Recently, a company created a fascinating toy available to the sufficiently rich. It is not hard to imagine that military types have taken a close look at this, and have thought about ways to tweak and expand the idea, possibly to be deployed from something like the stern-gate of a Wasp-class ship. Each "submersible fighter" takes a crew of one or two pilots, has an array of active and passive sensors, and is armed with up to four mini torpedoes. They are also very stealthy- if detected at all, one would easily be mistaken for a flatulent beluga whale.

Now we make the leap from reality to fantasy. Two belligerent entities have each developed these small submersibles. The submersibles patrol around and under their carrier searching for the enemy. Their weapons might not be powerful enough to blow a large ship out of the water, but can certainly twist up its propellers and rudders and leave it crippled. But occasionally they encounter each other, and a dogfight ensues. What will that dogfight be like?

Certainly, it won't be like the submarine versus submarine combat of WWII, nor the cold war cat-and-mouse games, which is very slow and methodical; it can last hours, even days. Likewise, it won't be like the high-speed high-g affair of aerial dogfights, not even that of the Sopwith Camel versus Albatross days.

How will the submersible pilots act in this situation? What maneuvering will they do? Which sensors (sonar, IR, MAD, electroreception) will be most useful?

NOTE: Entered as part of the fortnightly challenge.

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    $\begingroup$ hmm, ow do they patrol for enemies? by that I mean we already have strong active sonar running from a carrier, do these subs really have much of a better ability to detect an enemy sub then the carrier already has? their sonar is weaker and risks interfearing with the carrier if not corrected for. I ask because I need to know how they see each other to speculate how they fight. $\endgroup$
    – dsollen
    Commented Nov 30, 2015 at 21:24
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    $\begingroup$ @dsollen, Good Point! But take it a little further... the defending sub-fighters could definitely receive guidance from the better equipped capital ships that they are defending, but the attacker would be limited to only what their limited sonar can see. That would definitely influence the defender's strategy. $\endgroup$ Commented Nov 30, 2015 at 21:28
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    $\begingroup$ The limited ammo supply will likely be the biggest determining factor especially when you consider that a sub-fighter that has fired all of its torpedoes has almost no antagonistic value on the battlefield (aside from kamakaze ramming which given the cost of the sub-fighters would not be encouraged). Strategy would therefore involve getting the attacker to fire all their torpedoes before they get in range of your capital ships, then following them back to their resupply ship for an attack of your own. $\endgroup$ Commented Nov 30, 2015 at 21:30
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    $\begingroup$ @HenryTaylor who needs subs weapons. If the subs have better 'vision', required to make them worth having at all, then perhaps all they do is spot the foe and relay target data to the cruiser above and let it blow their foe out of the water. But that gets back to my earlier question, what is their large scale tactical advantage, if it's vision then I see no reason to give them weapons. If it's weapons they likely are about positioning to fire somewhere the cruiser can't hit. Either way their probably being guided by the cruiser to support the cruiser, not much time to dogfight. $\endgroup$
    – dsollen
    Commented Nov 30, 2015 at 21:36
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    $\begingroup$ I was going to post an answer, but i guess it's more of a comment. Why would anyone deploy "fighter submarines"? They would have small range, they would be relatively slow, having small engines, they would be incredibly vulnerable, not having nearly the plating and defenses of a real submarine, and their weapons would be either severely limited (a few decent sized torpedoes), or incredibly under-powered(machine guns not capable or harming a real submarine). Last but not least, why bother with windows, or life support, etc? That's what drones are for. $\endgroup$
    – AndreiROM
    Commented Nov 30, 2015 at 21:42

2 Answers 2


I suspect these would be used either for sneak and peak for clandestine demo ops in places hard to get to. Such as navel yards or other areas reachable by the sea and rivers. Sinking a boat in harbor in lake Michigan could be a pretty impressive feat causing terror.

Sneaking in and peaking at classified boats in dry dock would also be beneficial, maybe even planting explosives on the haul. So having other small subs patrolling high risk areas would be the best bet for small subs to be employed on both sides. The interesting parts would be for those not in a sub to know which is which.

If a carrier is under way, it will likely be wanting to move at much faster pace than these small subs can do, especially at any sustained rate. So unless the subs are willing to sacrifice themselves to prevent damage to the 'mother' ship, there really isn't anything they would add to the protection of the main ship when at sea.

I suspect that disabling the screw of your opponent and harpooning them and dragging them back to be POW's might be the likely scenario. I think making them fairly impact resistant would be a good idea, so in a pinch they can ram an enemy to escape or subdue with minimal damage. say ram the screw would leave a sub helpless in the water. Maybe give it a 'Rhino' horn for ramming, so it has maximum penetration with minimal grip so is can back out and not get stuck.


Suicide robots aka torpedoes

The largest problem is endurance, followed by striking power and speed.

A small sub would have trouble fitting a nuclear reactor, which would be very expensive, so they would have to use diesel to power the sub. Diesel generators use lots of oxygen so the diesel subs have to surface and get fresh air to run their generators and charge their batteries.

Smaller subs would have smaller batteries and have to surface more often instead of once a day once every 2-3 hours. Small surface ships could pick them off when they surface.

The subs would also still have to move fast enough to keep up with main ships with better power sources. They would also need outsized weapons to still be able to damage larger ships.

You could use them as sensor platforms, but then why put people in them. Just relay the signal back to a main ship with weapons. Taking the pilots out makes the sub much higher endurance and cheaper.

The best analog today are automated torpedoes and mines, that can recognize the sonar characteristics of enemy ships and home in on them. They are at least a third explosive so they hit hard enough to kill a large ship, and endurance doesn't matter because they will only run for an hour or two.

As for sensors passive sonar is the main one, active sonar is used when closing in for the kill. What absorbs infrared so it is not useful. MAD only works in very short ranges (magnetic fields fall off as the square of the distance) so it is of limited use. Most active sensors have the problem that they make you visible at roughly twice the distance they reveal an enemy because it has to have enough energy to hit the enemy and then bounce back and reach you.


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