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PostPosted: Mon Jul 10, 2017 2:01 pm 
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Corolinth wrote:
1800 miles is seven times the orbital distance of the international space station. While I suppose it's possible, that number is highly suspect.

I need a more credible source than either RD's or DE's say-so.


This.

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PostPosted: Mon Jul 10, 2017 2:31 pm 
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everything i'm seeing says 1500 to 1700 miles.


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PostPosted: Mon Jul 10, 2017 2:49 pm 
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Arathain Kelvar wrote:
everything i'm seeing says 1500 to 1700 miles.


Up, or range?

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PostPosted: Mon Jul 10, 2017 3:28 pm 
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Up; the range estimates are around 4-5k from what I've seen in most places. I'd provide links, but it's easy enough to Google as pretty much every report has the same basic info. Normal ICBM altitudes are apparently more like 750 miles or so, with "hortizontal" ranges of 6000 miles or more (for land-based missiles), at least according to Wikipedia: Ballistic Missile Flight Phases


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PostPosted: Mon Jul 10, 2017 3:50 pm 
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Yeah, that's why this height estimate seems so strange.

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PostPosted: Mon Jul 10, 2017 4:51 pm 
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NephyrS wrote:
Arathain Kelvar wrote:
everything i'm seeing says 1500 to 1700 miles.


Up, or range?


vertical.


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PostPosted: Mon Jul 10, 2017 9:08 pm 
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https://www.nytimes.com/2017/07/04/worl ... -icbm.html

So they're getting 1700 miles by calculation based on taking 37 minutes to fly 578 miles. This proposes a 71.22° firing angle. To say that's odd is an overstatement. Then I thought, who the **** are the Union of Concerned Scientists, and why haven't I ever heard of them before? A quick glance at their page digs up three main areas of focus:

1) Climate Change
2) Food and Environment
3) Nuclear Weapon Policy

Now, #3 sounds like they're some experts on ICBMs, until I consider that in light of the first two points, nuclear weapon policy could mean activism about how nuclear weapons are bad for life rather than expertise in how missiles work. To be sure, a nonprofit founded by MIT students is likely to be full of intelligent people, but they're experts in scientific fields unrelated to missile flight. These are not aerospace engineers, they're nuclear disarmament activists.

Hey, I get emails from Raytheon's HR department, too! Guess I'm an expert.

I did some math based on a simple projectile equation problem, and I came up with just under 25,000mph for the initial upward speed. For reference, Earth's escape velocity is 25,020 mph. This is probably not out of the question for an actual ICBM, but I'm making some implicit assumptions about North Korea's technological capabilities. Then I realized that we're talking about a height that is seven times the orbital height of the ISS, as well as 43% of Earth's mean radius. At this height, gravitational acceleration is only 49% of it's value on the surface of the Earth. I should probably adjust my equation to account for Earth's changing gravitational pull. If I recalculate based on an average of 75% of Earth's gravitational acceleration for the entire vertical distance, I come up with about 18,000mph. I'm still neglecting wind resistance, but that's only relevant for about 30 miles.

That's pretty goddamn fast. Also, I'm assuming that North Korea has the capacity to build an ICBM in order to prove they can build an ICBM. That isn't very good science. It's possible they do, but I should examine the problem from another angle.

A quick calculation based on its horizontal distance yields roughly 940mph along the surface of the Earth. That's a little bit above the speed of sound. If we assume a 45° firing angle, that puts its total speed at around Mach 2.

These two velocities are way out of proportion with one another. Now, I have to consider that this isn't a simple projectile motion problem, and that the missile could be experiencing some amount of upward thrust throughout its flight path. As I'm not a rocket scientist, I'll have to defer to one regarding the mechanics of flight as soon as one presents him or herself. In the meantime, as airplanes manage to maintain some sort of upward force opposing Earth's gravity, I am going to assume this is plausible for a missile as well.

Obviously, the missile doesn't instantaneously accelerate to either speed upon launch. This isn't like throwing a rock. It's going to maintain some speed throughout most of its flight, until it runs out of fuel and crashes.

