3 ms·

I can't believe that's possible. I really want to know where that number came from. Maybe you could reduce the weight of just the frame of the fuselage by 50%,

I can't believe that's possible. I really want to know where that number came from. Maybe you could reduce the weight of just the frame of the fuselage by 50%, but I bet you'd save at most 2-3% of the total takeoff weight, once you include fuel, wings, tail, engines, gear, cabin, baggage, people, cockpit, etc. Edited: I looked into this more deeply and found the following: https://aerospace-europe.eu/media/books/CEAS2015_211.pdf https://aerospace-europe.eu/media/books/CEAS2015_211.pdf It claims a total possible weight reduction on an A320 from 2155kg to 1560kg, or 600kg off the fuselage (plus an additional 150kg elsewhere for a total savings of 750kg). An A320 weighs 42,000kg empty and 78,000kg at takeoff. 2155kg is probably the weight of the fuselage frame sections containing the windows - makes sense that you could save 50% off that piece. That's a reduction of 1% or so off the takeoff weight. Also, note that cargo planes are already windowless. I couldn't find a good example of a plane that has both freight and passenger versions that are otherwise identical.

ethagknight 8y ago
Not to mention that their projection system will bring some weight and use energy, surly offsetting gains, so that whole sentence should be stricken from the article.
kolinko 8y ago
Well, it's not just the added weight of windows, but, I imagine, additional reinforcements for the structure that are needed when you have windows? (IANAPE - I'm not a plane expert :) )
- WalterBright 8y ago
  You are correct. There's a forged doubler that goes around the window opening to reinforce it. The DeHaviland Comet lost several airplanes due to cracks starting from the windows; Boeing was having none of that.
  - tikhonj 8y ago
    Which is a real shame because that plane looked gorgeous, especially with square windows. It's always sad when physics gets in the way of aesthetics...
  - manigandham 8y ago
    A fantastic video about the De Havilland Comet from one of my favorite channels: https://www.youtube.com/watch?v=v0Cg2ZeYa5E https://www.youtube.com/watch?v=v0Cg2ZeYa5E
  - jacquesm 8y ago
    That was more due to the shape of the windows then due to the fact that it had windows. Square holes are not a good idea in aluminum that's under tensile stress. For the same reason you end a straight cut into metal in a round hole, otherwise you'll surely end up with a stress fracture.
    - WalterBright 8y ago
      The square corners were indeed a problem, but round windows wasn't enough. The doubler was added.
dmurray 8y ago
> It claims a total possible weight reduction on an A320 from 2155kg to 1560kg...An A320 weighs 42,000kg empty Does this seem odd? The fuselage only accounts for 5% of the empty weight of the plane. I checked your sources and that's what I see too, but it still sounds low. Where does the rest of the weight go? The engines weigh about 4600 kg total. Seats weigh 35 kg x 200 or about 7000 kg. That leaves 28,000 kg. Wings? Landing gear?
- deleted 8y ago
  [deleted]
- innocenat 8y ago
  Wings can easily take up 20-30% of total plane weight. Then there's a whole flight electronics and hydraulics, other interior (like ceiling, A/C), APU, tail, landing gears, etc.
  - dmurray 8y ago
    So wings could be as much as 14,000 kg (7 times the weight of the fuselage) and all those other bits total 14,000 together? I'm on a plane now and it's still hard to believe that each wing (without the engine) could be 3 times the weight of the body of the plane. But I guess it must be true. Thanks for the colour.
- manigandham 8y ago
  That is the Operating Empty Weight: https://en.wikipedia.org/wiki/Operating_empty_weight https://en.wikipedia.org/wiki/Operating_empty_weight The operating empty weight (OEW) is the sum of the manufacturer's empty weight (MEW), standard items (SI), and operator items (OI). Basically the whole plane, interior outfit and crew needed for full operations, excluding the actual fuel and payload.
- forapurpose 8y ago
  Fuel (all numbers approximate): An A320 carries around 25,000 L of fuel.[0] Jet fuel weighs ~0.81 kg/L (it varies by temperature).[1][2] 25,000 L * 0.81 kg/L = 20,250 kg = 44,550 lbs. [0] https://en.wikipedia.org/wiki/Airbus_A320_family https://en.wikipedia.org/wiki/Airbus_A320_family [1] https://en.wikipedia.org/wiki/Jet_fuel https://en.wikipedia.org/wiki/Jet_fuel [2] https://aviation.stackexchange.com/questions/48785/how-is-fuel-weight-calculated https://aviation.stackexchange.com/questions/48785/how-is-fu...

