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Are New Airplanes TOO Complex?  
User currently offlinetraindoc From United States of America, joined Mar 2008, 360 posts, RR: 0
Posted (3 years 10 months 5 days 10 hours ago) and read 3805 times:

The problems with the Trent 900 and 1000 engines and the 787 raise the question: "Are these things getting too complex?". I am not being critical of or attacking Airbus, Beoing or Rolls. However, you need "almost" perfection with a commercial airplane. You cannot pull off the road to fix the problem. As planes and engines become more complex, there is a greater possibility of failure.

I am a physician, so I know something about complexity and systems failure. But I don't (usually) have to treat them at 35,000 feet while going 500+ MPH. How about some input from those of you with expertise in these areas?

Thanks, Traindoc

11 replies: All unread, jump to last
 
User currently offlinedl767captain From United States of America, joined Mar 2007, 2539 posts, RR: 0
Reply 1, posted (3 years 10 months 5 days 10 hours ago) and read 3750 times:

I'm thinking it's more of a problem with being brand new engines on a brand new plane than being too complex

User currently offlineDecromin From United Kingdom, joined Feb 2008, 80 posts, RR: 0
Reply 2, posted (3 years 10 months 5 days 7 hours ago) and read 3568 times:

Quoting traindoc (Thread starter):
"Are these things getting too complex?"

Well, yes and no. Undeniably, modern aircraft are more complex in their systems than aircraft of a generation or two ago, but all of that complexity exists for a good reason. Whether that reason is safety, reliability, efficiency or productivity, all of the systems perform a job that is either required or desirable on a modern aircraft, otherwise airlines would not be willing to pay for those systems!

Just as cars are much more complex these days, the erosion of the ability to self fix a car is well offset by the massive increase in safety, reliability, efficiency and productivity that a modern vehicle possesses (even if some may argue they have given up their "souls" in the process!)


User currently offlineeta unknown From Comoros, joined Jun 2001, 2077 posts, RR: 0
Reply 3, posted (3 years 10 months 5 days 7 hours ago) and read 3497 times:

Well on the subject of cars, don't forget VW had to tweak the engines on the latest Golf- the previous model had a new generation engine that caused so many reliability problems VW's reputation was getting tarnished so they simplified it (or dumbed it down) for the current model.

User currently offlinecomorin From United States of America, joined May 2005, 4896 posts, RR: 16
Reply 4, posted (3 years 10 months 5 days 6 hours ago) and read 3458 times:

In a simple system, x=tau(y) where Tau, the transformation function is generally monotonic and easily deducible over a finite range of y values. x is behavior of aircraft, and y is an independent variable ( or scalar) that describes aircraft state and control inputs.

In a complex system, tau is non-linear, may have multiple values and not esily deducible without a complex solution that requires months of training in a simulator across all values of y.

So modern aircraft are too complex if the learning curve to understand the tau function is costlier than the benefit received.

While cockpit automation has helped reduce crew and workload, has it made flying any safer? What does the data show?

Seems to me that the Airbii pilots here seem OK with the degree of automation on aircraft.


User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 5, posted (3 years 10 months 5 days 6 hours ago) and read 3438 times:

I'm gonna go on a limb here and say airplanes today are overall less complex than airplanes of yore. Take a SuperConnie for example, each engine had 18 cylinders (aircraft total 72), which also equates to 144 spark plugs in the plane (two per cylinder) That's a TON of things that can break right there.

Then take jet engines, which even in their infancy, were vastly more simple. In the grand scheme of things, jet engines only have one moving part (dual and triple spools notwithstanding). Also, planes nowadays have much more redundancy than ever before. Not to mention you can start a plane nowadays literrally with just pushing a button. I don't necessarily aircraft systems nowadays to be more complex, maybe different, but certainly automation and redundancy enhances safety greatly.

Quoting eta unknown (Reply 3):
Well on the subject of cars, don't forget VW had to tweak the engines on the latest Golf- the previous model had a new generation engine that caused so many reliability problems VW's reputation was getting tarnished so they simplified it (or dumbed it down) for the current model.

Not to derail the thread, but that's utter hogwash. VW's have been getting more and more reliable with every new generation. Maybe in the 70s I would have believed that statement, nowadays, no way. All the late VWs I've owned (and friends own) have been extremely reliable, much more so than any Asian or US car I've owned or driven. I've worked on the MKV Golfs a LOT and the MKVI (current generation) are basically identical. The new FSI engines have been very reliable, even the first versions. May want to post a source for those ill-informed claims.

