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For Questions That Don't Merit Their Own Thread


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23 minutes ago, mikegarrison said:

Probably in a holding pattern for a non-DC airport. Lot of airports around there.

I thought that, but the aircraft were clearly at max altitude and the loops were easily 80-100 miles in diameter. I can’t imagine why they would be in a holding pattern at cruising altitude. But maybe that’s something that happens.

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8 hours ago, sevenperforce said:

Hey, so I was in DC watching the sky lazily and spotted an aircraft making an extremely wide turn at around 35,000 feet. It was heading west towards DC but performed a full loop headed back out toward the Atlantic. Kept watching and saw two planes basically making one single loop with the western edge over the Chesapeake and the eastern edge over the Atlantic.

Both aircraft were white and generally appeared to be commercial, but I suppose they could have been AWACS or something. They both did two full loops before disappearing over the horizon for good. Any idea what this could have been and why?

Coincidentally or not,

 

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On WW2-era vehicles, especially tanks and ships, we can see coincidence rangefinders mounted on it, from small, portable unit used by tank crew, mounted on tank's cupola, integrated on tank's turret, and then we have the one mounted on fire control unit on destroyers, all the way up to a massive duplex rangefinder mounted on Yamato's fire control tower. All of those are from the smallest to the largest, so what I want to ask is, does the length of the 2 viewports (aka the width of the unit) corresponds to the maximum range that can be measured? (thus the effective firing range of the unit using it) Because the small ones are mounted on tanks since it's expected to engage other tanks at an average range of 1-2km , while the larger ones are mounted on ships because destroyers might engage each other at 5-10km+ range while battleships at over 15-20km+ range

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12 minutes ago, ARS said:

On WW2-era vehicles, especially tanks and ships, we can see coincidence rangefinders mounted on it, from small, portable unit used by tank crew, mounted on tank's cupola, integrated on tank's turret, and then we have the one mounted on fire control unit on destroyers, all the way up to a massive duplex rangefinder mounted on Yamato's fire control tower. All of those are from the smallest to the largest, so what I want to ask is, does the length of the 2 viewports (aka the width of the unit) corresponds to the maximum range that can be measured? (thus the effective firing range of the unit using it) Because the small ones are mounted on tanks since it's expected to engage other tanks at an average range of 1-2km , while the larger ones are mounted on ships because destroyers might engage each other at 5-10km+ range while battleships at over 15-20km+ range

Yes they used parallax for getting the distance so an larger with of the beam help with accuracy as it increase the difference in angle the two view ports had. Combat range and space was the important factors here. 
On warships radar tended to take over but the optical ones could not be jammed and it was an backup. On an warship you could use both the rangefinder and the radar to spot shell splashes 

This is used today for measuring the distance to stars, you tend to measure the direction to the star, then try again in half an year for an 2 AU difference, now some accurate telescopes in the outer solar system could increase the accuracy by an magnitude. 

Edited by magnemoe
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25 minutes ago, ARS said:

does the length of the 2 viewports (aka the width of the unit) corresponds to the maximum range that can be measured?

@magnemoe answered effectively, but I will add a couple of things.  There are lots of ways to guestimate range,   Special marks on the reticle can be referenced against a known profile (height, width, length) of a target or more technological aids -  like radar, lasers, etc.  Parallax is only one solution, with the obvious limitations you assumed correctly.

I use 'guestimate' because there are also a myriad of ways for the range estimation to be off - it's really just to increase your chance of a hit on the first shot.  

Modern fire control systems are pretty effective; the firing agency (thing with the gun) rarely has to be able to see its own target anymore.

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36 minutes ago, ARS said:

On WW2-era vehicles, especially tanks and ships, we can see coincidence rangefinders mounted on it, from small, portable unit used by tank crew, mounted on tank's cupola, integrated on tank's turret, and then we have the one mounted on fire control unit on destroyers, all the way up to a massive duplex rangefinder mounted on Yamato's fire control tower. All of those are from the smallest to the largest, so what I want to ask is, does the length of the 2 viewports (aka the width of the unit) corresponds to the maximum range that can be measured? (thus the effective firing range of the unit using it) Because the small ones are mounted on tanks since it's expected to engage other tanks at an average range of 1-2km , while the larger ones are mounted on ships because destroyers might engage each other at 5-10km+ range while battleships at over 15-20km+ range

Yes, but because of the human element involved it would vary quite a bit within that range as well.

Then there's height. Height is important because the Earth is round.

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On a completely different topic:  If anyone is looking for a really good read, that believe it or not has a tie-in to spaceflight, allow me to recommend: Entangled Life

Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures by Merlin Sheldrake (goodreads.com)

An exceptionally well written (and easy to read) dive into all things fungi.

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15 minutes ago, JoeSchmuckatelli said:

@magnemoe answered effectively, but I will add a couple of things.  There are lots of ways to guestimate range,   Special marks on the reticle can be referenced against a known profile (height, width, length) of a target or more technological aids -  like radar, lasers, etc.  Parallax is only one solution, with the obvious limitations you assumed correctly.

I use 'guestimate' because there are also a myriad of ways for the range estimation to be off - it's really just to increase your chance of a hit on the first shot.  

Modern fire control systems are pretty effective; the firing agency (thing with the gun) rarely has to be able to see its own target anymore.

Artillery tend to be indirect fire only, tanks, ships using guns against other ships are the exceptions , yes most self propelled artillery can aim and shoot but this is for self defense, you also have smaller guns on armored fighting vehicles but thy tend to be low caliber or slower projectiles. 

1 hour ago, DDE said:

Yes, but because of the human element involved it would vary quite a bit within that range as well.

Then there's height. Height is important because the Earth is round.

