sag about 6" at the tips when fully loaded with fuel. Also, the more fuel, the less the turbulence is, by a LOT. With almost empty tanks it feels like you are on a roller-coaster sometimes, with full tanks, the turbulence is probably 1/2 or a 1/4 of what it is empty.
The weight of the fuel counters the lift forces.
That was a really fascinating video. I'm a Chemical Engineer so its very interesting to know how similar safety principles used for fuel storage and transport in refineries are applied to the fuel systems in aeroplanes.
Your videos are so nice to watch and it's so stress-relieving just to look at the positive man talking about aviation stuff with a high level of professionalism and a constant smile on his face!
indeed!
STRESS? YOU WANT STRESS? AAAAAAAAGGGGGURRRRGHHHHHHHH!!! PUNCH YER FACE OUT!!!!
;p
joking right?
srdjan m very true
i will be glad when men stop acting like women
Thanks for great explanation. :) Your channel always provides easily understandable information.
I’m so happy that you think that.
Mentour Pilot can you do a video of aircraft pa system speakers?
Meaning the microphones, the speakers and if there is one can you tell us about the amplifiers on the planes that power the speakers? Btw I'm very into audio and have always been interested in how those sound with music.
+Jonathan Keenan ĺo
being smart is stupid
Highly appreciate the way you have explained as to why Fuel Tanks are located where they are located, I am in my seventies but such information is always beneficial.... Thank You.
Man - this guys' good - well explained - I could listen to him for hours ! thx much for posting
Go SHILL ELSEWHERE>
Thank you Mentour so much for this explanation of the fuel storage , I have to say that there is no one out there on RUclips or outside, explaining the Boeing 3 800 NG the way you do, just unique. yes, I liked the new feature about the nitrogen.
Ok but if the wings fall off, how would the plane get the fuel to land safely?
Oh ok never mind..
🤣🤣🤣
😆😆😆
Thanks, this comment made me laugh and brightened my morning 😂
I will vote you for the best comment.
He gave you the answer! The center tank! So then........er-wait, erm......
Thanks for your video! Well explained, fuel system is a very wide subject and just the effort to consolidate it in 12 min is very well👉 appreciated.
I love watching this channel, when I was a small boy I admired to be a pilot but later a long the way my dream wasn't achieved. When I watch this channel I get to easily learn more of what happens in the skies.
Big up to this senior captain for always sharing this information. Fly high and high sir❤️
I love the footage inside the center tank. I worked in the wing shop on the Citation X, where the largest part was still tiny, so now I'm jealous of those people who didn't have to contort their arms and hands to buck the rivets, lol.
FlesHBoX our fuel tank repair guys would get into the tanks and do their work. Very hard on the knees. They learned to always take the access panel with them into the tank to ensure they didn't get trapped in there.
Shill!
The center wing tanks are about the size of a two car garage.
I commented on another of your vids, suggesting that you move the sponsor advertisement, which would be of interest mainly to students, to the end. I see that you have done that here and I think it works very well. I'm not a student myself, and even *I* watched the ad! Thanks for another informative video.
I would be interested in a video or three that talked about the role of ATC and how pilots interact with it, both on short-haul and long-haul (incl. trans-oceanic) flights. I myself, a non-pilot, have, for example, a vague idea of zones of ATC control (in the USA anyway) and that "hand-offs" occur between them in some way, but have no understanding of the details and no idea if it all works the same way everywhere in the world. Likewise it would be interesting to know what (if any) hierarchies of ATC exist - for example are there national/regional/local ones that have different responsibilities and authorities? I'm sure many of your viewers already know all this but I suspect that most do not.
Another idea for a vid: my civilian airport, GEG, lies only a few miles from an Air Force base. SEA has several large military aviation facilities nearby. How is ATC coordinated between military and civilian authorities in shared airspace? Who has authority (military vs civilian), over what, under what circumstances, and how do they manage to stay on the same page?
There's a good analogy to storing fuel in the wings-tightrope walkers who carry a heavy pole. The danger with tightrope walking isn't failing to step down squarely on the rope. That's easily learned. It's maintaining a vertical stance, not rotating about the rope far enough to one side or the other that you fall. Think about it a moment. Once you start leaning to the right, how do you correct that? There's nothing to grab on.
