Why are fuel tanks located in wings?











up vote
29
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Passenger aircraft have fuel tanks in the wings. Why?
What are the advantages and disadvantages of this location ?



examples of disadvantages I would suspect:




  • added weight increases the structural load applied to the wings

  • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span

  • higher risk of catastrophic damage to wings in case of in-flight fuel ignition

  • higher risk of fire when lightning strikes a wing


img










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  • 25




    Keeping fuel in the wings actually helps to maintain their structural integrity, see aviation.stackexchange.com/questions/42613/…
    – DeepSpace
    yesterday








  • 13




    On the ground, the aircraft rests on the wheels. In flight, it rests on the wings - so weight in the wings reduces structural loading, not increases it.
    – Therac
    yesterday










  • @Therac: Following your explanation, I would see that it does not add structural load? But how would weight "reduce" structural load?
    – summerrain
    yesterday










  • @summerrain By balancing out the fuselage, which is a big central load. See A340 vs A330. Of course, this implies total weight is equal or within some limit.
    – Therac
    yesterday










  • @summerrain it doesn’t reduce it per se, it reduces the need for an even high structural (bending) load that would come from storing it in the main body.
    – Notts90
    23 hours ago















up vote
29
down vote

favorite
3












Passenger aircraft have fuel tanks in the wings. Why?
What are the advantages and disadvantages of this location ?



examples of disadvantages I would suspect:




  • added weight increases the structural load applied to the wings

  • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span

  • higher risk of catastrophic damage to wings in case of in-flight fuel ignition

  • higher risk of fire when lightning strikes a wing


img










share|improve this question




















  • 25




    Keeping fuel in the wings actually helps to maintain their structural integrity, see aviation.stackexchange.com/questions/42613/…
    – DeepSpace
    yesterday








  • 13




    On the ground, the aircraft rests on the wheels. In flight, it rests on the wings - so weight in the wings reduces structural loading, not increases it.
    – Therac
    yesterday










  • @Therac: Following your explanation, I would see that it does not add structural load? But how would weight "reduce" structural load?
    – summerrain
    yesterday










  • @summerrain By balancing out the fuselage, which is a big central load. See A340 vs A330. Of course, this implies total weight is equal or within some limit.
    – Therac
    yesterday










  • @summerrain it doesn’t reduce it per se, it reduces the need for an even high structural (bending) load that would come from storing it in the main body.
    – Notts90
    23 hours ago













up vote
29
down vote

favorite
3









up vote
29
down vote

favorite
3






3





Passenger aircraft have fuel tanks in the wings. Why?
What are the advantages and disadvantages of this location ?



examples of disadvantages I would suspect:




  • added weight increases the structural load applied to the wings

  • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span

  • higher risk of catastrophic damage to wings in case of in-flight fuel ignition

  • higher risk of fire when lightning strikes a wing


img










share|improve this question















Passenger aircraft have fuel tanks in the wings. Why?
What are the advantages and disadvantages of this location ?



examples of disadvantages I would suspect:




  • added weight increases the structural load applied to the wings

  • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span

  • higher risk of catastrophic damage to wings in case of in-flight fuel ignition

  • higher risk of fire when lightning strikes a wing


img







aircraft-design wing fuel-tanks aircraft-structures fuel-systems






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited yesterday

























asked yesterday









summerrain

764517




764517








  • 25




    Keeping fuel in the wings actually helps to maintain their structural integrity, see aviation.stackexchange.com/questions/42613/…
    – DeepSpace
    yesterday








  • 13




    On the ground, the aircraft rests on the wheels. In flight, it rests on the wings - so weight in the wings reduces structural loading, not increases it.
    – Therac
    yesterday










  • @Therac: Following your explanation, I would see that it does not add structural load? But how would weight "reduce" structural load?
    – summerrain
    yesterday










  • @summerrain By balancing out the fuselage, which is a big central load. See A340 vs A330. Of course, this implies total weight is equal or within some limit.
    – Therac
    yesterday










  • @summerrain it doesn’t reduce it per se, it reduces the need for an even high structural (bending) load that would come from storing it in the main body.
    – Notts90
    23 hours ago














  • 25




    Keeping fuel in the wings actually helps to maintain their structural integrity, see aviation.stackexchange.com/questions/42613/…
    – DeepSpace
    yesterday








  • 13




    On the ground, the aircraft rests on the wheels. In flight, it rests on the wings - so weight in the wings reduces structural loading, not increases it.
    – Therac
    yesterday