I'm asked to accept one of two propositions.

1) North Korea is able to launch objects into medium Earth orbit.
2) North Korea has a missile that's somewhat slower than an F-15.

Of those two, one of them doesn't involve assuming some absolutely ludicrous flight path, and that every missile is going to miraculously avoid burning up in re-entry after running out of fuel.

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PostPosted: Tue Jul 11, 2017 9:46 am 
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Corolinth wrote:
I'm asked to accept one of two propositions.

1) North Korea is able to launch objects into medium Earth orbit.
2) North Korea has a missile that's somewhat slower than an F-15.

Of those two, one of them doesn't involve assuming some absolutely ludicrous flight path, and that every missile is going to miraculously avoid burning up in re-entry after running out of fuel.

Actually, there's a third proposition you could accept:

3) You have neither the information nor the expertise to independently evaluate the capabilities of a North Korean missile launch, so given that the governments and organizations that do have that information and expertise all seem to agree that this was a steep-angle launch of a missile with a potential range of 4-5k miles, that's probably the case, notwithstanding your back of the envelope math.

Seriously, I don't get the skepticism on this. All the major news organizations are reporting the same thing, and none of the governments with an interest in the situation (even those with very different interests) are contradicting those reports. If reputable organizations or governments start contradicting or questioning the current estimates, then fine, uncertainty will be warranted. Until then, back of the envelope internet speculation is just silly.


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PostPosted: Tue Jul 11, 2017 10:17 am 
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For one, because a 71.25 angle is ludicrous. It doesn't prove something can be launched a longer distance at a lower angle, because the time spent during re-entry is a lot greater, which puts a lot more stress on the nose cone.

Just because a "lot" of news sources are reporting something with no good citations doesn't mean it makes sense.

For some more detailed math, and a discussion of payload weights, see here:

http://breakingdefense.com/2017/07/this ... n-missile/

Just because it makes a good scare to say "it's got a huge range" doesn't mean that actually translates. Rocket science is not just simple trajectory calculations.

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PostPosted: Tue Jul 11, 2017 11:44 am 
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When I say I'm not a rocket scientist, that means something very different than when other people say it.

So far, the only citation I have seen for the 1700 mile altitude is from some organization I've never heard of that focuses on climate and the environment. Their expertise on this matter is no better than mine, and likely worse. That number appears to be calculated by applying simple projectile motion equations, as the kind I started my analysis with. That altitude, as I have indicated previously, is ridiculous for several reasons. When you find that you've predicted a missile launch to an altitude where gravity is half its value on the surface, the responsible thing to do is double check that you haven't made a mistake in either your calculations or your base assumptions - which is what I did in my second step.

Other things to consider is that the mechanics of flight change past about 100 miles (actually, lower, but we'll be conservative). The Earth's atmosphere thins to practically a vacuum, and so there is no air resistance, hence fins and wings do not appreciably alter the flight path. This means the missile does not turn around and come back, so much as simply fall back to Earth.

The evidence I have points to a number thrown out by an alarmist nuclear disarmament activist group. News outlets took it and ran with it so they could scoop one another. Until I see the 1700 mile altitude backed up by a more credible source, perhaps Boeing or NASA, I'm sticking with my original assessment.

It's bullshit.

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PostPosted: Tue Jul 11, 2017 12:34 pm 
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*sigh* It's really amazing how stupid smart people can be sometimes. Arrogance is an impressive thing.

For the record - yes, it's entirely possible that further information or analysis will indicate that the initial range estimates are wrong. The point, however, is that so far, all indications are that it has a range that puts it in the ballpark of "ICBM" status, and the US, Japan and SK governments have all reacted in ways that are fully consistent with that evaluation - the US didn't call for an emergency UN Security Council meeting for shits and giggles - so this kneejerk instinct to substitute your own back-of-the-envelope calculations for what the experts are saying is just arrogance masquerading as intelligence.


