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Originally Posted by Brian Carlton
Doh. Should have remembered this. Thanks for the clarification.
I presume that you mean "1.5 inches of pedal travel produces the full rudder movement."
This seems like a very small number and would make the aircraft very difficult to fly. The pedals would be way too sensitive, correct?
Is it the general agreement that rudder on the A300-600R made three full deflections, full left, then full right, then full left again?
Have you had to change procedures for the DC9-80?
So, what good are all the limits that are placed upon the aircraft if the limits will not prevent the pilot from overstressing the aircraft? If you are going to follow a given philosophy, and put the control of the aircraft in a computer, then DO IT. Don't just do it half-assed.
All very interesting, Dave. Thanks.
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1.5 inches from neutral for full rudder pedal tavel and that will give you full deflection and yes it did make 3 full deflections prior to failure. Why he did this we will never know. And the rate of this movement I do question if it was physically possible. I have not flown the A300 so I'm not sure of the control sensitivity.
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The dificulty in controling the aircraft is a learned proces. The T38 was so sensitive that you flew the aircraft with your wrist on your right leg and used just your finger tips, otherwise you would get into a pilot induced oscilations. A very sensitive aircraft flight control system. But you learned it. Why is the A300 so sensitive in just the rudders I don't know. The flight control "feel" in the MD80 is much heavier that the DC10 that I flew. A power steering Vs. manual steering idea. BUT all the flight controls had the same basic sensitivity.
MD80 procedures have change in reguards to rudder usage. Applying full rudder is OK just don't swap from side to side. This is now taught to all our pilots and since the FAA came down with this probably all airlines.
Computer fly be wire. Up until the fly by wire sytems that were started , to my knowledge, in the F16 type aircraft, all aircraft would allow the pilot to overstress the aircraft to the point of failure. That is part of our job. Every day I fly I can screw up and kill all 129 passengers. Many people have some false sence of security, or thought, that something on the aircraft would not let the airplane crash. That something are the 2 pilots in the cockpit. And only the 2 pilots. Look at the Egyptian airline crash out of JFK. The copilot wanted to crash the airplane and he did. The Captain could not stop him in that situation. If at 200' AGL I applied full aileron and rudder My coplit could not counteract my inputs with the time remaining. So what keeps you safe up there are the pilots.
The first electronic flight controls for fighters were neccesary due to the instability of the aircraft, that is how you design a high performance fighter. They designed it very unstable and used computers to control it. BUT they have ejection seats, so if it goes south you can eject.
Have I had to exceed the limits of the aircraft in any way, no, knock on wood. But if in a thunderstorm downburst I could firewall the engines and ignore the stall warning computer to prevent the aircraft form hitting the ground ( it is easier and safer to just not fly approaches thru , near or around thunderstorms) . In the A320 you would apply full throttle but the computers would not let you exceed max thrust ( actually these systems are also in newer Boeings) , I could pull on the control stick with all I have but the computer would limit me. Hopefully my next 9 years of flying I will never have to exceed any limits, but in an emergency I would like that option.
Some of the new Boeings are getting limits on engine fuel systems and flight controls. It is inevitable and will be the norm in the future. But the computer systems will also be more advanced.
On the A320 they realize they had to put a override button on the captains stick controller. Here's why. The brand new copilot with very little time in the aircrat is flying. On approach if the Capt has to take over due to poor skill level in the aircraft, IE he's messing up the landing. The old system accepted the strongest input. Not a overiding input. So now the Captain presses a button on his stick and it is now a overide stick. The copilots will no longer work. Took them a couple of years to find this was needed.