  • @Therac: Following your explanation, I would see that it does not add structural load? But how would weight "reduce" structural load?
    – summerrain
    yesterday










  • @summerrain By balancing out the fuselage, which is a big central load. See A340 vs A330. Of course, this implies total weight is equal or within some limit.
    – Therac
    yesterday










  • @summerrain it doesn’t reduce it per se, it reduces the need for an even high structural (bending) load that would come from storing it in the main body.
    – Notts90
    23 hours ago








25




25




Keeping fuel in the wings actually helps to maintain their structural integrity, see aviation.stackexchange.com/questions/42613/…
– DeepSpace
yesterday






Keeping fuel in the wings actually helps to maintain their structural integrity, see aviation.stackexchange.com/questions/42613/…
– DeepSpace
yesterday






13




13




On the ground, the aircraft rests on the wheels. In flight, it rests on the wings - so weight in the wings reduces structural loading, not increases it.
– Therac
yesterday




On the ground, the aircraft rests on the wheels. In flight, it rests on the wings - so weight in the wings reduces structural loading, not increases it.
– Therac
yesterday












@Therac: Following your explanation, I would see that it does not add structural load? But how would weight "reduce" structural load?
– summerrain
yesterday




@Therac: Following your explanation, I would see that it does not add structural load? But how would weight "reduce" structural load?
– summerrain
yesterday












@summerrain By balancing out the fuselage, which is a big central load. See A340 vs A330. Of course, this implies total weight is equal or within some limit.
– Therac
yesterday




@summerrain By balancing out the fuselage, which is a big central load. See A340 vs A330. Of course, this implies total weight is equal or within some limit.
– Therac
yesterday












@summerrain it doesn’t reduce it per se, it reduces the need for an even high structural (bending) load that would come from storing it in the main body.
– Notts90
23 hours ago




@summerrain it doesn’t reduce it per se, it reduces the need for an even high structural (bending) load that would come from storing it in the main body.
– Notts90
23 hours ago










7 Answers
7






active

oldest

votes

















up vote
64
down vote













Several advantages:




  1. Wing structures are hollow and voluminous in order to provide structural rigidity against flutter and carry flight loads. This provides the space needed to store fuel.

  2. On a conventional aircraft, placing fuel tanks in the wings places the fuel mass very close to, or on, the center of lift. This dramatically reduces Cg shift during flight and reduces the size and weight of the tailplane to maintain stable flight.

  3. In the event of a crash landing, having the fuel in the wings keeps it away from the cabin and the occupants, reducing risks of cabin fires.

  4. The weight of the fuel reduces the loading moment on the wing roots, reducing the weight of the structure needed to support the aircraft during flight.






share|improve this answer






























    up vote
    38
    down vote













    I see what you're saying, but there's something you're overlooking in your logic. You're looking at an airplane sitting on the ground, where the wheels are under the fuselage and the wings are dead weight that creates strain on the structure.



    Think about one in flight. Now all the lift is coming from the wings, imagine the airplane suspended by a couple dozen (billion) cables spread around the wing surfaces. Now the fuselage is dead weight and the strain in the structure is from carrying the fuselage.



    So when you add weight to the wings evenly, it adds practically zero structural load for the wings. What's being lifted is inside the source of the lift. So from a structural load perspective, it's a wash: it doesn't matter.



    Whereas if you add more tanks in the fuselage, that's fine on the ground, but it adds huge stresses to the wings in flight, effectively reducing practical cargo capacity.



    The strain on wings from sitting on the ground is much less worrisome to designers than the strains in flight.



    See also "Zero Fuel Weight".






    share|improve this answer



















    • 1




      Exactly what I was thinking, but you said it much better!
      – Michael Hall
      yesterday


















    up vote
    19
    down vote














    added weight increases the structural load applied to the wings
    different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




    As a result of the effects of lift (and the deceasing need for it as the plane lightens) the reverse is actually true see here




    higher risk of catastrophic damage to wings in case of in-flight fuel ignition




    As opposed to higher risk of catastrophic damage to the cabin in the case of in-flight fuel ignition?



    Assuming a non-explosive ignition having the fuel in the wings means you can take action to dump the fuel. If you have a fire begin in the main fuselage however you've got a higher chance of the fire incapacitating the crew before they can take steps. Or damage occuring to the avionics, the pressure cabin etc.




    maybe higher risk of fire when lightning strikes a wing ?




