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I hope they design and build the airframe properly this time. A plane that needs [cheaply outsourced] software (that relies on one sensor) to correct bad behavi

I hope they design and build the airframe properly this time. A plane that needs [cheaply outsourced] software (that relies on one sensor) to correct bad behavior at the flight envelope is just not acceptable. I still refuse to fly on the 737 MAX. I know it’s probably fine given what pilots now know about the how to control the thing, but I just refuse to support Boeing’s malicious negligence or any carrier that enables it. There are few companies on earth I’m as mad at as Boeing. As I see it, they are not done repenting for their crimes.

quibono 1y ago
It'd be a new airframe and not an elongation of an elongation of an existing one... So we might be lucky this time.
silverquiet 1y ago
I read "Airframe" by Michael Crichton probably twenty years ago, and it was around ten years old at that time. I remember that that book talked about how the planes were unstable by design and required software to maintain proper flight characteristics, and that this was so because it was more efficient. The book is fiction, but I doubt it was far off the mark at the time. I suspect that there is no going back from this state of things, and so if there must be software, it should be good software.
- masklinn 1y ago
  War planes dropped natural stability a while ago, IIRC the F16 was the first relaxed stability production aircraft (it's naturally stable at supersonic speeds but not subsonic). In fact there was a flying airliner with relaxed stability (though only neutral not negative) when Airframe was published: the MD-11. Though I don't know that there have been others since.
  - hypercube33 1y ago
    Isn't the high landing speed one of the unstable traits of this plane?
  - kqr 1y ago
    I think you're right about the F-16 being the first. My money would have been on the F-117, but that apparently started development three years later – the F-16 is surprisingly old!
- Centigonal 1y ago
  Starting with the F-16, many fighter jets are designed to be intentionally unstable to improve maneuverability. https://en.wikipedia.org/wiki/Relaxed_stability#Intentional_instability https://en.wikipedia.org/wiki/Relaxed_stability#Intentional_...
- kjs3 1y ago
  Fighter planes are unstable by design, and require computer control to stay in the air, because they're expected to do some pretty insane things in the air. A passenger plane has a somewhat different performance envelope, and while they are by-and-large fly-by-wire these days, they aren't designed to be aerodynamically very unstable.
- mrguyorama 1y ago
  The 737-MAX is not "unstable by design". It has the exact same positive stability as other planes in 99% of it's flight envelope. The remaining exception is that, at a certain AoA, speed, thrust, etc, there is a case where adding thrust pushes the nose up more than it does for the normal 737 The nose push is not abnormal, it is not unsafe, it is not unexpected. All planes with engines below the inertial "center" of the plane have this, including every 737 and every A320. The problem was, this meant that it's flight characteristics were "different" from the older 737s. The entire point of any plane that is even a little bit 737 is to sell to airlines as "This is still a 737 and you don't need to train anyone in anything extra". MCAS was built to change how the plane acts in this very specific regime, to act more like older 737s and counteract this nose push. MCAS was entirely unnecessary except for business and policy goals. MCAS killed people because properly training aircrews for it would have gone against the entire point of the 737 MAX.
  - chris393434 1y ago
    This is no different than modern traction control, and in no way is "wrong" from a design perspective. If I recall, the more fundamental flaw here is the degraded behavior of MCAS with dual-sensor AoA system was not they adequately trained pilots for, which was clearly part of the business case for Boeing, negligent or not.
  - ViewTrick1002 1y ago
