Gyrojet Underwater Weapons ?

[rust]

While doing some research for my Pandora setting I found a few informa-
tions about the Lancejet, a prototype version of an underwater gyrojet pis-
tol.

A light, recoilless weapon that fires "microtorpedoes", for example 15 mm
"torpedoes" with different "payloads" (from HE to Tranqu), would be a per-
fect weapon for my water world setting.

Unfortunately there seem to be no Gyrojet weapons in any of the Traveller
versions (at least I did not find any), and so I have no good idea how to
"translate" such a weapon into Traveller terms, and what its advantages
and disadvantages (e.g. low velocity at close range) could look like in Tra-
veller terms.

I think that a 15 mm "microtorpedo" could basically be a dart with a kind
of propulsion engine at the back (I am not sure whether a rocket would
do well under water, perhaps compressed air or something else would be
a better idea ?) and either a point (making it a "harpoon") or a standard
ammunition round (shotgun, HE, tranqu) at the tip.

Thinking about the kind of underwater combat that would be most likely
in my setting, a range of 10 m to 15 m would be sufficient, and perhaps
a magazine of 3 to 5 rounds, with the option to load the weapon with sin-
gle "torpedoes" instead of using the magazine.

Any help with turning something of that kind into Traveller stats would be
most welcome.

 

[rinku]

The snub pistol and accelerator rifles are gyrojet types.

 

[rust]

The snub pistol and accelerator rifles are gyrojet types.

Thank you very much, somehow I managed to miss that.

I guess this would make my underwater weapon the equivalent of an ac-
celerator rifle.

 

[rinku]

Of course, the actual stats are going to be very different - the effective ranges for the various underwater weapons seem to be pretty short (around 15m for the H&K P11).

Mind you, tech will help. You could have smart mini-torpedoes that home in on the target.

 

[rust]

Of course, the actual stats are going to be very different - the effective ranges for the various underwater weapons seem to be pretty short (around 15m for the H&K P11).

Yes, but I think for the purposes of my setting an effective range of 10 m
to 15 m is good enough, as the weapon would mostly be used in self de-
fence against native predators.

 

[rinku]

Oh, appropriately tuned lasers may be feasible too - depends on the opacity of Pandora's water, though it's unlikely that the blue end of the spectrum will have anything useful. You can always rule there is a window that allows weapon grade laser use at some depths.

 

[rust]

Oh, appropriately tuned lasers may be feasible too - depends on the opacity of Pandora's water, though it's unlikely that the blue end of the spectrum will have anything useful. You can always rule there is a window that allows weapon grade laser use at some depths.

Bluegreen lasers work underwater, but require an awful lot of power to
do any damage. I think the "microtorpedoes" would be far more efficient,
especially in a high explosive version that also generates a shock wave
underwater - and my setting's colonists could probably manufacture an
underwater gyrojet weapon and its ammunition more easily than a laser
weapon.

 

[BP]

Do you already have ultrasonic weapons, rust?

Actually worked on a research project (many moons back) where we used piezoelectric crystals and metal focusing lens to generate acoustic waves for disintegrating rubber. It seemed to have great potential for doing the same to human bones/tissue as well (careless research scientists )

One useful RP aspect - such a weapon would be useless in atmo or vacuum :twisted:

 

[Browncoatone]

The gyrojet pistol (or at least it's fictional counterpart) is an excellent weapon. It's simple construction and operation make it unlikely to malfunction and depending upon which ammunition you care to load it can be an effective weapon on land, under the sea, or in the depths of space. Concealable and practically recoilless it's versatility makes it the perfect choice for the generic sci-fi spacer that needs an effective sidearm for every environment.

So I'm a gyrojet fanboy- we all have our failings.

 

[rust]

Do you already have ultrasonic weapons, rust?

Yep, they are the standard weapons of the setting, used as stunners on
land and deadly weapons for hunting and against predators underwater.
Their only disadvantage is that those with a high damage value are both
heavy and bulky, only divers expecting serious problems will carry them,
while a gyrojet weapon could me much lighter and easier to transport.

 

[BP]

... only disadvantage is that those with a high damage value are both heavy and bulky...

So handheld meson guns are out as well? :lol:

Yep, gyrojets are a definite must have. (even if like low tech Gyrojet Lancejet?)

I assume you also have more conventional dart weapons, ala:
http://en.wikipedia.org/wiki/Underwater_firearm
http://en.wikipedia.org/wiki/Heckler_%26_Koch_P11
http://en.wikipedia.org/wiki/SPP-1_Underwater_Pistol
http://en.wikipedia.org/wiki/ASM-DT_Underwater_Assault_Rifle

 

[rust]

I assume you also have more conventional dart weapons ...

