At the end of the day, that's the practical answer to most of these complaints. Why wasn't the access panel screwed down? Because four screws are more expensive than one pressure-fit spring - which is why panels in your car are no longer screwed down, either. Why is the extinguisher not strapped securely in? "Well, we did some safety simulations and found out that it'll only pop loose like 3% of the time, and in most of those cases the occupant dies anyway, so we don't see justification for the extra expense." We don't need armor on a research sub, so we're not going to put it on - just make the hull barely as thick as it needs to be to survive the depth on the label. Sure, it could endanger a crew, but that's their fault for not buying a better model from us; maybe their leadership will decide to buy one of our fine military machines after the Cyclops gets whacked.
Everything we see in-game points to Alterra being the quintessential megacorporation: profits before all. Which means unnecessary expenses won't be made - and the definition of "unnecessary" is highly distorted. Three cents in screws versus one cent for a spring - use the spring. Doesn't matter that screws are better; they're more expensive.
Well, we'll see how much it costs alterra to get their faces to look like they did before I re-arranged them.
So... USN retired submariner here to throw in his own two cents on the discussion. For reference, when I say retired, I mean I left the service about a month ago.
1) Cavitation. The explanation was great, and he's got the main thrust of what it is. He was incorrect on one point, but I'll save that for a different point of my own here in a moment. What I will say though is this - the OP is correct in that cavitation should be tied to depth, though not numbers they suggested. 150m (450-ish feet) is deep enough that most speeds below about 20 knots would be free of cavitation on a military prop. Even apart from the prop though, is the hull form - and in this case, that hull is all kinds of not sleek or hydrodynamic. That would make the prop work harder, meaning more RPM to get the same speed as a ship with a more hydrodynamic hull design. Of course, that doesn't matter because the Cyclops don't have a military prop... or any kind of propeller at all... what we have is something else entirely.
2) The Cyclops doesn't HAVE a propeller... it has an IMPELLER. Also sometimes called a pump-jet or propullsor. It's used on current submarine designs (the US VIRGINIA and SEAWOLF classes currently, and appeared on a single hull of the Russian KILO class as well), and is a lot quieter than even military props. I'm not gonna get into the whys because it's not relevant here (aside from having to contradict SciFi's comment about how the Cyclops' prop design would be louder... sorry guy!), but the important thing here is to know that because of their design, they rotate at much slower RPM to create the same kind of forward movement. Less RPM = less chance of cavitation = quieter system.
Image for reference only - note the design on the aft end - very similar to the Cyclops.
Anyway, long and short of this is that even if the Cyclops had the best propulsion method ever designed (Unlikely... Alterra!), that still wouldn't matter in this case. Keep in mind that sharks are able to sense electromagnetism, and have been the source of many US Navy towed arrays being destroyed just by biting them. It's very possible that it isn't sonics that the creatures are attracted to, but the ship's other emissions or 'noise'. As was pointed out earlier, 'Silent Running' may be turning off equipment and the like, and that would be why the creatures no longer react to the ship's presence.
At the end of the day, that's the practical answer to most of these complaints. Why wasn't the access panel screwed down? Because four screws are more expensive than one pressure-fit spring - which is why panels in your car are no longer screwed down, either. Why is the extinguisher not strapped securely in? "Well, we did some safety simulations and found out that it'll only pop loose like 3% of the time, and in most of those cases the occupant dies anyway, so we don't see justification for the extra expense." We don't need armor on a research sub, so we're not going to put it on - just make the hull barely as thick as it needs to be to survive the depth on the label. Sure, it could endanger a crew, but that's their fault for not buying a better model from us; maybe their leadership will decide to buy one of our fine military machines after the Cyclops gets whacked.
Everything we see in-game points to Alterra being the quintessential megacorporation: profits before all. Which means unnecessary expenses won't be made - and the definition of "unnecessary" is highly distorted. Three cents in screws versus one cent for a spring - use the spring. Doesn't matter that screws are better; they're more expensive.
Why put money into giving the Aurora A+ Leasiure facilities when the C will pass galactic standards?
@Shadriss You should watch Jive Turkey play Cold Waters, he used to be a bubblehead on the 688s. Also, @ApoNono here is former USN, also has a YT channel, mostly plays Astroneer at this point (but has a Subnautica series and I'd love to see him play Cold Waters).
