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Godholio posted:It probably doesn't. Given that I know basically zero about the details of radar, what would be the resolution error for a low-ish frequency radar (say the L-Band from the Nebo-M system)?
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Nov 23, 2016 06:20
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Ukranian Flanker pilots doing dumb poo poo at airshows? What could possibly go wrong? https://www.youtube.com/watch?v=PPtYo7pYUyY
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Nov 23, 2016 06:57
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Alaan posted:My brother is an electrical engineer and worked at a company that made a bunch of radio components for both Motorola and airlines and stuff, most of it being made in China. Part of his job was going to the Chinese factories when the gently caress up rate got too high and see what the hell was up. He said the usual trip consisted of him going, tell them what was wrong, a lot of bobbing heads, and then nothing actually getting changed as they kept using a crap component or something. Used to work in the semiconductor industry and this is pretty true. You'd go out there, visit your contract manufacturer, go over the specs and they'd do a run with all your specified components. As soon as you left, they'd start swapping in the cheapest "equivalents" they could find.
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Nov 23, 2016 07:08
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Sperglord posted:Back to missile guidance for a second, I have wondered on and off if the following is a solution to the anti-stealth SAM problem: The field of regard and resolution of any reasonable missile seeker is insufficent to conduct a search of that large a volume and prosecute an attack during the ToF available in the terminal phase of the intercept. LF radar antennas tend to be large, power thirsty affairs, indicating fixed installations or at best limiting mobility. Large fixed targets are not the future of air defense. The solution to bridging the gap between long range early warning radar and a missile seeker is called "a manned interceptor with onboard radar."
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Nov 23, 2016 07:54
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Captain von Trapp posted:The actual answer is probably South America, fwiw. In a full scale nuclear exchange, even countries like Australia, Brazil, or New Zealand could catch a few warheads during a secondary or tertiary phase of exchange simply to present them with hardships. All three of these example countries could offer shelter and partial replenishment to naval vessels or expeditionary forces in transit. A few detonations would foster a national crisis, reducing their ability, incentive, and/or openness to render aid or shelter to allies for fear of further reprisal or giving up valuable commodities and resources desperately needed by their own people. Basically any city in a country friendly to the United States with a deep water port, and especially those with very large ship maintenance and repair capabilities is going to eat a nuke at some phase regardless of their standing if poo poo really goes wrong.
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Nov 23, 2016 07:56
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Alaan posted:My brother is an electrical engineer and worked at a company that made a bunch of radio components for both Motorola and airlines and stuff, most of it being made in China. Part of his job was going to the Chinese factories when the gently caress up rate got too high and see what the hell was up. He said the usual trip consisted of him going, tell them what was wrong, a lot of bobbing heads, and then nothing actually getting changed as they kept using a crap component or something. The Chinese firms habit of subcontracting to the nth degree is definitely the heart of the problem (also probably an overeliance on IP theft which was the cause of the cap failures in the early aughts); the US military system of tracking parts is something that would be very hard to emulate by the PLAAF. Hell, just look at the B-2 parts scandals of the late 80s, the Chinese might not notice a problem of that magnitude until another couple J-20s fall out of the air.
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Nov 23, 2016 12:17
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I'm loathe to criticise Chinese engineering too much when right now they can put people into space and we can't.
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Nov 23, 2016 13:10
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That Works posted:I'm loathe to criticise Chinese engineering too much when right now they can put people into space and we can't. Not having a currently qualified manned launch platform due to political reasons has pretty much nothing to do with engineering capability.
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Nov 23, 2016 14:22
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Murgos posted:Not having a currently qualified manned launch platform due to political reasons has pretty much nothing to do with engineering capability. Other than to highlight their engineering capability can be quite good. I've worked with / currently work with a lot of Chinese scientists and I feel like making a blanket statement about their skills and/or training is shortsighted.
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Nov 23, 2016 14:30
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Sperglord posted:Given that I know basically zero about the details of radar, what would be the resolution error for a low-ish frequency radar (say the L-Band from the Nebo-M system)? That depends on things other than just the frequency. Like really notably, the aperture. How wide an antenna can you fit into a AAM body? Answer: not very.
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Nov 23, 2016 16:04
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Sperglord posted:Given that I know basically zero about the details of radar, what would be the resolution error for a low-ish frequency radar (say the L-Band from the Nebo-M system)? This is one of those questions that is a constant area of research in the military and specific enough no one will answer it. That Works posted:Other than to highlight their engineering capability can be quite good. I don't think we're criticizing the intelligence of any of the engineers or the Chinese in general. You do have three people working for three different companies saying they had the exact same experience though. There's an undeniable culture I'm calling the "cheapest ingredients" mentality and in electronics and aerospace manufacturing that causes tremendous problems largely related to part and process control. It's not the engineering itself that is bad, necessarily.
