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DrQuine
The law of unintended consequences: the more rocket launches fail and the more ...
Severe vibrations likely brought down N. Korean rocket
George Leopold
4/13/2012 3:15 PM EDT
WASHINGTON – The failure of North Korea’s three-stage Unha-3 rocket on Thursday (March 12) was most likely caused by severe vibrations at an early point in the flight trajectory known as Max Q, or maximum dynamic pressure, about one minute into the launch, according to a rocket expert.
While the lower stages of the North Korean rocket continued to function for several minutes, resonance at the top of the launch vehicle resulted in “catastrophic disassembly of the third stage at Max Q,” said Charles Vick, senior technical and space policy analyst at GlobalSecurity.org. “The vibrations just tore it apart.”
The third stage along with a satellite payload shroud failed about one minute into flight, analysts said. North Korea claimed the flight test, which drew international condemnation, was designed to place a satellite into a polar orbit. But many experts, including Vick, believe Pyongyang was testing the three-stage rocket for use as a ballistic missile.
North Korea's Unha-3 rocket lifts off on Thursday. The planned orbital flight lasted only about four minutes
The Unha-3 is based on the TaepoDong-2 missile. The third stage was jointly developed by North Korean and Iranian rocket engineers. The latest failure is the third for North Korea, prompting Vick to conclude that North Korea will likely look elsewhere for a new third stage design.
He said the timing of the failure at about 60 seconds into the flight points to severe vibration at Max Q, the point where aerodynamic stresses on rocket traveling through the atmosphere are greatest. Unlike American rockets, the North Koreans lack the ability to throttle their liquid-fueled rockets up or down to diminished the stresses at Max Q.
According to U.S. military observers, the failed orbital launch lasted about four minutes. Vick estimated that the Unha-3’s first stage fired for nearly 2 minutes before dropping into the sea about 102 miles west of Seoul, South Korea. Intelligence reports estimated parts of the rocket traveled on a southern trajectory over the Yellow Sea as far as 151 km (about 94 miles).
Given the severe vibrations and the early failure of the third stage, Vick said he was surprised that the other two stages held together as long as they did. He estimated the Unha-3 might have reached a velocity of about Mach 4, well below the speed needed to achieve orbit.
North Korea said it was aiming to place its satellite in a 500-km circular polar orbit.
For the first time, Pyongyang issued a statement Friday acknowledging the launch failure. “Whatever North Korea wanted to achieve geopolitically [with the rocket launch] is now in Davy Jones’s locker,” Vick observed.
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BicycleBill
4/13/2012 4:50 PM EDT
Achieving an equatorial orbit from N Korea's latitude is difficult, see http://www.space.com/15228-north-korea-rocket-launch-complications.html
as well as the comments to it for some insight.
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prabhakar_deosthali
4/14/2012 6:20 AM EDT
But as the report says they were trying to launch it in the polar orbit.
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BrianFraser
4/16/2012 1:52 AM EDT
They could bend it around to any orbit they wanted. See:
"Responsive Coverage Using Propellantless Satellites", George E. Pollock, Joseph W. Gangestad, James M. Longuski,
http://www.responsivespace.com/Papers/RS6/SESSIONS/SESSION%20II/2002_POLLOCK/2002P.pdf
Also: "New Synchronous Orbits Using the Geomagnetic Lorentz Force", Brett Streetman, Mason A. Peck (2007)
http://www.spacecraftresearch.com/files/StreetmanPeck_JGCD2007.pdf
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Sanjib.Acharya
4/14/2012 5:33 AM EDT
Was this the first time that North Korea developed the third stage of rocket? If they have done this before then what might have gone wrong this time? Another question....is it the first time Iran and North Korea worked together?
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george.leopold
4/16/2012 9:15 AM EDT
No, this was the third launch in the Unha series. The two previous launches also failed. For an analysis of NK-Iranian collaboration on multistage rockets, see:
http://www.globalsecurity.org/wmd/world/dprk/td-2-3rd-flighttest.htm
(I attempted to link to the above when I first posted the story, but the link, like the North Korean launch, failed during launch. It has been fixed in the story.)