Also, to satisfy my (and I imagine @scifiwriterguy 's) curiosity, how can you tell an impeller from a ducted propeller?
I'm not gonna get into the whys because it's not relevant here (aside from having to contradict SciFi's comment about how the Cyclops' prop design would be louder... sorry guy!), but the important thing here is to know that because of their design, they rotate at much slower RPM to create the same kind of forward movement.
No sweat, Navy. It was a great catch; I didn't look closely enough. Penalty of working from a memory that was a little too rusty this time out.
For the rest of us: A ducted prop and a propulsor are similar at first glance, but on second look can be differentiated - and have some very substantial differences.
A ducted propeller is effectively an ordinary prop enclosed in a tube only somewhat longer than the prop is deep (the shroud is a tad longer than the blade pitch). It makes for more efficient operation at low speed, but once the prop is turning fast enough for instabilities to occur, the shroud has a tendency to magnify the turbulence specifically because there's a large enough gap between prop and shroud. Noisy water in, noisier water out. Ducted props are common on high-strength, low speed applications like tugboats, but they're being phased out in favor of designs like azipods.
Pumpjets, on the other hand use blades that are sized very close to the inner diameter of the duct. This minimizing the area in which tip turbulence can form and, as a result, improving efficiency. It also serves to increase and focus pressure, making the propeller (correctly called an impeller in this situation) operate far more efficiently than it could otherwise. Increasing the difference is the fact that pumpjets typically employ dynamic guide vanes to "tune" the flow of water into the impeller for maximum efficiency, whereas ducted propellers do not. Smooth water in and a very efficient propulsion system mean high-pressure, smooth water out.
The pumpjet most people are familiar with is the Jet-Ski, which brings water into the propulsion duct through an intake under the keel, feeds it to the impeller, and ejects the accelerated water through a discharge nozzle. This is a tiny example; they can be scaled up - torpedoes have used this design for years, and newer subs (as mentioned) have begun employing them. It's more technically complex and requires far more sophisticated engineering, but in terms of effectiveness, they're hard to beat.
Where I screwed up - and what @Shadriss and his sharp eyes caught - was that the design of the Cyclops does, in fact, use a propulsor. Take a look at its aft end and you'll see that the blades are very closely fitted to the size of the shroud. Were it a simple ducted prop, it'd be considerably noisier at any speed over about 10 knots. But it's not a ducted prop; as Shadriss pointed out, it's a pumpjet - and that completely changes the math.
Oh, and Shadriss? If nobody's said it yet: welcome to the forums! Glad to have you here.
I'm not gonna get into the whys because it's not relevant here (aside from having to contradict SciFi's comment about how the Cyclops' prop design would be louder... sorry guy!), but the important thing here is to know that because of their design, they rotate at much slower RPM to create the same kind of forward movement.
No sweat, Navy. It was a great catch; I didn't look closely enough. Penalty of working from a memory that was a little too rusty this time out.
For the rest of us: A ducted prop and a propulsor are similar at first glance, but on second look can be differentiated - and have some very substantial differences.
A ducted propeller is effectively an ordinary prop enclosed in a tube only somewhat longer than the prop is deep (the shroud is a tad longer than the blade pitch). It makes for more efficient operation at low speed, but once the prop is turning fast enough for instabilities to occur, the shroud has a tendency to magnify the turbulence specifically because there's a large enough gap between prop and shroud. Noisy water in, noisier water out. Ducted props are common on high-strength, low speed applications like tugboats, but they're being phased out in favor of designs like azipods.
Pumpjets, on the other hand use blades that are sized very close to the inner diameter of the duct. This minimizing the area in which tip turbulence can form and, as a result, improving efficiency. It also serves to increase and focus pressure, making the propeller (correctly called an impeller in this situation) operate far more efficiently than it could otherwise. Increasing the difference is the fact that pumpjets typically employ dynamic guide vanes to "tune" the flow of water into the impeller for maximum efficiency, whereas ducted propellers do not. Smooth water in and a very efficient propulsion system mean high-pressure, smooth water out.
The pumpjet most people are familiar with is the Jet-Ski, which brings water into the propulsion duct through an intake under the keel, feeds it to the impeller, and ejects the accelerated water through a discharge nozzle. This is a tiny example; they can be scaled up - torpedoes have used this design for years, and newer subs (as mentioned) have begun employing them. It's more technically complex and requires far more sophisticated engineering, but in terms of effectiveness, they're hard to beat.