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Nov 23, 2016 16:07
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That Works posted:I'm loathe to criticise Chinese engineering too much when right now they can put people into space and we can't. Something something space race something missile gap something lagging behind the Soviets something something Mayak something Nedelin.
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Nov 23, 2016 16:13
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Murgos posted:Not having a currently qualified manned launch platform due to political reasons has pretty much nothing to do with engineering capability. Yes, the fact that China's government is diverting more of its resources toward prestige projects of questionable economic value doesn't mitigate the fact that we are many times wealthier than they are.
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Nov 23, 2016 17:13
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I think there is a big difference between the Chinese commercial engineering world where "cheap is best" vs what the Chinese military and government engineering companies. The military can spend more and demand better quality so I don't think using Chinese OEMs that service the commercial market is a good benchmark. It probably doesnt cover the full gap in capabilities but I don't think we can just say that these engineers that work in the military companies and government agencies behave the same as a OEM electronics company and have the same resource and low quality bar constraints.
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Nov 23, 2016 17:22
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Sperglord posted:Given that I know basically zero about the details of radar, what would be the resolution error for a low-ish frequency radar (say the L-Band from the Nebo-M system)? 
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Nov 23, 2016 17:37
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China has most of, if not all of the top 10 supercomputers in the world. That is, the ones we know about 
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Nov 23, 2016 17:38
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CarForumPoster posted:This is one of those questions that is a constant area of research in the military and specific enough no one will answer it. You know, in retrospect, that was a really stupid question. I'm sorry. (As I said, I really know nothing about physics / design of radars. Not even where interesting questions end and sensitive questions begin.) Ok, let me rephrase: many people say that low-frequency radar cannot get sufficient accuracy for a missile seeker-head basket. That is presented as a fact, without supporting evidence based upon radar physics / weapon seeker physics. Is this an actual physical fact or a limitation of current technology / sensor processing / etc?
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Nov 23, 2016 18:02
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In the Chinar thread they pointed out that all these "supercomputers" are just rebadged data centers. Also, raw calcs per second is not the ultimate grade of SC function. Also for Mil-Spec parts being better, the Type-98 in this year's tank Biathlon broke a roadwheel suspension arm.
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Nov 23, 2016 18:06
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Sperglord posted:You know, in retrospect, that was a really stupid question. I'm sorry. (As I said, I really know nothing about physics / design of radars. Not even where interesting questions end and sensitive questions begin.) Passive sonar frequency sensitivity is very dependent on the size of the array. In ham radio, you can get by with an 8" antenna for 2m but you'll have to string about 80 feet of wire to use 160m. Both are because of the wavelength of the different frequencies. I presume the limitations are similar for radar. e: strictly speaking, I don't know if it's the wavelength, but low frequency transmitters/receivers generally need bigger antennas/sensors. hogmartin fucked around with this message at 18:17 on Nov 23, 2016 |
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Nov 23, 2016 18:12
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Chinese engineers are fine, it's the corporate culture that will screw you. Culture is by its nature pervasive, and with something complex and interlocking like aerospace supply chains it only takes one guy in one office deciding he's going to "outsmart" the system for something to go wrong. So in a culture where duplicity is considered just part of the business day and practices like quality fade are common, it must be a constant uphill battle to keep your supply chain safe. Even if you've got a head office full of superb people who have a culture of excellence themselves.
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Nov 23, 2016 18:23
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Sperglord posted:You know, in retrospect, that was a really stupid question. I'm sorry. (As I said, I really know nothing about physics / design of radars. Not even where interesting questions end and sensitive questions begin.) Basically, the higher the frequency, the more accurate the data. Higher frequency radars focus a narrower beam and have fewer spurious returns. I've forgotten half the physics I ever learned on this, but it's all out there if you really want to read it. Buthis is why fighters use much higher frequencies than search radars...you need the higher fidelity to actually guide a missile close enough. And the further out you go, your beamwidth (resolution cell) gets larger. So for a truly long-distance target, your radar has to be a tight beam to get any kind of fidelity. And that's just not how low-freq radars work. It's a lot easier to narrow that beam with a larger antenna...which is where a missile is hampered severely. And that is why you need drat good guidance supporting that missile until it's close enough that it can find the target with it's soda-straw radar beam. The larger the search volume (and at 300km it's loving huge) the harder it is for it to find the target...and then you've got the speed and battery life to factor in.
