For Questions That Don't Merit Their Own Thread

[JoeSchmuckatelli]

10 minutes ago, TheSaint said:

I keep telling everyone to stock up on green tip.

My buddy went to a carbine training course at Gunsite Academy. One of his biggest takeaways was that every instructor there was using a pencil-barrel AR with a lightweight red dot. No government-profile barrels, no LVPOs, no ACOGs, no aluminum rails, none of that. They shaved every ounce they could off the rifle, target was the 5-pound-ish range. It's kinda making me rethink my priorities.

Yeah - there's a bunch of guys who show up to every range with all kinds of kit: I always see them as hobbyists.   (Kitting out your gun is fun and definitely a conversation starter).  But when you really start to think about having to carry it and use it... priorities change.

Think about the difference between backpacking (through-hiking) and camping.  When I go camping with the kids, I take a truckload of stuff.  But when I'm on the trails?  Every ounce counts - whether I'm only going 5 miles or 25 on any given day.  Just like when hiking you want simple, rugged, dependable and versatile... the same philosophy informs gun selection.

Ammo considerations, too.  As an infantryman I would often carry 200 rounds plus other fun things around, because a) I was a professional and might have needed all of that, and b) if I needed it - resupply was unlikely to be dependable.

Were I through hiking in feral pig territory where I might need to dump a mag to save my butt, I'm unlikely to need more than one extra mag, ever.  

It's fairly cheap to buy stuff that will make you look like a ReconRanger (or a fat, cosplay wannabe  ) - but unless you are a fit, 20-something with a professional need to carry that much... walking across the first field is gonna kick your butt.

[ARS]

So I got something to ask...

Build towers across earth. Each tower must have a line of sight to at least 1 other tower and 1 tower must be directly on south and north pole, whether the tower is placed on ground or sea doesn't matter, each tower has a height roughly 50m

Considering that earth's surface area are roughly 510 million km², and the distance to the horizon is roughly 5 km (which means there must be another tower within a radius of 78.5 km² for each tower), the formula for the number of towers required would be: 510,000,000/ 78.5=6,496,815 towers

Is this correct?

[lrd.Helmet]

33 minutes ago, ARS said:

So I got something to ask...

Build towers across earth. Each tower must have a line of sight to at least 1 other tower and 1 tower must be directly on south and north pole, whether the tower is placed on ground or sea doesn't matter, each tower has a height roughly 50m

Considering that earth's surface area are roughly 510 million km², and the distance to the horizon is roughly 5 km (which means there must be another tower within a radius of 78.5 km² for each tower), the formula for the number of towers required would be: 510,000,000/ 78.5=6,496,815 towers

Is this correct?

From 50meters up the horizon is about 25km away. And circles don't really stack nicely, however I don't really know how much you'd need to overlap them.

[Gargamel]

33 minutes ago, ARS said:

Build towers across earth. Each tower must have a line of sight to at least 1 other tower and 1 tower must be directly on south and north pole, whether the tower is placed on ground or sea doesn't matter, each tower has a height roughly 50m

I'm ignoring your fundamental question, of is my math right, but I want to investigate the idea behind this question more.    I think we need to define Line of Sight here.    Do we mean A human standing on the top of a tower can see another tower?  Or do we mean a radio (EM) signal of some wavelength can reach another tower without interference?  Or just the traditional LOS were there isn't another object in the way?  I ask because placing towers on the seafloor vs as floating buoys would be a concern.   Dropping a premade structure off a ship and having it land in place vs getting a floating structure to stay stable is a bit of a difference, each with their own difficulties.    Or, perhaps, are we not covering the ocean surface?   That will reduce the numbers in the math considerably. 

If we start off by plopping towers on the summits of mountains with large distances to horizon, such as lone volcanoes, we can probably reduce the number of required towers by a significant amount. 

Next, why only 50m?   That's relatively short.  As the height of the mast goes up, the distance to the horizon would also increase.   I don't know the ratio, but there's probably a reason that building 500m+ tall radio towers are a thing, instead of a small network of shorter ones.   Let's assume cost of materials is our biggest limiting factor, there's a function that has a minimum amount of materials used.  That would dictate the optimum height of the towers.   Assuming these towers would have some guide lines holding them up, (ie the taller a tower, the wider the base of the guide wires) the amount of airspace used up might be another variable to consider.   Less airspace impinged on would be more desirable.  That could be included in the function, giving us another optimum height.

