"Rocket torpedo" in HERO?

[Cancer]

A question for the folks who think about these sorts of things and are more familiar with the mechanics than I...

 

People have heard of the "rocket torpedo", a supercavitating underwater missile, that travels much faster than standard torpedoes. The lowest number I've seen for these things is 200 miles/hr; some places I've seen up to 500. There was an article about these in the May 2001 Scientific American; apparently the Soviets/Russians have had a version (the Shkval) that seems not to work real well, but the concept is scary, especially if you put a nuclear warhead on it.

 

This being a Champions question ... I want to extrapolate this concept to its logical conclusion, where the torpedo travels faster than the speed of sound in water. The speed of sound in sea water is temperature and pressure dependent but is listed at about 1500 meters/s, which converts to over 3300 miles/hr.

 

Because it is supersonic, from the target's point of view (in the water), such a device would be absolutely invisible by sonar (active or passive). If you're behind it, yes, it makes a lot of noise, but if it's heading for you, any sound it makes or reflects cannot reach you until after it has hit you. Electromagnetic tracking has its own difficulties, given that sea water doesn't transmit light very well, and radio/radar is attenuated in the water and generally reflected from the surface.

 

How would you build one of these things for a Champions campaign? (Ignore the payload ... I assume a standard Big F***in Bang warhead on top, and even I know how to look up/compute/add on non-nuclear RKA-AP equivalents ... but as someone is certain to notice, just the raw impact/move-through damage will be impressive as all get-out.)

 

A second, seemingly unrelated question: how deep in the ocean can GPS signals be reliably detected?

 

Obviously a hypersonic weapon cannot use active sonar for target acquisition, so other means are needed; the options are active electromagnetic target acquisition and homing of some kind, or "ballistic" (there is undoubtedly a better word than that ... what I mean is, shoot it so that it will be at the predicted position of the target, but it doesn't search for/recognize the target itself). Both modes are possible depending on the target. Firing at a standard attack submarine means you probably need active homing, but against a large static target (like an undersea domed base), the second mode is viable. But I don't think GPS is detectable at depth, so...

 

(I know, from HERO build p.o.v. the mechanism by which it homes isn't all that important until you try to counter it. But I know there will be efforts to counter these things, so I'm thinking ahead.)

[MitchellS]

Re: "Rocket torpedo" in HERO?

 

You build the torpedo as a summon or computer, and then give it however much swimming you want [and invisibility to sonars with the limitation only in front]. That way it can go as fast or slow as you need it to go.

 

As far as what the torpedo uses for guidance you can give it any detect you want and I'd throw in the rapid ability to represent that it can detect faster then it is moving in the water.

[psm]

Re: "Rocket torpedo" in HERO?

 

I assume the rocket torpedo has the same targeting a bullet has. Your "ballistic" describes it best. The submarine has the responsibility for choosing the right tragectory even with moving targets. I can't imagine the torpedo possessing the capability to detect anything at that speed in that environment. Of course I really don't know much about undersea warfare so I'm probably wrong. Unfortunately, I don't know how to build this and my book is home so I can't help (and yet I'm still replying, kinda weird huh?).

[Flames]

Re: "Rocket torpedo" in HERO?

 

I think it's just a long-range attack with some limitations based on what could be done to evade or deflect it. It's really just an underwater missile, right? Does it really have to be built as if it were some kind of vehicle?

[MitchellS]

Re: "Rocket torpedo" in HERO?

 

I think it's just a long-range attack with some limitations based on what could be done to evade or deflect it. It's really just an underwater missile' date=' right? Does it really have to be built as if it were some kind of vehicle? [/quote']

As it can be outrun, out maneuvered, etc., IMO, yes. Think about what a torpedo does in the water. That's not the same thing an energy blast does when fired. It's really 2 different effects. Also, unless you want to make house rules as to the speed of an energy blast/ranged killing attack the torpedo would always hit in the phase it's fired. Why re-invent the wheel when the wheel is just waiting to be used?

[Zeropoint]

Re: "Rocket torpedo" in HERO?

 

Realistically, a supersonic underwater missile would have severe problems sensing its environment. No form of electromagnetic radiation penetrates water reasonably well, except maybe very, very low frequency radio waves. I doubt that these would work well for radar. The only form of guidance that I could really see working would be inertial navigation. Hmm. Maybe magnetic fields? Those penetrate water just fine, but are hard to detect at long range.

