- Posts: 9
- Joined: 21 Oct 2003, 12:45
Many here have given many good reasons. Let me add some or at least try to make things a little clearer, but I’m liable to confuse some of you even more. :lol
Redundancy with good programming and enough working input sensors, and different controls surfaces can fill in for others if a single (or more in some cases) fails. Example if one elevator jams it won’t jam the other in an isolated system. Or Example if you lose elevators the computer can use flaps or and vectored thrust to control the aircraft.
Enhanced flight characteristics. Example: While braking the control surfaces can cross control, then net effect is increased braking. (for those that don’t understand sample: flaps down, down elevator can cancel out each others response but the extra drag from doing so will act as a brake) Example: If you have elevators that operate independently if you cross control them with the ailerons the net effect will be braking. Example: Rolling with the ailerons can be enhance by having elevators that act independently of each other but complement the ailerons.
If you still don’t understand what I am talking about, watch a modern aircraft land on a carrier. In the old days, each elevator acted as one, the ailerons always acted diametrically opposed. With computer assisted flight controls it’s not necessary to do that anymore, so each flight control can act independently. You can have a single control input get mixed into several controls. So you can have redundancy, and enhanced flight performance. If your ailerons can act independently, then they can be used as flaps.
Fly by wire and fly by light is essentially the same thing, the only difference in flyby light is the electrical signal is converted to light then back to be transferred over fiber optics. Fly by light is not faster. Light travels the same speed as electricity. In the world of data you can fit more bandwidth on fiber optic systems so in that way it could in theory be faster if the bandwidth was the limiting factor. The bandwidth needed for flight controls is very low so data backup is not very likely. Fly by wire systems are a little slower as they have another stage of conversion as they are an electrical signal before and after they are light. The key advantage to fly by light over of fly by wire systems can be more jam/ECM EMP resistant if built right. Long sensitive wires of fly by wire systems can act like antennas to pull stray signals, ECM, EMP and can more easily be jammed or damaged, so sometimes in a hostile environment fly by light is better.
If your going to send data a long distance or at high bandwidth then optical would be more efficient but I would hardly call from one end of a plane to another long distance :rollin Flight controls really shouldn’t use up much bandwidth either. Since the distance across an aircraft is so short no repeaters will be needed :lol
Computer assisted flight controls generally make an aircraft easier to fly; I also agree with those that say computer assisted aircraft have a lot less of a feel to them. In non computer assisted aircraft, you are more likely to notice a response in an aircraft is changing before things are terminal. With older aircraft you could often tell if they were icing up, or the fuel or hydraulic fluid was running out ect.
If Alaska Airlines Flight 261 had redundancies in the elevator control, the aircraft would have made it to the mainland and probably would have been able to land safely. If there was redundancies and it had a flyby wire system that was semi smart in compensating for failures, the plane could probably landed safely without even noticing much of a problem.
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