6 ms·

The issue isn't the bank angle exactly, it is the acceleration of the roll. Pilots will need to be careful not to throw people or drinks around, but I think it

The issue isn't the bank angle exactly, it is the acceleration of the roll. Pilots will need to be careful not to throw people or drinks around, but I think it would be doable.

aaronblohowiak 4y ago
depends on the flight paths for different airports. some require tighter turns.
dan_quixote 4y ago
Pilots can control the bank acceleration, sure. They have much less control over acceleration due to uneven turbulence.
- thot_experiment 4y ago
  I'm not sure this tracks, I think turbulence powerful enough to cause passenger discomfort is usually so big that it affects the whole plane pretty uniformly. I think it's exceedingly unlikely that you'll spend enough time on a shear line to induce a large roll. At least it's never happened to me, but I am only a passenger.
  - HPsquared 4y ago
    In a typical plane in turbulence, you can see the wings bending up and down. Perhaps a blended wing would be stiffer, though.
    - thot_experiment 4y ago
      Yes a blended wing would be stiffer, but wing stiffness isn't really relevant here. The wing bending isn't evidence of differential pressure between the two wings, it's only showing that the wings are the part of the plane that's most affected by turbulence while not accounting for the majority of the inertia. The point is that air currents powerful enough to appreciably affect a large plane are large scale and therefore you're unlikely to have enough differential pressure from one wing to the other to impart much torque. I'm not certain about this and I'd love to be corrected if I'm wrong.
      - HPsquared 4y ago
        Ah, so in other words the whole plane bumps up and down but doesn't rotate. Therefore the location of passengers doesn't matter much, as all locations experience the same acceleration. (Provided the cabin is stiff)
    - gcanyon 4y ago
      When I was younger, watching the wings flex up and down in turbulence was one of my favorite things about flying, like an amusement park ride. Over the years my perspective has changed.
  - hindsightbias 4y ago
    I've been in turbulence with high roll rates and even as a pilot unbothered by moderate chop, it will cause me to sweat. I've been in the last rows of a 777 and watched the fuselage flex in chop. A blended body would be pretty rigid and have a very low wing loading because it's basically all a wing. So it would be pretty uniform. It would work if all turns were managed via controls to be a 1/4g, otherwise riding the outside would be like a roller coaster. I'd prefer to go back to the MD-80. Very high wing loading, fast and never broke down. Skated through turbulence.
    - dublin 4y ago
      The DC-9 and MD-[89]X were great airplanes. One of the great tragedies of unchecked American corporate consolidation/acquisition is that Boeing was allowed to borg McDonnell-Douglas. (Although some climed the opposite was closer to the truth...) Anyway, the resulting company is too large to fail, and thus, too large to exist. We're at a point where we could really use the competition we had in aerospace companies back in the 80s, when there were enough competitors in both military and commercial aviation for competitive pressures to keep the players working to provide innovation and value. (Rather than milking the market with intentionally poor designs a la Boeing's 737MAX.) Modern airlines have only two vendors to choose from now that Boeing and Airbus have gobbled up even their second-tier competitors. Personally, I'd love to see what the old Convair, LTV, pre-Martin Lockheed, or pre-McDonnell Douglas might come up with in this competition...
      - bobthepanda 4y ago
        The problem is that, what airlines want, and what regulators want, is now too expensive to independently develop and start a new competitor for, even if you are well resourced like China, Japan or Russia (which all have attempted and failed to break into international aviation sales). A new aircraft development is a $15B+ R&D investment, for the price and fuel efficiency and safety required. McDonnell-Douglass and more recently Bombardier messed up their bets and it cost them their independent existence.
    - nunez 4y ago
      can't speak to aeronautics of it, but from a pax perspective, the md80 was a fantastic jet. probably the last vestige of what flying "used to be like" since they were too old to retrofit for "efficiency". also its planform looked AMAZING; retro-futuristic even closest modern aircraft to it is the 717/MD90, which Delta is still flying, but not for much longer iirc
gauravjain13 4y ago
True, but absolute bank angle would also matter (say endpoint of roll when roll acceleration is zero) because now there's a component of gravity pulling you sideways.
- AnimalMuppet 4y ago
  Not if the pilot did it right. The net force on you should always be directly toward the floor.
  - alistairSH 4y ago
    Even when the plane is tipped over at 15* (or whatever their max bank angle happens to be)? The floor is no longer directly underneath you.
    - orangepurple 4y ago
      The plane turns while banking which results in a force vector mostly straight down towards the floor. If the plane did not turn while banking what you wrote is true. The ground is whatever you accelerate towards.
    - edh649 4y ago
      Balanced out by the centripetal force of the plane turning!
    - vel0city 4y ago
      Underneath is a relative term.
    - mannykannot 4y ago
      It is called a coordinated turn and it is what one normally aspires to fly. https://www.boldmethod.com/learn-to-fly/aerodynamics/the-aerodynamics-of-a-turn-in-an-airplane/ https://www.boldmethod.com/learn-to-fly/aerodynamics/the-aer... A coordinated turn with 60 degrees bank should be achievable by any airworthy airplane (it requires pulling 2g), and the maximum bank angle for a steady-state coordinated turn depends on how many g you can pull before you run out of control authority, cause an accelerated stall, or reach the airframe's structural limit. Next time you fly, get a beverage of your choice and observe how it behaves. Here's an example, courtesy of the great test pilot Bob Hoover: https://www.youtube.com/watch?v=V9pvG_ZSnCc https://www.youtube.com/watch?v=V9pvG_ZSnCc
rootusrootus 4y ago
I think that would be tough. Out in relatively empty airspace, sure, the pilot can make pretty slow turns. But major airports with multiple runways, other airports in the vicinity, military bases, etc, all put hard requirements on the flight corridor. Sometimes the pilot has no choice but to make pretty sharp turns, and that means a pretty fast roll acceleration.
- hnuser123456 4y ago
  How about... more rudder? Of course, more control surface area means more drag and less fuel efficiency. Wonder if a flying wing style craft that has enough rudder to match traditional cylinder fuselages bank-and-yank capabilities is still more efficient.
  - Retric 4y ago
    Lateral acceleration is less pleasant for passengers. You don’t want peoples drinks to fall off their tray tables for example. That said there is a fair about of wiggle room so I doubt it’s a significant issue in practice.
    - midoridensha 4y ago
      Maybe they could try inventing a way of keeping drinks from spilling when the container is tipped over... I even have a cool name word to describe it: "lid"!
      - Retric 4y ago
        Lid or no lid, it’s still a problem if your drink falls off the tray table. Which is one of the reasons they say to put your tray tables in upright an locked position. But even beyond that feeling like you’re falling out of your seat is unpleasant.
        midoridensha 4y ago
        Automakers solved this problem many years ago, by making cupholders that are deeply recessed instead of thinking that cups wills somehow magically stay in place with a very minimal indentation (see the "cup holders" on the backsides of glove compartments in 1970s American cars).
georgeecollins 4y ago
you could also put the passengers more towards the middle and the fuel / cargo on the tips. Doesn't solve the problem and balance would be tough I imagine.
bongoman37 4y ago