    This is not correct and a gross simplification of the true issue. All aircraft with underslung engines have similar pitch up tendencies to varying degrees and different handling characteristics between models are fine. As seen with 757/67, 777/787 and A330/40/50 sharing type ratings despite being massively different aircraft. > As the nacelle is ahead of the C of G, this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall. This abnormal nose-up pitching is not allowable under 14CFR §25.203(a) "Stall characteristics". Several aerodynamic solutions were introduced such as revising the leading edge stall strip and modifying the leading edge vortilons but they were insufficient to pass regulation. MCAS was therefore introduced to give an automatic nose down stabilizer input during elevated AoA when flaps are up. http://www.b737.org.uk/mcas.htm http://www.b737.org.uk/mcas.htm The feeling of the aircraft is not the problem. The stall characteristics not complying with the regulation is.
- 6SixTy 1y ago
  When that book was published, the F-117 Nighthawk was already retired after 10 years in service. The thing doesn't even look like it could fly on account of the rudimentary stealth features.
- whatevaa 1y ago
  Passenger aircraft are stable by design. Fighter jets are unstable as this reduces drag and increases maneuverability.
hinkley 1y ago
The 737 is a clusterfuck because the giant engines throw off the physics of the plane both inertially and aerodynamically. It’s easier to make a turbofan more efficient by making it bigger. But power density also tends to go up with new models, so there’s at least a chance that there’s a smaller, lighter engine with the same thrust and fuel economy out there, allowing them to improve (restore) the physics of the aircraft.
- masklinn 1y ago
  While not great, the MAX would have been fine if Boeing (and their airlines) had not clung so hard to the type rating. Without that, MCAS could have been left out entirely alongside its utterly botched implementation. But that would have required a heavier certification process, and some pilot re-training. And they couldn't have that. Of course that wouldn't have freed Boeing from the rest of its dismal record (MCAS didn't cause door blowouts), but...
  - hinkley 1y ago
    Indeed. A fully new airframe likely won’t try to avoid training and certification overhead. Ripping that bandaid off will cut a lot of bullshit. But, there’s only so much engine you can shove under a narrow body aircraft. Landing gear is limited by physics and just making it taller won’t fix everything. I just looked and from what I can find on Wikipedia this may warrant a new model from P&W or CFM because I’m not seeing a documented turbofan family with similar thrust and smaller diameter except ones with much lower bypass ratios and thus garbage fuel efficiency. RR seems to be concentrating on bigger engines. They have a demonstrator that’s 2x the diameter of the Max’s engines. JFC.
    - mrguyorama 1y ago
      >Landing gear is limited by physics and just making it taller won’t fix everything. Every other plane is higher than the 737. The only reason the engines needed to be pushed forward on the 737, is that the 737 was built back in the day to be lower to the ground for easier operations at poorer airports, with things like stairs and baggage. The 737 doesn't need to be as short as it is anymore because the vast majority of them now fly to airports with jetbridges and modern bag handling equipment. The A320 is not as short as the 737 despite serving the same market, and can handle bigger engines. But the entire problem stems from wanting to abuse the 737 type rating even further. If they were fine with a new type rating, they could put the engines pretty much wherever they want, put nice tall landing gear, etc.
raverbashing 1y ago
The only instability most comercial planes have is the so called Dutch roll caused by swept wings and is compensated by the yaw damper (no sw needed)
bapak 1y ago
> I just refuse to support Boeing’s malicious negligence I get, but if everyone does that, Boeing does and we're left with a monopoly. Is that better? Will you feel safer flying on a COMAC?
- someperson 1y ago
  Did you mean Airbus?
  - rkomorn 1y ago
    Or dies instead of does ?
- KeplerBoy 1y ago
  Boeing would get a bailout and hopefully do better next time. No way, they are ever going under unless there is a superior domestic alternative.