And then there's the topography.   On a local scale, it's fairly easy to play around with potential layouts and find a near optimum layout.  But on the scale of the whole planet, this is a really complicated problem.   I would think plugging our various preferred features of the towers and applicable GIS data into the appropriate machine learning style program would be the best solution.  Let it work through the many many different layouts it can come up with.   I would posit that an AI designed layout would reduce the number of towers required, as the appropriate height of a tower would be calculated for each location. 

And final question would be, why would a series of towers be superior to a low orbit cloud of satellites (a la Starlink)?  I don't know the intended use of the towers, so satellites might not be a good option. 

[kerbiloid]

1 hour ago, ARS said:

and the distance to the horizon is roughly 5 km

L_direct ~= sqrt(2 * R * h)  = sqrt(2 * 6.37*10⁶ * h_m) ~= 3570 * sqrt(h_m), m = 3.57 * sqrt(h_m), km

A human, h_m = 1.7 m → L_direct ~= 4.7 km 
A cat, h_m = 0.15 m → L_direct ~= 1.4 km 

A 50 m tower, h_m = 50 m → L_direct ~= 25.2 km 

So, 2*25 = 50 km between the towers.

ISS, h_m = 420 000 m → L_direct ~= 2 300 km 

Edited October 15, 2021 by kerbiloid

[kerbiloid]

18 minutes ago, Gargamel said:

I'm ignoring your fundamental question, of is my math right, but I want to investigate the idea behind this question more.  

Spoiler

 

[Gargamel]

8 minutes ago, kerbiloid said:

  Hide contents

 

I was thinking more like

Spoiler

 

 

[kerbiloid]

7 minutes ago, Gargamel said:

I was thinking more like

U R moar lawfulgooder than me...

[ARS]

23 minutes ago, Gargamel said:

I'm ignoring your fundamental question, of is my math right, but I want to investigate the idea behind this question more.    I think we need to define Line of Sight here.    Do we mean A human standing on the top of a tower can see another tower?  Or do we mean a radio (EM) signal of some wavelength can reach...

Okay, I should add other things to consider about my question. Assume the earth-sized planet, with little to no variations in geographical features. Line of sight is defined from the top of the tower

28 minutes ago, Gargamel said:

Next, why only 50m?   That's relatively short.  As the height of the mast goes up, the distance to the horizon would also increase.   I don't know the ratio, but there's probably a reason that building 500m+ tall radio towers are a thing, instead of a small network of shorter ones.   Let's assume cost of materials is our biggest limiting factor, there's a...

From practical, safety ad economic standpoint, which one is better? A network of 10 towers with height of 50m or a single 500m tall tower?

30 minutes ago, Gargamel said:

And then there's the topography.   On a local scale, it's fairly easy to play around with potential layouts and find a near optimum layout.  But on the scale of the whole planet, this is a really complicated problem.   I would think plugging our various preferred features of the towers and applicable GIS data into the appropriate...

If we just assume an earth-sized planet with smooth surface area, how many towers it takes to do it? (basically ignoring the variable terrain topography)

32 minutes ago, Gargamel said:

And final question would be, why would a series of towers be superior to a low orbit cloud of satellites (a la Starlink)?  I don't know the intended use of the towers, so satellites might not be a good option. 

let's just say I'm writing a semi-realistic sci-fi story where in a nutshell, space launch has become impossible due to... Over-kesslering the planet?

[kerbiloid]

If you need a visual contact, then take into account that the air is never perfectly transparent.

100+ km is the maximal distance you can look through.

Usually 10..20 km in sunny day.

Also the mountains are often hidden in clouds, so no watch tower or signal smoke could be visible at several kilometers from it.

If they are directly connected radioantennas, it's visible.

***

50 vs 500 mdepends, for example on whether they need to climb by ladder.

[ARS]

13 minutes ago, kerbiloid said:

50 vs 500 mdepends, for example on whether they need to climb by ladder.

LMAO you got me there

[K^2]

3 hours ago, ARS said:

So I got something to ask...