That heavy pole extending far out to the side helps in two ways. First, because of its length, it creates rotational inertia. It takes far more force to cause you to rotate. That makes balancing easier. Second, it offers a way for the walker to adjust his balance. He simply moves the pole slightly. If he starts to fall to the left, he can just move the pole a bit to the right to restore his balance.
Planes are much like that. Having the weight of the fuel out on the wings makes the plane more stable than it would be if all that weight were close to the centerline. And being able to consume fuel from those tanks also allows the pilot to keep the plane more balanced.
----
My guess is that this difference is also reflected in how fighters and, cargo planes bombers are built. Fighters store most of their fuel in the body of the plane or in tanks close to the centerline. For them, the ability to maneuver quickly is a plus. On the other hand, cargo planes and bombers store fuel in their wings. That has the additional benefit of opening up space in the body for bombs for cargo.
Mentor Pilot might want to look into a related question that has long intrigued me. Why do almost all commercial cargo and passenter planes have low wings while most military cargo planes have high wings? I can think of a number of reason for the latter, including greater inherent stability when doing tight maneuvers and placing the engines further from the ground so foreign material is less likely to get ingested taking off from crude runways. Is that why? I don't know.
THANK YOU..... I find it absolutely terrific that people like yourself generously share their knowledge here. MUCH appreciated!
It's clear you listened to the professors in uni. Makes me feel safer when flying!
Haha i don't knew that aircraft store fuel in wings ... Thanks for a little knowledge
You fucking dumbass
You fucking dumbass
Didn't know
@@animalmother5287 your are just mean 🚮😑
@@animalmother5287 shut up mate you're about 12 years old 😂
Consistently fascinating and beautifully produced content on a subject that captured my mind and imagination for much of my 61 years. Aviation and flight, the machines, the theory and tech., aviation's turning points, aviation heroes, as well lessons learned from tragedy. Deep bow to you sir.
Love hearing about these obscure systems we are completely unaware that are keep us safe. Excellent vids
How simple & clear explanation !
Glad you liked it!
Been waiting for your video all day :D
Me too, and I am looking so much forward flying again with a nice ryanair trip in a month and this time again with more knowlege what's all going on around me.
Sir, please explain about Air root settings in Air Craft, Departure to Destination how do you set
This guy and team series is awesome. Well done all who produce these videos. I know a lot about aviation and now know more :-)
I think that channel is excellent and the explanations you give are very informative, thanks
Fun Fact: The SR-71, when fully fueled would leak like a sieve. It was designed, when at extreme altitudes to then seal up the wing fuel panels from expansion/contraction.
Reference: We had one stored in our hanger many, many years ago and talked to the pilots as the SR-71 leaked all over the hangar floor.
Wow!
Yup. But it was made of titanium.
@@jshepard152 It was but the issue was that the titanium metallurgy was in its infancy (the US needed to import titanium from russia in secret through shell companies). So the alloys had a much higher expansion factor than what we have today, and the components (like welding) couldn't take as much pressure. The SR-71 would grow by almost a foot in flight. Fuel tankswith "slack" was the solution the designers found to solve the problem, and the plane had a pretty light fueling on the ground then would be immediately refueled once it'd taken off.
And the JP7 fuel for the SR-71 was created specifically for that plane, with a much higher thickness and flashpoint than standard avgas (hence the use of TEB slugs to restart the engines if they shut down, which did happen on some maneuvers, a blackbird had 16 TEB shots so for very long flight this was a strategic resource). The fuel in the SR-71 was also used as coolant, as hydraulic fluid for some systems.
JP7 was much later reused for the X-51 Waverider, where it was also used as coolant and lubricant.
Thanks for the excellent explanations. For a person like myself who is not a pilot or wanting to be a pilot, this is very nice to know these background details.
I’m a Fueler for DGS and I approve this message lol
Apparently, there is a conspiracy made by flat Earthers that fuel isn't stored in the wings.
Do you know the flow rate of the pumps used to refuel commercial aircraft?
🤣🤣🤣👍
Thank you for making it so easy to understand with your articulated explanation of an important topic on aircraft
This was another fine presentation, which I appreciate.