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Nov 23, 2016 18:45
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Sperglord posted:You know, in retrospect, that was a really stupid question. I'm sorry. (As I said, I really know nothing about physics / design of radars. Not even where interesting questions end and sensitive questions begin.) FY2005 - Defense Advanced Research Projects Agency posted:The Wide Area All Terrain Change Indication Technologies (WATCH-IT) initiative is developing real-time VHF/UHF synthetic aperture In 2005 DARPA thought they could build a 3D model of a vehicle from a UAV using UHF/VHF. Keep in mind ground clutter is likely the biggest issue with this frequency band. No idea what became of this program but it along with ~5 other related programs got $32 million in funding so I'd hazard a guess it isn't totally ridiculous. EDIT: Just noticed you said seeker head. I'm guessing the answer is no WRT the seeker head due to size/weight/power limitations. YOu need a decently sized platform to support the radar and processing. CarForumPoster fucked around with this message at 19:18 on Nov 23, 2016 |
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Nov 23, 2016 19:12
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CarForumPoster posted:In 2005 DARPA thought they could build a 3D model of a vehicle from a UAV using UHF/VHF. Keep in mind ground clutter is likely the biggest issue with this frequency band. No idea what became of this program but it along with ~5 other related programs got $32 million in funding so I'd hazard a guess it isn't totally ridiculous. That's SAR, though, which fundamentally depends on the radar moving quickly and in a known way relative to the target. This works great for airplanes and satellites imaging the ground, but it's not effective for search and track against an adversary in a fast-moving aircraft who's actively looking for ways to mess with your radar signal.
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Nov 23, 2016 19:48
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Gervasius posted:Ukranian Flanker pilots doing dumb poo poo at airshows? What could possibly go wrong?  jfc that dude who dived under the wing probably blew a hole in his pants.
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Nov 23, 2016 19:50
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Space Gopher posted:That's SAR, though, which fundamentally depends on the radar moving quickly and in a known way relative to the target. This works great for airplanes and satellites imaging the ground, but it's not effective for search and track against an adversary in a fast-moving aircraft who's actively looking for ways to mess with your radar signal. This is not my area of expertise but...the J-20 and PAK-FA are probably obsolete if you can get a UHF/VHF radar to make fire control quality tracks against airborne targets. The only planes that wouldn't be would have to be quite large. It is not impossible to do this in theory. This will likely not be achieved with a seeker head but it doesn't need to be if you've got a working datalink and an FC quality track or generally better than whats thought of for scan/surveillance radars. The terminal phase can then be with any of the existing technologies in seeker heads. CarForumPoster fucked around with this message at 20:16 on Nov 23, 2016 |
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Nov 23, 2016 20:08
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For those who might be interested, ultimate modern milsperg game Command Modern Naval/Operations is not only now on Steam, but is 65% off it's usual ludicrous price.
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Nov 23, 2016 20:31
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Cyrano4747 posted:
Dude's a pussy https://www.youtube.com/watch?v=VC0AW7G50NA
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Nov 23, 2016 21:37
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Sperglord posted:
It's not so much the frequency that's directly relevant here. Again, what you are really neglecting is *aperture*. Aperture goes in large part to determining both gain and resolution, and you are limited to how wide an aperture you can have by more-or-less the diameter of the missile body. Gain = 4*pi*aperture/wavelength^2 Low-frequency = high-wavelength. So for a given size antenna, like what you can fit into a missile, if you use a low-frequency beam then your wavelength is big and your wavelength^2 is really big so your gain sucks so you're not getting a return unless you get closer. That's why when you're trying to hit something with a missile, you use high-frequency radars so that you maximize the gain of your relatively tiny antenna.
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Nov 23, 2016 21:50
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Arglebargle III posted:Chinese engineers are fine, it's the corporate culture that will screw you. Culture is by its nature pervasive, and with something complex and interlocking like aerospace supply chains it only takes one guy in one office deciding he's going to "outsmart" the system for something to go wrong. So in a culture where duplicity is considered just part of the business day and practices like quality fade are common, it must be a constant uphill battle to keep your supply chain safe. Even if you've got a head office full of superb people who have a culture of excellence themselves. The corporate culture probably is a big issue, but when it comes to military supplies I would think they have an effective counter measure, the execution squad. Trying to scam foreign companies with cheaper parts is obvious tactic, because what are they gonna do, find a more expensive manufacturer? But trying the same with military sounds like an easy way for the CEO to receive corruption charges and a personal execution squad. I doubt they would have to kill that many before the supply chain got the hint.
