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CarForumPoster posted:you take it back This is how roughly half of all aircraft programs have been, though. It's not like that's what makes the F-35 program unique. I think concurrent development is the big issue here.
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Dec 4, 2016 08:38
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hobbesmaster posted:Only 21 B-2s were built. 1 crashed, so there are 20 in service. Across those 20 aircraft there are five different block numbers. quote:AV-22 through AV-165 Cancelled They had way way more planned to be built than I thought 
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Dec 4, 2016 10:43
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I really want to see what the soviet counterpart would have looked like. Did they even have a stealth program in the 70-80s?
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Dec 4, 2016 11:53
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Party Plane Jones posted:They had way way more planned to be built than I thought They should have built them out and at least replaced the last of the B-52s.
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Dec 4, 2016 13:15
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Suicide Watch posted:I really want to see what the soviet counterpart would have looked like. Did they even have a stealth program in the 70-80s? Yeah, it was called "try to steal our secrets." Their lack of computer modeling ability really hurt them, and even the PAK-FA, their first true "stealthy" fighter evidently is about as stealthy as a Flanker with RCS reduction. That's why they've spent most of their time and effort into refining their missiles and radar and way less on planes. Hell, at one point I remember hearing/reading they were trying to pioneer "plasma bubble" stealth so they could skip the whole damned process altogether.
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Dec 4, 2016 14:56
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Mazz posted:I think one element that might be possible is that the AF is acutely aware of how hosed the F-35/KC-46A have put them budget-wise, so it seems like the B-21 was pushed forward to be as evolutionary (instead of revolutionary) as possible. Godholio posted:This is how roughly half of all aircraft programs have been, though. It's not like that's what makes the F-35 program unique. I think concurrent development is the big issue here. True. Maybe they'll do like the programs of recent that actually worked, build a flying test bed, then build 1-2 SDD aircrafts...it's a slow development process but you don't end up with 40 planes of varying configuration all of which mostly don't work
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Dec 4, 2016 15:32
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BIG HEADLINE posted:Hell, at one point I remember hearing/reading they were trying to pioneer "plasma bubble" stealth so they could skip the whole damned process altogether. Yeah, plasma stealth and photonic radars are the Russian wonderweapons that Indian fanboys fantasize the PAKFA/FGFA collaboration will bring them. There was also something about a magical ultra-absorbing paint that could turn any existing plane into a stealth plane for much cheaper than "traditional" RAMs...
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Dec 4, 2016 15:43
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CarForumPoster posted:True. Maybe they'll do like the programs of recent that actually worked, build a flying test bed, then build 1-2 SDD aircrafts...it's a slow development process but you don't end up with 40 planes of varying configuration all of which mostly don't work Honestly they should've learned from the F-22. There was a little of the same issue there, where the first few aircraft were physically incapable of being upgraded to combat standard. They were sent to the 43 FS at Tyndall as trainers. That should've been the warning sign that you can't manufacture aircraft this advanced WHILE figuring out if the loving design works. But of course the fighter fleet is in such dire straits that we'll probably end up accepting Lockheed's plan to upgrade those Block 20s despite the cost. GG Gates.
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Dec 4, 2016 17:34
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BIG HEADLINE posted:Yeah, it was called "try to steal our secrets." Ironically the research paper at the heart of early stealth technology/work was written by a Soviet scientist. It just took 2 decades for the US to have the computing power capable of modelling it.
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Dec 4, 2016 17:46
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My favorite was when they would paint funky airplane "shadows" on the tarmac for soviet spy satellites to take pictures of, just to mess with them.
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Dec 4, 2016 18:44
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BIG HEADLINE posted:Yeah, it was called "try to steal our secrets." My take away is that the whole "learning how to do stealth properly for about 40 years" is one of those cultural skill things that you really can't just "catch up" on in a few years. If the Russians were really interested in working on their stealth skills, starting where the Americans started (IE a purpose-built invisible recon/strike aircraft) would be a good place to start. Now I'm not suprised that when it came to 1980s electronics, the Soviets were at a severe disadvantage. (One thing I've noticed about the cold war science competition is that both the USA and USSR start in the same place, but slowly the Soviets get left behind technologically because they didn't have access to new industries like semicondoctor manufacture.) But it still surprise me a bit that the Soviets had problems with computer modelling. When it came to defense, I assumed they would just buy western chips/computers and use those. Y'know, like Iraq buying a shipping container of PS2s to make a supercomputer out of? Also I've never heard of "plasma bubble" stealth. Let me guess: the airplane creates some sort of plasma bubble which absorbs all radar emissions?