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sharps_eng
4/14/2012 8:24 AM EDT
To me the most interesting question is, ' How do they know about the vibrations?'
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george.leopold
4/16/2012 9:24 AM EDT
Max Q is well understood to occur at about 60 seconds after a launch. According to Western intelligence assets, the top of the rocket began to break up as the NK rocket passed through Max Q, even through the first (and probably second) stage continued to function as designed.
Many of the Apollo astronauts commented on the intense vibrations during Saturn V launches. Alan Bean, the LM pilot on Apollo 12, said he was amazed at how bumpy the ride was: Do the engineers realize how this thing shakes, Bean recalled, because it shakes and vibrates so much more than I'd ever imagined. The difference of course is that the Saturn V held together every time.
(Incidentally: Our source, Charles Vick, worked on the Saturn V program. He believes it should be taken out of mothballs and used again as the primary U.S. "heavy lifter.")
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Brutus_II
4/16/2012 6:59 PM EDT
When the space shuttle Challenger exploded in 1986, there was talk about bringing back the Saturn V for use as "the heavy lifter". One of the big issues with that was much of the tooling had been destroyed (on purpose), so it would have been like starting over from scratch. After all, it was only our tax dollars that paid for it all to begin with. Why not pay for it all again?
I remember in the movie "The Right Stuff", John Glenn was freaking out over those vibrations. I thought his ship was just passing through the transonic range, but it must've been Max Q.
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Duane Benson
4/15/2012 2:48 PM EDT
It sounds to me like someone was just speculating on the cause. On the other hand, it's also possible that several governments as well as a few very talented amateurs managed to capture telemetry from the rocket and have done a preliminary analysis of that data.
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george.leopold
4/18/2012 10:09 AM EDT
Duane, it is the latter. Charles Vick at GlobalSecurity.org has been tracking the North Korean, Iranian, Chinese and other rocket programs for years. He also closely tracks how scientists and engineers in each of these countries have worked together over the years to develop ballistic missiles, which appears to be the ultimate goal. Vick also is a veteran of the Saturn V program, the greatest rocket ever built and arguably the greatest machine ever built. Vick literally overwhelmed us with data and analysis when we spoke with him last Friday as more data on the NK launch was filtering in. It's good to know smart folks like Vick is tracking this stuff and can explain it all to journalists.
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daleste
4/15/2012 3:52 PM EDT
Beside the political ramifications, it seems to me that North Korea would be better off expending their resources and energy in ways that would help their people and economy. But I guess dictators don't really care about the people.
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george.leopold
4/16/2012 9:25 AM EDT
The Unha-3 launch alone was estimated to have cost Pyongyang $1 billion.
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steve.freestone
4/19/2012 12:55 PM EDT
You got that right.
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kinnar
4/16/2012 5:40 AM EDT
Designing the rockets are always critical task, there are too many sections working together that too for only one event. One this kind of event affects a lot to the development plans of a developing country like North Korea, lets hope they will come with a better applications in Space Technology.
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george.leopold
4/16/2012 9:28 AM EDT
You are correct, kinnar. Multistage rockets are the ultimate systems integration problem. The NK and Iranian rocketeers should have known that their third stage was take the brunt of the resonance associated with entry into the period of maximum dynamic pressure (Max Q). The fact that their rocket couldn't withstand these vibrations indicates they are a long way from launching a ballistic missile.
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george.leopold
4/16/2012 9:33 AM EDT
Note to fellow space enthusiasts: I expect to be near the end of the runway at Dulles International Airport on Tuesday (April 17) when the Smithsonian Air & Space Museum facility at Dulles, the Udvar-Hazy Center, takes possession of Shuttle Discovery. It's unclear whether I would be able to see Discovery and its 747 carrier during its final victory lap around Washington, DC, so the end of the runway is the next best place since the 747 carrier has to land sooner or later.