    Wing tips are one of the locations on a plane that is more prone to lightning strikes - and the potential for fuel fires is there but steps are taken to counter this and in the vast majority of cases lightning does very little damage






    share|improve this answer




























      up vote
      12
      down vote













      Quite simply: there's a lot of empty space in those wings, and there's a lot of empty space needed for fuel.



      Creating space elsewhere for fuel would make the entire aircraft larger and heavier, so makes little sense.



      And it's not just the wings, many aircraft carry fuel in the vertical stabiliser as well.






      share|improve this answer

















      • 46




        In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
        – Tanner Swett
        yesterday






      • 27




        @TannerSwett Don't give them any ideas...
        – pipe
        yesterday






      • 5




        @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
        – DeepSpace
        yesterday










      • @TannerSwett hmm, Ryanair wants to talk with you about that idea.
        – jwenting
        yesterday


















      up vote
      7
      down vote













      Along with the other answers, I'll point out the cases where an aircraft fuel tank exploded, the center tank, which is in the fuselage, was implicated. There are two reasons:



      First, a fuselage tank is located lower than the engines and requires pumps to raise the fuel. Electrical pump failures have caused explosions. This also means that a pump failure results in unusable fuel, whereas wing tanks can naturally feed the engines via gravity.



      Second, fuselage tanks are closer to sources of heat. This was a cause of the TWA flight 800 accident, where heat from nearby air conditioning equipment lead to a flammable vapor in the fuel tanks. In contrast, wing tanks are naturally cooled by airflow and are less susceptible to forming such explosive vapors.






      share|improve this answer





















      • Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
        – jcaron
        18 hours ago


















      up vote
      4
      down vote















      • added weight increases the structural load applied to the wings




      Only when the plane's on the ground. When it's in the air, it decreases the load on the wings because their lift balances the weight.





      • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




      At the rate of one cycle per flight. And the wings already go through a stress cycle once per flight (flexed down when the plane's on the ground and up when it's in the air).





      • higher risk of catastrophic damage to wings in case of in-flight fuel ignition




      The fuel tanks catching fire in flight is catastrophic wherever you put them.





      • higher risk of fire when lightning strikes a wing




      When did that last happen? Wikipedia's list of plane crashes suggests LANSA flight 508 in 1971. Such incidents are so rare because fuel tanks have been fitted with inerting systems as recommended after the crash of Pan Am flight 214 in 1963.






      share|improve this answer

















      • 1




        This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
        – David K
        18 hours ago










      • @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
        – David Richerby
        16 hours ago




















      up vote
      1
      down vote













      Because the passengers would drown if you put it in the cabin.






      share|improve this answer








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      7 Answers
      7






      active

      oldest

      votes








      7 Answers
      7






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

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      up vote
      64
      down vote













      Several advantages:




      1. Wing structures are hollow and voluminous in order to provide structural rigidity against flutter and carry flight loads. This provides the space needed to store fuel.

      2. On a conventional aircraft, placing fuel tanks in the wings places the fuel mass very close to, or on, the center of lift. This dramatically reduces Cg shift during flight and reduces the size and weight of the tailplane to maintain stable flight.

      3. In the event of a crash landing, having the fuel in the wings keeps it away from the cabin and the occupants, reducing risks of cabin fires.

      4. The weight of the fuel reduces the loading moment on the wing roots, reducing the weight of the structure needed to support the aircraft during flight.






      share|improve this answer



























        up vote
        64
        down vote













        Several advantages:




        1. Wing structures are hollow and voluminous in order to provide structural rigidity against flutter and carry flight loads. This provides the space needed to store fuel.

        2. On a conventional aircraft, placing fuel tanks in the wings places the fuel mass very close to, or on, the center of lift. This dramatically reduces Cg shift during flight and reduces the size and weight of the tailplane to maintain stable flight.

        3. In the event of a crash landing, having the fuel in the wings keeps it away from the cabin and the occupants, reducing risks of cabin fires.

        4. The weight of the fuel reduces the loading moment on the wing roots, reducing the weight of the structure needed to support the aircraft during flight.






        share|improve this answer

























          up vote
          64
          down vote










          up vote
          64
          down vote









          Several advantages:




          1. Wing structures are hollow and voluminous in order to provide structural rigidity against flutter and carry flight loads. This provides the space needed to store fuel.

          2. On a conventional aircraft, placing fuel tanks in the wings places the fuel mass very close to, or on, the center of lift. This dramatically reduces Cg shift during flight and reduces the size and weight of the tailplane to maintain stable flight.