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Dec 4, 2016 18:55
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Nebakenezzer posted:Also I've never heard of "plasma bubble" stealth. Let me guess: the airplane creates some sort of plasma bubble which absorbs all radar emissions? That's the idea. Last I heard it strained physical plausibility because the energy needed to generate it far exceeds what engines can generate; but there have been research on the subject, including in the US and in Europe. https://en.wikipedia.org/wiki/Plasma_stealth Some random vids: https://www.youtube.com/watch?v=I11ClvQ6Fpc https://www.youtube.com/watch?v=EvBalLsuYGA
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Dec 4, 2016 19:11
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Party Plane Jones posted:Ironically the research paper at the heart of early stealth technology/work was written by a Soviet scientist. It just took 2 decades for the US to have the computing power capable of modelling it. Well...there was the Model 853 which may look a bit familiar... 
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Dec 4, 2016 19:11
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Nebakenezzer posted:But it still surprise me a bit that the Soviets had problems with computer modelling. When it came to defense, I assumed they would just buy western chips/computers and use those. Y'know, like Iraq buying a shipping container of PS2s to make a supercomputer out of? We went to extraordinary efforts to prevent Western computers from getting to the Soviets.
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Dec 4, 2016 19:14
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Midjack posted:We went to extraordinary efforts to prevent Western computers from getting to the Soviets. All the while, buying up titanium from them through dummy corps.
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Dec 4, 2016 19:33
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All's fair in cold love and war.
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Dec 4, 2016 20:29
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Nebakenezzer posted:My take away is that the whole "learning how to do stealth properly for about 40 years" is one of those cultural skill things that you really can't just "catch up" on in a few years. If the Russians were really interested in working on their stealth skills, starting where the Americans started (IE a purpose-built invisible recon/strike aircraft) would be a good place to start. Its not just processing power like number of CPUS, afaik HFSS was the only commercial software FEM game in town for this sort of thing in the early 90s and that was an American product in English and not easy to use without any training or support from the vendor. The soviets also dont have some of the quality control and manufacturing secrets that F-117, B-2, etc. employed that made good design actually work. America also has the ability to have low probability of detection comms and a satellite network for navigation. If they shape it they might not be able to build it and if they build it, it might not know where it is and even if it did the beyond engagement range AEW assets probably can't talk to it to say "hey theres a missile flying at you". All of those things are necessary to make stealth work and all of them are very difficult.
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Dec 4, 2016 20:51
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Hilarious Dreamliner bug, you might lose all three flight control computers if they've been powered on for 22 days. http://www.seattletimes.com/business/boeing-aerospace/faa-orders-787-safety-fix-reboot-power-once-in-a-while/
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Dec 4, 2016 22:28
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I'm amazed they had a plane up for that amount of time. https://www.youtube.com/watch?v=APX_uXXQvCc
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Dec 4, 2016 22:52
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Ola posted:Hilarious Dreamliner bug, you might lose all three flight control computers if they've been powered on for 22 days. Yeah they've always been like that, and it's never really been a problem, but someone leaked it to the media and now they need to be seen to be doing something so an AD has come out. The Embraer has a similar thing with the flight control pbit (power on bit (built in test) expiring if the computers have been powered for more than something like 50 hours. It's a complete non-issue and it will just be just rolled into the routine checks to reset the FCMs and run the bit. Finger Prince fucked around with this message at 23:26 on Dec 4, 2016 |
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Dec 4, 2016 23:22
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Finger Prince posted:Yeah they've always been like that, and it's never really been a problem, but someone leaked it to the media and now they need to be seen to be doing something so an AD has come out. The Embraer has a similar thing with the flight control pbit (power on bit (built in test) expiring if the computers have been powered for more than something like 50 hours. It's a complete non-issue and it will just be just rolled into the routine checks to reset the FCMs and run the bit. I even remember seeing reporting about this a year or so ago. poo poo, it might even still be in this thread.