[Edited 2010-11-16 21:17:16]

User currently offlineBMI727 From United States of America, joined Feb 2009, 15742 posts, RR: 27
Reply 6, posted (3 years 10 months 5 days 6 hours ago) and read 3418 times:

Quoting traindoc (Thread starter):
However, you need "almost" perfection with a commercial airplane.

You do, and in the past the way to ensure that was to overengineer and overbuild everything. It worked pretty well, but wasn't the most efficient. The industry needs to push the envelope but I think that a lot of the bean counters and managers don't have a good handle on just how difficult pushing the envelope can be, which leads to some problems.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlinespacecadet From United States of America, joined Sep 2001, 3629 posts, RR: 12
Reply 7, posted (3 years 10 months 5 days 5 hours ago) and read 3320 times:

Quoting comorin (Reply 4):
While cockpit automation has helped reduce crew and workload, has it made flying any safer? What does the data show?

The data shows a steady decline in accident rates attributed to all causes.

I'm assuming the OP's post was not just about cockpit complexity but really overall engineering complexity. But the thing is, with the extra complexity of the design also comes higher quality engineering and better build quality due to things like computer aided design and testing and improved production methods. You don't see planes just break up in mid-air anymore, for one example, which was not really unheard-of in the old days.

And all the extra complexity in the way airplane systems are designed is actually to lessen the pilots' workload. Pilots no longer have to scan dozens of dials in the cockpit and hand-fly their aircraft. One of the earliest "complex" systems fitted to airliners was auto-pilot, and they have only improved over the years to the point that now they're integrated with the FMC and can control the plane from takeoff to landing, freeing the pilots up to do other tasks. But the auto-pilot and FMC are themselves complex systems that early airliners didn't have. The airliners became more complex, but that reduced the chances of pilot error.

You could say the same for weather radar, GPWS, and TCAS. All complex computerized systems, but all there for extra safety.

Most of the added complexity in any aircraft design over the years is in response to a problem that needed to be solved. And the solutions have for the most part worked, even if it means airliners are not as simple as they used to be.



I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
User currently offlinecomorin From United States of America, joined May 2005, 4896 posts, RR: 16
Reply 8, posted (3 years 10 months 4 days 21 hours ago) and read 3100 times:

Spacecadet, thank you for the reply.

One factor at play here is also the trend towards growing machine autonomy - an aircraft trying to fly itself. I think Airbii were the first to do it with their rules-based 'laws'. It's the difference between riding a passive object like a bike, versus learning how to ride a fuzzy-logic Horse.

As for the comparison with the old Connies and their recip engines, I would say that they were more complicated rather than more complex.


User currently offlinetraindoc From United States of America, joined Mar 2008, 360 posts, RR: 0
Reply 9, posted (3 years 10 months 4 days 19 hours ago) and read 2944 times:

Thanks to all who have given input thus far. I appreciate the expertise and information.

Traindoc


User currently offlinerottenray From United States of America, joined Jun 2010, 279 posts, RR: 0
Reply 10, posted (3 years 10 months 4 days 19 hours ago) and read 2887 times:

An additional thought about complexity.

Not bashing Boeing, but the 787 program seems to suffer from some "self-induced" complexity - the vast amount of outsourcing.

This makes collaboration a bit more difficult - you can't just "walk down the hall" and speak to whatever department and point to the piece under discussion.

As far as recips vs. turbines, it's more moving parts vs. much tighter tolerances. You can gap a spark plug with a coin from your pocket.


Cheers!


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25311 posts, RR: 22
Reply 11, posted (3 years 10 months 4 days 10 hours ago) and read 2667 times:

Quoting Fly2HMO (Reply 5):
I'm gonna go on a limb here and say airplanes today are overall less complex than airplanes of yore. Take a SuperConnie for example, each engine had 18 cylinders (aircraft total 72), which also equates to 144 spark plugs in the plane (two per cylinder) That's a TON of things that can break right there.

Or the 28-cylinder (2 spark plugs per cylinder) Pratt & Whitney R-4360 used on the Boeing 377 Stratocruiser and various military types. Total 224 spark plugs for the 4 engines on the B377.


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