Build towers across earth. Each tower must have a line of sight to at least 1 other tower and 1 tower must be directly on south and north pole, whether the tower is placed on ground or sea doesn't matter, each tower has a height roughly 50m

Considering that earth's surface area are roughly 510 million km², and the distance to the horizon is roughly 5 km (which means there must be another tower within a radius of 78.5 km² for each tower), the formula for the number of towers required would be: 510,000,000/ 78.5=6,496,815 towers

Is this correct?

Are you just trying to build a chain? Or do you need at least one tower visible from every point on Earth? Even in the later case, you can come up with a space-filling pattern that's more efficient. Think a branching out fractal-like structure. Simply filling all space with a grid of tower is not the optimal solution if you're trying to build fewer towers.

[ARS]

1 hour ago, K^2 said:

Are you just trying to build a chain? Or do you need at least one tower visible from every point on Earth? Even in the later case, you can come up with a space-filling pattern that's more efficient. Think a branching out fractal-like structure. Simply filling all space with a grid of tower is not the optimal solution if you're trying to build fewer towers.

Just need one tower visible, it doesn't have to chain into an entire network

[tomf]

Arranging your towers onto the earth looks like it is going to be equivalent to the Thomson problem of packing charges onto a sphere. It looks like the optimum solution isn't known for more than a few towers.

[JoeSchmuckatelli]

17 minutes ago, tomf said:

Arranging your towers onto the earth looks like it is going to be equivalent to the Thomson problem of packing charges onto a sphere. It looks like the optimum solution isn't known for more than a few towers.

Why wouldn't it be as simple as this? 

https://en.m.wikipedia.org/wiki/Geodesic_polyhedron

(presumes a smooth sphere) 

 

[DDE]

6 hours ago, ARS said:

LMAO you got me there

Dilemmas, dilemmas

540 m

3544 steps

Three people took the elevator up and didn't make it down

[StrandedonEarth]

7 hours ago, Gargamel said:

but there's probably a reason that building 500m+ tall radio towers are a thing, instead of a small network of shorter ones. 

The primary reason for building the 553m CN Tower in Toronto was so the signal from the TV antenna on top could reach  into the small valleys in the area, something no 10m tower could do unless there was one on every ridgeline, which would probably cause some sort of multipath interference, please excuse the run-on sentence I’ll stop now. 

[kerbiloid]

The Wardenclyffe Tower was 187 ft (57 m) high.
50 m... Hmm... Seems, we see what @ARS is doing there...

But for a Global Tesla Power Network the oceans should be taken into account. Either the width, or the bypass route.

Drake Passage is 800 km wide. Other gaps look narrower.
So, probably at least 400 km visibility distance is required. 

400² / (2 * 6371) ~= 12.5 km.
The rocks can be just ~10 km high on the Earth. So, it should be from steel. 

Such towers can also directly connect Iceland and Europe.
A chain of 25 is to connect the poles.

Also 25 km is enough high to let the air drag be negligible. So, these can be launchtowers.

[FleshJeb]

14 hours ago, kerbiloid said:

100+ km is the maximal distance you can look through.

Over 300km, actually...In 1878. And that's just the one I know about. At the time it was the longest surveying observation ever conducted.

https://celebrating200years.noaa.gov/theodolites/heliotrope.html

Never underestimate nerds who think sweating and bleeding is fun.

[kerbiloid]

2 hours ago, FleshJeb said:

Over 300km, actually...In 1878. And that's just the one I know about. At the time it was the longest surveying observation ever conducted.

I don't talk about record event, it's about usual conditions he is going to use the towers in.

[kerbiloid]

Just read about D-Mars.

https://en.wikipedia.org/wiki/D-MARS

Some video (in Russian).

https://www.rbc.ru/technology_and_media/16/10/2021/61695dbf9a79476e532699f8

Musk should hurry up.

[SunlitZelkova]

Three questions-

1. How do rocket paint schemes work? Is it just to make it look cool, or do the black portions of the Saturn series and the grey of the Soyuz boosters actually have a purpose?

2. Why do modern Soyuz variants still get GRAU designations? Is it because the original Soyuz had it so the modern variants still get it, or am I not realizing how close Russia's space industry is to the military in modern times?