ethagknight 8y ago

Not to mention that their projection system will bring some weight and use energy, surly offsetting gains, so that whole sentence should be stricken from the article.

kolinko 8y ago

Well, it's not just the added weight of windows, but, I imagine, additional reinforcements for the structure that are needed when you have windows? (IANAPE - I'm not a plane expert :) )

WalterBright 8y ago
You are correct. There's a forged doubler that goes around the window opening to reinforce it. The DeHaviland Comet lost several airplanes due to cracks starting from the windows; Boeing was having none of that.
- tikhonj 8y ago
  Which is a real shame because that plane looked gorgeous, especially with square windows. It's always sad when physics gets in the way of aesthetics...
- manigandham 8y ago
  A fantastic video about the De Havilland Comet from one of my favorite channels: https://www.youtube.com/watch?v=v0Cg2ZeYa5E https://www.youtube.com/watch?v=v0Cg2ZeYa5E
- jacquesm 8y ago
  That was more due to the shape of the windows then due to the fact that it had windows. Square holes are not a good idea in aluminum that's under tensile stress. For the same reason you end a straight cut into metal in a round hole, otherwise you'll surely end up with a stress fracture.
  - WalterBright 8y ago
    The square corners were indeed a problem, but round windows wasn't enough. The doubler was added.

dmurray 8y ago

> It claims a total possible weight reduction on an A320 from 2155kg to 1560kg...An A320 weighs 42,000kg empty Does this seem odd? The fuselage only accounts for 5% of the empty weight of the plane. I checked your sources and that's what I see too, but it still sounds low. Where does the rest of the weight go? The engines weigh about 4600 kg total. Seats weigh 35 kg x 200 or about 7000 kg. That leaves 28,000 kg. Wings? Landing gear?

deleted 8y ago
[deleted]
innocenat 8y ago
Wings can easily take up 20-30% of total plane weight. Then there's a whole flight electronics and hydraulics, other interior (like ceiling, A/C), APU, tail, landing gears, etc.
- dmurray 8y ago
  So wings could be as much as 14,000 kg (7 times the weight of the fuselage) and all those other bits total 14,000 together? I'm on a plane now and it's still hard to believe that each wing (without the engine) could be 3 times the weight of the body of the plane. But I guess it must be true. Thanks for the colour.
manigandham 8y ago
That is the Operating Empty Weight: https://en.wikipedia.org/wiki/Operating_empty_weight https://en.wikipedia.org/wiki/Operating_empty_weight The operating empty weight (OEW) is the sum of the manufacturer's empty weight (MEW), standard items (SI), and operator items (OI). Basically the whole plane, interior outfit and crew needed for full operations, excluding the actual fuel and payload.
forapurpose 8y ago
Fuel (all numbers approximate): An A320 carries around 25,000 L of fuel.[0] Jet fuel weighs ~0.81 kg/L (it varies by temperature).[1][2] 25,000 L * 0.81 kg/L = 20,250 kg = 44,550 lbs. [0] https://en.wikipedia.org/wiki/Airbus_A320_family https://en.wikipedia.org/wiki/Airbus_A320_family [1] https://en.wikipedia.org/wiki/Jet_fuel https://en.wikipedia.org/wiki/Jet_fuel [2] https://aviation.stackexchange.com/questions/48785/how-is-fuel-weight-calculated https://aviation.stackexchange.com/questions/48785/how-is-fu...