For Questions That Don't Merit Their Own Thread

[K^2]

That might just make neturonium the most convenient fuel for sci-fi setting. "Where did you get all this neutron matter?" - "Get in, there is not time to explain!"

[Spacescifi]

2 hours ago, K^2 said:

That might just make neturonium the most convenient fuel for sci-fi setting. "Where did you get all this neutron matter?" - "Get in, there is not time to explain!"

 

Nah... the ship would probably vaporize just like  with pure metallic hydrogen fueled rockets.

They could do a nuclear pulse pusher plate style though.

Edited August 3, 2020 by Spacescifi

[kerbiloid]

Unlikely, as neutrons are less interactive than cores.

Edited August 3, 2020 by kerbiloid

[DDE]

Anyone willing to do a yield estimate?

 

[kerbiloid]

500 Santas

***

Upd.
Judging by the cabins on the top, the entrance, and the storey above the entrance,
and after measuring them in Inkscape (cabin ~=5.6 px, (entrance+2nd storey) ~= 20 px, building ~72 px),
taking cabin ~2- m, average storey ~3+ m
the building is ~8 storey, i.e. ~25 m.

Watching this a 1/16^x speed in VLC, we can clearly see that the fireball stops expanding at ~3.5 building heights diameter, 290 px, i.e. ~90 m.
Then the shockwave breaks away, while the fireball keeps calmly floating up and smoking.

It stops expanding because its internal pressure got equal to the outside.
So, total energy of its expansion is ~pV ~ 100 000 Pa * pi *90³ / 6 ~= 3.8*10¹⁰ J ~= 9 t TNT.

Together with shockwave, it's probably twice as great, i.e. ~18 t TNT.

But we can clearly see that the fireball starts deforming and shading out at ~190 px diameter, i.e. 0.655 of max, so we should presume that actually the plain expansion stopped at ~ 60 m fireball diameter, so actually it's ~0.655³ * 18 ~= 5 t.

So, i bet on several (5+) tonnes of TNT. Maybe 10 as upper limit.

Edited August 4, 2020 by kerbiloid

[K^2]

The last buildings you see shredded before camera turns away are about 600m from explosion (using Google Maps). So the blast wave is a supersonic shock at that distance. Back of the napkin estimate puts energy requirement at about 0.5 kT. That's conservative lower bound, of course. A much better estimate would try to estimate actual speed of the shock wave, and will probably give a higher number. I can see if I can get something a bit later.

Edit: @kerbiloid This is what 5000lb of ANFO going up looks like, which is 1.6T of TNT equivalent. I'm not bothering to check your math, but 5T isn't even close to explosion in Beirut.

Spoiler

 

 

Edited August 4, 2020 by K^2

[kerbiloid]

As I can see, just the first row of buildings has been completely destroyed.

Even the second row just had lost the roof.

So, the first row ~50 kPa, the last row ~10 kPa.

From the video this is ~8 building heights away, ~200 m.

So, we can take 200 m as equivalent for 1 Mt 7 500 m, and get (200/7 500)³ * 1 000 000 ~= 18 t again.

So, I correct my guesing to the very initial 20 t, as both estimations match.

If it was 500 kt, we would see the operator flying away rather than ducking, it would be a rare aerial live.

***

BLU-82 Daisy Cutter, 5.7 t of substance.

Spoiler

 

 

Edited August 4, 2020 by kerbiloid

[kerbiloid]

Spoiler

 

 

[K^2]

Look at the map. It's 600m to buildings that are getting evaporated. Much closer to your 500T footage.

Edit: Similar analysis on Reddit. https://www.reddit.com/r/Physics/comments/i3otmk/order_of_magnitude_estimates_of_the_beirut_port/

Edited August 4, 2020 by K^2

[magnemoe]

2 hours ago, kerbiloid said:

As I can see, just the first row of buildings has been completely destroyed.

Even the second row just had lost the roof.

So, the first row ~50 kPa, the last row ~10 kPa.

From the video this is ~8 building heights away, ~200 m.

So, we can take 200 m as equivalent for 1 Mt 7 500 m, and get (200/7 500)³ * 1 000 000 ~= 18 t again.

So, I correct my guesing to the very initial 20 t, as both estimations match.

If it was 500 kt, we would see the operator flying away rather than ducking, it would be a rare aerial live.

***

BLU-82 Daisy Cutter, 5.7 t of substance.

  Hide contents

 

 

Daisy cutters are fuel air bombs using the oxygen in the air making them around 8 times stronger than standard high explosives. 
Downside is that you have to deploy the bomb in the air so you can not easy punch trough things and forget shaped charge. An standard artillery shell has no issue penetrating an concrete wall and explode on the inside. 

