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> An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick. Without any disrespect to the flying abilities of your Dad, as an ae

> An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick. Without any disrespect to the flying abilities of your Dad, as an aerospace engineer, the short answer to that is "no". You will have the luck to feel a "burble" if the airplane has been been built to be give you that warning. You have absolutely no guarantee that once the airplane has been modified beyond its original configuration, you will get any form of warning. This extreme behavior is actually partly present in the current case, with the stalling point jumping from the wing tip immediately to the wing root. That's no good. It can be even worse if you're flying a plane that is licensed under the "experimental" category by the FAA. One of the preferred airfoil for some time was the NACA 5-series, as it can have very little lift-induced pitching moment. It has also criminal stalling characteristics with absolutely no warning. Something beautifully illustrated by the following lift polar: https://media.cheggcdn.com/media/76b/76b33250-7f26-41f6-8f2c-30653c543431/php1R9qvY.png https://media.cheggcdn.com/media/76b/76b33250-7f26-41f6-8f2c...

I_Am_Nous 3y ago
Is it possible there's a mechanical/design cutoff where most planes designed to be fully mechanical would feel the "burble" while a more modern plane would not, similar to ABS vs non-ABS brakes or powersteering vs none? Are there hydraulic assists for flight controls that might smooth out those mechanical tells?
- fransje26 2y ago
  Not necessarily, no. It's a design feature to give pilots an advanced, physical warning that they are about to stall, and fall out of the sky. Electronic systems are all nice an well, but they can fail. So why not simply make it a physical feature of your airplane design, that triggers reliably not matter what? In some very specific edge cases a designer might decided that the planform trade-offs needed to bake the feature into the wing is not worth the performance loss in other metrics, and might forgo a nice, buffeting pre-stall wing. But plenty of pilots have died because they unexpectedly stalled, so it is not a design decision that should be taken lightly.
jcalvinowens 3y ago
> You will have the luck to feel a "burble" if the airplane has been been built to be give you that warning. Airplanes which are designed to do this (most airplanes) do it very reliably, it's not luck. Several of the Citabrias I fly don't have stall horns, all I have is the buffet. Complexity is always a tradeoff: it's harder to fuck up building and/or repairing a simpler airfoil.
- fransje26 2y ago
  > Several of the Citabrias I fly don't have stall horns, all I have is the buffet. That's fine, as long as the airfoil and wing planform you chose have a forgiving-enough lift vs angle-of-attack curve that you get plenty of buffeting before you start loosing significant lift and fall out of the sky. > Airplanes which are designed to do this (most airplanes) do it very reliably Yes, this is by design. Enough pilots were killed because their planes were not doing this reliably, and they literally fell out of the sky.

I_Am_Nous 3y ago

Is it possible there's a mechanical/design cutoff where most planes designed to be fully mechanical would feel the "burble" while a more modern plane would not, similar to ABS vs non-ABS brakes or powersteering vs none? Are there hydraulic assists for flight controls that might smooth out those mechanical tells?

fransje26 2y ago
Not necessarily, no. It's a design feature to give pilots an advanced, physical warning that they are about to stall, and fall out of the sky. Electronic systems are all nice an well, but they can fail. So why not simply make it a physical feature of your airplane design, that triggers reliably not matter what? In some very specific edge cases a designer might decided that the planform trade-offs needed to bake the feature into the wing is not worth the performance loss in other metrics, and might forgo a nice, buffeting pre-stall wing. But plenty of pilots have died because they unexpectedly stalled, so it is not a design decision that should be taken lightly.

jcalvinowens 3y ago

> You will have the luck to feel a "burble" if the airplane has been been built to be give you that warning. Airplanes which are designed to do this (most airplanes) do it very reliably, it's not luck. Several of the Citabrias I fly don't have stall horns, all I have is the buffet. Complexity is always a tradeoff: it's harder to fuck up building and/or repairing a simpler airfoil.

fransje26 2y ago
> Several of the Citabrias I fly don't have stall horns, all I have is the buffet. That's fine, as long as the airfoil and wing planform you chose have a forgiving-enough lift vs angle-of-attack curve that you get plenty of buffeting before you start loosing significant lift and fall out of the sky. > Airplanes which are designed to do this (most airplanes) do it very reliably Yes, this is by design. Enough pilots were killed because their planes were not doing this reliably, and they literally fell out of the sky.