John Schilling's Most Recent Comments
in: OSINT Brief for PEOTUS
in: OSINT Brief for PEOTUS
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For the duration of Trump’s first and perhaps only term in office, I would expect North Korean ICBM-class missiles to be even less reliable than American ICBM-class missile defenses. So Trump’s boasting may come to pass, as comedy in the first act. Illustrated with a nice montage of exploding missiles, even. Should be fun.
That still leaves POTUS/2021-2025 to deal with the tragic version.
in: Unilateral or Bilateral Reductions?
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“This transition to multilateral nuclear arms control, which Moscow and defense hawks in the United States have called for, will be hard to pull off under the best of circumstances”
This, I think, is critical. The next round of cuts could be done safely on either a unilateral or bilateral basis, but if that’s the end of the story then all we get are modest cost savings and a persistent risk of apocalypse. Moving forward beyond the next round will require bringing at least China on board, so I would suggest that whatever we do in this round should be judged heavily on whether it makes that task easier or harder – and the easiest way to do that might even be to bring China in on this round when we wouldn’t be asking them to give up anything they have already invested in.
in: New DPRK ICBM Engine
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If you plan to operate in a very cold winter, which sometimes does happen in Korea, you’d need tank heaters or the like. That’s hardly an insurmountable problem; anyone who has to deliver liquid water has to be able to solve it, and any engine that can pull a tanker truck can generate enough heat to keep the contents above freezing, and at least in the United States such systems are commercially available for tanker trucks. Refrigeration is harder, but as already noted probably not necessary if you are careful in your choice of paints.
And from your reference, it does look like the US and China have different standards. As far as I know, China never contemplated using NTO/UDMH missiles outside of fixed sites, and so presumably never developed the necessary procedures. The US Air Force, in the 1950s and early 1960s at least, was considering every option even though it never actually used NTO outside of silo-based missiles. Mostly because we developed good solid motors first; North Korea is still catching up in that area.
in: New DPRK ICBM Engine
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For satellites we do actual propellant loading in a climate-controlled building, but the propellants are delivered by truck in non-refrigerated cylinders in Florida, which iwas probably about 30 deg C when I did it last summer. The only large rocket we have left using NTO is the soon-to-be-retired Delta II, in which case the propellant is loaded on the pad, again possibly in the Florida summer. And in at least one case I worked, left on the pad for more than a month before launch, so even if the propellant were cooled during the transfer it would have seen full local temperatures by time of launch. Looking at the payload planner’s guide, the maximum allowable temperature seems to be 54.4 deg C, and that is due to a limit on the solid kick motor rather than the liquid propellants.
As for metal tanks getting hot in the sun, that depends very much on the surface coating. Ignoring convection for the moment, the equilibrium temperature for a steel surface with black enamel paint lying flat under the Pyongyang summer sun would be 110 deg C; clearly unacceptable(*). But white enamel paint would stay at a cool 2 deg C. Counterintuitively, bare metal is even worse than black paint – while shiny and reflective, it has an extremely low infrared emissivity. I don’t have figures for camouflage paints handy, but it is likely that if the North Koreans stick to lighter hues the tankers would not get above 30 deg C.
If you do an image search for liquid propane tanks or tank trucks, you’ll see that they are almost never refrigerated but almost always painted white. NTO is somewhat more tolerant of high temperatures than propane and should be able to handle tan or khaki. From a military standpoint, I’d rather be able to use any sort of camouflage and so I’d rather have the still more forgiving nitric acid oxidizers, but if North Korea’s only high-performance engines are designed for NTO, they can handle that without too much trouble. I do suspect they will be spending most of their time in tunnels and bunkers anyway.
(*) In reality, convection will keep any of these temperatures from getting too far from the local air temperature.
in: New DPRK ICBM Engine
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I’m not sure why you think refrigerated tankers and protective canisters would be required; could you elaborate? Summer high temperatures in Pyongyang are usually less than 30 deg C, http://www.north-korea.climatemps.com/ , and lower still in the mountains where such a missile would be based. At 30 C, the vapor pressure of nitrogen tetroxide is only 21.6 psia (1.5 bar). The fuel tanks will need to be pressurized to roughly 30-50 psia to suppress cavitation and pogo instability anyway, so there will be no issue of the propellant boiling. Transporting liquids under modest pressure is a well-established industrial practice that does not generally require refrigeration. I am looking right now at the USAF Propellant Handbook for Nitrogen Tetroxide Oxidizers, which states that N2O4 is shipped “in cylinders, tank trucks, and tank cars”, goes on for several pages about the relevant specifications and procedures while making absolutely no mention of refrigeration or temperature limits except to note that high-pressure containers may be required at 60 deg C or above. At the low temperature limit, it freezes at -11.2 deg C. That’s not terribly difficult to deal with either.