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Dec 4, 2016 23:41
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The workaround isn’t that bad but why are they unable to design a system that Just Works?
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Dec 4, 2016 23:49
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Platystemon posted:The workaround isn’t that bad but why are they unable to design a system that Just Works? When you're given standards and specifications to develop against it turns out you never bother to see what happens if they are exceeded. This attitude is one of the biggest contributors to information security problems and other dumb things that happen in technology.
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Dec 4, 2016 23:58
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Midjack posted:When you're given standards and specifications to develop against it turns out you never bother to see what happens if they are exceeded. This attitude is one of the biggest contributors to information security problems and other dumb things that happen in technology. This is not true. Domain testing (what happens if the values are outside norms, what happens if theyre right at the boundaries) is systems engineering/V&V 101. Whether they hosed it up or not I can't say as I don't know what those specs and requirements were. If the users said "Yea planes are always turned off after a week" and you tested leaving it on for 3x that, can you be blamed for this emergent behavior? (Yes is the answer but its still an understandable mistake) EDIT: I didn't look up the AD but since we haven't heard anything about safety events, it was probably found on the Boeing/subcontractors test bench. CarForumPoster fucked around with this message at 00:48 on Dec 5, 2016 |
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Dec 5, 2016 00:40
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CarForumPoster posted:This is not true. Domain testing (what happens if the values are outside norms, what happens if theyre right at the boundaries) is systems engineering/V&V 101. Whether they hosed it up or not I can't say as I don't know what those specs and requirements were. If the users said "Yea planes are always turned off after a week" and you tested leaving it on for 3x that, can you be blamed for this emergent behavior? (Yes is the answer but its still an understandable mistake) The question is whether it's "the planes are always turned off after a week" or if there is an absolute maximum electronics on time rating. If the latter, this is the same as finding out the wing breaks under 250% rated load. No poo poo?
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Dec 5, 2016 00:48
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hobbesmaster posted:The question is whether it's "the planes are always turned off after a week" or if there is an absolute maximum electronics on time rating. If the latter, this is the same as finding out the wing breaks under 250% rated load. No poo poo? Yea this is a good point, there are probably relevant system level requirements too "turn the plane off every XXXX days" aka the Patriot Missile Lesson
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Dec 5, 2016 00:49
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Finger Prince posted:Yeah they've always been like that, and it's never really been a problem, but Same with shuttle SRB O-ring blowby and debris strikes on the TPS.
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Dec 5, 2016 01:07
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Cocoa Crispies posted:I even remember seeing reporting about this a year or so ago. poo poo, it might even still be in this thread. Turns out I was thinking of a different computer issue that required periodic reboots of your 787. bull3964 posted:Remember to reboot your 787 daily!
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Dec 5, 2016 01:10
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vessbot posted:Same with shuttle SRB O-ring blowby and debris strikes on the TPS. It's more like everyone who operates the plane knows about it, because Boeing tells you about it, and nobody operates in a way that would exceed that limit, and if they did they'd get fair warning about it. And then someone independent of the whole thing said "yeah but what if..." The incorrect response to it is "there is no what if". The correct response is "... Ahh, well, everyone, make sure to reboot your computers by this date please thanks" which is what Boeing did. And all the operators go "seriously?... Fine." Like it's honestly No Big Deal. It's like if Tesla said your car wouldn't start if you didn't plug it in at least once a month, even if the battery wasn't flat. When would this ever happen in practice? Never. But someone said, well, what if you hypothetically started driving on day 29 and 23:50, and 10 minutes later, would the car turn off? Except it's aviation. There's no room for "well, technically" or "we've never actually even tried it". Just make sure you plug it in once a month. By federal mandate. You will be fined or worse if you don't comply.