Where I screwed up - and what @Shadriss and his sharp eyes caught - was that the design of the Cyclops does, in fact, use a propulsor. Take a look at its aft end and you'll see that the blades are very closely fitted to the size of the shroud. Were it a simple ducted prop, it'd be considerably noisier at any speed over about 10 knots. But it's not a ducted prop; as Shadriss pointed out, it's a pumpjet - and that completely changes the math.
Oh, and Shadriss? If nobody's said it yet: welcome to the forums! Glad to have you here.
BTW @scifiwriterguy you've probably taught me more about underwater engineering and physics than my school teacher
will be nice add this options in the seamoth beacuse it's a sub too, cavitation, levels of speed...
my experience on cavitation is with cold waters too xD
@Shadriss You should watch Jive Turkey play Cold Waters, he used to be a bubblehead on the 688s. Also, @ApoNono here is former USN, also has a YT channel, mostly plays Astroneer at this point (but has a Subnautica series and I'd love to see him play Cold Waters).
Also, to satisfy my (and I imagine @scifiwriterguy 's) curiosity, how can you tell an impeller from a ducted propeller?
Familiar with the game - head onto Subsim's forums and you'll see me over there correcting a lot of misunderstandings there as well. Decent game, but very much an arcade type game, and not a simulation.
As to your second question, well, SciFi already explained it far better than I would have.
So thanks, SciFi... also, nice Hitchhiker's Guide reference in your 'location'. Wonder how many have caught that? Also: What were the probability figures on that?
@Shadriss You should watch Jive Turkey play Cold Waters, he used to be a bubblehead on the 688s. Also, @ApoNono here is former USN, also has a YT channel, mostly plays Astroneer at this point (but has a Subnautica series and I'd love to see him play Cold Waters).
Also, to satisfy my (and I imagine @scifiwriterguy 's) curiosity, how can you tell an impeller from a ducted propeller?
Familiar with the game - head onto Subsim's forums and you'll see me over there correcting a lot of misunderstandings there as well. Decent game, but very much an arcade type game, and not a simulation.
As to your second question, well, SciFi already explained it far better than I would have.
So thanks, SciFi... also, nice Hitchhiker's Guide reference in your 'location'. Wonder how many have caught that? Also: What were the probability figures on that?
There's a Realism Mod for Cold Waters over on the SubSim forums, are you familiar with it, and if so, does it do a decent job of increasing realism, or only a little? Also, if you have a Cold Waters series or something (or if you ever do) be sure to post it; I'd love to check it out!
BTW @scifiwriterguy you've probably taught me more about underwater engineering and physics than my school teacher
Thank you.
Believe it or not, once upon a time it was my job to teach science teachers how to teach science. Something I kept trying to hammer into their skulls was that in order to make science and engineering not just interesting but also approachable, you have to put it in a context and scope that people can relate to. A math-heavy explanation in a textbook won't hook many people into wanting to learn it - but show them something cool in the real world, and most people have this itch to know the hows and whys. It's like seeing a magic trick; most of us just can't help but want to know how it's done.
So thanks, SciFi... also, nice Hitchhiker's Guide reference in your 'location'. Wonder how many have caught that? Also: What were the probability figures on that?
Maybe not the same as a sperm whale turning into a bowl of petunias...but probably not much better.
Incidentally, it's worth noting that cavitation isn't always the enemy. A whole branch of marine engineering has opened up that uses cavitation as an asset rather than a liability. A vapor produces less friction than a liquid, so engineers have harnessed a concept called supercavitation to increase efficiency. Fast and dirty, it involves deliberately causing cavitation around a propeller or impeller - or the whole vehicle.
Super-powerboats are now widely using supercavitating propellers; the reduced friction profile means faster turns and, as a result, more transmitted power. There are two design factions for supercavitating props: one uses exotic-geometry scimitaresque blades; the other more closely resembles a screw - which, ironically, is a step back to the beginning of propeller design. (The first props really were threaded like screws, hence why we still refer to them as screws; it's a shortening of the original name "water screw" and, well, it just stuck.) The leading edge of the prop, be it blade or screw design, drops the water pressure low enough to induce cavitation, allowing the prop to cut through the lower-density water/vapor mixture and enjoy massive savings on friction loss. The design also avoids the damage caused by cavitation void collapse by tuning the pressure profile such that the cavitation bubbles collapse after leaving the screw, not on it.