          3. In the event of a crash landing, having the fuel in the wings keeps it away from the cabin and the occupants, reducing risks of cabin fires.

          4. The weight of the fuel reduces the loading moment on the wing roots, reducing the weight of the structure needed to support the aircraft during flight.






          share|improve this answer














          Several advantages:




          1. Wing structures are hollow and voluminous in order to provide structural rigidity against flutter and carry flight loads. This provides the space needed to store fuel.

          2. On a conventional aircraft, placing fuel tanks in the wings places the fuel mass very close to, or on, the center of lift. This dramatically reduces Cg shift during flight and reduces the size and weight of the tailplane to maintain stable flight.

          3. In the event of a crash landing, having the fuel in the wings keeps it away from the cabin and the occupants, reducing risks of cabin fires.

          4. The weight of the fuel reduces the loading moment on the wing roots, reducing the weight of the structure needed to support the aircraft during flight.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 8 hours ago









          smci

          1193




          1193










          answered yesterday









          Carlo Felicione

          39.7k272147




          39.7k272147






















              up vote
              38
              down vote













              I see what you're saying, but there's something you're overlooking in your logic. You're looking at an airplane sitting on the ground, where the wheels are under the fuselage and the wings are dead weight that creates strain on the structure.



              Think about one in flight. Now all the lift is coming from the wings, imagine the airplane suspended by a couple dozen (billion) cables spread around the wing surfaces. Now the fuselage is dead weight and the strain in the structure is from carrying the fuselage.



              So when you add weight to the wings evenly, it adds practically zero structural load for the wings. What's being lifted is inside the source of the lift. So from a structural load perspective, it's a wash: it doesn't matter.



              Whereas if you add more tanks in the fuselage, that's fine on the ground, but it adds huge stresses to the wings in flight, effectively reducing practical cargo capacity.



              The strain on wings from sitting on the ground is much less worrisome to designers than the strains in flight.



              See also "Zero Fuel Weight".






              share|improve this answer



















              • 1




                Exactly what I was thinking, but you said it much better!
                – Michael Hall
                yesterday















              up vote
              38
              down vote













              I see what you're saying, but there's something you're overlooking in your logic. You're looking at an airplane sitting on the ground, where the wheels are under the fuselage and the wings are dead weight that creates strain on the structure.



              Think about one in flight. Now all the lift is coming from the wings, imagine the airplane suspended by a couple dozen (billion) cables spread around the wing surfaces. Now the fuselage is dead weight and the strain in the structure is from carrying the fuselage.



              So when you add weight to the wings evenly, it adds practically zero structural load for the wings. What's being lifted is inside the source of the lift. So from a structural load perspective, it's a wash: it doesn't matter.



              Whereas if you add more tanks in the fuselage, that's fine on the ground, but it adds huge stresses to the wings in flight, effectively reducing practical cargo capacity.



              The strain on wings from sitting on the ground is much less worrisome to designers than the strains in flight.



              See also "Zero Fuel Weight".






              share|improve this answer



















              • 1




                Exactly what I was thinking, but you said it much better!
                – Michael Hall
                yesterday













              up vote
              38
              down vote










              up vote
              38
              down vote









              I see what you're saying, but there's something you're overlooking in your logic. You're looking at an airplane sitting on the ground, where the wheels are under the fuselage and the wings are dead weight that creates strain on the structure.



              Think about one in flight. Now all the lift is coming from the wings, imagine the airplane suspended by a couple dozen (billion) cables spread around the wing surfaces. Now the fuselage is dead weight and the strain in the structure is from carrying the fuselage.



              So when you add weight to the wings evenly, it adds practically zero structural load for the wings. What's being lifted is inside the source of the lift. So from a structural load perspective, it's a wash: it doesn't matter.



              Whereas if you add more tanks in the fuselage, that's fine on the ground, but it adds huge stresses to the wings in flight, effectively reducing practical cargo capacity.



              The strain on wings from sitting on the ground is much less worrisome to designers than the strains in flight.



              See also "Zero Fuel Weight".






              share|improve this answer














              I see what you're saying, but there's something you're overlooking in your logic. You're looking at an airplane sitting on the ground, where the wheels are under the fuselage and the wings are dead weight that creates strain on the structure.



              Think about one in flight. Now all the lift is coming from the wings, imagine the airplane suspended by a couple dozen (billion) cables spread around the wing surfaces. Now the fuselage is dead weight and the strain in the structure is from carrying the fuselage.