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Dec 5, 2016 03:00
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Cocoa Crispies posted:Turns out I was thinking of a different computer issue that required periodic reboots of your 787. Haha, 248 * 24 * 3600 = 21427200, so if it's counting something 100 times a second it overflows a 32-bit integer. Sure you can just reboot it once in a while, but I don't think there's any aeronautic engineering reason for not writing that bit of code better. It makes it look like a stupid airplane and you wonder what other else is lurking in there.
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Dec 5, 2016 07:12
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Ola posted:Haha, 248 * 24 * 3600 = 21427200, so if it's counting something 100 times a second it overflows a 32-bit integer. Sure you can just reboot it once in a while, but I don't think there's any aeronautic engineering reason for not writing that bit of code better. It makes it look like a stupid airplane and you wonder what other else is lurking in there. All the good coders are too busy making sure Candy Crush Star Wars thoroughly and effectively data mines your iPhone.
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Dec 5, 2016 12:16
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Ola posted:Haha, 248 * 24 * 3600 = 21427200, so if it's counting something 100 times a second it overflows a 32-bit integer. Sure you can just reboot it once in a while, but I don't think there's any aeronautic engineering reason for not writing that bit of code better. It makes it look like a stupid airplane and you wonder what other else is lurking in there. What else is lurking in there is an INCREDIBLY EXPENSIVE certification process to fix what should be a simple code change. If it had been caught earlier in the process, it doubtless would have been fixed, but changing flight-critical software after certification freeze can cost millions of dollars, and you don't do it if there is literally any other way to fix the issue.
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Dec 5, 2016 13:10
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Additionally, there may well be a fix in a block software upgrade down the road (which will do doubt introduce all sorts of new issues in the process of fixing all the existing ones). But you don't get little micro-patches and bug fixes rolled out like you do with commercial software when it comes to airplanes.
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Dec 5, 2016 14:31
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Ola posted:Haha, 248 * 24 * 3600 = 21427200, so if it's counting something 100 times a second it overflows a 32-bit integer. Sure you can just reboot it once in a while, but I don't think there's any aeronautic engineering reason for not writing that bit of code better. It makes it look like a stupid airplane and you wonder what other else is lurking in there. Welcome to embedded software?
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Dec 5, 2016 14:40
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Ola posted:Haha, 248 * 24 * 3600 = 21427200, so if it's counting something 100 times a second it overflows a 32-bit integer. Sure you can just reboot it once in a while, but I don't think there's any aeronautic engineering reason for not writing that bit of code better. It makes it look like a stupid airplane and you wonder what other else is lurking in there. No. There is almost certainly a requirement that the GCU be able to operate nominally while powered on for X days. The coder met the requirement and probably exceeded it by two orders of magnitude( at a guess). If you want to levy the requirement on the system that it shall be able to operate nominally when powered on indefinitely you can probably ad a bunch of zeros to the cost. This is almost certainly a case of where a counter roll over is being read by lots of other systems that are built concurrently by other parties and you have to draw the line somewhere. e: The 'shall operate for X days while powered on' is a common requirement and is almost always specifically used to make sure counters don't roll over during the expected period of operation which is generally much larger than the actual use case being considered. I've seen it in at least half a dozen different systems. Murgos fucked around with this message at 15:50 on Dec 5, 2016 |
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Dec 5, 2016 15:47
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How likely is it that a plane wouldn't be shut down once for over 248 days? It seems like a lot of time. I don't think aircraft have a requirement for contiguous uptime measured in years. I'm not sure even boats have.
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Dec 5, 2016 16:15
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A simple restart which takes between 1-10 mins also solves all your problems. And most airplanes are doing restarts to clear error messages thru the day.
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Dec 5, 2016 16:25
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Cat Mattress posted:How likely is it that a plane wouldn't be shut down once for over 248 days? It seems like a lot of time. I don't think aircraft have a requirement for contiguous uptime measured in years. I'm not sure even boats have. It would have to be deliberate, and you probably wouldn't be flying it anywhere.
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Dec 5, 2016 16:27
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Greataval posted:A simple restart which takes between 1-10 mins also solves all your problems. So does carrying enough fuel to actually get to your destination, but 
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Dec 5, 2016 16:57
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Godholio posted:So does carrying enough fuel to actually get to your destination, but Brutal
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Dec 5, 2016 17:38
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