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Sun May 21, 2017, 04:55 AM

North Korea fires 'projectile'

Source: BBC

North Korea fires projectile of unspecified type, South Korea's military says - it follows recent missile tests

This breaking news story is being updated and more details will be published shortly. Please refresh the page for the fullest version.


Read more: http://www.bbc.com/news/world-asia-39990836

8 replies, 3308 views

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Arrow 8 replies Author Time Post
Reply North Korea fires 'projectile' (Original post)
nitpicker May 2017 OP
bathroommonkey76 May 2017 #1
nitpicker May 2017 #2
Bernardo de La Paz May 2017 #3
defacto7 May 2017 #4
Bernardo de La Paz May 2017 #5
defacto7 May 2017 #6
Eugene May 2017 #7
Eugene May 2017 #8

Response to nitpicker (Original post)

Sun May 21, 2017, 05:08 AM

1. From Yonhap

 

(URGENT) N. Korea's missile flew about 500 kilometers: S. Korea's JCS


http://english.yonhapnews.co.kr/news/2017/05/21/0200000000AEN20170521003300315.html

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Response to nitpicker (Original post)

Sun May 21, 2017, 05:17 AM

2. More from the BBC thread

North Korea has conducted another missile test, South Korea's military has said. South Korea's Office of Joint Chiefs of Staff said the projectile was launched on Sunday afternoon local time.

The test comes a week after North Korea tested another missile, which it said was a new type of rocket capable of carrying a large nuclear warhead.
(snip)

The latest missile flew about 500km (310 miles), the Joint Chiefs of Staff said, according to South Korean news agency Yonhap. Last week's missile travelled about 700km.
(snip)

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Response to nitpicker (Reply #2)

Sun May 21, 2017, 06:56 AM

3. Actually,


The missile last week traveled about 4500 km because it rose to a height of about 2100 km. The surface distance is deceptive.

As a very rough calculation, a rocket that can fly 2100 km high and land 700 km distant is one that can fly 3500 km when launched at a 45 degree angle.

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Response to Bernardo de La Paz (Reply #3)

Sun May 21, 2017, 11:16 AM

4. I've read the posts about height and distance but something is strange...

So it rose to a height 7x higher than is necessary to attain orbit, turned around and reentered the earth's atmosphere 700km distant from its takoff point without exploding on reentry from the force of slamming into earth's atmosphere at that trajectory. Are we sure it didn't rise to 210km which is low space then pivot easily around to its destination without an extreme reentry angle? It makes a lot more sense.

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Response to defacto7 (Reply #4)

Sun May 21, 2017, 11:44 AM

5. Several points remove the sense of strangeness

1) Height is not what makes orbit. Speed makes orbit. A certain height is needed to get out of the atmospheric drag to maintain orbit. If the earth had no atmosphere you could orbit a few feet (meters) above the height of Mount Everest.

2) The speed going down is about the same speed as going up. The rocket fuel is spent before the rocket leaves the atmosphere, so the re-entry speed is the same as the speed leaving the atmosphere.

3) However, there will be considerable aerodynamic drag unless the re-entry vehicle is bullet shaped, which it surely was, along with heat shielding because the speed and drag increases as it goes deeper into the atmosphere on re-entry.

4) Projectiles follow parabolic paths. The rocket is a projectile after it spends all its fuel. From that point up and over the top and down again it follows a parabola. When it gets down to the same level as the fuel ran out, it continues dead-heading on an extension of that parabola. To follow the path you describe would take considerable more power (fuel) and perhaps re-starting the engine.




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Response to Bernardo de La Paz (Reply #5)

Sun May 21, 2017, 12:19 PM

6. Thanks for the reply...

#1 I knew, #2 makes up for some of the strangeness. So after usug up fuel and escaping atmospheric drag the object utilizes it own momentum in low gravity to continue, slow, and turn within a pre-determined natural geometry and reenter at the same speed as its exit from the atmosphere. The calculation of the weight, fuel, dynamics to the target would have to be made at the git-go. I had the idea there would be too much fuel and didn't consider there would be no need for adjustments to target. Orbit velocities aren't an issue because there's no orbit, just out and fall back.

Thanks...

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Response to nitpicker (Original post)

Sun May 21, 2017, 07:35 PM

7. Updated at OP link: North Korea confirms 'successful' new ballistic missile test

Source: BBC

North Korea confirms 'successful' new ballistic missile test

21 May 2017 Asia

North Korea has confirmed it "successfully" launched another medium-range ballistic missile on Sunday.

The state-run KCNA news agency said the weapon was now ready to be deployed for military action.

The White House said the missile had a shorter range than those used in North Korea's last three tests.

[font size=1]-snip-[/font]

North Korean leader Kim Jong-un oversaw the launch of the Pukguksong-2 missile on Sunday, KCNA reports, adding that he had "approved the deployment of this weapon system for action."

[font size=1]-snip-[/font]


Read more: http://www.bbc.com/news/world-asia-39990836


[font size=1]Pyongyang said the missile launched was the Pukguksong-2, which was also tested in February[/font]

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Response to nitpicker (Original post)

Mon May 22, 2017, 07:42 PM

8. North Korea says missile ready for mass production, U.S. questions progress

Source: Reuters

WORLD NEWS | Mon May 22, 2017 | 6:48pm EDT

North Korea says missile ready for mass production, U.S. questions progress

By Ju-min Park and Phil Stewart | SEOUL/WASHINGTON

North Korea said on Monday it successfully tested what it called an intermediate-range ballistic missile, which met all technical requirements and could now be mass-produced, although U.S. officials and experts questioned the extent of its progress.

The United States, which has condemned repeated North Korean missile launches, said Sunday's launch of what North Korea dubbed the Pukguksong-2 was of a "medium-range" missile, and U.S.-based experts doubted the reliability of the relatively new solid-fuel type after so few tests.

U.S. officials, who spoke on condition of anonymity, said the test did not demonstrate a new capability, or one that could threaten the United States directly. But the test was North Korea's second in a week and South Korea's new liberal government said it dashed its hopes for peace.

U.S. officials have been far less sanguine about the test of a long-range KN-17, or Hwasong-12, missile just over a week ago, which U.S. officials believe survived re-entry to some degree.

[font size=1]-snip-[/font]


Read more: http://www.reuters.com/article/us-northkorea-missiles-idUSKBN18H12S

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