For Questions That Don't Merit Their Own Thread

[razark]

9 minutes ago, wumpus said:

But I doubt that electronic IFF (identify friend or foe) was a thing during WWII.

In fact, there were early systems in use. https://en.wikipedia.org/wiki/Identification_friend_or_foe#History

 

[wumpus]

49 minutes ago, razark said:

In fact, there were early systems in use. https://en.wikipedia.org/wiki/Identification_friend_or_foe#History

 

Which sure enough mentions a British use to target German aircraft responding to their own IFF.  The technology just wasn't there to make the encryption fast, light, and strong enough at the same time.  But apparently it didn't stop them from trying (and of course British vs. German air battles were typically fought at night where visual identification was far, far, worse.  So they pretty much had to try).

[DDE]

1 hour ago, wumpus said:

True, and a gun optimized to hit a V-1 is unlikely to hit a spitfire (wrong lead times).

As if a late WWI mechanical computer couldn't account for lead time on the fly, pun intended.

[kerbiloid]

2 hours ago, wumpus said:

But I doubt that electronic IFF (identify friend or foe) was a thing during WWII.

Ordnung und Disziplin.
If you can synchronize your watches, it's Germans.
Otherwise it's somebody else.

***

In forest also shibboleths, like "дорога" /dar'oga/.

[wumpus]

44 minutes ago, DDE said:

As if a late WWI mechanical computer couldn't account for lead time on the fly, pun intended.

Sure it could, but if you simply lockout any lead slower than the fastest British Vne you don't have to worry about IFF (assuming you are only targeting V-1s).

[kerbiloid]

You can try colored smokes.
 

[tater]

Apollo 17 image. Jack Schmitt heading back to the rover.

[kerbiloid]

Quote

Recently Retired USAF General Makes Eyebrow Raising Claims About Advanced Space Technology
... fantastic technology exists that could transport a human anywhere on earth within an hour.  

https://www.thedrive.com/the-war-zone/31445/recently-retired-usaf-general-makes-eyebrow-raising-claims-about-advanced-space-technology

Spoiler

 

[Spacescifi]

 

So Elon was willing to consider aerospikes in the past... enough to actually watch a demo test fire. You can bring up the video if you wish, but the test fire failed.

The plug aerospike shot off when the exhaust ran over it after a matter of seconds. Elon was not impressed.

 

 

Question: What if you magnetized the plug aerospike? Could that prevent the exhaust from blowing it off?

 

By the way... plug aerospikes resemble truncated cones with flat noses.

[DDE]

3 hours ago, Spacescifi said:

Question: What if you magnetized the plug aerospike? Could that prevent the exhaust from blowing it off?

Why bother with magnetics rather than solid fixtures?

I imagine it was just a retrofit aerospike and not an engine with multiple peripheral thrust cells to reduce the load on the actual aerospike.

[ARS]

What are those circular thing on most Soviet and Russian submarine that looks like the logo of Umbrella Corporation? Is that a hatch?

[kerbiloid]

44 minutes ago, ARS said:

What are those circular thing on most Soviet and Russian submarine that looks like the logo of Umbrella Corporation? Is that a hatch?

https://en.wikipedia.org/wiki/Rescue_buoy_(submarine)

[ARS]

Does big-caliber guns still have place in current day naval warfare? Like 200mm caliber guns of heavy cruisers and above, up until battleship-caliber gun of 300mm-400mm, or does the missiles have taken their place in naval warfare that they become insignificant today? What's the maximum caliber of modern naval guns (as in the one intended to be used on ship-to-ship combat) that's in service today?

[razark]

1 hour ago, ARS said:

Does big-caliber guns still have place in current day naval warfare? Like 200mm caliber guns of heavy cruisers and above, up until battleship-caliber gun of 300mm-400mm, or does the missiles have taken their place in naval warfare that they become insignificant today?

They are outdated¹.  By the time a ship is in range to use them, missiles and aircraft would have long since dealt with any significant targets.