 

Of course, that's "realistically". If you're talking about supertech, all bets are off.

 

Zeropoint

[Cancer]

Re: "Rocket torpedo" in HERO?

 

Realistically, a supersonic underwater missile would have severe problems sensing its environment. No form of electromagnetic radiation penetrates water reasonably well, except maybe very, very low frequency radio waves. I doubt that these would work well for radar. The only form of guidance that I could really see working would be inertial navigation. Hmm. Maybe magnetic fields? Those penetrate water just fine, but are hard to detect at long range.

 

Of course, that's "realistically". If you're talking about supertech, all bets are off.

 

Zeropoint

 

Yeah, I had many of the same thoughts (though you remembered the word "inertial" while I spaced it). ELF radar just isn't going to work. But what you mention there ... quasistatic magnetic field detection (magnetic anomalies) is a possibility ... shades of the old magnetic exploders that cursed the US Navy in WW2. It won't "see" very far, and it isn't going to work on nonferrous targets very well, but it's still something to think about.

[Zeropoint]

Re: "Rocket torpedo" in HERO?

 

A brief look at the web indicates that the speed of sound in water is approximately 1.5 kilometers per second. You could fire a torpedo like this from quite a ways out, without having to worry about your target taking much evasive action while the torpedo was in transit. Remember, they won't hear it coming, either. I think that predicting an intercept point and giving the torpedo just enough brains to stick to a straight line and know when it's time to explode would work just fine. It's moving around, or over, a mile per second.

 

Wait, this raises other problems. Now you're trying to hit something from ten miles away when you can't actually see it. This bears further thought.

 

Zeropoint

[Cancer]

Re: "Rocket torpedo" in HERO?

 

A brief look at the web indicates that the speed of sound in water is approximately 1.5 kilometers per second. You could fire a torpedo like this from quite a ways out, without having to worry about your target taking much evasive action while the torpedo was in transit. Remember, they won't hear it coming, either. I think that predicting an intercept point and giving the torpedo just enough brains to stick to a straight line and know when it's time to explode would work just fine. It's moving around, or over, a mile per second.

 

Wait, this raises other problems. Now you're trying to hit something from ten miles away when you can't actually see it. This bears further thought.

 

Zeropoint

 

Well, if you have whatever the CAPTOR system is called now ... in effect, an all-ocean fixed-in-place sonobuoy network ... working for you, and you're launching from a fixed base maybe hundreds of kilometers away, then it's not so big an issue. But from a lone intruding vessel, you're right.

[ghost-angel]

Re: "Rocket torpedo" in HERO?

 

Of course, given that velocity, shooting it at a close target will effectively be "Instant Hit" on the targeted location, allowing one to build a Torpedo using an RKA/EB instead of a Vehicle as is normal for this kind of construct.

[Dr. Anomaly]

Re: "Rocket torpedo" in HERO?

 

Well' date=' if you have whatever the CAPTOR system is called now ... in effect, an all-ocean fixed-in-place sonobuoy network ... working for you, and you're launching from a fixed base maybe [i']hundreds[/i] of kilometers away, then it's not so big an issue. But from a lone intruding vessel, you're right.

Uh...fuel? I doubt something like that would have the endurance for a transit of hundreds of kilometers. It's not a cruise missile, after all...and the energy costs for its movement are considerbly higher than those of a cruise missile.

 

Given its speed, a ballistic approach would probably get it close enough for a magnetic anomaly detector to help it do a last-moment course correction for impact, or let it know it was close enough to detonate and damage the target.

[Zeropoint]

Re: "Rocket torpedo" in HERO?

 

Uh...fuel? I doubt something like that would have the endurance for a transit of hundreds of kilometers. It's not a cruise missile, after all...and the energy costs for its movement are considerbly higher than those of a cruise missile.

 

Going supersonic in WATER? Darn right they are!!

[SvZurich]

Re: "Rocket torpedo" in HERO?

 

Bear in mind that such a weapon is a dead shot weapon. You fire and hope it hits (hence the nuclear warhead payload to guarantee a big explosion, like our old Subroc weapons http://www.designation-systems.net/dusrm/m-44.html ).

