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Guest B1900 Mech

Boeing vs. the inevitable?

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Jonathan Sacks's articles re his 737/A320 experiences were an eye opening read for me - the radical difference between Airbus logic and Boeing pilot-control (even in the 777) really struck home.Even when flown manually, the Airbus flight computers do the actual 'flying' - interpreting the pilot's input; I knew this, but the way he described it really hit me - deflect the stick and the aircraft banks - rock-stable, no trim required and not budging unless commanded or trying to bank beyond what some French/British/German HUMAN:)designed as a safe angle. Yet to me this seems to be really nothing more than part and parcle of the inevitable, inexorable march of technology, no different in principle than your itty bitty cell phone, LCDs, DVD-RWs, your spanking new pc the power of which was almost undreamt of only 10 years ago and on and on...We happily embrace programmed machines that make our lives easier every day, trusting them to be well designed enough not to kill us - indeed we clamour for more! Why is it so inconceivable that that technology should not stop at the cockpit door?How long will it be before Boeing gives in to the inevitable and lets the computers 'interpret' and fly their civilian a/c just as I'm sure they do in their military applications? The jury is long dismissed, the technology is proven, and can only get better.Don't get me wrong, I LOVE Boeing a/c, but looking ahead, can they really 'hold out' much longer? Should they - or is Airbus philosophy just a precursor to an inevitable future?regards,Mark

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Good post MarkThis system has, as you briefly state, been implemented in modern fighter aircraft for years. Relieveing pilots of not having to think about bending the envelopes etc with our without payload. Making it possible for the pilots to pay more attention to the mission planning and tactics and less about the flying.Though I would think that the limits set on the airbuses is well within the limits while the fighters are set more "on the edge". It's only a matter of time before it's standard on all the airliners we see in the air. An interesting bit of information comes to mind. The swedish airforce's newest fighter (JAS 39 Griffon where JAS stands for Fighter/Attack/Recon) which entered service in 1997 is a true multi-role, light-weight fighter with a triple data bus fly-by-wire system. The aircraft is unstable in sub-sonic speeds and needs a computer aided flight control system as it would fly as well as a leaf without it. Anyhoo...During one of it's first official appearences, in an airshow over central Stocholm in 1993, the pilot, also the chief test pilot for the manufacturer, lost control of the aircraft at low altitude during a low speed turn. He did not manage to gain control over the aircraft but had to eject at a very low altitude. The aircraft hit the ground on an island in central Stockholm. Fortunately it hit a spot with no spectators or the outcome would not have been as good as it turned out. Just a plane lost.The crash investigation board that followed made some pretty interesting remarks. The board found that the crash was caused by pilot induced oscillations during the low speed turn. These PIOs was made more severe when passing through the FCS computers and they early became saturated with signals from the joystick and the control surface sensors. They also concluded that if the pilot had released the stick, the computers would most probably straightened the aircraft up.The conclusions of the board made the manufacturer do some pretty drastic changes in the software. The most drastic one being that they lessened the authority of the pilot input on the FCS calculations. FBW is interesting stuff I tell ya.Cheers,

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>How long will it be before Boeing gives in to the inevitable>and lets the computers 'interpret' and fly their civilian a/cIt is only 'inevitable' in your own interpretation. It will become inevitable once it is proven that Airbus technology either enhances safety, is more economical, more reliable or reduces pilot's workload (reducing chance of human error). And then airlines will demand it. But so far there is no data to support any of the above and Boeing's approach will be one more way to do flying. March-of-technlogy does not have to mean that everyone uses the same technology - to this day some of the finest automobiles are made with manual transmission and to this date people grill on real charcoals as opposed to using (technologically advanced) gas stove. Different strokes for different folks.Michael J.WinXP-Home,AMD64 3500+,Abit AV8, Radeon X800 Pro,WD 36GB Raptor,1 GB PC3200 http://www.reality-xp.com/community/nr/rsc/rxp-higher.jpg

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Mark, Just a couple of general observations. FBW started out as a method to control dynamically unstable aircraft easier. Fighters being the most obvious application. I don't know if this is why Airbus implements it in their airliners. As long as Boeing airliners are dynamically stable there is no real imperative to implement FBW.Glenn"If God would have wanted man to fly He would have given him more money"

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Thanks for the responses gents - I'm no expert by any stretch, and learn from all you have said - just thinking waaay ahead y'know?. I know we still grill on charcoal(yum:)), manual xmissions abound (when I was a child automatics were for the few, look at them now), heck we even ride horses! :), but I'm not even thinking only of fbw as it is now, but how long before pilot control of even dynamically stable a/c becomes, well, a pleasant option for the leisure flight enthusiast rather than par for the course on mainstream commercial airliners? 50 years, 100?We live in an age where people who should know better :) speak of 'pilotless' commercial transport - that's a stretch for me I'll admit, but we as a race have a way of achieving what we conceive....eventuallyregards,Mark

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Mark,I just did some research on the net and it seems Boeing is already there! The 777 already have a FBW system and the 7E7 will be fitted with one.One interesting fact here. The A380 will be fitted with a PBW system. PBW is power-by-wire and replaces all hydraulic devices with electrical devices. Thus eliminating the hydraulic system with all it's flaws.Technology eh? :-)Cheers,

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Hey Mats,Well I knew the 777 had fbw, but apparently its not implemented like an Airbus at all - in that the level of authority that the pilot has is greater 1 and 2 the pilot gets simulated (i think) feedback in the control column, which is so cool I think. The 'detached', 'along for the ride' feeling that Jonathan speaks of is not there. That may be just his first-timer impression, seasoned Airbus pilots love the aircraft.Think I'll do some research myself, get more aquainted with Boeing's no doubt still developing fbw philosophy. Wonder if the 7E7 system is exactly as the 777?Technology indeed:)regards,Mark