Then there's the supercavitation design school that applies it to the entire vessel. In this case, we're talking torpedoes. By encasing the entire torpedo in cavitation-induced bubbles, friction between the torpedo and the water around it drops dramatically. Coupled with a high-efficiency propulsion system, supercavitating torpedoes can achieve speeds conventional torpedoes can't even dream at. These designs have been around since the late '70s, but haven't enjoyed a lot of success. They're temperamental, expensive, and extraordinarily complicated. The Russians have a version called the Shkval - which is less a torpedo and more an underwater solid-fueled rocket - capable of speeds up to 370kph and hasn't been used in combat or combat conditions, though the Russians insist that it's operational. The Germans built a better mousetrap in the early 2000s with their Barracuda design, which could top 400 kph, but they decided that the thing was too expensive for the benefits provided and pretty much shelved it.
These designs were fast - the average conventional torpedo moves at around 100 kph, so supercavitation represents a fourfold increase - but the drawbacks have been just too severe. Expensive to build, expensive to maintain, difficult to field, and smaller carrying capacity have, so far, failed the cost-benefit test. Future improvements in materials and manufacturing technology may fix this (or future threats may justify the added headaches), but for now they remain just an interesting bit of marine engineering.
Incidentally, it's worth noting that cavitation isn't always the enemy. A whole branch of marine engineering has opened up that uses cavitation as an asset rather than a liability. A vapor produces less friction than a liquid, so engineers have harnessed a concept called supercavitation to increase efficiency. Fast and dirty, it involves deliberately causing cavitation around a propeller or impeller - or the whole vehicle.
Super-powerboats are now widely using supercavitating propellers; the reduced friction profile means faster turns and, as a result, more transmitted power. There are two design factions for supercavitating props: one uses exotic-geometry scimitaresque blades; the other more closely resembles a screw - which, ironically, is a step back to the beginning of propeller design. (The first props really were threaded like screws, hence why we still refer to them as screws; it's a shortening of the original name "water screw" and, well, it just stuck.) The leading edge of the prop, be it blade or screw design, drops the water pressure low enough to induce cavitation, allowing the prop to cut through the lower-density water/vapor mixture and enjoy massive savings on friction loss. The design also avoids the damage caused by cavitation void collapse by tuning the pressure profile such that the cavitation bubbles collapse after leaving the screw, not on it.
Then there's the supercavitation design school that applies it to the entire vessel. In this case, we're talking torpedoes. By encasing the entire torpedo in cavitation-induced bubbles, friction between the torpedo and the water around it drops dramatically. Coupled with a high-efficiency propulsion system, supercavitating torpedoes can achieve speeds conventional torpedoes can't even dream at. These designs have been around since the late '70s, but haven't enjoyed a lot of success. They're temperamental, expensive, and extraordinarily complicated. The Russians have a version called the Shkval - which is less a torpedo and more an underwater solid-fueled rocket - capable of speeds up to 370kph and hasn't been used in combat or combat conditions, though the Russians insist that it's operational. The Germans built a better mousetrap in the early 2000s with their Barracuda design, which could top 400 kph, but they decided that the thing was too expensive for the benefits provided and pretty much shelved it.
These designs were fast - the average conventional torpedo moves at around 100 kph, so supercavitation represents a fourfold increase - but the drawbacks have been just too severe. Expensive to build, expensive to maintain, difficult to field, and smaller carrying capacity have, so far, failed the cost-benefit test. Future improvements in materials and manufacturing technology may fix this (or future threats may justify the added headaches), but for now they remain just an interesting bit of marine engineering.
Of course, supercavitation is also loud as all heck. Not really much good for a submarine either.
Also, SciFi - RE: "Maybe not the same as a sperm whale turning into a bowl of petunias...but probably not much better." The whale didn't turn into the bowl of petunias. The two deadly missiles with nuclear warheads did... at a probability factor of Infinity minus one to one against.
The very, very, very short version, though, is bubbles formed by low water pressure caused by the movement of a propeller. These bubbles, when they collapse, create noise and can damage even hardened steel and other durable materials.