 

Remember, being supersonic, it can't use sonar (Sound Navigation and Ranging) to detect its target, nor do course corrections. You dead reckon where to fire it at, fire, and hope it kills with a huge explosion. Like the Subroc, it practically ensures your own death for launching. See, in order for you to make the detection from their own emitted sound waves via your passive sonar, you have to be within a few miles yourself. If you have a nuclear warhead (you will on this weapon), the shockwaves will get you. Bad.

 

Kimmie, former Sonar Technician.

[Zed-F]

Re: "Rocket torpedo" in HERO?

 

I would tend to think that such a weapon would not work well for underwater targets unless they are stationary. Usually, from long range, it is difficult enough to detect an underwater target so as to be unsure of its location with any degree of certainty. Unless you have something else doing the detecting for you, and pretty accurately, or are using a nuke warhead, it won't work. Moreover, SOSUS-type in-place sonobuoy nets are IIRC not that good for pinpointing enemy submarines, though they can give a good general idea of where a contact is.

 

Where I see this sort of weapon working better is against surface ships, which are generally easier to detect both with sonar and with radar or elint. Since surface ships tend to travel in groups, and since this weapon would undoubtedly be very expensive to build relative to conventional technology, I would tend to think a tacnuke would be the warhead of choice. Of course, since this is clearly supertech, you can define the parameters of what is possible/expensive and what isn't to suit your preference.

 

EDIT: perhaps a better way to do this would be to have a variable speed torpedo. Have it get launched in supersonic mode, and as it closes to its target area, it drops in speed to about a third the speed of sound in water. That gives it the ability to start using sonar to acquire targets, while still moving fast enough to be impossible to evade. Of course, cavitation noise might still render this option unfeasible.

[psm]

Re: "Rocket torpedo" in HERO?

 

Uh...fuel? I doubt something like that would have the endurance for a transit of hundreds of kilometers. It's not a cruise missile' date=' after all...and the energy costs for its movement are [i']considerbly[/i] higher than those of a cruise missile.

 

Believe it or not, it doesn't use much more fuel than an a regular missile. The main reason being that it doesn't travel through water but air. These torpedos use a process called supercavitation. The torpedo (I believe) release gas from the nose cone to encase itself in a pocket of air. Now the torpedo doesn't have to deal with the extra drag/fuel coefficient that would come from the water. This would allow a torpedo to cover large expanses with limited fuel. Pretty cool huh?

 

It appears that both the Chinese and Russians have these torpedos and the US is finally getting on board.

 

Also, I read somewhere the torpedo is controlled remotely by the submarine. As already stated the torpedo wouldn't have the capability to see underwater do to its speed and environment. Of course it would be difficult to dodge regardless because no one would know its coming anyway.

 

And thats one to grow on.

[hooligan x]

Re: "Rocket torpedo" in HERO?

 

elieve it or not' date=' it doesn't use much more fuel than an a regular missile. The main reason being that it doesn't travel through water but air. These torpedos use a process called supercavitation. The torpedo (I believe) release gas from the nose cone to encase itself in a pocket of air. Now the torpedo doesn't have to deal with the extra drag/fuel coefficient that would come from the water.[/quote']

 

OK, that's just freaking NEAT!

[Dr. Anomaly]

Re: "Rocket torpedo" in HERO?

 

Believe it or not' date=' it doesn't use much more fuel than an a regular missile. The main reason being that it doesn't travel through water but air. These torpedos use a process called supercavitation. The torpedo (I believe) release gas from the nose cone to encase itself in a pocket of air. Now the torpedo doesn't have to deal with the extra drag/fuel coefficient that would come from the water. This would allow a torpedo to cover large expanses with limited fuel. Pretty cool huh?[/quote']

Believe it or not, I knew that.

 

There's still a fuel usage problem, though. The torpedo needs to generate enough gas to keep a bubble around itself at all times. It's going to be constantly leaving that gas behind as it moves forward. For a trip length of many hundreds of kilometers, it's flatly impossible for it to carry enough compressed gas inside it to keep the bubble refreshed. Frankly, I'd have a tough time believing it could for more than, say, 5 or 10 miles.

 

A potential solution is to not carry compressed gas to create the bubble, but to use some kind of chemical reaction to continually generate gas as it travels. This would let you get a lot more "mileage" (from a fuel-based gas generator) than by using compressed gasses.

