h a l f b a k e r yThe leaning tower of Piezo
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Modern anti-torpedo weapons work by creating an
explosion in the path of the incoming torpedo,
disabling
or destroying it.
This torpedo would search for potential incoming
countermeasures and fire a rocket to stop itself dead
in
the water at the right time to avoid likely explosions.
It
would then speed up again and continue to seek its
target.
8th's "russian supercavitators"
http://en.wikipedia.org/wiki/Shkval
In case anyone missed the reference. I can't beleive that someone actually paid for the research on this one. "we want to build an underwater rocket torpedo" "yeah right". But it turns out to work, rather well in fact. [Custardguts, Sep 07 2014]
[link]
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It goes into surly teenager mode, and paints the inside
of the torpedo tube black? |
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Excellent technology for didn't-mean-to-hit-that-button nuclear incidents, if you just want it to perch on a tree or hide in a swamp somewhere in North Carolina for a time. |
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// fire a rocket to stop itself dead // |
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You mean use a reaction motor to decelerate ? |
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Have you ever wondered why, after all this time, torpedoes are still
propelled by screws, rather than rockets (Russian supercavitators
excepted) ? |
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/torpedoes are still propelled by screws/ |
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A screw would let you stop and back up. Do torpedoes do that? Because that is the idea here, I think. |
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You could just have a random path torpedo which swoops and dives unpredictably on the way to the ship. |
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Or how about one that sneaks along the bottom and comes straight up from below? Like the Red Baron but upsidedown. An explosion directly below the ship would make a rough ride, whether from torpedo or countermeasure. |
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//Modern anti-torpedo weapons work by creating an explosion in the path of the incoming torpedo, disabling or destroying it.// |
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Got some examples? Not that I doubt you, I just can't find much information on the subject, other than some oblique references to "hard kill" modes for lightweight torpedos to be used in the anti-torpedo role. Are there any dedicated systems? |
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If you want to stop the torpedo, drogues would work pretty well, and you could get lots of them on one torpedo. |
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Suspect some military somewhere is working on some smaller, flocking torpedoes that follow different paths to the target, then group together before detonation. |
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Some rumour about a Chinese supercavitating submarine, which sounds interesting. But, the launch speed is high, so if it stops, a devil to get it up to high speed again.. |
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// A screw would let you stop and back up. Do
torpedoes do that? // |
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They do not. The screw of a torpedo is powered by a
turbine that spins only in one direction and once started
does not stop until it runs out of propellant. Stopping or
reversing the torpedo might be possible by remotely
altering blade pitch, but (I'm guessing) it would take more
energy than a conventional torpedo motor is capable of
delivering, and restarting would not be possible. |
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On the other hand, there are torpedo-like vehicles that
perform as this idea describes: they're called 'unmanned
submersibles', and they are slow and easily countered or
avoided. You might as well pack a rowboat with
gunpowder. |
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^ That's cuz they're doing it wrong... |
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//You might as well pack a rowboat with
gunpowder.// |
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Al Qaeda tried that, didn't they? |
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// // A screw would let you stop and back up. Do
torpedoes do that? // |
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They do not. The screw of a torpedo is powered by a
turbine that spins only in one direction and once started
does not stop until it runs out of propellant. Stopping or
reversing the torpedo might be possible by remotely
altering blade pitch, but (I'm guessing) it would take more
energy than a conventional torpedo motor is capable of
delivering, and restarting would not be possible. // |
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We have turbine engines that can be stopped and started
arbitrarily. They're used in some series hybrid road
vehicles. Changing the speed and direction of the
propeller while maintaining the speed and direction of
the turbine is also possible; just use a transmission,
continuously variable if necessary. |
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And controlling the pitch of the propeller's blades is easy;
there are now a few quadcopters that do that for each of
their four rotors independently. The shallower the pitch
commanded, the less torque necessary to turn the
propeller at a given speed. (At zero pitch, the torque is
also (almost) zero, because it's not propelling.) So pitch
control could only make it easier, not harder, on the
engine. |
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I imagine all of this would be controlled by an onboard
autopilot, like pretty much all guided missiles—and, I
assume, some torpedoes—use. |
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OTOH, if you wanted to do this with an underwater
missile
like the Shkval, it would be considerably harder. To be
able
to stop and start, you need a hybrid or liquid rocket, solid
rockets being unthrottleable, as well as some kind of
ignitor
(or a hypergolic propellant combination). The supercavity
would collapse upon stopping; I don't know if the missile
would be able to achieve a high enough speed to
reestablish
it while experiencing lots of drag from the water.
Low-speed maneuverability could be achieved using
thrust
vectoring (which Shkval 2 is rumored to have) with the
rocket at low throttle. |
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Mildly interestingly, I misremembered the Shkval's
method
of control. This is what I had thought: It has only a small
flat
plate on its nose that can be tilted in one axis only. This
is
the only part that contacts the water; its angle deflects
the
missile one way or the other. The whole missile rolls
continuously to enable it to adjust its pitch and yaw
alternately (sinusoidally alternately). |
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This is how it actually works, according to Wikipedia: It
has
four fins (text) or several rods (photo) on its tail end that
can be extended or retracted. These dip into the water
outside the supercavity, implementing differential drag. |
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It clearly does have some kind of tilting plate on its nose,
though. |
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