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Nov 23, 2016 22:56
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Saukkis posted:The corporate culture probably is a big issue, but when it comes to military supplies I would think they have an effective counter measure, the execution squad. I'd be very surprised to learn that the supply chain is tightly controlled in the Chinese military. It is a tremendous effort here where we do have the "culture of quality" as American companies like to say. As someone above me mentioned, subbing to your subs subcontractors is very common there. To have each link in the chain be from a qualified manufacturer, especially when it comes time to buy spares of obsolete components, yea good luck. ...even worse when the OEM is a now defunct Russian/American/Israeli company.
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Nov 23, 2016 23:01
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Sperglord posted:Ok, let me rephrase: many people say that low-frequency radar cannot get sufficient accuracy for a missile seeker-head basket. That is presented as a fact, without supporting evidence based upon radar physics / weapon seeker physics. Is this an actual physical fact or a limitation of current technology / sensor processing / etc? There's a pretty large body of open civil/academic/industry radar research that's not sensitive about this kind of thing. Basically the shorter the wavelength, the narrower the beam. The wider the aperture, the narrower the beam. Finding the direction of the peak return is therefore more or less a function of the beam width at the target, the signal to noise ratio coming off of the target, and terms involving how clever your signal processing is. Now, the size of that reflected signal coming from targets that try very very hard not to reflect a signal is the sensitive bit for the most part. That's what makes your question difficult, not so much the radar physics itself.
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Nov 24, 2016 00:03
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Saukkis posted:The corporate culture probably is a big issue, but when it comes to military supplies I would think they have an effective counter measure, the execution squad. You might think that the Chinese military is a bastion of integrity. You'd be wrong though.
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Nov 24, 2016 00:11
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CarForumPoster posted:I'd be very surprised to learn that the supply chain is tightly controlled in the Chinese military. It's not at all, if you think the bull that US Airforce, Army, Navy, and Marines pull against one another is cringe worth, you would not believe the kind rear end in a top hat power plays that happen within the Chinese military on a micro level as Generals sabotage other Generals, Majors screw with other Majors, and so forth.
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Nov 24, 2016 01:01
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david_a posted:Speaking of giant-rear end missiles, here's the ASM-135 ASAT that I found at the AF Museum: I never suspected that the Air Force had Farscape One mothballed in a hangar.
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Nov 24, 2016 02:41
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Preechr posted:I never suspected that the Air Force had Farscape One mothballed in a hangar. I swear you have to go to this place like a minimum of three times before you even notice half the stuff. See that big green thing next to the XB-70? That's a HEXAGON KH-9, the last and most badass film-based spy satellite the US used. Amazing in its own right, but I didn't pay any notice to it until my third trip because it used to be wedged between a B-36 and RB-47 and there was a model atomic bomb close by and omigosh look at that B-58 over there   Anyway, the "Big Bird's" camera could take stereo pictures with a maximum resolution of 0.6 meters. The KH-9 had four enormous film pods that it would detach and let fall back to earth, where something like a Flying Boxcar would snatch it in midair(!) david_a fucked around with this message at 05:05 on Nov 24, 2016 |
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Nov 24, 2016 04:59
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david_a posted:Anyway, the "Big Bird's" camera could take stereo pictures with a maximum resolution of 0.6 meters. The KH-9 had four enormous film pods that it would detach and let fall back to earth, where something like a Flying Boxcar would snatch it in midair(!) That reminds me: How did they de-orbit the film canisters when they were ejected? Retro-burn/eject/pro-burn the satellite seems... too kerbal
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Nov 24, 2016 10:37
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Here is some Russian Air/Ground power photos that I took this year at Army 2016. http://imgur.com/a/jRtTe Xerxes17 fucked around with this message at 11:54 on Nov 24, 2016 |
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Nov 24, 2016 11:49
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I went with my elderly Dad (flew jets in the 60s for the Air Force) to visit the Museum of Flight in Seattle and just ended up numbed by it all All my favorite planes crammed close together. Too much to take in on one visit.
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Nov 24, 2016 12:19
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I would never normally tell anyone to go to Florida but Eglin Airforce base has an amazing air museum. Pensacola Navy base also has an outstanding air museum so at least you could do a 2 for 1 trip.
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Nov 24, 2016 14:18
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Captain Postal posted:That reminds me: How did they de-orbit the film canisters when they were ejected? Retro-burn/eject/pro-burn the satellite seems... too kerbal
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Nov 24, 2016 14:22
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