 

You still end up with a fuel problem, though, because I find it difficult to believe the torp could carry a sufficient supply of gas-generating fuel to refresh a bubble over a journey of several hundred kilometers.

 

I'm afraid when I was referencing the "power" requirements in my earlier post, I was thinking along these lines, not of it simply "brute forcing" its way through the water. I see now, though, while I was thinking that, there was no way for someone to have realized that from what I posted.

[Zeropoint]

Re: "Rocket torpedo" in HERO?

 

Also keep in mind that the existing supercavitating torpedoes travel at speeds of hundreds of miles per hour, while this discussion is centered on a supersonic torpedo, which opens a whole new can of worms.

 

Zeropoint

[psm]

Re: "Rocket torpedo" in HERO?

 

There's still a fuel usage problem, though. The torpedo needs to generate enough gas to keep a bubble around itself at all times. It's going to be constantly leaving that gas behind as it moves forward. For a trip length of many hundreds of kilometers, it's flatly impossible for it to carry enough compressed gas inside it to keep the bubble refreshed. Frankly, I'd have a tough time believing it could for more than, say, 5 or 10 miles.

 

A potential solution is to not carry compressed gas to create the bubble, but to use some kind of chemical reaction to continually generate gas as it travels. This would let you get a lot more "mileage" (from a fuel-based gas generator) than by using compressed gasses.

 

Yeah, I was thinking along the same lines about carrying compressed gas to create the air bubble too. Although, it appears there are also two other possibilities. One is where the exhaust from the rocket itself is diverted to the nose cone to create the gas bubble. A third solution is a specially designed nose cone to increase the natural tendency for any swift moving object in water to cavitate. I assume this would also require higher fuel demands due to the higher amount of friction.

 

As for the distance, I've read that the new russian torpedos can reach a 60+mile range. This would give it close to 100km. However, the sites I read this on seem less than respectable (or completely made up). I really believe the weapon is a better short range tactical devise (within 10-20 miles max).

Of course the technology is relatively new and could change in the next decade.

[TaxiMan]

Re: "Rocket torpedo" in HERO?

 

Just having fun....

 

1. Supersonic .NE. supercavitating (thanks Zeropoint). The H2O molecules aren't going to be pushed out of the way by compressed gas so easily. Power requirements go way up.

 

2. Power isn't a problem if you posit a big torpedo with on-board power generation - think a mini-nuclear sub.

 

3. Something like this is going to leave a mark as it moves. Remote sensing (satellites, reconnaisance aircraft) or distributed sound-sensing equipment (think sonobouys 10 miles out) should be able to pick it up if it travels very far.

 

4. Countermeasures - if it's controlled, jam it / redirect it. But if it's carrying a nuke, you gotta stop it. How about a anti-torpedo torpedo? If the Big Boy hits metal, it's going to crash & the nuke won't go off. Or, if that's too hard, get in front of it and use a shaped explosion to push some more-solid seawater into contact with the torpedo. If the Big Boy loses his leading H2O shield, it'll be like hitting a brick wall. No torpedo, no nuke.

 

Just ideas...

[gewing]

Re: "Rocket torpedo" in HERO?

 

A question for the folks who think about these sorts of things and are more familiar with the mechanics than I...

 

People have heard of the "rocket torpedo", a supercavitating underwater missile, that travels much faster than standard torpedoes. The lowest number I've seen for these things is 200 miles/hr; some places I've seen up to 500. There was an article about these in the May 2001 Scientific American; apparently the Soviets/Russians have had a version (the Shkval) that seems not to work real well, but the concept is scary, especially if you put a nuclear warhead on it.

 

This being a Champions question ... I want to extrapolate this concept to its logical conclusion, where the torpedo travels faster than the speed of sound in water. The speed of sound in sea water is temperature and pressure dependent but is listed at about 1500 meters/s, which converts to over 3300 miles/hr.

 

Because it is supersonic, from the target's point of view (in the water), such a device would be absolutely invisible by sonar (active or passive). If you're behind it, yes, it makes a lot of noise, but if it's heading for you, any sound it makes or reflects cannot reach you until after it has hit you. Electromagnetic tracking has its own difficulties, given that sea water doesn't transmit light very well, and radio/radar is attenuated in the water and generally reflected from the surface.