If you are looking for ideas for future videos, I second the idea to tell about the great flexibility we see in wings now, and also why the wings are now so narrow.
Thank you.
Michael.
TANKS for all the info.
You have to indicate that this video refers to MODERN Commercial aircraft. Briefly & historically - fuel tanks were in engine nacelles e.g. WW1 - Gotha G4 & Vimy; and in fuselage e.g. Gotha G5; also in WW2 - Spitfire, Me-109; later fighters had Bladder tanks / bag tanks or fuel cells - reinforced rubberised bags were installed in sections of aircraft structure. Increased commercial flying (1930's onwards) required cabin space for passengers & cargo where the hollow structure of wings makes fuel storage an efficient use of space. Introduced in e.g. Douglas DC-1, DC-2, DC-3, Boeing 247, 307, Ju52 and post-WW2 designs; the "wet wing" - with Integral tanks in areas inside the aircraft structure, including the empennage (Tail-section) that have been sealed to allow fuel storage. The weight of the wing tanks and fuel counteract wing bending loads and locating fuel tanks in the wings also moves fuel further from passengers and crew in the event of a leak or explosion.
Just got a job as a refuler XNA, so, doing all the YT learning and plane research I can before my first day, they of course train you, but knowing what to do and what to expect and why things are done is always good.
The most famous example of a commercial aircraft that DID use fuel to alter its centre of gravity is the Concorde; it had a tank at the extreme end of the aircraft as shifting the CoG was necessary as part of shifting between supersonic and subsonic flight.
The Concord stored its fuel in the nose. Thats why it could move up and down as the fuel was used.
@@Sandler23 The nose and the wings.
Having the fuel in the wings, above the engines, also allows the fuel to gravity feed the engines in case of pump failure.
Yes, he said that.
Since I started working in the airport as the pax bus driver, have been really interested to know much about the aircraft and how they operate both on ground and on Air..
Thanks for your channel has been so helpful to me🙏👌
Many thanks for a very complete and interesting explanation! Congrats from Brazil!
I was surprised when I found out that the deHavilland Beaver has belly tanks. But, that was a part of it being a purpose built bush plane. Apparently, it makes it easier to refuel with gas cans. Makes sense, not having to climb into the wings with a gas can to refill it in some remote outpost.
You are so cool and relaxed while you do your video...keep it up...and may god keep you safe...🤠
You just cleared the many questions I had in my head since I never studied aviation. Am now knowledgeable
Thank you. Am a Telecommunications Engineer with a passion in aeronautical engineering. Such info comes in handy
Furthermore, it also reduces the distance need to pump the fuel to the engines.
That’s also true!
Another part not touched on in the video or in the comments that I have read so far is for fire safety in crashes. The fuel being in the main body could make for some bad explosions and more injuries / deaths from burns. (aside from the middle tank which is used first) With it in the wings, not only is it on the other side of the cabin walls, but it is more likely to be spilled and or have the wings ripped off in the crash. Which means the fuel will be not where the passengers are when everything comes to a stop. It also allows fire fighters to get foam on the fuel faster, versus inside the cabin with the passengers and or cargo.
Johan badenhort
True that mate
There is and lots of of it, my hands on experience with aircraft fuel tank overhaul as a mechanic proves you’re lying.
I would like to see a video that explains the differences between the different types of approaches: Visual, ILS, GPS, etc. Also, what is your assessment of the "Next Gen" air traffic control (ATC) system and why is it taking so long to implement?
Thnkuu so much for the amazing info..I didn't knew this before.. just used to wonder all the time..👍 u r awesome.
New sub. I've got hooked on your videos the last couple of days. I find your channel very interesting my friend.
There's a common story of the WW2 bomber Consolidated B-24 Liberator; the design of the wings were so long and thin that aircrews mentioned that they bent into a Y shape with a full bomb load.
Thanks for the great video as always. Really enjoyed this one!
I sort of knew why this happened, but this video showed me even more reasons. Very informative!
This is soo great! Thanks for explaining. Also the thing that made me feel most confident here is the nitrogen system. I was worried the tank would explode by some mysterious reason... You rock!