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PostPosted: Tue Jul 11, 2017 1:16 pm 
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Why is a 71.22° firing angle so unbelievable? If you want to test an ICBM, it's probably better to keep it close to you and not send it halfway around the world where it could piss off some other country. And 1800 miles isn't that high. That's less than 10% of the distance to a geosynchronous satellite. Your point about it being 7x as high as the ISS just highlights how close the ISS is.

Also, it's hard to trust someone's back of the envelope calculations when they assume a rocket is fired like a bullet. It's not THAT hard to account for a rocket's thrust. It doesn't need to travel anywhere near 18,000 mph to achieve that kind of flight path. You're probably better off trying to recreate the launch in Kerbal Space Program.


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PostPosted: Tue Jul 11, 2017 1:53 pm 
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If you're not willing to trust a back-of-the-envelope calculation, than it appears we are in agreement that a 1700 mile altitude is bullshit.

Alternatively, you did not read and/or can't understand anything else I posted about why that altitude is suspect. I'm going with the former, as you've mentioned several points that I directly called out. I'm not ruling out the latter, as a general rule.

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PostPosted: Tue Jul 11, 2017 2:22 pm 
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RangerDave wrote:
*sigh* It's really amazing how stupid smart people can be sometimes. Arrogance is an impressive thing.

For the record - yes, it's entirely possible that further information or analysis will indicate that the initial range estimates are wrong. The point, however, is that so far, all indications are that it has a range that puts it in the ballpark of "ICBM" status, and the US, Japan and SK governments have all reacted in ways that are fully consistent with that evaluation - the US didn't call for an emergency UN Security Council meeting for shits and giggles - so this kneejerk instinct to substitute your own back-of-the-envelope calculations for what the experts are saying is just arrogance masquerading as intelligence.


Actually, my point was that so far there have been almost no experts commenting. And the people who are, are skeptical. In fact, I point you to comments in the article I linked by

You're extrapolating (a) news articles, and (b) government responses to say that something is accurate, but that's far from having "experts" saying that this range is valid and how they came to it.

I also point you to comments from "experts" in this AP article: http://www.wral.com/analysis-despite-te ... /16803960/ that see more skeptical of claims.

With all the discussions we've had over the years with respect to the reliability of news reporting, I'm really shocked you're standing up for a single number with no good source that's just been echoed over and over. It may well turn out to be correct, but I think it's silly to take it at face value.

As for our government taking it seriously? They would have to. Also, there's a large benefit to some elements of our government to have a dangerous enemy to unify against, and making the threat seem more rather than less serious does that.

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PostPosted: Tue Jul 11, 2017 2:27 pm 
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Amanar wrote:
Why is a 71.22° firing angle so unbelievable? If you want to test an ICBM, it's probably better to keep it close to you and not send it halfway around the world where it could piss off some other country. And 1800 miles isn't that high. That's less than 10% of the distance to a geosynchronous satellite. Your point about it being 7x as high as the ISS just highlights how close the ISS is.

Also, it's hard to trust someone's back of the envelope calculations when they assume a rocket is fired like a bullet. It's not THAT hard to account for a rocket's thrust. It doesn't need to travel anywhere near 18,000 mph to achieve that kind of flight path. You're probably better off trying to recreate the launch in Kerbal Space Program.


Coro's back of the envelope calculations aren't actually that bad when you look at how ICBM flight is actually calculated:

http://www2.mae.ufl.edu/~uhk/ICBM.pdf

Moreover, a 71.22° firing angle is.... unusual. For the tables compiled from Rand for ARPA (in pre-darpa days) (https://www.rand.org/content/dam/rand/p ... RM3475.pdf), specifically designed for missile defense, you can look through trajectories and find that angles above 60° aren't even considered. Sure, as you point out, it's what you do if you want it to be close, but it's still odd in the context of "rocket science".

Not impossible, just unusual. And not something that translates quite as directly to range comparisons as people are making it seem.