3. This is not a question I am seeking a definitive answer for as much as it is one that I am curious to hear the opinions of the members of this forum on. To what extent would you (anyone who chooses to respond) say that as subjects of interest, the military and space exploration are intertwined? Is one's interest in military affairs enriched and enhanced by also holding an interest in space, and/or is one's interest in space enriched and enhanced by also holding an interest in military affairs (or at least paying attention to it a little)?. On this forum pure (but brief) pure military equipment related questions often come up and a number of space related discussions have drifted into military technology and operations recently. On the other hand, in the military video game forums I am a member of, while discussion of reconnaissance satellite constellations and ASAT capabilities does occur, mention of space is not common, apart from the occasional KSP meme. I myself am not sure how I would answer the question, but I can say that it was much easier learning about the Soviet space program having already acquired prior knowledge of the USSR's ballistic missile and nuclear weapon development (from pure military, non-space related sources, prior to my re-interest in space).

[kerbiloid]

57 minutes ago, SunlitZelkova said:

or do the black portions of the Saturn series and the grey of the Soyuz boosters actually have a purpose?

Optical measurements of the test launches.

58 minutes ago, SunlitZelkova said:

Why do modern Soyuz variants still get GRAU designations?

It's a rocket. They have it.

1 hour ago, SunlitZelkova said:

the military and space exploration are intertwined?

They have civilian applications, too.

[JoeSchmuckatelli]

5 hours ago, SunlitZelkova said:

to hear the opinions

From any standpoint, I think our ability to get to space last century was so intertwined with government and military issues that it's almost impossible to untangle.  First World / Superpower conflict drove the development of technology that needed input from civilian scientists and as the technology matured and achieved 'firsts', revealing more and more data about the cosmos, the civilian applications of the technology were revealed. 

But part of what you are interested in has been discussed in places on this site - where people opine that a given booster is useful for little more than an ICBM - or that one is way overkill for use as an ICBM. 

I think the 'pure science' missions came out of both mature technology /skill and having the luxury of money and time to do it... And without wanting to cast aspersions, you can look around the world at the space nations to see that when both technical knowledge and spare cash are high, peaceful, pure-science applications are common. 

Then you also the "guest" mission, where some country with no technical knowledge is permitted to fly civilian missions for a low, low price.  Guest military missions don't happen 

Edited October 16, 2021 by JoeSchmuckatelli

[DDE]

5 hours ago, SunlitZelkova said:

2. Why do modern Soyuz variants still get GRAU designations? Is it because the original Soyuz had it so the modern variants still get it, or am I not realizing how close Russia's space industry is to the military in modern times?

A simplistic explanation is that Soyuz-2.1b and Soyuz-2.1v can be launched from Plesetsk, which is all-military. I'm also not sure if military QA is carried out on all production at Progress and Khrunichev/Polyot by default, therefore requiring a Space Troops index (GUKOS took over indexing space hardware from GRAU long ago... each branch actually had its own index system and authority).

5 hours ago, SunlitZelkova said:

3. This is not a question I am seeking a definitive answer for as much as it is one that I am curious to hear the opinions of the members of this forum on. To what extent would you (anyone who chooses to respond) say that as subjects of interest, the military and space exploration are intertwined? Is one's interest in military affairs enriched and enhanced by also holding an interest in space, and/or is one's interest in space enriched and enhanced by also holding an interest in military affairs (or at least paying attention to it a little)?. On this forum pure (but brief) pure military equipment related questions often come up and a number of space related discussions have drifted into military technology and operations recently. On the other hand, in the military video game forums I am a member of, while discussion of reconnaissance satellite constellations and ASAT capabilities does occur, mention of space is not common, apart from the occasional KSP meme. I myself am not sure how I would answer the question, but I can say that it was much easier learning about the Soviet space program having already acquired prior knowledge of the USSR's ballistic missile and nuclear weapon development (from pure military, non-space related sources, prior to my re-interest in space).

Using several years of active posting on r/space as a more representative sample, I believe that the intersection between "militarists" (military buffs?) and "space fans" is fairly rare. This is perhaps best indicated by how many people believe the Outer Space Treaty bans all weapons in space, or that the US ASAT missile was the first ASAT.

I believe that there are several clusters of knowledge (e.g. classic Earth-based warfare centered on guns and tanks, planetology and exoplanetology, and current or near-future spaceflight with realistic physics) that most people have trouble integrating. Heck, it's rare for "militarists" to have a comprehensive interest outside a particular domain (air, land, sea) or era.

This sounds a bit self-gratifying, but I am well aware I know only "a little bit of everything" and just don't feel like diving deep into the quantitative nitty-gritty.