The issue isn't the bank angle exactly, it is the acceleration of the roll. Pilots will need to be careful not to throw people or drinks around, but I think it would be doable.

aaronblohowiak 4y ago

depends on the flight paths for different airports. some require tighter turns.

dan_quixote 4y ago

Pilots can control the bank acceleration, sure. They have much less control over acceleration due to uneven turbulence.

thot_experiment 4y ago
I'm not sure this tracks, I think turbulence powerful enough to cause passenger discomfort is usually so big that it affects the whole plane pretty uniformly. I think it's exceedingly unlikely that you'll spend enough time on a shear line to induce a large roll. At least it's never happened to me, but I am only a passenger.
- HPsquared 4y ago
  In a typical plane in turbulence, you can see the wings bending up and down. Perhaps a blended wing would be stiffer, though.
  - thot_experiment 4y ago
    Yes a blended wing would be stiffer, but wing stiffness isn't really relevant here. The wing bending isn't evidence of differential pressure between the two wings, it's only showing that the wings are the part of the plane that's most affected by turbulence while not accounting for the majority of the inertia. The point is that air currents powerful enough to appreciably affect a large plane are large scale and therefore you're unlikely to have enough differential pressure from one wing to the other to impart much torque. I'm not certain about this and I'd love to be corrected if I'm wrong.
    - HPsquared 4y ago
      Ah, so in other words the whole plane bumps up and down but doesn't rotate. Therefore the location of passengers doesn't matter much, as all locations experience the same acceleration. (Provided the cabin is stiff)
  - gcanyon 4y ago
    When I was younger, watching the wings flex up and down in turbulence was one of my favorite things about flying, like an amusement park ride. Over the years my perspective has changed.
- hindsightbias 4y ago
  I've been in turbulence with high roll rates and even as a pilot unbothered by moderate chop, it will cause me to sweat. I've been in the last rows of a 777 and watched the fuselage flex in chop. A blended body would be pretty rigid and have a very low wing loading because it's basically all a wing. So it would be pretty uniform. It would work if all turns were managed via controls to be a 1/4g, otherwise riding the outside would be like a roller coaster. I'd prefer to go back to the MD-80. Very high wing loading, fast and never broke down. Skated through turbulence.
  - dublin 4y ago
    The DC-9 and MD-[89]X were great airplanes. One of the great tragedies of unchecked American corporate consolidation/acquisition is that Boeing was allowed to borg McDonnell-Douglas. (Although some climed the opposite was closer to the truth...) Anyway, the resulting company is too large to fail, and thus, too large to exist. We're at a point where we could really use the competition we had in aerospace companies back in the 80s, when there were enough competitors in both military and commercial aviation for competitive pressures to keep the players working to provide innovation and value. (Rather than milking the market with intentionally poor designs a la Boeing's 737MAX.) Modern airlines have only two vendors to choose from now that Boeing and Airbus have gobbled up even their second-tier competitors. Personally, I'd love to see what the old Convair, LTV, pre-Martin Lockheed, or pre-McDonnell Douglas might come up with in this competition...
    - bobthepanda 4y ago
      The problem is that, what airlines want, and what regulators want, is now too expensive to independently develop and start a new competitor for, even if you are well resourced like China, Japan or Russia (which all have attempted and failed to break into international aviation sales). A new aircraft development is a $15B+ R&D investment, for the price and fuel efficiency and safety required. McDonnell-Douglass and more recently Bombardier messed up their bets and it cost them their independent existence.
  - nunez 4y ago
    can't speak to aeronautics of it, but from a pax perspective, the md80 was a fantastic jet. probably the last vestige of what flying "used to be like" since they were too old to retrofit for "efficiency". also its planform looked AMAZING; retro-futuristic even closest modern aircraft to it is the 717/MD90, which Delta is still flying, but not for much longer iirc