Well, unfortunately one of the the reasons why they introduced nitrogen filling - that Petter didn't mention - was actually a terrible accident, where most likely a short circuited cable in the wing caused the explosion of a B747-100 just off the coast of New York: TWA 800 in 1996, so not even that long ago...
The extract of this story is, balance is the key for stability and things should be divided equally, while giving limited freedom, if stakes are, such as plane !
Great info,thks.
Always something new and great to learn on this channel. Great work.
Like your show.. I love planes. Been around them from a child.
The knowledge you're giving i like sir. Thanks.
i love how RUclips recommends videos i love to watch to me.
I liked ur channel Logo..
Thanks for the well explanation though
fantastic way to deliver speech. easy understanding. thank you very much.
Brother thank you for educating us on airplanes keep up the good work
I can hear Scott Manley screaming "center of mass should be forward of the center of lift! Lest it will be highly unstable!"
The part about the fuel cooling the fuel pumps reminds me of something I heard from auto mechanics about keeping the fuel level to at least a one quarter of a tank, especially during the summer months. That is, the gasoline in the fuel tank prevents the fuel pump from over heating, a problem leading to fuel pump failure.
which doesn't sound logical because the fuel pump is usually not located inside the tank itself.
@@kallewirsch2263 Actually it is for that reason on most modern day cars...
@@chasemiller7974
Really? I didn't know. Thank you for the correction.
That's correct about the low fuel level being hard on the pump but there isn't much of an explosion risk because at typical temperatures, gasoline actually generates TOO MUCH vapor to be flammable in air. The flammability range of gasoline in air is 1.2 to 7.1% by volume. The upper limit of 7.1% corresponds to a partial pressure of about 7 kPa at standard pressure air. Typical gasoline has a vapor pressure of 7 kPa down at -20 deg C (-4 deg F) and is higher than 7 kPa at all higher temperatures. So as long as there is still some liquid fuel in the tank and as long as the temperature inside the tank is above -20 deg C, the mixture inside is too rich to burn even if the pump were to make a spark.
@@sbreheny Not really but I do see your point. A fuel pump won’t suddenly spark from overheating. However, over time from excess heat as they’re electronics. Accelerated wear occurs which can cease functioning.
Very interesting. I didn't know that fuel was stored on the wings. Thank you very much.
Fantastic explanation of fuel system, well done
I am not technical in this field but the way you put it makes me understand, good job!!!
You semi-covered this: There is a great deal of stress at the point where the wings connect to the fuselage. Transferring weight from the fuselage into the wings relieves a lot of that stress.
In the event of a fuel fire, having the fuel in the wings, rather than under the passengers adds a margin of safety.
And, of course, Aircraft, like ships, like recreational vehicles... Everything has multiple uses, no wasted space... Empty wings are wasted space.
The point is known as the wing root, and the wing root undergoes incredible amount of stress due to the weight of the fuselage and the lift pushing on the wing! Storing fuel in the wing relieves the lift-induced stress.
@@mach6893 Yeah he said that kid
Great videos, really informative, No BS! Awesome 👏🏻 😎
Very very good explanation... these kind of videos are what makes your channel SO GOOD....
I did not know the SR71 used fuel for trimming also. Makes perfect sense. I knew the J7 fuel has a huge boiling/ignition point and is utilised as an airframe coolant due to surface friction at warp speed. I also thought baffling(steel wool) was used in all aircraft to stop sloshing. Good thing this educated gent knows his stuff lol
i will like you to do a video on how the pilot manage to maintain the front tires to be exactly on the line during taxing on the apron to the runway vise versa
I loved this video. Thank you so much. I learned so much today.
great ,thanks for your lovely information on the subject.
Very well explained with a lot of information... Thanks Metour Pilot, and please keep it up
Where else you gonna put it, 5 gallon cans under each seat?
😂😂😂
@Milt Farrow what do ya mean?
LOL! I'm picturing passengers doing a "Bucket Brigade" down the isle to keep the plane flying. Passengers in the last 3 rows have the reserve fuel. ;-)
Lol I can just see it now as part of the safety speech. "In the event of us running out of fuel, you may be required to hand a jerry can to the flight attendant, the fuel cans can be found under your seat next to the life jacket. Seats 14A and 14B have diesel fuel, this is used for the equipment on the tarmac once we land, please do not use this fuel for the plane."
you must be a comedian.