I have used them for a previous setting, but this time their stats would fall
into the same range as those of the setting's sonic weapons without offe-
ring any additional advantage (in fact, they would have more disadvanta-
ges), so I decided not to use them. However, if a character should decide
to get and use one, he is free to do so - he will soon enough find out that
lots of noise will attract lots of creatures on Pandora ... :wink:

 

[locarno24]

A light, recoilless weapon that fires "microtorpedoes", for example 15 mm "torpedoes" with different "payloads" (from HE to Tranqu), would be a perfect weapon for my water world setting.

I could imagine the ammunition essentially being something like the Shkvall supercav torpedo - no real moving parts required, making it easier to engineer into pistol ammo, and with enough velocity to actually act as a conventional bullet.

That gives you a muzzle velocity (when the drive lights) of about 100km/h, accelerating up to about three or four times that.

That gives you an impact velocity (and hence damage) not dissimilar to a longbow or crossbow at close range, assuming no specific warhead other than "rapidly moving chunk of metal", paired up with the range and rate of fire of an autopistol or carbine.

 

[rust]

I could imagine the ammunition essentially being something like the Shkvall supercav torpedo ...

Yes, what you described is exactly what my setting's colonists would love
to have as an efficient way to deal with certain native predators.

 

[locarno24]

In which case I would suggest the following:


Lancejet underwater carbine

TL: 9 - no reason for it to be especially more or less complex than a regular accelerator carbine

Range: Ranged (shotgun) - the slugs move fast enough that a competent user should be able to hit a target at more or less the same range as a normal sub-rifle weapon, since they're not the most accurate things to begin with.

Damage: D6+2 - this is better than a bow, but not as good as a crossbow or longbow. The projectile will hit at speed, but since it's accelerating up to speed, not being fired at high speed and dropping with atmospheric resistance, the odds are that most fights will not be at enough range to give a full speed hit.

Recoil: 0(0) - it's an accelerator weapon, after all.

Auto: 4 - again, assume it works off the same mechanism as the accelerator carbine. I was tempted to give it a higher rate of fire, as the fact that it's immersed in water means the traditional big problem - barrel overheating - goes away, but then an accelerator doesn't generate much heat inside the weapon anyway.

Mass: 1.5Kg - Same as an accelerator. Perceived weight, of course, can be significantly less since you get the upthrust from the displaced water...

Magazine: 12 - if you want the same as an accelerator carbine. Given the weight advantage, I'd be tempted to make it an 18 round mag.

Cost: 880 - A 10% surcharge for modification to cope with firing in deep water - pressure damage to the firing mechanism, springs that can force their way past water rather than just air, etc.

Ammo Cost: 20 - Since the design of the round - especially the tip - is going to be a custom job, I doubled the ammo cost. Call it an ammo cost of 30 if using 18 round mags.



Sound okay? D6+2 isn't going to have anything with natural armour swimming for its life, but with auto 4 you can lay down enough fire to scare most opponents.

 

[rust]

A nice design, thank you very much indeed.

 

[rinku]

Given the limits on velocity, you may want to look at explosive, tranq or taser rounds. Having said that, I have no idea what the practical issues are for HE or taser ammo on the firer (tranq should be safe - and you can load up with something lethal to Pandoran life but not-as-lethal to Terran).

 

[rust]

Having said that, I have no idea what the practical issues are for HE or taser ammo on the firer ...

HE rounds should be safe for someone wearing a diving hardsuit, but they
could perhaps be dangerous for someone with only a scuba outfit. On the
other hand, some minor damage from the use of the HE round seems an
acceptable disadvantage if the alternative would be to be eaten by a pre-
dator.

While Tranqu rounds (and perhaps other chemical rounds, like a repellant
for some native creatures) are on my "shopping list", I think I will not use
Taser rounds, mainly because they would require isolated wires connec-
ting them to the weapon, and these could well get into the way of accura-
cy and range (and the diver).

 

[rinku]

Hmm... I was thinking in terms of self-contained taser rounds that contain the battery and discharge upon contact (possibly delayed until the round has penetrated?). These might not be feasible at current tech, but advances in battery technology might make them practical in a saltwater environment. The underwater rounds we've been discussing have a fair degree of volume and batteries are nice and dense, so it shouldn't compromise ballistic performance too much. The shock is unlikely to actually kill, but on top of the tissue damage caused by the round itself, it could still be fatal to a sea creature.

(This is starting to get a bit Judge Dredd-ish Hmm... no reason heat seekers *couldn't* work...)

 

[rust]

I was thinking in terms of self-contained taser rounds that contain the battery and discharge upon contact ...

Ah, I see.

I will have to think about it. Looking at my technology notes, batteries of
the required size and power would be possible, but somewhat expensive.
Since many of the taser rounds would not be recovered, this would make
their use a bit of a luxury, and I am not sure whether they would have an
advantage that would balance the comparatively high cost.

On the other hand, it could be an interesting idea to design and introduce
a native creature that is dangerous and especially vulnerable to the taser
rounds, and to see whether the characters would recognize this and think
of developing such rounds. :wink: