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A Side Affect of Planetary Bombardment

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Re: A Side Affect of Planetary Bombardment
Post by Loren Pechtel   » Sat Oct 08, 2022 11:19 am

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I don't believe you can apply ordinary physics to the passage of a Honorverse KEW through the atmosphere. The problem is the wedge. Applying normal physics produces an awful lot of energy release in the upper atmosphere and nowhere near as much boom on the ground. They're wedge-driven, though, so I think they're penetrating the atmosphere without substantial energy loss, the energy shows up when they hit the ground.

As for new elements--no. We've already mapped out everything that's stable. There might be an island of relative stability but there's nothing stable in it. Instead of looking at supernovas, look at the real synthesizers of the truly heavy elements: neutron stars. The very surface is normal matter, as you go down the pressure builds to electron degeneracy levels--you've got a layer of atomic nuclei packed together. Going still deeper you have neutron degeneracy--what the stars are named for.

Note what you have at that boundary, though--tightly packed atomic nucleii encountering a veritable storm of neutrons. You will have an insane amount of r-process neutron captures. Some of the results undergo beta decay and thus take a step up the periodic table. Some undergo alpha decay and take two steps down and some fission, a few will undergo alpha capture and take two steps up. Basically anything that can be created will be created. Some of this material gets ripped off in neutron star mergers. If anything stable is created we would have already found it.
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Re: A Side Affect of Planetary Bombardment
Post by Joat42   » Sat Oct 08, 2022 7:46 pm

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Loren Pechtel wrote:I don't believe you can apply ordinary physics to the passage of a Honorverse KEW through the atmosphere. The problem is the wedge. Applying normal physics produces an awful lot of energy release in the upper atmosphere and nowhere near as much boom on the ground. They're wedge-driven, though, so I think they're penetrating the atmosphere without substantial energy loss, the energy shows up when they hit the ground.

KEW's don't use wedges, they are launched using mass-drivers. I don't remember if this has been explicitly explained in the books, but it can be inferred from textev:
Shadow of Freedom - Chapter 1 wrote:The thunderbolt descended from the heavens like the wrath of Zeus. Born two hundred and sixty-five kilometers above the planet’s surface, it traced a white line from atmosphere’s edge to ground level, riding a froth of plasma. The two hundred-kilo dart arrived without even a whisper, far outracing the sonic boom of its passage, and struck its target coordinates at thirty times the speed of sound.


In regards to the physics for KEW's, the energy-loss for traveling through atmosphere isn't really a concern since the KEW's are dart-formed and the travel through the atmosphere creates a plasma-sheath around them that significantly reduces drag which I assume you didn't take into account when calculating any energy-release attributed to atmospheric interactions.

Edit:
I just remembered, Manticore have the Damocles weapon system which is launched through the CMS. It is package containing several KEW's that have impellers, the impellers are used to accelerate it (to get an estimated yield) and guide the KEW to it's final trajectory and it was this weapon system that was used in Shadow of Freedom, Chapter 31 to take out the Lombroso Tower.

So, errare humanum est.. So there seems to exist different flavor of KEW's, some have impellers, some have not. Regardless if they have them or not, they don't loose much energy in the atmosphere for the reason I described above.
Last edited by Joat42 on Sat Oct 08, 2022 8:03 pm, edited 1 time in total.

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Re: A Side Affect of Planetary Bombardment
Post by tlb   » Sat Oct 08, 2022 7:51 pm

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Loren Pechtel wrote:I don't believe you can apply ordinary physics to the passage of a Honorverse KEW through the atmosphere. The problem is the wedge. Applying normal physics produces an awful lot of energy release in the upper atmosphere and nowhere near as much boom on the ground. They're wedge-driven, though, so I think they're penetrating the atmosphere without substantial energy loss, the energy shows up when they hit the ground.

I found the description of the Honorverse KEW in chapter 31 of Shadow of Freedom:
Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton...but this particular application called for a slightly smaller sledgehammer than that.

The projectile impacted at barely one tenth of a percent of light speed. The tower was enormous, the projectile wasn't all that huge, and its velocity might seem snail-like compared to the eighty percent of light speed a Mark 23 could obtain, but it was sufficient.
Note that the weight is considerable more than the five kilogram figure that people were suggesting. I take the "short-lived" comment to mean that the wedge is down by the time of atmospheric entry. Thirty times the speed of sound is close to the tenth of a percent of light speed.
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Re: A Side Affect of Planetary Bombardment
Post by Loren Pechtel   » Sat Oct 08, 2022 10:25 pm

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tlb wrote:Note that the weight is considerable more than the five kilogram figure that people were suggesting. I take the "short-lived" comment to mean that the wedge is down by the time of atmospheric entry. Thirty times the speed of sound is close to the tenth of a percent of light speed.