The only ship-to-ship gun battles that are likely to occur today would be on the order of destroyer vs. small boat types of engagements.  Basically, someone's being attacked by a boat small enough to make expending a missile too costly to justify, or too hard to hit with it.  Any larger threats are going to be engaged at the missile/air support range, before guns reach effective distance.  When the Iowas were brought back in the '80s, they were basically turned into missile boats, to the point that removing some of the heavy guns to add fixed-wing aircraft facilities was under consideration.

 

1 hour ago, ARS said:

What's the maximum caliber of modern naval guns (as in the one intended to be used on ship-to-ship combat) that's in service today?

To my knowledge, guns in the 5-inch (127mm) range are the high end of the range, anything larger being used for shore bombardment, and very few of those in service anyway.

 

 

¹For naval combat. They've been outdated since the early 1940s for anything beside gunfire support. 

Edited December 23, 2019 by razark

[DDE]

3 hours ago, ARS said:

What's the maximum caliber of modern naval guns (as in the one intended to be used on ship-to-ship combat) that's in service today?

130 mm, with one German boat experimenting with a turret from a 155 mm self-propelled howitzer. The Zumwalt carries two 155 mm guns, but the $1 mln/round guided munitions won't be delivered 'in the foreseeable future', leaving the magazines empty.

3 hours ago, ARS said:

Like 200mm caliber guns of heavy cruisers and above, up until battleship-caliber gun of 300mm-400mm, or does the missiles have taken their place in naval warfare that they become insignificant today?

Missiles have longer range and in many cases travel faster. That leaves guns two advantages: more rounds in less space, and cheaper rounds. That leaves them no room in ship-to-ship engagements unless the target is of the "Somali pirates with RPGs" type. They do have a niche in naval gunfire support (hence the two guns on Zumwalt and the four guns on Sovremennyi) and there's controversy whether large-bore flak guns have use in the present environment. The Italians, who tend to plop a 76 mm rapid-fire gun whenever there's room, have developed guided anti-aircraft/missile rounds for it, which should act as close-range mini-missiles with alternative, much more compact propulsion.

[DDE]

@ARS

[tater]

 

[magnemoe]

14 hours ago, DDE said:

130 mm, with one German boat experimenting with a turret from a 155 mm self-propelled howitzer. The Zumwalt carries two 155 mm guns, but the $1 mln/round guided munitions won't be delivered 'in the foreseeable future', leaving the magazines empty.

Missiles have longer range and in many cases travel faster. That leaves guns two advantages: more rounds in less space, and cheaper rounds. That leaves them no room in ship-to-ship engagements unless the target is of the "Somali pirates with RPGs" type. They do have a niche in naval gunfire support (hence the two guns on Zumwalt and the four guns on Sovremennyi) and there's controversy whether large-bore flak guns have use in the present environment. The Italians, who tend to plop a 76 mm rapid-fire gun whenever there's room, have developed guided anti-aircraft/missile rounds for it, which should act as close-range mini-missiles with alternative, much more compact propulsion.

Zumwalt can use standard 155 mm shells of various types including smart ones. The reason for using 155 mm is that this is the shells who see most developmemt. 

Zumwalt guns however has extra capabilities, it can take longer shells than standard i think. And yes making a spesial shell for 8 guns is stupid.

[Guest]

On 12/14/2019 at 12:39 PM, tater said:

Apollo 17 image. Jack Schmitt heading back to the rover.

"ight imma head out"

Edited December 23, 2019 by Guest

[DDE]

29 minutes ago, magnemoe said:

Zumwalt can use standard 155 mm shells of various types including smart ones.

Citation needed. It is my understanding that there are no "standard" shells for it to use.

Quote

AGS can only use ammunition designed specifically for the system. Only one ammunition type was designed, and the Navy halted its procurement in November 2016 due to cost ($800,000 to $1 million per round), so the AGS has no ammunition and cannot be used.

 

[ARS]

Submarines use passive sonar to find other surface ships and submarines by the noise they make. Could a modern-day submarine find wooden age of sail ships on the surface solely by passive sonar? (No periscope, no active sonar, no raising radar mast) Especially considering age of sail ships don't have propellers. Going further, here's some variation:

1. Age of sail ship does not move, is it more difficult to detect using passive sonar? Assuming the crew also stays quiet and doesn't act like Black Pearl crew. Does moving without propellers (only sails) could make the noise that's high enough to be detected by passive sonar?