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PostPosted: Tue Jul 11, 2017 6:07 pm 
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Corolinth wrote:
I did some math based on a simple projectile equation problem, and I came up with just under 25,000mph for the initial upward speed. For reference, Earth's escape velocity is 25,020 mph. This is probably not out of the question for an actual ICBM, but I'm making some implicit assumptions about North Korea's technological capabilities. Then I realized that we're talking about a height that is seven times the orbital height of the ISS, as well as 43% of Earth's mean radius. At this height, gravitational acceleration is only 49% of it's value on the surface of the Earth. I should probably adjust my equation to account for Earth's changing gravitational pull. If I recalculate based on an average of 75% of Earth's gravitational acceleration for the entire vertical distance, I come up with about 18,000mph. I'm still neglecting wind resistance, but that's only relevant for about 30 miles.

That's pretty goddamn fast.


It's not a projectile. It's a two-stage rocket. You're adding energy to the system for a large portion of the upward trajectory. You don't need to have as high a velocity if you're still adding thrust.

*edit: never mind, already brought up.


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PostPosted: Tue Jul 11, 2017 8:51 pm 
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NephyrS wrote:
You're extrapolating (a) news articles, and (b) government responses to say that something is accurate, but that's far from having "experts" saying that this range is valid and how they came to it.

....With all the discussions we've had over the years with respect to the reliability of news reporting, I'm really shocked you're standing up for a single number with no good source that's just been echoed over and over. It may well turn out to be correct, but I think it's silly to take it at face value.

Well, unlike most people here, I actually do have a fairly high degree of confidence in mainstream Western news sources to get the core elements of major stories correct and to vet the qualifications of sources referred to as "experts", though I obviously recognize that early reports on breaking news often get refined and/or corrected over time. In this case, like I said, I'm entirely open to the possibility that further analysis and information will lead to a walking back of the initial estimates. What drives me nuts though - and what I admit just kind of got under my skin this time for some reason - is when internet know-it-alls act like their B.S. in whatever and general experience of being the smartest fish in their particular little pond somehow makes them qualified to evaluate and haughtily dismiss the reports as bullshit. I see it all the time here on subjects like economics and climate science, and now apparently rocket science as well. It just rubbed me the wrong way this time, I guess.


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PostPosted: Tue Jul 11, 2017 9:16 pm 
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Holy hell I'd hate to think of the SI of a"here you go you're on your own" even sub orbital launch.

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PostPosted: Tue Jul 11, 2017 9:53 pm 
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The math and analysis here is pretty good. We're getting some decent discussion.

First, the RAND study refers to re-entry angles, not launch angles and while very interesting, isn't relevant here.

Now, here is the underlying problem with all the above math - and it's not with the math itself.

The problem is that the missile A) flew the entire way; it did not fail prior to reaching its target and B) it flew under 600 miles and C) it was in the air 37 minutes.

This is why the 1800 mile altitude makes sense. It is absolutely true that normally an ICBM would not fly that high. However, one would not normally attack a target 600 or so miles away with an ICBM; that is a target for an SRBM or MRBM. The NKs already have those; it would not be a new development (provocative as it might be) to test one. Such missiles do not fly for 37 minutes though; they are supposed to reach their targets in under 15 minutes, possibly under 10, and do not fly anywhere near that high.

So, why would the Norks fire an ICBM in a really high altitude but low distance trajectory? What purpose would that serve?

Well, it's quite simple: They want to observe their own test. Firing one on a normal trajectory might appear to be an actual attack and...

Aside from that, it's a simple matter of the Earth's curvature. North Korea does not have a world-wide sensor establishment or an blue-water Navy to fully and properly observe an ICBM test across the Pacific as we do, and it's territory is not Russia's immense expanse where a missile can be fired from one end to the other.

By sending it up in a high arc and bringing it back down relatively close to home, it would be visible on radar for almost the entire, flight, yielding much better information. To use it in a more normal flight profile would be a simple matter of changing the trajectory. If it only went to a normal ICBM altitude it would obviously be able to fly much farther across the Earth's surface.