quibono 1y ago

It'd be a new airframe and not an elongation of an elongation of an existing one... So we might be lucky this time.

silverquiet 1y ago

I read "Airframe" by Michael Crichton probably twenty years ago, and it was around ten years old at that time. I remember that that book talked about how the planes were unstable by design and required software to maintain proper flight characteristics, and that this was so because it was more efficient. The book is fiction, but I doubt it was far off the mark at the time. I suspect that there is no going back from this state of things, and so if there must be software, it should be good software.

masklinn 1y ago
War planes dropped natural stability a while ago, IIRC the F16 was the first relaxed stability production aircraft (it's naturally stable at supersonic speeds but not subsonic). In fact there was a flying airliner with relaxed stability (though only neutral not negative) when Airframe was published: the MD-11. Though I don't know that there have been others since.
- hypercube33 1y ago
  Isn't the high landing speed one of the unstable traits of this plane?
- kqr 1y ago
  I think you're right about the F-16 being the first. My money would have been on the F-117, but that apparently started development three years later – the F-16 is surprisingly old!
Centigonal 1y ago
Starting with the F-16, many fighter jets are designed to be intentionally unstable to improve maneuverability. https://en.wikipedia.org/wiki/Relaxed_stability#Intentional_instability https://en.wikipedia.org/wiki/Relaxed_stability#Intentional_...
kjs3 1y ago
Fighter planes are unstable by design, and require computer control to stay in the air, because they're expected to do some pretty insane things in the air. A passenger plane has a somewhat different performance envelope, and while they are by-and-large fly-by-wire these days, they aren't designed to be aerodynamically very unstable.
mrguyorama 1y ago
The 737-MAX is not "unstable by design". It has the exact same positive stability as other planes in 99% of it's flight envelope. The remaining exception is that, at a certain AoA, speed, thrust, etc, there is a case where adding thrust pushes the nose up more than it does for the normal 737 The nose push is not abnormal, it is not unsafe, it is not unexpected. All planes with engines below the inertial "center" of the plane have this, including every 737 and every A320. The problem was, this meant that it's flight characteristics were "different" from the older 737s. The entire point of any plane that is even a little bit 737 is to sell to airlines as "This is still a 737 and you don't need to train anyone in anything extra". MCAS was built to change how the plane acts in this very specific regime, to act more like older 737s and counteract this nose push. MCAS was entirely unnecessary except for business and policy goals. MCAS killed people because properly training aircrews for it would have gone against the entire point of the 737 MAX.
- chris393434 1y ago
  This is no different than modern traction control, and in no way is "wrong" from a design perspective. If I recall, the more fundamental flaw here is the degraded behavior of MCAS with dual-sensor AoA system was not they adequately trained pilots for, which was clearly part of the business case for Boeing, negligent or not.
- ViewTrick1002 1y ago
  This is not correct and a gross simplification of the true issue. All aircraft with underslung engines have similar pitch up tendencies to varying degrees and different handling characteristics between models are fine. As seen with 757/67, 777/787 and A330/40/50 sharing type ratings despite being massively different aircraft. > As the nacelle is ahead of the C of G, this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall. This abnormal nose-up pitching is not allowable under 14CFR §25.203(a) "Stall characteristics". Several aerodynamic solutions were introduced such as revising the leading edge stall strip and modifying the leading edge vortilons but they were insufficient to pass regulation. MCAS was therefore introduced to give an automatic nose down stabilizer input during elevated AoA when flaps are up. http://www.b737.org.uk/mcas.htm http://www.b737.org.uk/mcas.htm The feeling of the aircraft is not the problem. The stall characteristics not complying with the regulation is.
6SixTy 1y ago
When that book was published, the F-117 Nighthawk was already retired after 10 years in service. The thing doesn't even look like it could fly on account of the rudimentary stealth features.
whatevaa 1y ago
Passenger aircraft are stable by design. Fighter jets are unstable as this reduces drag and increases maneuverability.

hinkley 1y ago

The 737 is a clusterfuck because the giant engines throw off the physics of the plane both inertially and aerodynamically. It’s easier to make a turbofan more efficient by making it bigger. But power density also tends to go up with new models, so there’s at least a chance that there’s a smaller, lighter engine with the same thrust and fuel economy out there, allowing them to improve (restore) the physics of the aircraft.

masklinn 1y ago
While not great, the MAX would have been fine if Boeing (and their airlines) had not clung so hard to the type rating. Without that, MCAS could have been left out entirely alongside its utterly botched implementation. But that would have required a heavier certification process, and some pilot re-training. And they couldn't have that. Of course that wouldn't have freed Boeing from the rest of its dismal record (MCAS didn't cause door blowouts), but...
- hinkley 1y ago
  Indeed. A fully new airframe likely won’t try to avoid training and certification overhead. Ripping that bandaid off will cut a lot of bullshit. But, there’s only so much engine you can shove under a narrow body aircraft. Landing gear is limited by physics and just making it taller won’t fix everything. I just looked and from what I can find on Wikipedia this may warrant a new model from P&W or CFM because I’m not seeing a documented turbofan family with similar thrust and smaller diameter except ones with much lower bypass ratios and thus garbage fuel efficiency. RR seems to be concentrating on bigger engines. They have a demonstrator that’s 2x the diameter of the Max’s engines. JFC.
  - mrguyorama 1y ago
    >Landing gear is limited by physics and just making it taller won’t fix everything. Every other plane is higher than the 737. The only reason the engines needed to be pushed forward on the 737, is that the 737 was built back in the day to be lower to the ground for easier operations at poorer airports, with things like stairs and baggage. The 737 doesn't need to be as short as it is anymore because the vast majority of them now fly to airports with jetbridges and modern bag handling equipment. The A320 is not as short as the 737 despite serving the same market, and can handle bigger engines. But the entire problem stems from wanting to abuse the 737 type rating even further. If they were fine with a new type rating, they could put the engines pretty much wherever they want, put nice tall landing gear, etc.

raverbashing 1y ago

The only instability most comercial planes have is the so called Dutch roll caused by swept wings and is compensated by the yaw damper (no sw needed)

bapak 1y ago

> I just refuse to support Boeing’s malicious negligence I get, but if everyone does that, Boeing does and we're left with a monopoly. Is that better? Will you feel safer flying on a COMAC?

someperson 1y ago
Did you mean Airbus?
- rkomorn 1y ago
  Or dies instead of does ?
KeplerBoy 1y ago
Boeing would get a bailout and hopefully do better next time. No way, they are ever going under unless there is a superior domestic alternative.