Blast was in an area where high explosives are stored. now you will not store high explosives in an urban harbor district. No the main issue with lots of military stuff like shells and rockets is the cordite and solid rocket fuel not the warheads. 
All the magazine detonation, from WW1 battle cruisers to Hood and then Yamato  was cordite. Same with tanks popping their turrets. 
However this is not US or EU, not even China, Thailand or Brazil so very weird stuff happens here. 

Agree with others its 10's of ton high explosive. Set off right it can be spectacular. Had an blast in the army dug down 100 kg  high explosives in an bog. We got an mushroom cloud, and and an fallout victim as in the guy set as an guard and the officers forgot to swap out bacause they was blowing stuff up came back getting soaked after getting all the fallout rain from blowing an crater in an bog

[kerbiloid]

1 hour ago, K^2 said:

It's 600m to buildings that are getting evaporated.

I see nothing evaporated here.
At 1/16 speed the first row of buildings is destroyed (50 kPa), the second row stays straight, but its roof is teared off and stays perpendicular (10 kPa).
The observer (4th-5th row of buildings, twice as far) is not thrown away, the glasses aren't broken (1 kPa).

The observer can clearly see the roof cabin and the entrance of the building next to the GZ, so he is ~500 m far (this matches the 2nd row estimation, 200+ m).

***

Reddit.

The fireball chapter is "blah-blah-blah-supersonic-I-think-a-whole-kiloton".
He even didn't estimate the fireball size.
Any shockwave is supersonic. Otherwise it's just an acoustic wave.

Shockwave chapter.
"I think, it's 1-2 kilometer away".
The guy has elvish eyes and can shoot a squirrel from a mile.
Where does he see 1-2 kilometer, when the building is clearly visible like at shooting range.

"1 psi breaks glasses"
1 psi breaks roofs, and this is what we can see at ~8 building heights away.

I would wait a little before believing the witnesses whose houses are damaged at 10 km away...
Especially if insurance is in order.

Summary.
Pure fantasies.

***

The smoke is maroon, probably nitrogen oxides.
As unlikely they stored nitric acid, probably stored saltpeter detonated from the pyro.
So, my guess is several hundred tonnes of stored saltpeter have given several tens tonnes of TNT equivalent.

Ready to listen a cool story about tens thousands tonnes of saltpeter in the dungeon.

***

P.S,
Why do they talk about the ship when the explosion is clearly next to the building.

Edited August 4, 2020 by kerbiloid

[K^2]

This one's from a MIIS professor, director for East Asia Nonproliferation Project.

We now also know that over 2,700 tons of ammonium nitrate was near the location as well as oil, granary, and other potential sources of fuel. That's potential for up to 1.8kT explosion. So now we know what the upper bound on the range is.

[StrandedonEarth]

Yeah, news report also listed a fireworks factory in the area.

240 tons yield puts it an order of magnitude below the 1917 Halifax explosion, estimated at 2.9 kilotons yield. Still devastating, of course, no hi-rise buildings in Halifax back then...

[Guest]

Consider a solar system with two planets orbiting around a single star. Is it possible for the planets to have orbits in such a way they are always in a "transfer window" from each other, or at least from planet A to B?

Edited August 5, 2020 by Guest

[GuessingEveryDay]

10 minutes ago, Aperture Science said:

Consider a solar system with two planets orbiting around a single star. Is it possible for the planets to have orbits in such a way they are always in a "transfer window" from each other, or at least from planet A to B?

Only if the planets are on the same orbit, and had atmosphere, then they could effectively become bus station, with space buses going in between each one, but they can't be too close, or they would crash into each other.

[StrandedonEarth]

11 minutes ago, Aperture Science said:

Consider a solar system with two planets orbiting around a single star. Is it possible for the planets to have orbits in such a way they are always in a "transfer window" from each other, or at least from planet A to B?

Well, there's always a transfer window, depending on how long you want the trip to be and how much dV you can spend. But for a Hohmann transfer window, I rather doubt it. 's possible to always have that window open. Unless it's 180⁰ around the sun...

[GuessingEveryDay]

1 minute ago, StrandedonEarth said:

Well, there's always a transfer window, depending on how long you want the trip to be and how much dV you can spend. But for a Hohmann transfer window, I rather doubt it. 's possible to always have that window open. Unless it's 180⁰ around the sun...

Like Kerbin and Kerbulus from @Kuzzter's Jool story?

[kerbiloid]

5 hours ago, K^2 said:

This one's from a MIIS professor, director for East Asia Nonproliferation Project.

A nonsense said by a professor doesn't cease to be a nonsense.
3 psi = 20 kPa would break the light walls at the observer's place and enstamp him against the wall, not just make to duck.
I now started worrying about the nonproliferation.

