5 ms·

Since the plane is aerodynamically flawed by design. I'll never step foot on one.

by richardARPANET 6y ago

NikolaeVarius 6y ago
But its not?
- gruez 6y ago
  But it is? I think the parent was talking about: >Travis is unequivocal in his assessment of the Boeing 737 MAX. “It’s a faulty airframe. You’ve got to fix the airframe [and] you can’t fix the airframe without moving the engines” back and away from their current position. >The root problem with the engine-forward design is “once this thing pitches up, it wants to keep pitching up,” said Travis. “That’s a big no-no,” he continued, because pitch-up on an aircraft increases angle of attack. https://www.eetimes.com/software-wont-fix-boeings-faulty-airframe/ https://www.eetimes.com/software-wont-fix-boeings-faulty-air...
  - ConceitedCode 6y ago
    FYI - Background on the guy being quoted "Gregory Travis, a veteran software engineer and experienced, instrument-rated pilot who has flown aircraft simulators as large as the Boeing 757" I know a few veteran software engineers that are instrument-rated and frankly I'm not sure I would listen to any of them over the FAA or aeronautical engineers. Probably good for some perspective, but not exactly a great source for determining if an airplane is "aerodynamically flawed by design".
    - raverbashing 6y ago
      I agree with you, aerodynamics and airframes are not something so trivial to understand. "who has flown aircraft simulators as large as the Boeing 757" Talk about a big aircraft simulator, those that I know are the size of a car, not of a 757 (jk)
  - cpgxiii 6y ago
    That article, and Gregory Travis' assessment, offer zero actual evidence that the design is unstable. Lot of hand waving and "the engines are different so it must be dynamically unstable" but no actual evidence, which is obvious because no independent engineer/pilot is going to be able to effectively assess the upset aerodynamics of an airliner and come to a different conclusion than both the FAA and EASA about whether or not the aircraft is dynamically unstable. He's somewhat right on other details, but that doesn't make his assessment of the aerodynamic issues correct.
  - NikolaeVarius 6y ago
    Airfoils pitch up by default. Its how they work. Aircraft are designed to not let that happen in an uncontrolled fashion. Software has been used to do this since the advent of computers in airplanes Maybe we should also start boycotting A320neo's too https://www.flightglobal.com/programmes/a320neo-also-potentially-vulnerable-to-pitch-up-scenario/133749.article https://www.flightglobal.com/programmes/a320neo-also-potenti...
atharris 6y ago
Aerospace controls engineer here - while the airframe might not be passively stable (as is common for civilian aircraft), dynamically unstable aircraft have been stabilized with control software since the 70s [0]. If you've flown on an MD-11, you've flown on an 'aerodynamically flawed' aircraft. Most real systems are dynamically unstable without some kind of controller (implying software) in the loop. [0] https://en.wikipedia.org/wiki/Relaxed_stability https://en.wikipedia.org/wiki/Relaxed_stability
- phkahler 6y ago
  Boeing has kind of a poor track record for software lately, from the Max to the SLS. Time will tell if this has resulted in real change.
  - atharris 6y ago
    Ah - I didn't say Boeing's ability to write and test that control software was particularly good (in fact, I think their current track record says exactly the opposite.) I just hate when non-domain experts make judgements about things being 'fundamentally flawed.' Insufficiently tested and documented? Sure. Bad UI/UX? Most definitely. Irredeemable 'because of aerodynamics' according to some private pilot that flew a 737 once in sim? Absolutely not.
    - d-sc 6y ago
      Amen. If we don’t focus on the root cause it will be harder to solve the problem. And understand that we have actually solved it. (Student Pilot and Mechanical Engineer here)
    - phkahler 6y ago
      >> because of aerodynamics But yes. MCAS was put in place due to concerns over aero. If that was just to avoid the need for extra pilot training then it should have been scrapped since new training will be required now anyway. But since great effort has been made to fix MCAS we can conclude that the root problem is aerodynamic. Can aerodynamic issues be compensated for with software? Sure. I need to read up on the final hardware/software/instruction solution before passing Judgement.

Since the plane is aerodynamically flawed by design. I'll never step foot on one.

NikolaeVarius 6y ago

But its not?

gruez 6y ago
But it is? I think the parent was talking about: >Travis is unequivocal in his assessment of the Boeing 737 MAX. “It’s a faulty airframe. You’ve got to fix the airframe [and] you can’t fix the airframe without moving the engines” back and away from their current position. >The root problem with the engine-forward design is “once this thing pitches up, it wants to keep pitching up,” said Travis. “That’s a big no-no,” he continued, because pitch-up on an aircraft increases angle of attack. https://www.eetimes.com/software-wont-fix-boeings-faulty-airframe/ https://www.eetimes.com/software-wont-fix-boeings-faulty-air...
- ConceitedCode 6y ago
  FYI - Background on the guy being quoted "Gregory Travis, a veteran software engineer and experienced, instrument-rated pilot who has flown aircraft simulators as large as the Boeing 757" I know a few veteran software engineers that are instrument-rated and frankly I'm not sure I would listen to any of them over the FAA or aeronautical engineers. Probably good for some perspective, but not exactly a great source for determining if an airplane is "aerodynamically flawed by design".
  - raverbashing 6y ago
    I agree with you, aerodynamics and airframes are not something so trivial to understand. "who has flown aircraft simulators as large as the Boeing 757" Talk about a big aircraft simulator, those that I know are the size of a car, not of a 757 (jk)
- cpgxiii 6y ago
  That article, and Gregory Travis' assessment, offer zero actual evidence that the design is unstable. Lot of hand waving and "the engines are different so it must be dynamically unstable" but no actual evidence, which is obvious because no independent engineer/pilot is going to be able to effectively assess the upset aerodynamics of an airliner and come to a different conclusion than both the FAA and EASA about whether or not the aircraft is dynamically unstable. He's somewhat right on other details, but that doesn't make his assessment of the aerodynamic issues correct.
- NikolaeVarius 6y ago
  Airfoils pitch up by default. Its how they work. Aircraft are designed to not let that happen in an uncontrolled fashion. Software has been used to do this since the advent of computers in airplanes Maybe we should also start boycotting A320neo's too https://www.flightglobal.com/programmes/a320neo-also-potentially-vulnerable-to-pitch-up-scenario/133749.article https://www.flightglobal.com/programmes/a320neo-also-potenti...

atharris 6y ago

Aerospace controls engineer here - while the airframe might not be passively stable (as is common for civilian aircraft), dynamically unstable aircraft have been stabilized with control software since the 70s [0]. If you've flown on an MD-11, you've flown on an 'aerodynamically flawed' aircraft. Most real systems are dynamically unstable without some kind of controller (implying software) in the loop. [0] https://en.wikipedia.org/wiki/Relaxed_stability https://en.wikipedia.org/wiki/Relaxed_stability

phkahler 6y ago
Boeing has kind of a poor track record for software lately, from the Max to the SLS. Time will tell if this has resulted in real change.
- atharris 6y ago
  Ah - I didn't say Boeing's ability to write and test that control software was particularly good (in fact, I think their current track record says exactly the opposite.) I just hate when non-domain experts make judgements about things being 'fundamentally flawed.' Insufficiently tested and documented? Sure. Bad UI/UX? Most definitely. Irredeemable 'because of aerodynamics' according to some private pilot that flew a 737 once in sim? Absolutely not.
  - d-sc 6y ago
    Amen. If we don’t focus on the root cause it will be harder to solve the problem. And understand that we have actually solved it. (Student Pilot and Mechanical Engineer here)
  - phkahler 6y ago
    >> because of aerodynamics But yes. MCAS was put in place due to concerns over aero. If that was just to avoid the need for extra pilot training then it should have been scrapped since new training will be required now anyway. But since great effort has been made to fix MCAS we can conclude that the root problem is aerodynamic. Can aerodynamic issues be compensated for with software? Sure. I need to read up on the final hardware/software/instruction solution before passing Judgement.