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Robotics Developer
4/16/2012 1:17 PM EDT
I was relieved when the rocket launch failed to achieve orbit but saddened by the cost in money and to the people of North Korea. The estimated billion dollar price tag could have gone a long way to fixing infrastructure, improving life for all the N Koreans and was not a needed effort. I am sure that leaders of countries have different values and goals than mine so maybe this made sense to them, but I am at a loss to understand.
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george.leopold
4/18/2012 10:10 AM EDT
We couldn't have stated it better, Robotics Developer.
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ReneCardenas
4/16/2012 5:38 PM EDT
It is a shame that the populous are not able or willing to remove their miss-guided leaders. I wonder how long will their patience last, and realize that thier economy can withstand such waste. Would it have been cheaper to paid another country China, or perhaps even Rusia. To luch that satelite for them, if such was the REAL intent.
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elPresidente
4/16/2012 10:15 PM EDT
The US need to keep shooting them down with the ABL, as they probably did in this instance. Don't kid yourselves - this is 1950's technology, not rocket science, in terms of getting it right in this day and age - kids are launching rockets in the desert that hit the edge of space.
The idea of not having any kind of thrust governor via the turbopump sounds ludicrous, which also means the claims of a lack of a throttle is also silly propaganda. They are disadvantaged, not stupid.
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Brutus_II
4/17/2012 12:04 PM EDT
The fact that all the major governments involved, NK included, are not saying anything about the possibility of the missile being shot down speaks volumes. I wonder whether the remnants of the rocket have already been recovered from the ocean floor and by whom. If it was indeed "disabled" in flight, it would be best to get a hold of it so there's no evidence of "a mysterious blast hole" in the rocket's body somewhere. Now that would be an interesting front page image to see (possibly with very bad repercussions).
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george.leopold
4/18/2012 10:12 AM EDT
Vick noted that some missile sections landed in waters off the S. Korean coast. He thinks Seoul will definitely attempt to retrieve these parts.
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KB3001
4/17/2012 3:45 PM EDT
I lean towards this view too.
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Frank Eory
4/18/2012 7:10 PM EDT
I see your point, but just because NK had another rocket failure doesn't mean somebody shot it down.
It's quite an exaggeration to say kids are launching rockets that hit the edge of space. It wasn't until 2004 that serious amateur rocketeers (adult engineers with money to spend) crossed the 100 km altitude -- the official edge of outer space -- and there were many failed attempts prior to that.
I agree, the North Koreans are not stupid, but they are in fact inexperienced. The fact that this rocket design has failed 3 times just makes NK like everybody else who has tried to reach orbit. And like everyone else, if they keep trying, learning and making adjustments, it is likely they will eventually succeed.
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ocm9057
4/17/2012 10:26 AM EDT
...heard Visiontech was their main supplier
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mfm0411
4/18/2012 6:43 AM EDT
Great opportunity for a directed energy weapon. I wonder.
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t.alex
4/18/2012 5:46 PM EDT
Interesting if we can have some teardowns pictures ;-)
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R G.Neale
4/18/2012 6:21 PM EDT
Do any of our expert contributors know the type of guidance system that the N Korean rocket used, was it a launch-and-leave inertial navigation system or was it under guidance control via radio links from the ground? If it was the latter then it would be relatively easy for the guidance to be interfered with (i.e.hacked)by a third party and course changes made that would introduce destructive vibrations.
It is even possible and ground controlled local area self destruct switch was left open and accessed. There would be more evidence of that.
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steve.freestone
4/19/2012 1:01 PM EDT
Vibration tore the thing apart? Reminds me of a motorcycle I used to own.
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DrQuine
4/21/2012 10:53 AM EDT
The law of unintended consequences: the more rocket launches fail and the more the west critiques their technology, the more driven the North Koreans are to continue their efforts with funds that would be much better devoted to humanitarian objectives. Now it becomes an ego issue. If only we could have ignored the entire venture. After the first or second launch, the North Koreans could have moved into another venture with better public relations potential.
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zeeglen
4/22/2012 2:39 AM EDT
good, Good, GOOD Vibrations. The Beach Boys got it right...
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