Math check! I think you're mixing up meters and kilometers.
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Re: A Side Affect of Planetary Bombardment
Post by Robert_A_Woodward   » Sun Oct 09, 2022 1:33 am

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tlb wrote:
Loren Pechtel wrote:I don't believe you can apply ordinary physics to the passage of a Honorverse KEW through the atmosphere. The problem is the wedge. Applying normal physics produces an awful lot of energy release in the upper atmosphere and nowhere near as much boom on the ground. They're wedge-driven, though, so I think they're penetrating the atmosphere without substantial energy loss, the energy shows up when they hit the ground.

I found the description of the Honorverse KEW in chapter 31 of Shadow of Freedom:
Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton...but this particular application called for a slightly smaller sledgehammer than that.

The projectile impacted at barely one tenth of a percent of light speed. The tower was enormous, the projectile wasn't all that huge, and its velocity might seem snail-like compared to the eighty percent of light speed a Mark 23 could obtain, but it was sufficient.
Note that the weight is considerable more than the five kilogram figure that people were suggesting. I take the "short-lived" comment to mean that the wedge is down by the time of atmospheric entry. Thirty times the speed of sound is close to the tenth of a percent of light speed.


I believe you made an error somewhere, I calculate that .001c is 87.5 times the speed of sound (at sea level at a standard temperature).
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Re: A Side Affect of Planetary Bombardment
Post by tlb   » Sun Oct 09, 2022 8:45 am

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Loren Pechtel wrote:I don't believe you can apply ordinary physics to the passage of a Honorverse KEW through the atmosphere. The problem is the wedge. Applying normal physics produces an awful lot of energy release in the upper atmosphere and nowhere near as much boom on the ground. They're wedge-driven, though, so I think they're penetrating the atmosphere without substantial energy loss, the energy shows up when they hit the ground.

tlb wrote:I found the description of the Honorverse KEW in chapter 31 of Shadow of Freedom:
Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton...but this particular application called for a slightly smaller sledgehammer than that.

The projectile impacted at barely one tenth of a percent of light speed. The tower was enormous, the projectile wasn't all that huge, and its velocity might seem snail-like compared to the eighty percent of light speed a Mark 23 could obtain, but it was sufficient.
Note that the weight is considerable more than the five kilogram figure that people were suggesting. I take the "short-lived" comment to mean that the wedge is down by the time of atmospheric entry. Thirty times the speed of sound is close to the tenth of a percent of light speed.

Robert_A_Woodward wrote:I believe you made an error somewhere, I calculate that .001c is 87.5 times the speed of sound (at sea level at a standard temperature).

I used Google, which gave the answer:
30 * speed of sound in dry air at 20 °C = 10 290 m / s
(or 10.29 km/s) and compared that the opening post:
Robert_A_Woodward wrote:It hit at .001c (30 kilometers per second)
Which gives only a factor of 3 difference (not the factor of 1000 that Loren Pechtel claims). Which part is in error?

Note that in this example the velocity was dialed back.
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Re: A Side Affect of Planetary Bombardment
Post by ThinksMarkedly   » Sun Oct 09, 2022 12:10 pm

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tlb wrote:Which gives only a factor of 3 difference (not the factor of 1000 that Loren Pechtel claims). Which part is in error?


I think Loren made the same mistake that I made when I read the post. You wrote:

Thirty times the speed of sound is close to the tenth of a percent of light speed.


My first read of that skipped the "percent" and my brain interpreted as "tenth of speed of light." That threw up alarm bells inside my head, "whoa, that's way off."

That's still off by an order and a half of magnitude, though. A tenth of a percent, or one one-thousandth, of the speed of light is 300 km/s, not the 30 that Robert said. Thirty times the speed of sound, as you've just confirmed with Google, it's 10.29 km/s, or nearly 30 times less.

