Nobody in their right mind would sign-off a complex circuit solely on the basis of a spice simulation. But Boeing is planning on doing the equivalent for their 777X!
"Specifically, Boeing is ?reducing the scope and duration of certain costly physical tests used to certify the planemaker?s new aircraft,? Reuters reported over the weekend. We're thus told that engineers working on Boeing's new 777X airliner project are intending to use computer simulations instead of real-world flight tests to validate their engineering decisions."
Er, no. Climate modelling, which is very different. But back to the main point...
Boeing can do non-destructive and destructive tests on their products, so simulation isn't /necessary/. I'd argue that simulation definitely isn't /sufficient/.
Precisely what destructive and non-destructive tests can we do with the climate?
Wrong question. A better question is whether modelling (not simulation) will help us understand possibilities and consequences in situations where tests are impossible.
What's going wrong, is that the world is melting down, as many are nay-saying, and we will end up with flooded cities, and devastated farming and living areas.
Boeing's business model is mostly doing slow evolution of proven products at this point and rarely does clean-sheet designs, it's wasteful to do a flight test of an improved 777 every time you make a mild improvement. We know the sumbitch flies OK already. The world is chaotic but not THAT chaotic.
The 737 Max handled very much like a 737 there were not huge engineering surprises there. It was just different enough that they wanted to avoid a different type rating. It was more of a bean-counting problem than an engineering problem.
Simulation is better at catching fails early than validating success.
in my experience, if the initial assumptions are valid, if something works in the sim then there is a very good chance it will work consistently IRL. But there's also no guarantee that the real circuit will perform consistently either just because it does on a breadboard, during one test run.
but again if the initial assumptions are valid, if something is going wrong with the sim then there is a 0% chance the real circuit will actually work to specification. Zip. Zero. None.
That's nothing really new. When atmospheric and underground nuclear bomb testing ended in 1992, weapons research and development switched to using super computahs to simulate nuclear weapons. Presumably, the bombs will work if needed, but nobody is certain.
"How Do You Know a Nuclear Weapon Works If You Can't Test It?"
The bad news is that increasingly complex systems and shorter development times are going to push manufacturers into taking short cuts, such as simulation as a replacement for testing. Or, they can take the Microsoft approach. Have the customers do the testing, return the crash reports to headquarters via "telemetry", and then do damage control on the wreckage. If an update erased a few users files, no big deal. What matters is the greatest good for the greatest vendor. It would interesting to see an airplane designed in that manner. Actually, we probably have seen airplanes designed that way. Much of the computah simulation software is already being used by the aerospace industry. Flight testing caught many of the problems before the passengers arrived, but with simulation replacing testing, I suspect we're going to see more regrettable incidents.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
On a sunny day (17 Jun 2019 18:21:49 -0700) it happened Winfield Hill wrote in :
Sure, basics, again:
formatting link
Climate WILL change, it is in no way caused by use humming-beans.
Better bring all power sources we have online, diversify.
That is much better than shutting down nuke plants out of radiation fear, and replacing those with windmills.
Human population will _have_ to decrease during glacial periods, or all will have live underground with nuclear heating? Mass migration to livable areas.., no trump walls will stop it. Fights for that land, wars. breakdown of civilization as we know it, maybe some SpaceX colony on mars looking through a telescope at a frozen earth..
No trannies, no factories, no commie-nukation, fight for survival.
On a sunny day (Mon, 17 Jun 2019 21:49:17 -0400) it happened bitrex wrote in :
No, that plane is unstable by nature due to the position of the engines if I understand it right. They wanted to fix that with some software. That worked, then they 'simplified' the software, removed a G sensor, and that did not work. The basic plane designs sucks. A good plane flight strait without correction.
If you make a paper airplane, and it is bad, it will do strange things, you could than add all sorts of systems to make it fly right but it would still be a POS.
I don't believe it was dynamically unstable inherently like some (most?) modern military combat aircraft are.
Toss it like a glider with no electronic flight controls, trimmed for level flight, and it will probably enter a phugoid like most (all?) large passenger aircraft do.
The Space Shuttle was a total brick without electronic flight controls it is pretty much impossible to fly, much less land the orbiter without them.
In the (unlikely, never happened) case of a total electrical or computer failure on final approach the only option the crew would have had would be to bail out, a safe landing is impossible. It was a "glider" in name only.
On a sunny day (Tue, 18 Jun 2019 00:37:50 -0400) it happened bitrex wrote in :
From what I have read, increasing engine power with the new engine positions gave it a tendency to stall. They moved the engine position to get better fuel efficiency?
The paper plane analogy holds.
As to the mil dynamically corrected fighter planes, Russian S400 and S500 will just blow all of that out of the air. Israel already has a F35 that was hit.. maybe even by a simpler missile, F35 'stealth' is an illusion, a 35 $ camera can see the F35 IR signature hundreds miles away. F35 a US snake oil sales product.
Look at the paranoia now Turkey (not the animal) is buying those Russian systems 'but they will figure out how to detect the F35' (quoted from the news).
We will see, trump just announced sending thousands of troops to the middle east. If that fire ignites there will be no more Israel, and possibly no more US government, Mr Xi and Mr Putin will divide the US up in a Chinese and Russian part in a Washington conference.
All 'merricans will have to learn a new language, either Mandarin or Russian.
In the EU, when / if? UK leaves it, English will be no longer be an accepted language it will likely mostly be German and French. I am so glad, here they started teaching French in kindergarten, been there several times no problem with that language,,, learning things as a small kid helps really.
On a sunny day (Tue, 18 Jun 2019 00:44:08 -0400) it happened bitrex wrote in :
So... only thing it ever did that was in any way useful was fix Hubble. But NASA should not have send up the wrong Hubble mirror in the first place.
Had US stayed with Von Braun's mars plan it would rule the solar system.
All politics, that shuttle, create a monster for some political purpose. And it killed people too. WAY more expensive than what SpaceX is now doing with reusable boosters, so back to rockets. NASA even had nuclear rockets that could just reach any place in the solar system, project scrapped because somebody cried 'radiation'. Those who ventured to America were not stopped by fear of falling of the flat earth, these days it is all old women and politics requiring more old women in command. I was reading today some university or whatever joke it was here is now only accepting women, is that not discrimination ;-)
One side effect of what we call 'demon-crazy' or whatever the word, is that idiots select idiots and are then ruled by same (trump an example). That one party system is what makes China stronger, that and no religious Pi is 4 crap. They are on the backside of the moon, and soon maybe have astronauts walk there, next mars, if global war does not interfere. OTOH wars cut the crap and create things that really work, much came out of the last WW, including rockets, radar, etc etc
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.