4 ms·

i haven’t looked at the fars in quite a few years, but i’m pretty sure there would be stuff in there that references stuff like pitch stability (which is how i’

by nopzor 7y ago

i haven’t looked at the fars in quite a few years, but i’m pretty sure there would be stuff in there that references stuff like pitch stability (which is how i’d define the “hardware problem”), is that not the case? i’m afk atm. i still maintain my macro point, either way. making the airframe on a pax airliner aerodynamically stable during normal takeoff and landing operations seems like basic “good engineering” to me.

burfog 7y ago
I'm not so sure that it is good engineering to be inherently stable during normal takeoff and landing operations. Modern fighter planes are inherently unstable because this is required for better maneuverability. Passenger planes can certainly benefit from that too. Consider gusty crosswinds during a landing. With an inherently unstable aircraft, there is greater capability to compensate. You can have a computer stabilize the plane, preventing the tail or wing tips from striking the ground. When wake turbulence threatens to flip the plane or when a microburst threatens to pound the aircraft into the ground, a fast response is possible. Stability would deaden the performance of the needed response. The extreme example is probably wings that are low-mounted anhedral and forward-swept, with the bending controlled by rapidly actuated aerodynamic surfaces near the tips.
- apcherry 7y ago
  A common fallacy I'm afraid - modern fighter planes are unstable for improved supersonic performance - reduced drag. So relaxed stability may benefit civil aircraft in terms of fuel efficiency. There is an argument that inherently unstable aircraft makes the manoeuvrability worse or harder. What many forget is that issue with manoeuvrability is actually at the end of the manoeuvre. The handling qualities aim is to point the nose in a new direction and an unstable aircraft makes the design challenge harder to stop the aircraft at the position required.

by nopzor 7y ago

burfog 7y ago

I'm not so sure that it is good engineering to be inherently stable during normal takeoff and landing operations. Modern fighter planes are inherently unstable because this is required for better maneuverability. Passenger planes can certainly benefit from that too. Consider gusty crosswinds during a landing. With an inherently unstable aircraft, there is greater capability to compensate. You can have a computer stabilize the plane, preventing the tail or wing tips from striking the ground. When wake turbulence threatens to flip the plane or when a microburst threatens to pound the aircraft into the ground, a fast response is possible. Stability would deaden the performance of the needed response. The extreme example is probably wings that are low-mounted anhedral and forward-swept, with the bending controlled by rapidly actuated aerodynamic surfaces near the tips.

apcherry 7y ago
A common fallacy I'm afraid - modern fighter planes are unstable for improved supersonic performance - reduced drag. So relaxed stability may benefit civil aircraft in terms of fuel efficiency. There is an argument that inherently unstable aircraft makes the manoeuvrability worse or harder. What many forget is that issue with manoeuvrability is actually at the end of the manoeuvre. The handling qualities aim is to point the nose in a new direction and an unstable aircraft makes the design challenge harder to stop the aircraft at the position required.