The impactor hit at 300 km/s, which is 874x the speed of sound. At that speed, it would go through the entire atmosphere in less than one second, one third if we consider "the atmosphere" the Kármán line at 100 km, and the stratosphere and troposphere on Earth in less than a fifth of a second. In this regime, I have no clue whether it's so short that it wouldn't have noticeably slowed down from the speed in space or the other extreme that it's so fast that the atmosphere would not be meaningfully distinguishable from concrete and rock!
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Re: A Side Affect of Planetary Bombardment
Post by Loren Pechtel   » Sun Oct 09, 2022 9:50 pm

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ThinksMarkedly wrote:
tlb wrote:Which gives only a factor of 3 difference (not the factor of 1000 that Loren Pechtel claims). Which part is in error?


I think Loren made the same mistake that I made when I read the post. You wrote:

Thirty times the speed of sound is close to the tenth of a percent of light speed.


My first read of that skipped the "percent" and my brain interpreted as "tenth of speed of light." That threw up alarm bells inside my head, "whoa, that's way off."

That's still off by an order and a half of magnitude, though. A tenth of a percent, or one one-thousandth, of the speed of light is 300 km/s, not the 30 that Robert said. Thirty times the speed of sound, as you've just confirmed with Google, it's 10.29 km/s, or nearly 30 times less.

The impactor hit at 300 km/s, which is 874x the speed of sound. At that speed, it would go through the entire atmosphere in less than one second, one third if we consider "the atmosphere" the Kármán line at 100 km, and the stratosphere and troposphere on Earth in less than a fifth of a second. In this regime, I have no clue whether it's so short that it wouldn't have noticeably slowed down from the speed in space or the other extreme that it's so fast that the atmosphere would not be meaningfully distinguishable from concrete and rock!


I didn't try to work out the math, just saw it was way off.
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Re: A Side Affect of Planetary Bombardment
Post by Robert_A_Woodward   » Mon Oct 10, 2022 1:36 am

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ThinksMarkedly wrote:
tlb wrote:Which gives only a factor of 3 difference (not the factor of 1000 that Loren Pechtel claims). Which part is in error?


I think Loren made the same mistake that I made when I read the post. You wrote:

Thirty times the speed of sound is close to the tenth of a percent of light speed.


My first read of that skipped the "percent" and my brain interpreted as "tenth of speed of light." That threw up alarm bells inside my head, "whoa, that's way off."

That's still off by an order and a half of magnitude, though. A tenth of a percent, or one one-thousandth, of the speed of light is 300 km/s, not the 30 that Robert said. Thirty times the speed of sound, as you've just confirmed with Google, it's 10.29 km/s, or nearly 30 times less.

The impactor hit at 300 km/s, which is 874x the speed of sound. At that speed, it would go through the entire atmosphere in less than one second, one third if we consider "the atmosphere" the Kármán line at 100 km, and the stratosphere and troposphere on Earth in less than a fifth of a second. In this regime, I have no clue whether it's so short that it wouldn't have noticeably slowed down from the speed in space or the other extreme that it's so fast that the atmosphere would not be meaningfully distinguishable from concrete and rock!


It is David Weber who claimed that the impactor hit at both 30 km/second and 1/10 of 1% of the speed of light. I will admit that I didn't notice the 1 order of magnitude error (all my calculations were based on 30KM/sec).
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Re: A Side Affect of Planetary Bombardment
Post by cthia   » Mon Oct 10, 2022 8:27 am

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tlb wrote:
cthia wrote:I wouldn't be surprised if a new element is made.

On that note: I had a friendly disagreement quite some time ago, I think with Jonathan, when I suggested that there might be new elements found elsewhere in the Universe that could enable advanced technology.

Jonathan disagreed.* Essentially he said our galaxy should contain any element of any other galaxy. IOW, there would be nothing new under the "Suns" to find. I think I argued the reality as a possibility that Darius might include elements that could make unbelievable technology possible.


Exhibit A: Nuclear fusion courtesy of the moon.

Helium-3 is not a new element, just a relatively rare isotope of Helium. The reason that some heavy isotopes are rare is that they transmute by fission into lighter elements, so any previously unknown heavy element probably has a very short lifetime.

True, not new. But the equation is the same if significant access to this element does not exist. It would be no different from third world countries having no access to uranium trying to build nuclear weapons.

Son, your mother says I have to hang you. Personally I don't think this is a capital offense. But if I don't hang you, she's gonna hang me and frankly, I'm not the one in trouble. —cthia's father. Incident in ? Axiom of Common Sense
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