5 hours ago, K^2 said:

We now also know that over 2,700 tons of ammonium nitrate was near the location as well as oil, granary, and other potential sources of fuel. That's potential for up to 1.8kT explosion.

You forgot to add petrol in the parked cars and everything flammable in the blast radius.
Not everything butning is exploding, and not every bag of saltpeter/other nitrate in the storage had exploded rather than burned.
Also, 2 700 t had been arrested 7 years ago, but we don't (and won't) know how much was still there actually (both nitrate is hygroscopic and some people are poor).

The impressive white cloud is not what the fireball is, it's just a fog. It can be larger or smaller depending on weather.
The fireball is orange.

4 hours ago, StrandedonEarth said:

240 tons yield puts it an order of magnitude below the 1917 Halifax explosion, estimated at 2.9 kilotons yield.

Halifax was loaded with TNT, picric acid, and nitrocellulose. It differs a little from the fertilizer.

***

Btw, exactly ammonium nitrate or a cargo of nitrates, including ammonium nitrate?

Edited August 5, 2020 by kerbiloid

[K^2]

37 minutes ago, kerbiloid said:

A nonsense said by a professor doesn't cease to be a nonsense.
3 psi = 20 kPa would break the light walls at the observer's place and enstamped him against the wall, not just make to duck.
I now started worrying about the nonproliferation.

You still haven't even bothered to look at the maps, have you? Camera is located at least a couple of kilometers away. Pressures quoted are for 600m. That's the line of buildings where we see walls smashed to bits before they disappear into the dust cloud. 3psi is low-balling it.

Ok, here's another piece of data for you. We now have seismographic data. The earthquake was estimated to be magnitude 3.3. For comparison, N. Korean 100kT test resulted in magnitude 5.7 and 250kT results in magnitude 6.1. The relationship is exponential, so it's easy to estimate the yield.

Yield = 100kT * (250kT / 100kT) ^ ((3.3 - 5.7) / (6.1 - 5.7)) = 0.409kT

Absolutely every bit of analysis based on real data, taking measurements from the map, and not just eyeballing it from footage, results in numbers in hundreds of tons of TNT equivalent.

Edit: Wikipedia now claiming "few hundred tonnes of TNT", citing Washington Post, for what it's worth. I haven't been able to confirm the source, as it is paywalled.

Edited August 5, 2020 by K^2

[DDE]

8 hours ago, magnemoe said:

Downside is that you have to deploy the bomb in the air so you can not easy punch trough things and forget shaped charge.

The Soviet RShG-1 and RShG-2 are RPG-26 and RPG-27 respectively, where the HEAT warhead is replaced with a thermobaric warhead with a small HEAT precursor. Apparently the newer RMG has an even fatter precursor, and is thus marketed as an anti-everything grenade:

Iknow the Israelis have been trying something similar with a rifle grenade.

8 hours ago, magnemoe said:

Had an blast in the army dug down 100 kg  high explosives in an bog. We got an mushroom cloud, and and an fallout victim as in the guy set as an guard and the officers forgot to swap out bacause they was blowing stuff up came back getting soaked after getting all the fallout rain from blowing an crater in an bog

 

Edited August 5, 2020 by DDE

[kerbiloid]

46 minutes ago, K^2 said:

You still haven't even bothered to look at the maps, have you? Camera is located at least a couple of kilometers away.

I just looked at Google Earth, and the camera is 500 m away from the building and 600 n away from the ship(s), exactly what I can see in video.

Behind that range there is absolutely different city landscape,  not visible on the video even when the camera gets down.
In front of that place there are exactly these buildings from video.
So, try a better look again.

46 minutes ago, K^2 said:

Ok, here's another piece of data for you. We now have seismographic data. The earthquake was estimated to be magnitude 3.3. For comparison, N. Korean 100kT test resulted in magnitude 5.7 and 250kT results in magnitude 6.1. The relationship is exponential, so it's easy to estimate the yield.

Yield = 100kT * (250kT / 100kT) ^ ((3.3 - 5.7) / (6.1 - 5.7)) = 0.409kT

Now open any book about the earthquake magnitude and its calculation.
Amplitude may vary by an order of magnitude, greatly depending on local mineral structure, and it's a logarithmic dependance (always)
Comparing N.Korea to Lebanon is great. You should also bring a Martian seismogram to compare.

So, you should write not "0.4 kt" (0.409 is a pearl itself, so precise answer...), but lg(yield) = 0.4+/-(say, 0.5) or so.