Wow! So many interesting information about aircraft! Thank you!!
Very interesting information as usual. Thanks very much for taking the time to do this videos.
i didn´t know about the nitrogen system..thank you.
I did not know about the nitrogen generation system.
It’s a quite new feature.
Flt 800 center tank explosion in '96 over Long Island prompted a relook at center tank safety.
Reminds me a bit of the inert gas generators used on crude oil tankers when they are offloaded.
the explosion was a result of an american missile
s mitchell
That's what I think. Didn't the Navy have maneuvers in the Atlantic just south of that area and didn't they say that one of their missiles "went a little funny in the head"? I didn't believe those stooges from NTSB and FBI. I can still see that Jim Whatsisname lying his ass of on TV. You are correct.
Great video, as always. This wing fuel storage setup probably changes a bit with the new Airbus A321 XLR. It has a new mid-body tank for longer range.
Beautifully explained. Thank you.
Suction of fuel in high altitude result reduction of pressure on (liquid) that reduces the boiling point to make liquid releases bubbles in a phenomenon so call (cavitation) which happens hydraulic systems
That's nonsense dude.
Alton Rowell it was poorly explained, but definitely not nonsense. The basic idea is right, and it was even mentioned (without any specific details) at 8:31. :-B
As the fuel is "sucked out" of the tanks, how does the air get in its place? On the reverse: when the plane is fueled, how do the air from the tanks get out? Is air pumped in/out or are there valves on the tanks by which air can enter and leave?
they use compressed air , not enough room for all that fuel
I also wonder about this question.
Until TWA800 the tanks used to be connected to the outside air. Kerosene is difficult to ignite as sea level pressure, so this was thought to be perfectly fine at the time. Turns out that at altitude the small amount of fuel vapour and the small amount of air, makes for a perfect explosive ratio.
If the tanks are now filled with Nitrogen, there has to be some valve system to keep the inside pressure the same as outside pressure. Or the wings will deform (get inflated or squeezed flat) with the change in altitude.
Some valve not unlike the scuba dive regulator ?????
The other option would be rubber inner fuel bladders, like in the military. (heavy and expensive)
Jet fuel is carbonated with oxygen; as the pressure drops from lack of fuel the carbonated air is released into the empty space....ok I have no idea but is sounds good hu?
There are vents near the wing tips. As the fuel is used, the air enters by the fuel vents through dynamic pressure (fancy word for Relative Wind Force). This way there´s never negative pressure inside the fuel tanks. :)
I remember one of his videos (it was why you can't walk underneath the wing, I think) he mentioned a valve at the bottom, which could fix the fueling issue. Maybe they use the same valve for balancing the pressure during flight, but this is only a guess.
Wonderfully explained, as always! Bravo!
Thats an awesome explanation, Nitrogen is an inert gas,filling inside the tank makes it fire safe & Also gives positive pressure for pump suction.
i am a marine engineer onboard VLCC, we use spent flue gas from boiler uptake to fill the cargo tanks as inert gas to mitigate fire hazard.
Nice
Why? Because it's free real estate.
Is this meme still running?
This is Pilot!!!
Very much infomatic video about aerodynamic.... excellent work sir ....Love from Pakistan
Many thanks about this topic !
Avoiding too much strenght applied to the area where both wings are linked to the fuselage is a very good reason why the fuel is stored inside the wings : clear explanation !
I have always been very surprised by the fact it is possible to store so many tons of fuel inside the wings !!! Aircraft wings seem quite thin; even they are very wide, you always
ask yourself how it is possible to put inside such a quantity/volume of kerozen !!!
For instance (if I'm right), B737-800 gets 3 fuel tanks : 1 in each wing (almost 5000l) and 1 main in the center (~15000l) that means each wing can load
at least 4 tons ! Furthermore, the center of the wing can only be loaded (other parts is dedicated to moving mechanisms like flaps slats...) and it can be loaded with more than 4 tons : that's surprising....