New thread on FBW?
Mooney_Driver wrote:
that Fly by Wire system … helped the A380 at Singapore to survive.
Me too!! :-)
Flyer59 wrote:
And i think while Concorde was a cool plane … it was simply too loud, thirsty and uneconmical.
Maybe. But I can assure you, she made me smile every time I heard that roar above London! A real pity that she’s gone.
Flyer59 wrote:
But by all available statistics the A320 is at least as safe as a non FBW Airliner like the B737. I would say safer, because of FBW.
True. Because most of the crews are properly trained and know what that system can do and what not. And btw, the 737 had it’s issues too, and not small ones either. It gets dangerous when people feel that the protections offered will keep them out of the dirt when things go haywire. And I would say that if the system gets degraded, which it can in many configurations, it can easily become much more difficult to handle than a simple rope and pully system. But have a look how Airbus is trying hard to keep their airplane out of certain areas of the world and the operators there. They do have their reasons why they rather see their airframes broken up for spares than them turning up in places like western Africa…
Flyer59 wrote:
The one exception I would agree on was the early autopilot panel of the A320, which had a part in the Air Inter Crash in France, because of the confusing indication of Glide Angle vs. Vertical Speed … which was changed (not to forget that the accident airplane did niot have a Ground Proximity system).
That was one of the early accidents which I would say were a consequence of bad ergonomics and insufficient training and experience, not much to do with the FBW system. The other one in that cathegory was Habsheim, where the crew was quite obviously over confident that the airplane would keep them out of the trees, yet it actually did save most of the lives on board. The accidents I am talking about are not those, but Armavia at Sochi as well as Gulf Air at Bahrein. Both were lost due to effective loss of pitch control due to overbanking. The other ones which got into severe trouble were massive in flight upsets due to failed air data computers, the most prominent one Qantas near Learmonth in 2008.
But you don’t need to look that far… not 2 years ago a 737 crew flew it’s airplane into the ground because they were following the flight director’s approach mode during a go around… something which most probably would not have happened on an A3xx because of the way that system works. That accident went right home on me, as I had flown on that airplane many times while it still was operating under another airline with more competent crews fortunately.
Fly by Wire system which so far has killed at least 3 airplanes
That’s your interpretation. But by all available statistics the A320 is at least as safe as a non FBW Airliner like the B737. I would say safer, because of FBW. The AF447 accident is directly related to Air France’s training and has little to do with the plane.
When I was still working for Airbus I had interviews with many experienced Airbus captains, most from LH. None of them thought that the FBW is a safety issue. The one exception I would agree on was the early autopilot panel of the A320, which had a part in the Air Inter Crash in France, because of the confusing indication of Glide Angle vs. Vertical Speed … which was changed (not to forget that the accident airplane did niot have a Ground Proximity system).
mh wrote:
Yes, we have. We have sold our dreams. Our financial crises have destroyed so much money, we could easily pull off dreams of moon bases, journeys to Mars, space vacations, ecological livng and basic research…
Somehow I think it is a mental thing. I remember when NASA had to fight Congress even during the Apollo Missions constantly for money. After the Apollo 1 fire then Senator Mondale tried to shut the program down, luckily he was outvoted on it. After 11 there were quite some voices who said, ok, we’ve beat the Russians so let’s stop now, with the consequence that the last 3 planned missions were scrapped. Some of the hardware flew with Skylab (which was a much larger structure than later space stations and hugely more comfortable too) and Apollo Soyuz and one LEM (Apollo 18’s) as well as the simulators were used in the Apollo 13 Movie as well as in the “From the Earth to the Moon” series by Tom Hanks. Both btw very well made and done with assistance by the people who actually were there. The Shuttle kind of picked up where the X15 had left off when the Moon frenzy began. Had it been developed as planned and not left in almost the original design state, they could have 20-30 of them flying today, which was the original plan. But after Challenger again some people lost faith and after Columbia Bush pulled the plug on it. Something which would never have been possible during the Cold War, as it obviously stopped the US from having access to manned space flight. The new Orion Capsule is nothing but a throwback to the Apollo days, if much larger and re-usable.
Concorde, in more than one way, was the first “Airbus” really, derived from the older French products such as the Caravelle and the British TSR2 and many other projects. It had several problems from the outset but I honestly think that but for it there would not be Airbus as it stands today. Quite a lot of stuff developped for Concorde went into Airbus’ model lines later, some stuff has even survived from earlier like the denominators of the hydraulic systems and some principles which can be traced back to the Caravelle even, which in turn took parts from the Comet and so on and on.
Concorde suffered from three major show stoppers: 1: The USA did not like the fact that Europe managed to get an SST working and they did not, so they hindered it for years until flights to the US could finally start. And by the time they did, the US had the 747 and made flying mass market. 2: The fuel crisis and massive price increase of the 1970ties made Concorde much more expensive to operate than planned. 3: The mass hysteria about the sonic boom made Concorde basically only viable over Oceans and even there with huge restrictions.
However, once it place, Concorde was very profitable for BA, but never for Air France. So when the French saw the chance after they lost the Air France one at Paris, they killed it. Airbus always looked at Concorde as a liability, which it was to an extent. Instead of developing a successor with modern engines and technology, they simply left it flying as long as it did not bother them too much, but then, after Gonesse, did all they could to shut it down. After 9-11, which cost Concorde quite a few very frequent fliers, it was easy in effect.