I have personally supervised the fueling of rockets with nitrogen tetroxide, and while I have some issues with the toxicity, those apply equally to IRFNA. In terms of temperature and stability, if you can handle e.g. water or propane in the field, you can handle nitrogen tetroxide. That’s why we chose nitrogen tetroxide for our rockets.
As for the Ukranian connection, the UN report says the North Koreans were found with information regarding propellant tanks and feed systems, not turbopumps or engines. And Yuzhnoye hasn’t built a large rocket engine in several decades. They build missile and satellite launch vehicle airframes, including propellant tanks and feed systems, that use Russian-made engines.
We have a great deal of circumstantial evidence that North Korea obtained R-27 missile technology, including engines, from Russia. We have no evidence to support any speculation that they have obtained any other high-performance engines. What we saw this weekend, looks almost exactly like what we’d expect a cluster of R-27 engines to look like, and a cluster of R-27 engines – yes, with nitrogen tetroxide oxidizer – is a technically sound approach to propelling an ICBM. If you are insisting that this must be something completely different, for which we have no evidence, simply because you read somewhere that nitrogen tetroxide is too volatile, you’re almost certainly wrong.
in: New DPRK ICBM Engine
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Some of us have been looking for literally years for a decent non-saturated color image of an SS-N-6 plume; if such a thing exists it probably is stuck on film in some ex-Soviet archive a mule cart ride away from any internet access.
in: New DPRK ICBM Engine
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@xutianran: The orange color in the plume has little to do with the oxidizer; that comes mostly from the carbon in the fuel. US missiles like Titan used a blend called Aerozene-50, which is ~20% carbon by weight. Russian missiles like the R-27 used unsymmetrical dimethylhydrazine, ~40% carbon by weight. So we’d expect a dual 4D10 engine set to produce a plume similar to the Titan’s LR-87 but with a more pronounced red-orange color, and that’s what we see.
And you’re right that NTO requires tighter controls in ground handling than IRFNA, but nobody has ever suggested that a lone KN-08 TEL is going to be headed into the countryside with a fully-fueled missile on top ready to fire. That’s not practical at this scale with any (liquid) propellant combination. As with e.g. the old US Jupiter, the KN-08 and KN-14 are going to be limited to road convoys with a dozen or more support vehicles including fuel tankers, and are probably going to spend most of their time in underground bunkers. You or I might use nitric acid if we were designing a system from scratch. The Russians, with different requirements, chose NTO, so that’s the system North Korea was able to buy.
in: Highlights and Initial Thoughts from the DPRK Launch
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Excellent work as always, Melissa. But I think you may be waiting a long while for that wreckage – South Korea is reporting that one of their Aegis destroyers tracked the first stage on the way down and recorded it breaking up into ~270 pieces. Quite possibly they don’t want curious wonks poking around inside their rocket this time 🙂
As for the orbit, 500 km circular and 97.4 degrees inclination would be a sun-synchronous orbit ideal for the Earth observation satellite North Korea says it launched; 501 x 466 km at 97.5 degrees would be slightly asynchronous (though still good enough to see if the thing works and conduct some limited operations). So I’m guessing the DPRK announcement was mostly aspirational and the JSpOC numbers are actual.
in: Video Analysis of DPRK SLBM Footage
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Excellent work, all of you. I caught the switch to a different missile for the flyout, but missed the few frames of incipient explosion.
Next question: Does anyone here have any color images or video of an R-27 launch? Based on plume coloration, I have moderate confidence that the KN-11 isn’t using the R-27’s UDMH/NTO propellants and is thus probably a standard Scud engine shoehorned into an SLBM testbed. If so, that would mean the ignition sequence is different (presumably slower for a Scud), making it hard for a direct comparison to tell us where the failure really began.
A direct comparison to other Scud tests isn’t terribly helpful because other Scud tests happen at ground level and the missile base is enveloped in the backwash for the critical period we’re looking at here.
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The 2016 tests show that North Korea can get a 1-2 out of 8 success rate for a new-ish single-stage missile with a proven engine design. From past experience, we know they can do better than that if they are willing to take their time, but if we take Jong-Un’s comments as promising an imminent test for political purposes, that suggests they would be rushing things.
Rushing into test with an entirely new multistage missile whose first stage propulsion system at least has seen only limited ground testing, is going to be a recipe for failure on a grand scale.
As for missiles breaking up on reentry, it is pretty clear that the North Koreans (like everyone else) is going for separable warheads on their long-range warheads. Those are generally more robust, and they have been doing some ground testing already. Probability of breaking up on reentry is small, but accuracy for the first tests will likely be very poor.