              So when you add weight to the wings evenly, it adds practically zero structural load for the wings. What's being lifted is inside the source of the lift. So from a structural load perspective, it's a wash: it doesn't matter.



              Whereas if you add more tanks in the fuselage, that's fine on the ground, but it adds huge stresses to the wings in flight, effectively reducing practical cargo capacity.



              The strain on wings from sitting on the ground is much less worrisome to designers than the strains in flight.



              See also "Zero Fuel Weight".







              share|improve this answer














              share|improve this answer



              share|improve this answer








              edited 14 hours ago









              T.J.L.

              303515




              303515










              answered yesterday









              Harper

              2,325618




              2,325618








              • 1




                Exactly what I was thinking, but you said it much better!
                – Michael Hall
                yesterday














              • 1




                Exactly what I was thinking, but you said it much better!
                – Michael Hall
                yesterday








              1




              1




              Exactly what I was thinking, but you said it much better!
              – Michael Hall
              yesterday




              Exactly what I was thinking, but you said it much better!
              – Michael Hall
              yesterday










              up vote
              19
              down vote














              added weight increases the structural load applied to the wings
              different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




              As a result of the effects of lift (and the deceasing need for it as the plane lightens) the reverse is actually true see here




              higher risk of catastrophic damage to wings in case of in-flight fuel ignition




              As opposed to higher risk of catastrophic damage to the cabin in the case of in-flight fuel ignition?



              Assuming a non-explosive ignition having the fuel in the wings means you can take action to dump the fuel. If you have a fire begin in the main fuselage however you've got a higher chance of the fire incapacitating the crew before they can take steps. Or damage occuring to the avionics, the pressure cabin etc.




              maybe higher risk of fire when lightning strikes a wing ?




              Wing tips are one of the locations on a plane that is more prone to lightning strikes - and the potential for fuel fires is there but steps are taken to counter this and in the vast majority of cases lightning does very little damage






              share|improve this answer

























                up vote
                19
                down vote














                added weight increases the structural load applied to the wings
                different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                As a result of the effects of lift (and the deceasing need for it as the plane lightens) the reverse is actually true see here




                higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                As opposed to higher risk of catastrophic damage to the cabin in the case of in-flight fuel ignition?



                Assuming a non-explosive ignition having the fuel in the wings means you can take action to dump the fuel. If you have a fire begin in the main fuselage however you've got a higher chance of the fire incapacitating the crew before they can take steps. Or damage occuring to the avionics, the pressure cabin etc.




                maybe higher risk of fire when lightning strikes a wing ?




                Wing tips are one of the locations on a plane that is more prone to lightning strikes - and the potential for fuel fires is there but steps are taken to counter this and in the vast majority of cases lightning does very little damage






                share|improve this answer























                  up vote
                  19
                  down vote










                  up vote
                  19
                  down vote










                  added weight increases the structural load applied to the wings
                  different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                  As a result of the effects of lift (and the deceasing need for it as the plane lightens) the reverse is actually true see here




                  higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                  As opposed to higher risk of catastrophic damage to the cabin in the case of in-flight fuel ignition?



                  Assuming a non-explosive ignition having the fuel in the wings means you can take action to dump the fuel. If you have a fire begin in the main fuselage however you've got a higher chance of the fire incapacitating the crew before they can take steps. Or damage occuring to the avionics, the pressure cabin etc.




                  maybe higher risk of fire when lightning strikes a wing ?




                  Wing tips are one of the locations on a plane that is more prone to lightning strikes - and the potential for fuel fires is there but steps are taken to counter this and in the vast majority of cases lightning does very little damage






                  share|improve this answer













                  added weight increases the structural load applied to the wings
                  different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                  As a result of the effects of lift (and the deceasing need for it as the plane lightens) the reverse is actually true see here




                  higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                  As opposed to higher risk of catastrophic damage to the cabin in the case of in-flight fuel ignition?



                  Assuming a non-explosive ignition having the fuel in the wings means you can take action to dump the fuel. If you have a fire begin in the main fuselage however you've got a higher chance of the fire incapacitating the crew before they can take steps. Or damage occuring to the avionics, the pressure cabin etc.




                  maybe higher risk of fire when lightning strikes a wing ?




                  Wing tips are one of the locations on a plane that is more prone to lightning strikes - and the potential for fuel fires is there but steps are taken to counter this and in the vast majority of cases lightning does very little damage







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered yesterday









                  motosubatsu

                  3937




                  3937






















                      up vote
                      12
                      down vote













                      Quite simply: there's a lot of empty space in those wings, and there's a lot of empty space needed for fuel.