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Again guys, just a couple of amateur/personal thoughts. I was raised in a Boeing family, Dad retired after 30 years as chief tool/die supervisor for military division, so I AM biased. Could Airbus' implementation of FBW to that extent possibly be a cover up or an excuse for design/fabrication leniencies? Is Airbus, maybe, using FBW because their aircraft aren't as stable as Boeing's?Or, is Airbus building such stable planes that the FBW is implemented as an enhancement such as cruise and stability control on the new Cadillac. Is Boeing trailing in the FBW implementation because they want to make certain they get the stability thing as perfect as can be first? Or are they just too conservative and resistant to change? What do you think?Glenn(Call me the instigator, hehehe...)"If God would have wanted man to fly He would have given him more money"

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Airliners have to be stable by regulation, even though it is possible to make an unstable airliner and "simulate" stability through computers. So I doubt the Airbus FBW system has anything to do with stability - it is clearly a system designed to enhance safety by reducing pilot workload and making sure the aircraft is not flown outside its flight envelope.Regarding control feedback, it is simulated in all (I think) aircraft with hydraulic flight controls, not just in FBW aircraft. In fact, if the artificial feel fails, the controls will feel soft and there is a risk of making excessive control inputs.Martin767 fetishistIt's a lot like life and that's what's appealing

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Consider the fact that the FAA requires there to be some positive (nose up) pressure on the h-stab to prevent a flutter problem, and you see that FBW is a plus in this case. It keeps the plane flying nice and level, even with some extra trim cranked in. :) BTW - Airbus insists the flutter is NOT a design flaw, and not dangerous (just a passenger inconvenience) so I guess they did it on purpose?

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Well thought out answers everywhere, and all pretty accurate I'd say. I don't think any aircraft mfr. would hide flaws purposely or throw technology in just to make do. FBW is enhancement of an already proven product. I think Boeing is just a little "old school" and will go total FBW when it's in their interest.Glenn"If God would have wanted man to fly He would have given him more money"

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>>I think Boeing is>just a little "old school" and will go total FBW when it's in>their interest."Old school" which 99% of world aircraft operate on. In fact FBW is so expensive that the chance that a student pilot will be learning to fly in an FBW-equipeed 172 is next to zero in the forseeable future. Even commuter type of airplanes (jet or turbo-prop) will remain "old" school too. And just because of that there will always be a demand for an old school heavy jet. People keep forgetting that there is as much technology in B777 as in A320 and the only difference is in the interface between pilot and the machine.Michael J.WinXP-Home,AMD64 3500+,Abit AV8, Radeon X800 Pro,WD 36GB Raptor,1 GB PC3200 http://www.reality-xp.com/community/nr/rsc/rxp-higher.jpg

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Michael,>In fact FBW is so expensive that the chance that a student pilot will >be learning to fly in an FBW-equipeed 172 is next to zero in the >forseeable future.This quote reminds me of the famous quote of someone at IBM in the early years of the computers stating: "I think there is a world market for maybe five computers." ;-)The Brake-by-wire system called ABS is already implemented on almost all new cars. You don't mechanically control your brakes on your car any longer. There is a computer in between. The ABS was by the way invented for the aviation industry from the beginning. Saab has done some extensive testing with steer-by-wire in one of their concept cars. You don't mechanically control your wheels with the steering wheel. Infact you have a stick in front of you instead. And a bunch of computers interpreting your intentions and sending signals to servo motors which controls the turning of the wheels.There is a reason both Boeing and Airbus has implemented FBW on their airliners. First of all. Reduced weight as a lot of hydraulics are not needed. Thus reducing both production costs and gaining a larger payload. It makes the planes more maneuverable in manual flight as the computer can make hundreds of adjustments per second. It allows airliners to perform smoother and more economical. And with the capability to add redundancy without adding too much weight it makes them safer to systems failures.So overall I would say there is economy in FBW. And as computing power gets cheaper and more powerful per square inch per every two months (or so it seems ;-)) the pay-off times for FBW will be even less.On the differences between the Boeing and Airbus approach. Some background. The Airbus has hard coded limits in their FCSs. They cannot be overridden by the pilot. Boeing implemented soft limits, basically consisting on ques to the pilot that he is reaching the envelope limits, but pilots are allowed by the FCSs to override these limits. Boeing states that this approach will give the final call to the pilot to pass the limits of the envelope and gain control if he ever is encountered in an uncontrolled flight. They have been making references to an incident that occurred with an Air China 747 in 1985 which tumbeled out of control where the pilots were able to recover using a 4G upward pitch movement. Airbus filosophy says that the above 747 would never been in the uncontrolled flight in the first place had they had a hard-coded system.So the battle continues.Cheers,

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>>Airbus filosophy says that the above 747 would never been in>the uncontrolled flight in the first place had they had a>hard-coded system.Of course, hard limits will prevent the pilots from doing that witht he aircraft controls, but not some natural event that effects the aircraft. Recovering from such an event could very well require some extraordinary manuervers or attitudes....

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I am ecstatic and inwardly very proud. This thread is a technically above average discussion, involves various acrft makes/models, delves into unknowns (by us anyway), and had all the potential to rub personalities wrong. BUT IT HASN'T!!!! No flames, no personal comments, and I am just... proud as punch. Hip hip for the maturity of all involved. It's a pleasure to converse with such as us.Glenn"If God would have wanted man to fly He would have given him more money"

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