Comments
Well, we'll see how much it costs alterra to get their faces to look like they did before I re-arranged them.
1) Cavitation. The explanation was great, and he's got the main thrust of what it is. He was incorrect on one point, but I'll save that for a different point of my own here in a moment. What I will say though is this - the OP is correct in that cavitation should be tied to depth, though not numbers they suggested. 150m (450-ish feet) is deep enough that most speeds below about 20 knots would be free of cavitation on a military prop. Even apart from the prop though, is the hull form - and in this case, that hull is all kinds of not sleek or hydrodynamic. That would make the prop work harder, meaning more RPM to get the same speed as a ship with a more hydrodynamic hull design. Of course, that doesn't matter because the Cyclops don't have a military prop... or any kind of propeller at all... what we have is something else entirely.
2) The Cyclops doesn't HAVE a propeller... it has an IMPELLER. Also sometimes called a pump-jet or propullsor. It's used on current submarine designs (the US VIRGINIA and SEAWOLF classes currently, and appeared on a single hull of the Russian KILO class as well), and is a lot quieter than even military props. I'm not gonna get into the whys because it's not relevant here (aside from having to contradict SciFi's comment about how the Cyclops' prop design would be louder... sorry guy!), but the important thing here is to know that because of their design, they rotate at much slower RPM to create the same kind of forward movement. Less RPM = less chance of cavitation = quieter system.
Image for reference only - note the design on the aft end - very similar to the Cyclops.
Anyway, long and short of this is that even if the Cyclops had the best propulsion method ever designed (Unlikely... Alterra!), that still wouldn't matter in this case. Keep in mind that sharks are able to sense electromagnetism, and have been the source of many US Navy towed arrays being destroyed just by biting them. It's very possible that it isn't sonics that the creatures are attracted to, but the ship's other emissions or 'noise'. As was pointed out earlier, 'Silent Running' may be turning off equipment and the like, and that would be why the creatures no longer react to the ship's presence.
Or it's a game, and nothing will ever be perfect.
Why put money into giving the Aurora A+ Leasiure facilities when the C will pass galactic standards?
Also, to satisfy my (and I imagine @scifiwriterguy 's) curiosity, how can you tell an impeller from a ducted propeller?
No sweat, Navy.
For the rest of us: A ducted prop and a propulsor are similar at first glance, but on second look can be differentiated - and have some very substantial differences.
A ducted propeller is effectively an ordinary prop enclosed in a tube only somewhat longer than the prop is deep (the shroud is a tad longer than the blade pitch). It makes for more efficient operation at low speed, but once the prop is turning fast enough for instabilities to occur, the shroud has a tendency to magnify the turbulence specifically because there's a large enough gap between prop and shroud. Noisy water in, noisier water out. Ducted props are common on high-strength, low speed applications like tugboats, but they're being phased out in favor of designs like azipods.
Pumpjets, on the other hand use blades that are sized very close to the inner diameter of the duct. This minimizing the area in which tip turbulence can form and, as a result, improving efficiency. It also serves to increase and focus pressure, making the propeller (correctly called an impeller in this situation) operate far more efficiently than it could otherwise. Increasing the difference is the fact that pumpjets typically employ dynamic guide vanes to "tune" the flow of water into the impeller for maximum efficiency, whereas ducted propellers do not. Smooth water in and a very efficient propulsion system mean high-pressure, smooth water out.
The pumpjet most people are familiar with is the Jet-Ski, which brings water into the propulsion duct through an intake under the keel, feeds it to the impeller, and ejects the accelerated water through a discharge nozzle. This is a tiny example; they can be scaled up - torpedoes have used this design for years, and newer subs (as mentioned) have begun employing them. It's more technically complex and requires far more sophisticated engineering, but in terms of effectiveness, they're hard to beat.
Where I screwed up - and what @Shadriss and his sharp eyes caught - was that the design of the Cyclops does, in fact, use a propulsor. Take a look at its aft end and you'll see that the blades are very closely fitted to the size of the shroud. Were it a simple ducted prop, it'd be considerably noisier at any speed over about 10 knots. But it's not a ducted prop; as Shadriss pointed out, it's a pumpjet - and that completely changes the math.
Oh, and Shadriss? If nobody's said it yet: welcome to the forums!