Also, ICBMs do not exactly have launch angles. They fire vertically and then roll and pitch onto their course, just like a spacecraft does. Observe; the missile pitches towards the target 3 seconds after launch and initiates roll 10 seconds following launch. Also, it is moving fairly slowly at first; it takes 62 seconds to fly the first 18 nautical miles out of thousands, but its total time of flight is only around 30 minutes:

https://www.youtube.com/watch?v=S-V6MZlyCqE

Note that the actual footage at the end is not of an armed warhead; such testing is obviously no longer done.

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PostPosted: Tue Jul 11, 2017 11:31 pm 
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RangerDave wrote:
NephyrS wrote:
You're extrapolating (a) news articles, and (b) government responses to say that something is accurate, but that's far from having "experts" saying that this range is valid and how they came to it.

....With all the discussions we've had over the years with respect to the reliability of news reporting, I'm really shocked you're standing up for a single number with no good source that's just been echoed over and over. It may well turn out to be correct, but I think it's silly to take it at face value.

Well, unlike most people here, I actually do have a fairly high degree of confidence in mainstream Western news sources to get the core elements of major stories correct and to vet the qualifications of sources referred to as "experts", though I obviously recognize that early reports on breaking news often get refined and/or corrected over time. In this case, like I said, I'm entirely open to the possibility that further analysis and information will lead to a walking back of the initial estimates. What drives me nuts though - and what I admit just kind of got under my skin this time for some reason - is when internet know-it-alls act like their B.S. in whatever and general experience of being the smartest fish in their particular little pond somehow makes them qualified to evaluate and haughtily dismiss the reports as bullshit. I see it all the time here on subjects like economics and climate science, and now apparently rocket science as well. It just rubbed me the wrong way this time, I guess.


I could be wrong, but I'm reasonably certain Coro is a lot closer to an expert than just a "BS in whatever". And I'm not claiming I'm an expert, but I feel like having a PhD in a physical science is a bit more than a "BS in whatever" as well. Certainly enough to look over the math and see when something looks reasonable or not.

DE, did you read the payload analysis article? As you mention, trajectories aren't simple arcs, and I feel like that analysis was a lot more thorough.

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PostPosted: Wed Jul 12, 2017 5:56 am 
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NephyrS wrote:
I could be wrong, but I'm reasonably certain Coro is a lot closer to an expert than just a "BS in whatever". And I'm not claiming I'm an expert, but I feel like having a PhD in a physical science is a bit more than a "BS in whatever" as well. Certainly enough to look over the math and see when something looks reasonable or not?

My comment wasn't really aimed at Coro specifically, though I confess his post was the immediate trigger for my irritation. It's just a common online phenomenon that drives me nuts and seems to be most prevalent among engineering and computer science types. I don't think having a PhD makes it reasonable either - it indicates a higher level of expertise in one's own field and probably a higher level of general intelligence and capability, but it doesn't indicate any increased knowledge of other fields. Now that I think about it, in fact, I see this particular know-it-all phenomenon from MDs all the time too. The number of Facebook rants I've seen from doctors I know going off about how "obvious" such and such a point about climate change is or how much of an idiot some Nobel Prize winning economist is, despite the fact that their own knowledge and training set has nothing whatsoever to do with those disciplines, simply amazes me. One of my closest friends is a doctor, and I swear it was all I could do to refrain from strangling him when he suddenly discovered his previously-untapped expertise in all aspects of economics and corporate finance when he got on board the Bernie bus in 2016 and started watching shitty anti-capitalist / anti-corporate "documentaries" on Netflix. I just think a lifetime of being smarter than most people and being treated like an expert in their particular field blinds people to the narrow limits of their knowledge and to the complexities of issues in other fields, so when they encounter a claim in some other field that doesn't jive with their own initial thoughts or preferences, their reaction is to dismiss and disdain that claim rather than to assume their own thoughts on the subject are likely mistaken. They're so used to being an expert in X that they forget they're just a layman in Y.