 

How would you build one of these things for a Champions campaign? (Ignore the payload ... I assume a standard Big F***in Bang warhead on top, and even I know how to look up/compute/add on non-nuclear RKA-AP equivalents ... but as someone is certain to notice, just the raw impact/move-through damage will be impressive as all get-out.)

 

A second, seemingly unrelated question: how deep in the ocean can GPS signals be reliably detected?

 

Obviously a hypersonic weapon cannot use active sonar for target acquisition, so other means are needed; the options are active electromagnetic target acquisition and homing of some kind, or "ballistic" (there is undoubtedly a better word than that ... what I mean is, shoot it so that it will be at the predicted position of the target, but it doesn't search for/recognize the target itself). Both modes are possible depending on the target. Firing at a standard attack submarine means you probably need active homing, but against a large static target (like an undersea domed base), the second mode is viable. But I don't think GPS is detectable at depth, so...

 

(I know, from HERO build p.o.v. the mechanism by which it homes isn't all that important until you try to counter it. But I know there will be efforts to counter these things, so I'm thinking ahead.)

 

 

Real word guidance? Either Inertial, to give it basically a "ballistic" course that stays straight despite currents and such

 

Fiber optic/wire guidance. I doubt it can handle that high of a speed, but I could be wrong. It will handle over 400 mph, iirc.

 

Blue green laser radar. I don't know if this would give a GOOD guidance due to the high speed of the torpedo and the relatively short range of the lasers under water, but it would probably work to fine tune the targeting on the attack run and operate as a proximity fuse.

 

 

Interesting idea.

 

 

I wonder if a salvo of smaller ones with inertial guidance might be a better way to go, kind of like a battleship salvo.

 

On a somewhat similar note, I read an article on a modified 25 and 30mm cannon that was intended to destroy mines. It iirc used a modified APFSDS design, that created a "cavitation bubble" around itself. The impressive thing was that the 30mm version, mounted on a helicopter, could hit a mine at iirc 80 METERS depth, still going fast enough to destroy it.

 

I wonder if larger versions of this concept might have a role for littoral anti-submarine warfare? A 106 0r 120 mm recoilless rifle modified to fire an HEFSDS round might be able to disable or destroy subs at over 100meters depth.

 

Just a thought.

[gewing]

Re: "Rocket torpedo" in HERO?

 

Just having fun....

 

1. Supersonic .NE. supercavitating (thanks Zeropoint). The H2O molecules aren't going to be pushed out of the way by compressed gas so easily. Power requirements go way up.

 

2. Power isn't a problem if you posit a big torpedo with on-board power generation - think a mini-nuclear sub.

 

3. Something like this is going to leave a mark as it moves. Remote sensing (satellites, reconnaisance aircraft) or distributed sound-sensing equipment (think sonobouys 10 miles out) should be able to pick it up if it travels very far.

 

4. Countermeasures - if it's controlled, jam it / redirect it. But if it's carrying a nuke, you gotta stop it. How about a anti-torpedo torpedo? If the Big Boy hits metal, it's going to crash & the nuke won't go off. Or, if that's too hard, get in front of it and use a shaped explosion to push some more-solid seawater into contact with the torpedo. If the Big Boy loses his leading H2O shield, it'll be like hitting a brick wall. No torpedo, no nuke.

 

Just ideas...

 

 

Good ideas too.

[TaxiMan]

Re: "Rocket torpedo" in HERO?

 

I read an article on a modified 25 and 30mm cannon that was intended to destroy mines. It iirc used a modified APFSDS design' date=' that created a "cavitation bubble" around itself. The impressive thing was that the 30mm version, mounted on a helicopter, could hit a mine at iirc 80 METERS depth, still going fast enough to destroy it. [/quote']

 

D@mn, it would suck to be a marine creature capable of hearing all that noise! Cavitating supersonic torpedoes, cavitation bubble mine destroyers, even water-burst nukes. If whales could talk, I bet we'd be hearing from them...

 

[jots down Champions idea...]

[SvZurich]

Re: "Rocket torpedo" in HERO?

 

Sonar does indeed make life hard for marine life.

 

High pressure sound waves in the water will rupture air bladders in fish.

 

There indeed does seem to be a link with ambient shipping noise, sonar, and aquatic mammal beachings.

 

Aquaman would not be a happy camper.