2. Could the modern submarine detect it using active sonar? If it raises the periscope, how visible the submarine is for the age of sail observer when it's observing the age of sail ship from minimum distance for direct visual contact? Assuming the observer only use age of sail era telescope

3. If the crew of age of sail ship DOES act like black pearl crew, aka being noisy pirates, could it be detected by passive sonar?

[kerbiloid]

As they periodically collide with fishing boats, probably they don't "see" them confidently.

And the periscope leaves a foam trace on the water, so probably this trace would be seen from the mast.
Also, looks like Jules Verne's readers considered that possible.

Edited December 25, 2019 by kerbiloid

[DDE]

12 hours ago, ARS said:

1. Age of sail ship does not move, is it more difficult to detect using passive sonar? Assuming the crew also stays quiet and doesn't act like Black Pearl crew. Does moving without propellers (only sails) could make the noise that's high enough to be detected by passive sonar?

very unlikely. You're stuck with considerable hydrodynamic noise, but close to the surface.

12 hours ago, ARS said:

Could the modern submarine detect it using active sonar?

With difficulty. Those were pretty small ships.

12 hours ago, ARS said:

If it raises the periscope, how visible the submarine is for the age of sail observer when it's observing the age of sail ship from minimum distance for direct visual contact? Assuming the observer only use age of sail era telescope

Assuming the observer even knows what to look for? Still rather short.

12 hours ago, ARS said:

3. If the crew of age of sail ship DOES act like black pearl crew, aka being noisy pirates, could it be detected by passive sonar?

Doubtful. Passive sonar isn't actually optimized to listen for human-made noises but rather for machinery-made noises.

[razark]

19 hours ago, ARS said:

1. Age of sail ship does not move, is it more difficult to detect using passive sonar? Assuming the crew also stays quiet and doesn't act like Black Pearl crew. Does moving without propellers (only sails) could make the noise that's high enough to be detected by passive sonar?

A wooden ship is going to make noise.  It would have moving parts that a modern ship does not.  Ropes rubbing against wood, wood planks moving against wooden planks and frames, sail noise transmitted to the hull, in addition to the water moving against the hull.  There was no reason to dampen the sounds at the time, so it was not an issue that was considered.  There will be something on passive sonar.

 

19 hours ago, ARS said:

2. ... If it raises the periscope, how visible the submarine is for the age of sail observer when it's observing the age of sail ship from minimum distance for direct visual contact? Assuming the observer only use age of sail era telescope

Depends on the sub skipper.  Minimizing periscope signature is a vital part of submarine operation, so the 'scope is exposed for seconds at a time.  In addition, a sail-era crew isn't going to be trained to look for a periscope or the feather it creates, much less recognize what it means if they do see it.

 

19 hours ago, ARS said:

3. If the crew of age of sail ship DOES act like black pearl crew, aka being noisy pirates, could it be detected by passive sonar?

I do not know exactly what you are referring to, as I haven't seen the movies.  A sailing ship is going to make a lot of noise.  It will be picked up on passive sonar.  Whether the sub crew knows what to do with strange transient sounds is a completely different question, even if it doesn't get filtered out first, anyway.  I think a competent skipper would be likely to investigate the source of the noise, unless his mission overrode the risk involved.

 

 

19 hours ago, ARS said:

2. Could the modern submarine detect it using active sonar?

Interesting question that I have not seen any info on.  I know a number of wooden-hulled ships were used in WWII, so an investigation into patrol reports from the era might provide some insight.  If anything later has been declassified, seek it out.

[kerbiloid]

If I was a sonar designer, I would just filter out all frequencies beyond the motor "knock-knock-knock...", so the drunken sailors on wooden boats would be filtered out like any other sea fauna.

If a submarine doesn't "see" a sailship, it's "a rhino's vision is poor , but with his mass that's not his problem".

If a sub commander is fond of listening whale songs when going to bed as a lullaby, but instead of whales he is hearing at 2 a.m. "What will we do with a drunken sailor!!!" from above, he may get angry an indeed show what he will do with.