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I don't think you really have a good grasp of what doctoral training in the sciences is about if that's your perspective.

There's a reason you can't get more than one doctorate in very broad swaths of fields, and that's because you are expected to be able to rapidly teach yourself what you need.

Knowing how to analyze data is a rather generally applicable thing.

The bigger issue seems to be that you assume the "experts" that news sources are using are any better. In the fields I am an expert on, they're wrong the vast majority of the time, and rarely do most news outlets report developments accurately or choose experts that have half a clue what they're talking about. Health and science reporting in the US is among the worst in the world, and is amazingly bad at the current time.

Taking a half of a side step from my field to "rocket science" I see no reason why that is suddenly going to universally change, especially when there's no legitimate source or backing for the information that is being released.

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PostPosted: Wed Jul 12, 2017 9:22 am 
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NephyrS wrote:
DE, did you read the payload analysis article? As you mention, trajectories aren't simple arcs, and I feel like that analysis was a lot more thorough.


I have read all three articles you posted, but I am not sure which article you mean by payload analysis.

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Diamondeye wrote:
NephyrS wrote:
DE, did you read the payload analysis article? As you mention, trajectories aren't simple arcs, and I feel like that analysis was a lot more thorough.


I have read all three articles you posted, but I am not sure which article you mean by payload analysis.


I posted 4 articles, so perhaps that's where you're missing it.

http://breakingdefense.com/2017/07/this ... n-missile/

Was the first one I posted, with what I think is a more nuanced discussion of thrust vs. likely payload of the missile, and effects of increased payload on range.

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NephyrS wrote:
I don't think you really have a good grasp of what doctoral training in the sciences is about if that's your perspective.


I don't think the issue here is actually one of being an expert or not. ICBM flight paths are not excessively complicated at the macro level; they're a very large arc. At the micro level of how you make the complicated device that an ICBM is actually work, sure, it's a lot more difficult, but the back-of-the-envelope math Coro did really can be done by anyone who has a high school education and puts their mind to doing it carefully. I could have done the same calculations - it just would have taken me significantly longer; I imagine it took Coro a few minutes while I'd have to get out some books and check myself very carefully and it would take several hours. I don't think there's any reason to quibble with the actual math that's been done here.

The thing to quibble with is the selection of data points. We have been provided with 3 basic pieces of information:

- A range achievement of about 578 miles
- A flight time of 37 minutes
- An apogee of greater than 1550 miles (in other words, 2x or more than a normal ICBM flight profile)

Now, the proposition put forth was that that anti-nuclear whackos at the Union of Concerned Scientists either jacked up or intentionally lied about the altitude achieved, which was based on the math done in this thread and the known normal altitude reached for ICBMs on a more normal attack flight path.

The problem with this proposition is that the numbers are not inconsistent with a "loft" flight path, such as the WRAL article discusses. Yes, an altitude of 1550 miles or even higher is highly inconsistent with a normal ICBM shot; it is not at all inconsistent with an ICBM flying in an unusually short-range, high-altitude arc for purposes that are consistent with North Korea's tracking capabilities and desire to conduct an ICBM demonstration for the world.

These measurements are also not coming from the UoCS; they are coming from the military. The UoCS does not have the network of radars and satellites that observe missile launches around the world - the military has that.

Let's look at the wral.com article, which does indeed provide a more skeptical analysis - but it is not skeptical that this missile did indeed fly 578 miles to an altitude of around 1550 miles for 37 minutes. It is skeptical that this demonstration flight represents and operational ICBM, which is a much more valid line of skepticism.

As the article points out early, test flights are special events. They can be carefully prepared for and the conditions highly controlled. This is not the case for a crew attempting to employ an ICBM (or any other weapon for that matter) in combat. The weapons needs to be reliable enough to sit in a silo or TEL for years with routine maintenance being done by technicians, not engineers or PhDs, keeping it operational, and in numbers.