46 minutes ago, K^2 said:

Absolutely every bit of analysis based on real data, taking measurements from the map, and not just eyeballing it from footage, results in numbers in hundreds of tons of TNT equivalent.

Currently I just can see voluntary assumptions and wrong Google data measuring (use the screen ruler, not fingers)..

***

Fuel-air explosion anyway gives a relatively small fireball surrounded by the fog cloud, so no difference here.

***

Btw, Beirut was a place of dreadful civil war for years not long ago, so I guess there were enough damaged buildings and before the xplosion.
So, I should not believe the witnesses without fact checking.

Edited August 5, 2020 by kerbiloid

[K^2]

1 hour ago, kerbiloid said:

Now open any book about the earthquake magnitude and its calculation.
Amplitude may vary by an order of magnitude, greatly depending on local mineral structure, and it's a logarithmic dependance (always)

If the earthquake is generated by breaks in the fault line, sure. If they are generated by an explosion wave reflecting off the surface, the only factor is relative density, and any kind of soil is "infinitely" dense compared to air. Look up any textbook on shock waves in continuous medium, but I recommend Landau and Lifexcrementsz. This is why earthquakes are a very good proxy for nuclear test yields and why we use them to estimate yields of tests in places like N. Korea. Naturally, actual formulae used are classified, but because the relationship is exponential, the two cited figures are sufficient for us to compute the yield to a pretty good precision.

1 hour ago, kerbiloid said:

I just looked at Google Earth, and the camera is 500 m away from the building and 600 n away from the ship(s), exactly what I can see in video.

Are you sure? Absolutely positive? Because there's a building I can identify in the frame, which is still pretty far from camera, that's at least 1,250 meters away from the explosion.

Edit: And just to clarify, the building that's 640m away from the explosion, is this one in the frame bellow. (Different red arrow from the above. Should have used another color.) This building? Yeah, anyone standing filming there would be dead. The damage is consistent with a shock wave hitting the front, fracturing parts of the wall, and the pressure wave following the shock lifting pieces of it up. From 640m away.

1 hour ago, kerbiloid said:

Btw, Beirut was a place of dreadful civil war for years not long ago, so I guess there were enough damaged buildings and before the xplosion.
So, I should not believe the witnesses without fact checking.

Aha, yeah. Looks totally fake and/or been that way for years now. Absolutely. Just, you know, 20T of TNT and not much destruction. Nope. Nothing to see here.

All of these buildings occupying the upper portion of the image are across the highway and are well over half a kilometer away from the center of explosion.

Edited August 5, 2020 by K^2

[kerbiloid]

I can't see this low-height buildings on the video, but this doesn't matter, as I estimate the damage radius from the first rows of buildings next to the GZ.
Their damage match the equilibrium fireball size, and both give ~20 t.
Well, +measurement error, +variable energy distribution, +taxes → "first tens of tonnes of TNT equivalent".

The observer site plays no role here at all, as its overpressure is "below 2..5 kPa" as he is not thrown away, and the glasses aren't broken,

Also I can't see crashed balcony in the buildings right behind the destroyed area.

I would prefer an aerial photo of the destroyed area rather than another "view from ground on sky background", just to see what exactly is damaged.

The city doesn't look totally fake, but I believe there will be many people wishing to say their property is destroyed now, rather than still.

Edited August 5, 2020 by kerbiloid

[K^2]

And you have "thin walls destroyed" in 640m radius from 20T? Where'd you get these numbers? Here are some comparisons for destruction zones from a well-established source.

0.5kT

20T

Now, on the 20T map, the light damage zone doesn't even reach the highway. We can clearly see windows of buildings across highways moderately damaged with 100% of the glass facing explosion destroyed. There are also plenty of photographs from streets around the city showing damage to glass on the other side of highway from the blast.

The 0.5kT map is closer to reality. If anything, damage seems to extend further than that.

[kerbiloid]

Here it is.

Spoiler

 

As we can see, exactly this city block is destroyed, and lightweight constructions around.
Multistorey buildings outside of the block are intact but lost their windows and doors (though, balcony platforms are intact).

The building right next to the GZ is not crashed, though is obviously to be removed. Even when it looks at the GZ with its front wall.

A typical picture of a largest WWII bomb.

So, I would guess, my "first tens of tonnes" are again "20 tonnes or less".

P.S.
Afair, the nitrates were stored not in the arrested ship, but in the storehouse, exactly like we can see on video (the crater).

P.P.S.
The glass is damaged at 2+ kPa. The same about furniture, siding, and other lightweight elements. Also such low pressure depends on reflections from neighboring buildings, etc, and does not form a plain pattern.
The roofs, drywalls need 10..20 kPa, and we can see where is this range exactly.

Edited August 5, 2020 by kerbiloid