CABLE vs FBW
Joined: Sep 1998
Posts: 1,615
Likes: 1
From: wherever
Lemurian
“The stall speed (equivalent airspeed) at 1 g normal to the flight path is the highest
of the following:
1. The speed for steady straight flight at CLmax
of the following:
1. The speed for steady straight flight at CLmax
Isn't this where i came in?
Sun worshipper
Joined: Dec 2001
Posts: 494
Likes: 0
From: Paris
FE Hoppy
You can take whatever definition of "stalling speed" you can, from any certification authority, you still cannot decide all by yourself that it describes the actual phenomenon called "stall" which is caused by complete airflow separation over the upper wing surface, i.e past the Clmax alpha, and is the start of uncontrolled flight.
For FBW airliners, the stall cannot be demonstrated, therefore the definition for stalling speed is taken from a spread of speeds, on a level flight (1 g) and during a descent (n< 1g).
The difference between certification definition and real life can be described with the example of that MD-82 that crashed uncontrolled in South America.
For a pilot, the recovery techniques from an actual aerodynamic full stall and an FBW airplane in "alpha prot" situation are very different, by some order of magnitude.
But I guess this discussion is about two different perspectives.
Tell that to Boeing and the UK CAA about the 727 certification (which ,in a slanted way proves my point about certification and handling perspectives).
You can take whatever definition of "stalling speed" you can, from any certification authority, you still cannot decide all by yourself that it describes the actual phenomenon called "stall" which is caused by complete airflow separation over the upper wing surface, i.e past the Clmax alpha, and is the start of uncontrolled flight.
For FBW airliners, the stall cannot be demonstrated, therefore the definition for stalling speed is taken from a spread of speeds, on a level flight (1 g) and during a descent (n< 1g).
The difference between certification definition and real life can be described with the example of that MD-82 that crashed uncontrolled in South America.
For a pilot, the recovery techniques from an actual aerodynamic full stall and an FBW airplane in "alpha prot" situation are very different, by some order of magnitude.
But I guess this discussion is about two different perspectives.
A stick pusher is not required if the aeroplane meets all the requirements as quoted above.
Last edited by Lemurian; 11th February 2009 at 12:34.
Joined: Sep 1998
Posts: 1,615
Likes: 1
From: wherever
For a pilot, the recovery techniques from an actual aerodynamic full stall and an FBW airplane in "alpha prot" situation are very different, by some order of magnitude.
But I guess this discussion is about two different perspectives.
But I guess this discussion is about two different perspectives.
Joined: Oct 2005
Posts: 7
Likes: 0
From: Belgium
By no means a "large" airliner, but the good old BAe-146 and AVRO RJ (last one produced in 2002) have unpowered, cable-controlled ailerons and elevators (using servo tabs) together with hydraulically powered roll spoilers and rudder.
You actually feel that you're moving the tab in the first half of the wheel deflection and then the whole tab + control surface in the second half (much heavier).
If you order too sharp a roll order you can even feel the downwing aileron tab being stalled for a second, a little bit like a car when you oversteer it ;-)
Now flying the A320 series, I do appreciate the full back stick procedure - it's simple and it works. And with EGPWS I guess you would never need more than 2,5G, would you ?
You actually feel that you're moving the tab in the first half of the wheel deflection and then the whole tab + control surface in the second half (much heavier).
If you order too sharp a roll order you can even feel the downwing aileron tab being stalled for a second, a little bit like a car when you oversteer it ;-)
Now flying the A320 series, I do appreciate the full back stick procedure - it's simple and it works. And with EGPWS I guess you would never need more than 2,5G, would you ?