                      Creating space elsewhere for fuel would make the entire aircraft larger and heavier, so makes little sense.



                      And it's not just the wings, many aircraft carry fuel in the vertical stabiliser as well.






                      share|improve this answer

















                      • 46




                        In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
                        – Tanner Swett
                        yesterday






                      • 27




                        @TannerSwett Don't give them any ideas...
                        – pipe
                        yesterday






                      • 5




                        @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
                        – DeepSpace
                        yesterday










                      • @TannerSwett hmm, Ryanair wants to talk with you about that idea.
                        – jwenting
                        yesterday















                      up vote
                      12
                      down vote













                      Quite simply: there's a lot of empty space in those wings, and there's a lot of empty space needed for fuel.



                      Creating space elsewhere for fuel would make the entire aircraft larger and heavier, so makes little sense.



                      And it's not just the wings, many aircraft carry fuel in the vertical stabiliser as well.






                      share|improve this answer

















                      • 46




                        In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
                        – Tanner Swett
                        yesterday






                      • 27




                        @TannerSwett Don't give them any ideas...
                        – pipe
                        yesterday






                      • 5




                        @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
                        – DeepSpace
                        yesterday










                      • @TannerSwett hmm, Ryanair wants to talk with you about that idea.
                        – jwenting
                        yesterday













                      up vote
                      12
                      down vote










                      up vote
                      12
                      down vote









                      Quite simply: there's a lot of empty space in those wings, and there's a lot of empty space needed for fuel.



                      Creating space elsewhere for fuel would make the entire aircraft larger and heavier, so makes little sense.



                      And it's not just the wings, many aircraft carry fuel in the vertical stabiliser as well.






                      share|improve this answer












                      Quite simply: there's a lot of empty space in those wings, and there's a lot of empty space needed for fuel.



                      Creating space elsewhere for fuel would make the entire aircraft larger and heavier, so makes little sense.



                      And it's not just the wings, many aircraft carry fuel in the vertical stabiliser as well.







                      share|improve this answer












                      share|improve this answer



                      share|improve this answer










                      answered yesterday









                      jwenting

                      10.9k12744




                      10.9k12744








                      • 46




                        In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
                        – Tanner Swett
                        yesterday






                      • 27




                        @TannerSwett Don't give them any ideas...
                        – pipe
                        yesterday






                      • 5




                        @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
                        – DeepSpace
                        yesterday










                      • @TannerSwett hmm, Ryanair wants to talk with you about that idea.
                        – jwenting
                        yesterday














                      • 46




                        In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
                        – Tanner Swett
                        yesterday






                      • 27




                        @TannerSwett Don't give them any ideas...
                        – pipe
                        yesterday






                      • 5




                        @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
                        – DeepSpace
                        yesterday










                      • @TannerSwett hmm, Ryanair wants to talk with you about that idea.
                        – jwenting
                        yesterday








                      46




                      46




                      In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
                      – Tanner Swett
                      yesterday




                      In other words: Why are fuel tanks located in the wings? Because the passengers wouldn't fit in there. :)
                      – Tanner Swett
                      yesterday




                      27




                      27




                      @TannerSwett Don't give them any ideas...
                      – pipe
                      yesterday




                      @TannerSwett Don't give them any ideas...
                      – pipe
                      yesterday




                      5




                      5




                      @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
                      – DeepSpace
                      yesterday




                      @pipe en.wikipedia.org/wiki/Junkers_G.38 ?
                      – DeepSpace
                      yesterday












                      @TannerSwett hmm, Ryanair wants to talk with you about that idea.
                      – jwenting
                      yesterday




                      @TannerSwett hmm, Ryanair wants to talk with you about that idea.
                      – jwenting
                      yesterday










                      up vote
                      7
                      down vote













                      Along with the other answers, I'll point out the cases where an aircraft fuel tank exploded, the center tank, which is in the fuselage, was implicated. There are two reasons:



                      First, a fuselage tank is located lower than the engines and requires pumps to raise the fuel. Electrical pump failures have caused explosions. This also means that a pump failure results in unusable fuel, whereas wing tanks can naturally feed the engines via gravity.