BTW @scifiwriterguy you've probably taught me more about underwater engineering and physics than my school teacher
my experience on cavitation is with cold waters too xD
Familiar with the game - head onto Subsim's forums and you'll see me over there correcting a lot of misunderstandings there as well. Decent game, but very much an arcade type game, and not a simulation.
As to your second question, well, SciFi already explained it far better than I would have.
So thanks, SciFi... also, nice Hitchhiker's Guide reference in your 'location'. Wonder how many have caught that? Also: What were the probability figures on that?
There's a Realism Mod for Cold Waters over on the SubSim forums, are you familiar with it, and if so, does it do a decent job of increasing realism, or only a little? Also, if you have a Cold Waters series or something (or if you ever do) be sure to post it; I'd love to check it out!
Thank you.
Believe it or not, once upon a time it was my job to teach science teachers how to teach science. Something I kept trying to hammer into their skulls was that in order to make science and engineering not just interesting but also approachable, you have to put it in a context and scope that people can relate to. A math-heavy explanation in a textbook won't hook many people into wanting to learn it - but show them something cool in the real world, and most people have this itch to know the hows and whys. It's like seeing a magic trick; most of us just can't help but want to know how it's done.
Maybe not the same as a sperm whale turning into a bowl of petunias...but probably not much better.
Incidentally, it's worth noting that cavitation isn't always the enemy. A whole branch of marine engineering has opened up that uses cavitation as an asset rather than a liability. A vapor produces less friction than a liquid, so engineers have harnessed a concept called supercavitation to increase efficiency. Fast and dirty, it involves deliberately causing cavitation around a propeller or impeller - or the whole vehicle.
Super-powerboats are now widely using supercavitating propellers; the reduced friction profile means faster turns and, as a result, more transmitted power. There are two design factions for supercavitating props: one uses exotic-geometry scimitaresque blades; the other more closely resembles a screw - which, ironically, is a step back to the beginning of propeller design. (The first props really were threaded like screws, hence why we still refer to them as screws; it's a shortening of the original name "water screw" and, well, it just stuck.) The leading edge of the prop, be it blade or screw design, drops the water pressure low enough to induce cavitation, allowing the prop to cut through the lower-density water/vapor mixture and enjoy massive savings on friction loss. The design also avoids the damage caused by cavitation void collapse by tuning the pressure profile such that the cavitation bubbles collapse after leaving the screw, not on it.
Then there's the supercavitation design school that applies it to the entire vessel. In this case, we're talking torpedoes. By encasing the entire torpedo in cavitation-induced bubbles, friction between the torpedo and the water around it drops dramatically. Coupled with a high-efficiency propulsion system, supercavitating torpedoes can achieve speeds conventional torpedoes can't even dream at. These designs have been around since the late '70s, but haven't enjoyed a lot of success. They're temperamental, expensive, and extraordinarily complicated. The Russians have a version called the Shkval - which is less a torpedo and more an underwater solid-fueled rocket - capable of speeds up to 370kph and hasn't been used in combat or combat conditions, though the Russians insist that it's operational. The Germans built a better mousetrap in the early 2000s with their Barracuda design, which could top 400 kph, but they decided that the thing was too expensive for the benefits provided and pretty much shelved it.
These designs were fast - the average conventional torpedo moves at around 100 kph, so supercavitation represents a fourfold increase - but the drawbacks have been just too severe. Expensive to build, expensive to maintain, difficult to field, and smaller carrying capacity have, so far, failed the cost-benefit test. Future improvements in materials and manufacturing technology may fix this (or future threats may justify the added headaches), but for now they remain just an interesting bit of marine engineering.
This game does that to you
Of course, supercavitation is also loud as all heck. Not really much good for a submarine either.
Also, SciFi - RE: "Maybe not the same as a sperm whale turning into a bowl of petunias...but probably not much better." The whale didn't turn into the bowl of petunias. The two deadly missiles with nuclear warheads did... at a probability factor of Infinity minus one to one against.
The above discussion explains it pretty well but I'd ask @scifiwriterguy for a full and thorough explanation
Here's the post where I run through the science: https://forums.unknownworlds.com/discussion/comment/2359041/#Comment_2359041
It's on page 1 of this thread.
The very, very, very short version, though, is bubbles formed by low water pressure caused by the movement of a propeller. These bubbles, when they collapse, create noise and can damage even hardened steel and other durable materials.