An very good point, France tested out a submarine with two 8" guns before WW 2, yes it was an way to cheat the arms treatises at the time.
It was crippled by short range for its rangefinders, so it would be well inside the range of enemy 5" guns and as an submarine you was extremely vulnerable to damage, just making holes in the un-pressurized ballast tanks could easy sink you. 

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24 minutes ago, magnemoe said:

It was crippled by short range for its rangefinders, so it would be well inside the range of enemy 5" guns and as an submarine you was extremely vulnerable to damage, just making holes in the un-pressurized ballast tanks could easy sink you. 

The idea behind the Surcouf and less stark but still gun-heavy fleet submarines was that they could last a lot longer because of their tiny target profiles.

However, it eventually dawned on people that making a submarine surface to engage in a gun duel with a destroyer was an all-around silly idea.

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5 hours ago, ARS said:

On WW2-era vehicles, especially tanks and ships, we can see coincidence rangefinders mounted on it, from small, portable unit used by tank crew, mounted on tank's cupola, integrated on tank's turret, and then we have the one mounted on fire control unit on destroyers, all the way up to a massive duplex rangefinder mounted on Yamato's fire control tower. All of those are from the smallest to the largest, so what I want to ask is, does the length of the 2 viewports (aka the width of the unit) corresponds to the maximum range that can be measured? (thus the effective firing range of the unit using it) Because the small ones are mounted on tanks since it's expected to engage other tanks at an average range of 1-2km , while the larger ones are mounted on ships because destroyers might engage each other at 5-10km+ range while battleships at over 15-20km+ range

The distance between the viewports doesn't correspond to the maximum range. The maximum range would be line of sight, by definition, adjusted for whatever optical magnification they installed in the rangefinder. The distance between the viewports would determine the accuracy of the rangefinder. The farther apart the viewports are the more accurately the rangefinder can determine the distance to the target. A battleship firing at a target 15 miles away would obviously need to have a much more accurate rangefinder than a tank firing at a target 1,000 yards away, so they would size the rangefinder accordingly. You could take the tank's rangefinder and use it to range targets at 15 miles, assuming that you could see them and that the mechanism on the rangefinder was calibrated for that distance. But the margin of error on that range is going to be much larger because of the much smaller parallax.

Amusingly, the larger the rangefinder the larger the minimum distance it can range as well, simply because of the limits on the rotation of the rangefinder's mechanical elements. But if they're getting that close, you probably have bigger things to worry about at that point.

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The wider the rangefinder, the more accurate the range.

The higher the rangefinder, the farther the range.

 

Conveniently, it is easier to mount a large (wide) rangefinder high up on a battleship than it is on a tank.

Edited by razark
Bourbon
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49 minutes ago, razark said:

Conveniently, it is easier to mount a large (wide) rangefinder high up on a battleship than it is on a tank

Fine for the old days - but modern naval combat is generally over the horizon.  Satellites do provide a nice, high vantage that assists with target acquisition and targeting: so, you are absolutely correct - the 

 

49 minutes ago, razark said:

higher the rangefinder, the farther the range.

 

Edited by JoeSchmuckatelli
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4 hours ago, JoeSchmuckatelli said:

Fine for the old days - but modern naval combat is generally over the horizon.  Satellites do provide a nice, high vantage that assists with target acquisition and targeting: so, you are absolutely correct

The manual, daytime-only, weather-sensitive coincidence rangefinders were rendered obsolete by radar-based fire control.

*laughs maniacally while charging at the Yamato in a destroyer*

Hornfischer%20F0%20SO%2009.jpg

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In a battle between ASAT and ABM orbital forces (in the midst of a nuclear exchange), who would win? Is it possible for one side to "win" the nuclear exchange (shoot down all of the other side's missiles and have theirs hit the enemy) or is there a way to still ensure mutually assured destruction?

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2 hours ago, SunlitZelkova said:

In a battle between ASAT and ABM orbital forces (in the midst of a nuclear exchange), who would win? Is it possible for one side to "win" the nuclear exchange (shoot down all of the other side's missiles and have theirs hit the enemy) or is there a way to still ensure mutually assured destruction?

It's still a MAD, MAD, MAD world.

MIRVs basically ensure that we should not get stupid enough as a species to try it. 

 

 

 

 

(Mind you - the D in MAD actually stands for 'Destruction' not 'Annihilation').  One estimate I read years ago is that the Northern Hemisphere economies would be reduced to something that resembles the 17th century (population numbers reduced to those levels as well).  Africa, most Islands and much of South America, OTOH survives largely unscathed - but subject to a crippled world economy.  (Note: this shouldn't relieve you... that world would be very difficult to survive in.  However, if you're just looking at survival of the species - chances are good humans will remain to pick up the pieces.  What comes out of that will be a very different place than we live now.).

Back to your original question - at some point we might get good enough with (or field enough) ABM platforms to shelter certain urban areas - but there's going to be stuff that gets through the best defenses.

As one smarty once said: the only way to win is not play the game.

Edited by JoeSchmuckatelli
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On 9/29/2021 at 12:22 PM, mikegarrison said:

One shot with the wave motion gun and there would be nothing left of that Star Destroyer.

 

Funny how the character that appears to be the chief engineer bears more than a passing resemblance to Scotty...

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6 hours ago, SunlitZelkova said:

In a battle between ASAT and ABM orbital forces (in the midst of a nuclear exchange), who would win? Is it possible for one side to "win" the nuclear exchange (shoot down all of the other side's missiles and have theirs hit the enemy) or is there a way to still ensure mutually assured destruction?

There's no good asnwer without considering the numerical match-up. It's why ABM has always been touted as a counter to "nuclear rogue states".

Particularly, ABM should be effective against many forms of ASAT - but it would find itself swamped by targets or could simply run out of ammo defending itself. Can't tell more without narrowing down the particular types of weapons on either side.

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