gauravjain13 4y ago

True, but absolute bank angle would also matter (say endpoint of roll when roll acceleration is zero) because now there's a component of gravity pulling you sideways.

AnimalMuppet 4y ago
Not if the pilot did it right. The net force on you should always be directly toward the floor.
- alistairSH 4y ago
  Even when the plane is tipped over at 15* (or whatever their max bank angle happens to be)? The floor is no longer directly underneath you.
  - orangepurple 4y ago
    The plane turns while banking which results in a force vector mostly straight down towards the floor. If the plane did not turn while banking what you wrote is true. The ground is whatever you accelerate towards.
  - edh649 4y ago
    Balanced out by the centripetal force of the plane turning!
  - vel0city 4y ago
    Underneath is a relative term.
  - mannykannot 4y ago
    It is called a coordinated turn and it is what one normally aspires to fly. https://www.boldmethod.com/learn-to-fly/aerodynamics/the-aerodynamics-of-a-turn-in-an-airplane/ https://www.boldmethod.com/learn-to-fly/aerodynamics/the-aer... A coordinated turn with 60 degrees bank should be achievable by any airworthy airplane (it requires pulling 2g), and the maximum bank angle for a steady-state coordinated turn depends on how many g you can pull before you run out of control authority, cause an accelerated stall, or reach the airframe's structural limit. Next time you fly, get a beverage of your choice and observe how it behaves. Here's an example, courtesy of the great test pilot Bob Hoover: https://www.youtube.com/watch?v=V9pvG_ZSnCc https://www.youtube.com/watch?v=V9pvG_ZSnCc

rootusrootus 4y ago

I think that would be tough. Out in relatively empty airspace, sure, the pilot can make pretty slow turns. But major airports with multiple runways, other airports in the vicinity, military bases, etc, all put hard requirements on the flight corridor. Sometimes the pilot has no choice but to make pretty sharp turns, and that means a pretty fast roll acceleration.

hnuser123456 4y ago
How about... more rudder? Of course, more control surface area means more drag and less fuel efficiency. Wonder if a flying wing style craft that has enough rudder to match traditional cylinder fuselages bank-and-yank capabilities is still more efficient.
- Retric 4y ago
  Lateral acceleration is less pleasant for passengers. You don’t want peoples drinks to fall off their tray tables for example. That said there is a fair about of wiggle room so I doubt it’s a significant issue in practice.
  - midoridensha 4y ago
    Maybe they could try inventing a way of keeping drinks from spilling when the container is tipped over... I even have a cool name word to describe it: "lid"!
    - Retric 4y ago
      Lid or no lid, it’s still a problem if your drink falls off the tray table. Which is one of the reasons they say to put your tray tables in upright an locked position. But even beyond that feeling like you’re falling out of your seat is unpleasant.
      - midoridensha 4y ago
        Automakers solved this problem many years ago, by making cupholders that are deeply recessed instead of thinking that cups wills somehow magically stay in place with a very minimal indentation (see the "cup holders" on the backsides of glove compartments in 1970s American cars).

georgeecollins 4y ago

you could also put the passengers more towards the middle and the fuel / cargo on the tips. Doesn't solve the problem and balance would be tough I imagine.

bongoman37 4y ago