3 ms·

> Airplanes are not gliders. Actually... Wasn't there a famous case where the pilots managed to save a plane without engines by just gliding to an airport? Wou

by d1zzy 8y ago

> Airplanes are not gliders. Actually... Wasn't there a famous case where the pilots managed to save a plane without engines by just gliding to an airport? Would such a thing even work on the MAX design? Ah yes, here it is: https://en.wikipedia.org/wiki/Air_Transat_Flight_236 https://en.wikipedia.org/wiki/Air_Transat_Flight_236

txcwpalpha 8y ago
> Would such a thing even work on the MAX design? Yes, because the problem with the MAX is that the engines provide an off-center-of-gravity thrust. If the engines weren't running, the MAX would glide just like any other 737. There is also the case of the Gimli Glider [1], and any commercial airliner is certainly capable of "gliding" for at least some time, but I think the GP was adhering more to the actual definition of "glider" [2], which is an aircraft that can fly entirely without power from any engines at all. 1: https://en.wikipedia.org/wiki/Gimli_Glider https://en.wikipedia.org/wiki/Gimli_Glider 2: https://en.wikipedia.org/wiki/Glider_(aircraft) https://en.wikipedia.org/wiki/Glider_(aircraft)
- ams6110 8y ago
  All jet airliners with engines under the wings have an "off-center-of-gravity" thrust. They all want to pitch up when thrust is applied. The MAX, with the engines higher and more forward, actually has less of an issue with this. The issue with the MAX is that the large engine nacelles forward of the wing can produce their own aerodynamic lift at high angles of attack. This is what MCAS compensates for.
cal5k 8y ago
Why would it not? You still have to be able to fly the thing in case of a dual engine failure. MCAS has one function: give the MAX 8 flight characteristics that are similar enough to previous versions to not require significant training. In fact, it's only when the engines are actually working that you'd need this... they're more powerful and further forward, meaning that at high thrust the aircraft will have more of a tendency to pitch up.
- salawat 8y ago
  Actually, the engines don't need to be on for the problematic behavior to manifest since the extra lift at high AoA is a direct result of the geometry of the wing+nacelle.
  - cal5k 8y ago
    That's fair, but I can't imagine it would be a problem at the attitude required for optimal glide slope in an engine-out scenario?
    - salawat 8y ago
      You are correct. The parts of the flight envelope where this is a problem are very high (approaching critical) AoA, or in a very tight, highly banked turn. These would not be maneuvers I'd imagine any pilot engaging in without engine power except maybe in the most dire circumstances.
jaclaz 8y ago
And it's not the only case, JFYI: List of airline flights that required gliding https://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding https://en.wikipedia.org/wiki/List_of_airline_flights_that_r... including several 737's (plain ones, not "MAX"), most notably: https://en.wikipedia.org/wiki/TACA_Flight_110 https://en.wikipedia.org/wiki/TACA_Flight_110

by d1zzy 8y ago

txcwpalpha 8y ago

> Would such a thing even work on the MAX design? Yes, because the problem with the MAX is that the engines provide an off-center-of-gravity thrust. If the engines weren't running, the MAX would glide just like any other 737. There is also the case of the Gimli Glider [1], and any commercial airliner is certainly capable of "gliding" for at least some time, but I think the GP was adhering more to the actual definition of "glider" [2], which is an aircraft that can fly entirely without power from any engines at all. 1: https://en.wikipedia.org/wiki/Gimli_Glider https://en.wikipedia.org/wiki/Gimli_Glider 2: https://en.wikipedia.org/wiki/Glider_(aircraft) https://en.wikipedia.org/wiki/Glider_(aircraft)

ams6110 8y ago
All jet airliners with engines under the wings have an "off-center-of-gravity" thrust. They all want to pitch up when thrust is applied. The MAX, with the engines higher and more forward, actually has less of an issue with this. The issue with the MAX is that the large engine nacelles forward of the wing can produce their own aerodynamic lift at high angles of attack. This is what MCAS compensates for.

cal5k 8y ago

Why would it not? You still have to be able to fly the thing in case of a dual engine failure. MCAS has one function: give the MAX 8 flight characteristics that are similar enough to previous versions to not require significant training. In fact, it's only when the engines are actually working that you'd need this... they're more powerful and further forward, meaning that at high thrust the aircraft will have more of a tendency to pitch up.

salawat 8y ago
Actually, the engines don't need to be on for the problematic behavior to manifest since the extra lift at high AoA is a direct result of the geometry of the wing+nacelle.
- cal5k 8y ago
  That's fair, but I can't imagine it would be a problem at the attitude required for optimal glide slope in an engine-out scenario?
  - salawat 8y ago
    You are correct. The parts of the flight envelope where this is a problem are very high (approaching critical) AoA, or in a very tight, highly banked turn. These would not be maneuvers I'd imagine any pilot engaging in without engine power except maybe in the most dire circumstances.

jaclaz 8y ago

And it's not the only case, JFYI: List of airline flights that required gliding https://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding https://en.wikipedia.org/wiki/List_of_airline_flights_that_r... including several 737's (plain ones, not "MAX"), most notably: https://en.wikipedia.org/wiki/TACA_Flight_110 https://en.wikipedia.org/wiki/TACA_Flight_110