                      Second, fuselage tanks are closer to sources of heat. This was a cause of the TWA flight 800 accident, where heat from nearby air conditioning equipment lead to a flammable vapor in the fuel tanks. In contrast, wing tanks are naturally cooled by airflow and are less susceptible to forming such explosive vapors.






                      share|improve this answer





















                      • Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
                        – jcaron
                        18 hours ago















                      up vote
                      7
                      down vote













                      Along with the other answers, I'll point out the cases where an aircraft fuel tank exploded, the center tank, which is in the fuselage, was implicated. There are two reasons:



                      First, a fuselage tank is located lower than the engines and requires pumps to raise the fuel. Electrical pump failures have caused explosions. This also means that a pump failure results in unusable fuel, whereas wing tanks can naturally feed the engines via gravity.



                      Second, fuselage tanks are closer to sources of heat. This was a cause of the TWA flight 800 accident, where heat from nearby air conditioning equipment lead to a flammable vapor in the fuel tanks. In contrast, wing tanks are naturally cooled by airflow and are less susceptible to forming such explosive vapors.






                      share|improve this answer





















                      • Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
                        – jcaron
                        18 hours ago













                      up vote
                      7
                      down vote










                      up vote
                      7
                      down vote









                      Along with the other answers, I'll point out the cases where an aircraft fuel tank exploded, the center tank, which is in the fuselage, was implicated. There are two reasons:



                      First, a fuselage tank is located lower than the engines and requires pumps to raise the fuel. Electrical pump failures have caused explosions. This also means that a pump failure results in unusable fuel, whereas wing tanks can naturally feed the engines via gravity.



                      Second, fuselage tanks are closer to sources of heat. This was a cause of the TWA flight 800 accident, where heat from nearby air conditioning equipment lead to a flammable vapor in the fuel tanks. In contrast, wing tanks are naturally cooled by airflow and are less susceptible to forming such explosive vapors.






                      share|improve this answer












                      Along with the other answers, I'll point out the cases where an aircraft fuel tank exploded, the center tank, which is in the fuselage, was implicated. There are two reasons:



                      First, a fuselage tank is located lower than the engines and requires pumps to raise the fuel. Electrical pump failures have caused explosions. This also means that a pump failure results in unusable fuel, whereas wing tanks can naturally feed the engines via gravity.



                      Second, fuselage tanks are closer to sources of heat. This was a cause of the TWA flight 800 accident, where heat from nearby air conditioning equipment lead to a flammable vapor in the fuel tanks. In contrast, wing tanks are naturally cooled by airflow and are less susceptible to forming such explosive vapors.







                      share|improve this answer












                      share|improve this answer



                      share|improve this answer










                      answered yesterday









                      user71659

                      2,284617




                      2,284617












                      • Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
                        – jcaron
                        18 hours ago


















                      • Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
                        – jcaron
                        18 hours ago
















                      Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
                      – jcaron
                      18 hours ago




                      Not sure if you meant "that in all the cases ... it was the center tank which was implicated" (which is apparently true), but if so, you could probably make it more explicit.
                      – jcaron
                      18 hours ago










                      up vote
                      4
                      down vote















                      • added weight increases the structural load applied to the wings




                      Only when the plane's on the ground. When it's in the air, it decreases the load on the wings because their lift balances the weight.





                      • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                      At the rate of one cycle per flight. And the wings already go through a stress cycle once per flight (flexed down when the plane's on the ground and up when it's in the air).





                      • higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                      The fuel tanks catching fire in flight is catastrophic wherever you put them.





                      • higher risk of fire when lightning strikes a wing




                      When did that last happen? Wikipedia's list of plane crashes suggests LANSA flight 508 in 1971. Such incidents are so rare because fuel tanks have been fitted with inerting systems as recommended after the crash of Pan Am flight 214 in 1963.






                      share|improve this answer

















                      • 1




                        This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
                        – David K
                        18 hours ago










                      • @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
                        – David Richerby
                        16 hours ago

















                      up vote
                      4
                      down vote















                      • added weight increases the structural load applied to the wings




                      Only when the plane's on the ground. When it's in the air, it decreases the load on the wings because their lift balances the weight.





                      • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                      At the rate of one cycle per flight. And the wings already go through a stress cycle once per flight (flexed down when the plane's on the ground and up when it's in the air).





                      • higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                      The fuel tanks catching fire in flight is catastrophic wherever you put them.





                      • higher risk of fire when lightning strikes a wing




                      When did that last happen? Wikipedia's list of plane crashes suggests LANSA flight 508 in 1971. Such incidents are so rare because fuel tanks have been fitted with inerting systems as recommended after the crash of Pan Am flight 214 in 1963.






                      share|improve this answer

















                      • 1




                        This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
                        – David K
                        18 hours ago










                      • @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
                        – David Richerby
                        16 hours ago















                      up vote
                      4
                      down vote










                      up vote
                      4
                      down vote











                      • added weight increases the structural load applied to the wings




                      Only when the plane's on the ground. When it's in the air, it decreases the load on the wings because their lift balances the weight.