The test didn't demonstrate that; no one has ever conducted such a mass test of ICBMs, and likely no one ever would. It would be expensive, and a mass launch simulating combat conditions would look very much like an actual attack. It also did not demonstrate that North Korea can actually reach CONUS with a missile - although the continued attempts to treat Alaska and Hawaii as less serious targets than CONUS are alarming in themselves; these are U.S. states and the fact that they are not contiguous is completely irrelevant.

Historically, this situation is somewhat similar to pre-Cuban Missile Crisis assessments of the soviet threat. The Soviets had the SS-6 missilewhich used the same booster system as the rocket used to put Yuri Gagarin into orbit. This was a wildly impractical system as an operational weapon; there were only 4-6 launchers, they cost an incredible amount, and they took some 20 hours to ready for firing - bombers could reach and destroy them before they could launch. The SS-7 was experiencing a lot of technical difficulties and was not ready for use. Nevertheless, the SS-6 did in fact work. If fired, it would indeed carry a 3-megaton warhead to the U.S., with atrocious accuracy (but it also didn't need to be that accurate; it just had to hit a city with a 3-megaton device; the idea of discrete targeting of facilities was out of the question with such a weapon).

10 years later, however, in 1969, the Russians had the SS-11, SS-13, and most importantly, the SS-9 (predecessor of the SS-18, which remains operational today and has a truly fearsome payload) in operational service, all of which were full-fledged ICBMs suitable for use as actual weapons, and the SS-7 was fully operation since well before than once its problems were worked out.

The Russians, in 1959, were very much in the state of North Korea now - they had conducted a few impressive demonstrational events, but they did not really have a working weapon system that was practical for combat use. The SS-7, however, is instructive. While North Korea is not Russia, North Korea is also not trying to build an ICBM in 1959 when ICBMs were a new, experimental concept for everyone world-wide. North Korea is much closer to building an ICBM force that 10 years; in 1969 the Russians had a workable ICBM force of several hundred missiles, not just their first ICBM.

In other words:

- It is, in fact, true that ICBMs do not normally fly to altitudes of 1550 miles; that does not mean they can't. It means the ICBM will come down much closer to its launch point than it would in an actual attack, which makes perfect sense if we are talking about NK conducting a test. While the suspicion of that figure and the supporting math are perfectly valid for a normal ICBM flight, this was not a normal ICBM flight.
- It is also true that North Korea did not demonstrate it has a practical, working ICBM as a weapon system. What it has demonstrated is that it has a prototype weapon that has a non-trivial level of reliability (i.e. it can, in fact, successfully fly) and that it could in fact fly at least 4,000 miles from its launch point assuming that it worked properly on future flights
- It may very well be true that the anti-nuke whackos at UoCS don't know what the hell they're doing, but there are better explanations for the unusual flight profile than "the numbers are all wrong" or "the altitude is bullshit".

In other words, everyone here is right and everyone is wrong. Coro and Nephyr were right to call into question the suspicious altitude figure, and do the math. RD was also right to call into question whether that expertise applied. The clue lies in the range figure; if the altitude is way to high, the range is equally way too short for an ICBM. The only figure that was in the right ballpark was the flight time. Taken altogether, they indicate a heavily modified trajectory used for testing purposes.

This example clearly illustrates the importance of understanding the enemy, from their own perspective. North Korea wants to prove to itself and the world that it has ICBMs; it also does not want to get nuked in the process of demonstrating that. Coro's back-of-the-envelope math is perfectly fine, it just does not incorporate reasons to fire an ICBM on a non-standard trajectory. The math Coro did was based on an assumption of normal behavior in a situation where normal behavior was actually undesirable, for reasons that have nothing to do with the accuracy of his calculations. The last sentence of Coro's post referred to "some absolutely ludicrous flight path." That, in fact, is exactly what happened - for reasons that are not at all ludicrous when looked at from the perspective of the North Koreans themselves.

_________________
"Kind-hearted people might of course think there was some ingenious way to disarm or defeat an enemy without too much bloodshed, and might imagine this is the true goal of the art of war. Pleasant as it sounds, it is a fallacy that must be exposed" - On War


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