Flyer59 wrote:
Look at the B787 and A350 … those are fantastic airplanes with technology that nobody even dreamed of when Concorde was developed.
In terms of engines I agree, I am not very fond of some of the innovations which are simply still not at the point where they should be. While I love to fly Airbusses (and I have done some major projects which required me to fly the A320 for a lot of time in full flight simulators) I still have huge reservations about certain aspects of that Fly by Wire system which so far has killed at least 3 airplanes and gotten several others in severe problems but, at the other side, helped the A380 at Singapore to survive. I have huge reservations about the French mindset which allowed crews like the one in AF447 to develop a total inability to deal with a rather simple stall condition. Yes, the Protections e.t.c. are great, but they give people a false sense of security which undermines basic flying skills. The A320 suffered from a number of avoidable accidents as a consequence. The 787, we almost lost two of them in battery fires, one could easily have been fatal, the other (near hull loss) proved a very massive problem with the new materials. Airbus has had the advantage of profiting from the lessons learnt by Boeing, so hopefully the A350 will not suffer from such stuff.
What I do lament is the fact that ground breaking technology such as the Shuttle and Concorde (and by far not only those) were abandoned and thrown out instead of improved and upgraded to newer and better models without the shortcomings of the original designs. And every time mankind gives up an achieved skill and capability, is a step back in evolution. We know today that many high cultures of the past had skills which went astray for centuries before re-surfacing again after dark ages passed and in a way we are in danger of some of this repeating itself.
Flyer59 wrote:
- glass cockpits for general aviation
- sophisticated autoflight systems (DFC90/100 and GF700)
Yes, affordable glass cockpits are a real development, especcially if they are retrofittable. They actually make getting good instrumentation much more affordable.
Autoflight systems, I started out on the KFC150 system many years ago which still is regaded by many as one of the best, even though it must be 40 years old by now. I guess the fact that King at the time had the quasi monopoly at the high end (full AP Systems with FD and so on) with only Cessna as a contender, hampered the development for proper GA Autopilots for decades. What the DFC’s and GF’s today do is mostly stuff airliners have had for a very long time. I never understood why GA Autopilots never had proper Speed modes or only now slowly get level change and stuff we had in airliners for granted even on the DC9 and Caravelle. Yes, Avidyne has gone a new way in the sense that the DFC’s today also do protections and finally have those Speed modes, but most folk from the airline industry have to say, well, yea about time too. I never saw the reasons why it was not done a long time before. I think it had a lot to do with the fact that a lot of folk in GA never knew or cared what the big boys were playing with. That changed with the accessibility of full airliner simulations to a wide public.
What worries me today is that most development really happens in the non certified markets, which make them pretty useless in Europe. Unless certification gets to a point where innovation can be introduced into GA Avionics wihout the need for billions of up front development money needed, the pace we see will not increase, even though pressure from folks who know what non certified things can do will mount.
Interesting times.
As a matter of fact, health monitoring of FRP structures is a very interesting topic that still has many unanswered questions to research on.
The Slingsby Firefly has an OAT probe on the fuselage, and the structure requires inspection before flying if the gauge reaches 50o C.
mh wrote:
At the moment, much of this is mitigated by adding more safety factors and producing heavier airframes.
I seem to remember some certification requirement that dictates structural redundancy (i.e. multiple load paths) for composite wings etc. That would generate extra weight, but I’m not really familiar with it. Also, looking at GA production composites (Cirrus and Extra for example) you find they are crude in comparison to sailplane or high performance UAV structures. I think Tecnam’s approach of acquiring (buying in their case) a composites capability for fuselages while keeping metal wings makes a lot of sense. There seems to be more to gain with a complex shaped fuselage than with a wing, particularly in ease of manufacture and even with regard to performance – witness the good performance of the constant chord RV wing.
Flyer59 wrote:
That’s an interesting perspective, although i think that (i know it’s true for Cirrus) did get lighter a bit with time. And they should have an aerodynamic advantage when a SR22 is faster than, let’s say, Bonanza with RG. But of course it’s not so much.
You have to factor the different shape when comparing performance, because the shape determines the counteracting forces to weight (as en effect of mass) and thrust (or chemical engergy supplied).
In general you always end up with a trade off between different advantages or disadvantages. Using FRP your production process doesn’t need too much tooling, but better skilled workers, who work in toxic fumes, big cure ovens. The mould is good for a distinctive set of airframes and you normally just can produce a few parts simultaneously. You are more prone to manufacturing inaccuracies and as a consequence, you either have to be much more thorough in your compliance checks, or add some flub factor to your strength calculations. This then requires more material and results in a heavier airframe. Of course, there have been advances in the production of FRP structures in the past years, but many of the drawbacks still remain.
Repairs of FRP structures are not impossible, but require a good shop and skilled workers. Plus, they add mass to the airframe, much more than when exchanging metal sheets. Changes on the airframe become more difficult, as you can’t just reinforce structures with just a couple of holes and rivets. Some aircraft structures are inaccessible after closing, and critical adhesion can be difficult to monitor. As a matter of fact, health monitoring of FRP structures is a very interesting topic that still has many unanswered questions to research on. At the moment, much of this is mitigated by adding more safety factors and producing heavier airframes.
Then there is the disposal. If you chop an FRP airframe, you have much hazardous waste to dispose. Metal and wood airframes can be recycled much easier and more ecologically.
To be succinct: There is no such thing as free lunch :-)