                      • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                      At the rate of one cycle per flight. And the wings already go through a stress cycle once per flight (flexed down when the plane's on the ground and up when it's in the air).





                      • higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                      The fuel tanks catching fire in flight is catastrophic wherever you put them.





                      • higher risk of fire when lightning strikes a wing




                      When did that last happen? Wikipedia's list of plane crashes suggests LANSA flight 508 in 1971. Such incidents are so rare because fuel tanks have been fitted with inerting systems as recommended after the crash of Pan Am flight 214 in 1963.






                      share|improve this answer














                      • added weight increases the structural load applied to the wings




                      Only when the plane's on the ground. When it's in the air, it decreases the load on the wings because their lift balances the weight.





                      • different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span




                      At the rate of one cycle per flight. And the wings already go through a stress cycle once per flight (flexed down when the plane's on the ground and up when it's in the air).





                      • higher risk of catastrophic damage to wings in case of in-flight fuel ignition




                      The fuel tanks catching fire in flight is catastrophic wherever you put them.





                      • higher risk of fire when lightning strikes a wing




                      When did that last happen? Wikipedia's list of plane crashes suggests LANSA flight 508 in 1971. Such incidents are so rare because fuel tanks have been fitted with inerting systems as recommended after the crash of Pan Am flight 214 in 1963.







                      share|improve this answer












                      share|improve this answer



                      share|improve this answer










                      answered yesterday









                      David Richerby

                      9,54833477




                      9,54833477








                      • 1




                        This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
                        – David K
                        18 hours ago










                      • @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
                        – David Richerby
                        16 hours ago
















                      • 1




                        This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
                        – David K
                        18 hours ago










                      • @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
                        – David Richerby
                        16 hours ago










                      1




                      1




                      This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
                      – David K
                      18 hours ago




                      This answer seems to imply that inerting systems have been used since sometime shortly after 1963, or at least that inerting systems are responsible for the lack of lightning-induced fire since 1971. The link you provided, however, says inerting systems were not installed for 40 years after the crash of Pan Am 214. Here's an article describing the state of the art in 2004: airspacemag.com/how-things-work/safer-fuel-tanks-5883916
                      – David K
                      18 hours ago












                      @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
                      – David Richerby
                      16 hours ago






                      @DavidK Yes, it looks like I've exaggerated what actually happened. I'll come back and edit when I have time, or you're welcome to propose an edit yourself if you have the time. Thanks for letting me know.
                      – David Richerby
                      16 hours ago












                      up vote
                      1
                      down vote













                      Because the passengers would drown if you put it in the cabin.






                      share|improve this answer








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                      up vote
                      1
                      down vote













                      Because the passengers would drown if you put it in the cabin.






                      share|improve this answer








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                        1 hour ago













                      up vote
                      1
                      down vote










                      up vote
                      1
                      down vote









                      Because the passengers would drown if you put it in the cabin.






                      share|improve this answer








                      New contributor




                      Capt. Obvious is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                      Because the passengers would drown if you put it in the cabin.







                      share|improve this answer








                      New contributor




                      Capt. Obvious is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                      share|improve this answer



                      share|improve this answer






                      New contributor




                      Capt. Obvious is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                      answered 10 hours ago









                      Capt. Obvious

                      191




                      191




                      New contributor




                      Capt. Obvious is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                      New contributor





                      Capt. Obvious is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.






                      Capt. Obvious is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.












                      • Welcome to aviation.SE! Because this is a Q&A site, not a discussion forum, we expect answers to actually answer the question. The tour might be helpful if you're new to the site.
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                        1 hour ago










                      • This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review
                        – Pondlife
                        1 hour ago


















                      • Welcome to aviation.SE! Because this is a Q&A site, not a discussion forum, we expect answers to actually answer the question. The tour might be helpful if you're new to the site.
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                      Welcome to aviation.SE! Because this is a Q&A site, not a discussion forum, we expect answers to actually answer the question. The tour might be helpful if you're new to the site.
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                      Welcome to aviation.SE! Because this is a Q&A site, not a discussion forum, we expect answers to actually answer the question. The tour might be helpful if you're new to the site.
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                      This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review
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