3 ms·

They should have a philosophy of building aerodynamically stable aircraft rather than relying on software and sensors to produce an illusion of stability.

WalterBright 8y ago
Consider that before WW2, pilots had direct connection between the control and moving the surface. After WW2, planes got too big and heavy for that, and hydraulic boost was added. Starting with the 747, where it is not credible a pilot could control it with muscle, the switch was made to fully powered surfaces. The trouble with that is the pilot's controls simply crack open a valve, and hydraulics do the rest, meaning the pilot gets no feedback via forces on the control column. He'll "overcontrol" the aircraft leading to a crash. The solution is the addition of a "feel computer" which pushes back on the stick making the airplane feel like direct control. Safe flying relies on the feel computer working properly. Also, the travel of the control surfaces is automatically reduced as speed goes up, because full travel at high speeds will literally tear the airplane apart. So right there are two flight critical computer systems on jets, and modern air travel would not be possible without them. Each produces an illusion to the pilot.
- crimsonalucard 8y ago
  Right, this makes sense. The system you describe magnifies or reduces the signals going back and forth between the pilot and the control surfaces. It can be modelled linearly and done with an analog system. However I'm referring to a computer literally trying to hide a stall that occurs when you pitch the nose up by producing an inverse signal out of thin air that has no input from the pilot. Why wasn't this needed before the max moniker was added to the plane? Seriously, build the plane so that this doesn't happen. Don't create some MCAS system to hide it.
  - WalterBright 8y ago
    MCAS was there to prevent a stall, not hide it. All airplanes will stall under varying circumstances. Much of pilot training goes towards avoiding and recovering from stalls, but they still result in crashes.
    - crimsonalucard 8y ago
      The stall didn't exist at that configuration previously. MCAS prevents the pilot from even knowing about this stall by preventing the plane from even going into that configuration. In other words it hides the stall by preventing you from maneuvering the plane into it. It fits the definition of "Hide." But that's besides the point, we're arguing about semantics here. I'm saying similar to the older design make the aerodynamic shape good enough so that it won't hit that stall when the plane is flying at that same configuration. I'm also saying that the control system should only magnify or reduce the signals the pilot sends to the control surfaces rather than actually sending it's own override signals itself. That's it... pure and simple.
      - speedplane 8y ago
        > MCAS prevents the pilot from even knowing about this stall by preventing the plane from even going into that configuration. In other words it hides the stall ...[.] [T]he control system should only magnify or reduce the signals the pilot sends to the control surfaces rather than actually sending it's own. What about fly-by-wire? Many aerodynamic controls are assisted by avionics, and have been for decades. The MCAS system is not fundamentally different. The intent of the system was to put the plane where the pilot wanted intended it to go, similar to how a fly-by-wire system will keep a plane flying straight if a pilot doesn't touch the yoke. The problem seems to be that the MCAS system breaks under certain conditions, however the fundamental idea is sound. Planes have been doing similar control adjustments for decades.
        crimsonalucard 8y ago
        No its not. Fighter planes like the F-16 are designed to be aerodynamically unstable for higher maneuverability. For this case an incredibly fast control system is required to make minor adjustments to the plane to maintain stability. This control system is in constant control of the plane and the entire jet aircraft is designed to operate in such a way. The 737 MAX was made more aerodynamically unstable then the original 737. A partial control system was put in place to hide this instability should the pilot maneuver the plane into the configuration that will trigger a stall. It's an entirely different situation than the jet plane above. Think of it like a bandaid to cover up a problem. I'm saying don't use bandaids. Design the plane correctly from the ground up.

WalterBright 8y ago

Consider that before WW2, pilots had direct connection between the control and moving the surface. After WW2, planes got too big and heavy for that, and hydraulic boost was added. Starting with the 747, where it is not credible a pilot could control it with muscle, the switch was made to fully powered surfaces. The trouble with that is the pilot's controls simply crack open a valve, and hydraulics do the rest, meaning the pilot gets no feedback via forces on the control column. He'll "overcontrol" the aircraft leading to a crash. The solution is the addition of a "feel computer" which pushes back on the stick making the airplane feel like direct control. Safe flying relies on the feel computer working properly. Also, the travel of the control surfaces is automatically reduced as speed goes up, because full travel at high speeds will literally tear the airplane apart. So right there are two flight critical computer systems on jets, and modern air travel would not be possible without them. Each produces an illusion to the pilot.

crimsonalucard 8y ago
Right, this makes sense. The system you describe magnifies or reduces the signals going back and forth between the pilot and the control surfaces. It can be modelled linearly and done with an analog system. However I'm referring to a computer literally trying to hide a stall that occurs when you pitch the nose up by producing an inverse signal out of thin air that has no input from the pilot. Why wasn't this needed before the max moniker was added to the plane? Seriously, build the plane so that this doesn't happen. Don't create some MCAS system to hide it.
- WalterBright 8y ago
  MCAS was there to prevent a stall, not hide it. All airplanes will stall under varying circumstances. Much of pilot training goes towards avoiding and recovering from stalls, but they still result in crashes.
  - crimsonalucard 8y ago
    The stall didn't exist at that configuration previously. MCAS prevents the pilot from even knowing about this stall by preventing the plane from even going into that configuration. In other words it hides the stall by preventing you from maneuvering the plane into it. It fits the definition of "Hide." But that's besides the point, we're arguing about semantics here. I'm saying similar to the older design make the aerodynamic shape good enough so that it won't hit that stall when the plane is flying at that same configuration. I'm also saying that the control system should only magnify or reduce the signals the pilot sends to the control surfaces rather than actually sending it's own override signals itself. That's it... pure and simple.
    - speedplane 8y ago
      > MCAS prevents the pilot from even knowing about this stall by preventing the plane from even going into that configuration. In other words it hides the stall ...[.] [T]he control system should only magnify or reduce the signals the pilot sends to the control surfaces rather than actually sending it's own. What about fly-by-wire? Many aerodynamic controls are assisted by avionics, and have been for decades. The MCAS system is not fundamentally different. The intent of the system was to put the plane where the pilot wanted intended it to go, similar to how a fly-by-wire system will keep a plane flying straight if a pilot doesn't touch the yoke. The problem seems to be that the MCAS system breaks under certain conditions, however the fundamental idea is sound. Planes have been doing similar control adjustments for decades.
      - crimsonalucard 8y ago
        No its not. Fighter planes like the F-16 are designed to be aerodynamically unstable for higher maneuverability. For this case an incredibly fast control system is required to make minor adjustments to the plane to maintain stability. This control system is in constant control of the plane and the entire jet aircraft is designed to operate in such a way. The 737 MAX was made more aerodynamically unstable then the original 737. A partial control system was put in place to hide this instability should the pilot maneuver the plane into the configuration that will trigger a stall. It's an entirely different situation than the jet plane above. Think of it like a bandaid to cover up a problem. I'm saying don't use bandaids. Design the plane correctly from the ground up.