Making Gyrocs Great

[Varyon]

Originally Posted by Varyon

APHEX isn't great but is an option.

Wrote this bit before I had done the proper analysis (had just looked at the damage and thought "Meh, 1d-2 + 1d-1 is pretty lame." APHEX is actually a pretty solid option for the 4d slow gyroc, what with it having a good shot at incapacitating a target. The 1d+1 (100 yard/sec) slow gyroc is going to be rather reliant on a non-KE payload, however.

Originally Posted by Varyon

On that topic, does UT Nerve gas seem a little tame to anyone else? It's fast-acting, sure, but only has around a 50% shot of killing a typical person, which seems a bit underwhelming.

I'm considering allowing for the GM neurotoxin from Genocide Man, but that stuff's pretty nasty. One dose (those darts are probably at most 3mm and have poor penetration in flesh - they're consistently depicted as being unable to cause any real damage on their own when up against a target with immunity) reliably causes total paralysis, including of the lungs, in 3 seconds. That's probably something like an HT-4 check each second for roughly 10 cycles (arguably more cycles than that, but if someone can pull it off 10 times in a row I'm going to give them a pass). One failure causes Neurological Disorder (Crippling), two causes Paralysis, three causes Choking (which requires an atropine injection to the diaphragm. HT-4 means an HT 10 character has a roughly 75% chance of hitting full body paralysis by the third second (90.74% chance to fail each second; failing the first 3 seconds has a probability of 0.9074^3, or 74.7%), which seems about right given its performance in the comic. HT-3 might also be acceptable (50% chance of 3 failures by the third second). Not certain on price per dose (the Genocide Project doesn't have any issues keeping their agents stocked with plenty of it, but said organization is also fabulously wealthy), but obviously LC0.

A toned down version might be HT-4 upon being initially dosed and every 5 seconds for 1 minute. One failure causes ND (Crippling) and possibly Mute, two causes Paralysis, three causes Choking. This gives characters longer to draw and use an autoinjector (or even attack their assailant). It's no less lethal if untreated, of course, although the extended time to use an autoinjector makes it less likely to instantly kill a character. I might have failure by 5+ (and any critical failure) automatically progress two steps.

[Rupert]

Originally Posted by Varyon

Wrote this bit before I had done the proper analysis (had just looked at the damage and thought "Meh, 1d-2 + 1d-1 is pretty lame." APHEX is actually a pretty solid option for the 4d slow gyroc, what with it having a good shot at incapacitating a target. The 1d+1 (100 yard/sec) slow gyroc is going to be rather reliant on a non-KE payload, however.

APHEX rounds are actually pretty good damage as a rule. They are fiddly, however.

[Jack Sawyer]

I've never been a fan of gyrojets as originally envisioned (although its hard to find alot of in-depth research on them, although I haven't checked in recent years) and like most 'rocket propelled' it can be challenging to stabilize (I've heard people suggest you would have to have some sort of guided munition just like with real life rocket assist. Fun fact: The US Military tried a 105mm rocket-propelled APFSDS - it could reach IIRC ~1500 m/s in around 700m or so, but it had accuracy issues beyond IIRC a few km. That was the start of alot of the guided KE tank gun rounds from what I read.)

Apart from the guided I suppose in some ways you might treat them like a 'recoilless' rifle (if the ports on the side angled like a muzzle brake, rather than a venturi at the back) - gyrocs actually do get a small amount of velocity I believe from the barrel although the ports lessen that. 'burn out' before leaving the barrel (or just after) may determine velocity or may be sustained for 'extended range' without velocity loss (again like real rockt-assist ammo like artillery uses.) I suspect even if unguided it would have some range (although it might be shorter than a conventional gun).

I tend to prefer something akin to a travelling charge propulsion system:

PARAMETERS FOR OPTIMIZING A TRAVELING CHARGE GUN SYSTEM

An Idealized description of the traveling charge effect has been
presented in an earlier work by Smith 4 and is shown in Figure 1. The
process is in two stages. Ignition of a conventional granular booster
charge is used to rapidly pressurize the chamber and accelerate both the
projectile and a very high burning rate (VHBR) traveling charge, (TC)
attached to the base of the projectile. At some point during this
initial pressurization, usually past the peak pressure due to the
booster charge, the traveling charge is Ignited. Subsequent idealized
burning of the TC is tailored to eject combustion products at sufficient
velocity so as to maintain constant thrust/pressure on the base of the
projectile until burnout of the propellant is achieved.

COMBUSTION DIAGNOSTICS AND BALLISTIC RESULTS OF PROPOSED TRAVELING CHARGE PROPELLANT

The traveling charge concept has long fascinated interior
ballisticians interested in hyperveIocity propulsion. This concept,
originally introduced by Langweiler as an "Impulse Gun," is
theoretically capable of producing muzzle velocities in the 2-3 km/s
regime without a large increase in maximum operating pressure. A number
of traveling charge (TC) projects have been undertaken to try to realize
this Increase in Tuzzle Xelocity. Thg reader is referred to reports by
Vest, O'Donnell , Baer, and Baldini• for experimental results on
various propellant and gun configurations. There have also been a
number of theoretical feasibility studies done on the topic by Lee,
Vinti, 7 and Barbarek. 8 In his preparations for the current Ballistic
Research Laboratory (BRL) TC program, May compiled a comprehensive
review on the subject.

A somewhat simplistic view of the traveling charge effect is
pictured in Figure 1. A very high burning rate (VHBR) propellant is
attached to a projectile and is given an initial acceleration or boost
from a conventional propellant. The VHBR ignites after a slight delay
to provide a continuous base pressure and thrust to the projectile until
muzzle exit.

And another if any is interested in more info: TRAVELING CHARGE COMPUTATIONS -
EXPERIMENTAL COMPARISONS AND SENSITIVITY STUDIES

Never really panned out obviously.. but then again neither did Gyrojets, liquid propellant guns or alot of other concepts lol.

[lwcamp]

Originally Posted by Black Leviathan

Silent is a strong word perhaps. How about "Suppressed"? Substantially quieter than a man-portable rocket for having a smaller, cooler propulsion system. I'm envisioning a lot of WHOOOSH and not so much BANG. In my mind it would be harder to locate where shots are being fired from, but now I'm thinking about rockets that would most likely have chemtrails.. Maybe a no-go either way.

Chemtrails? Just what are you using for rocket propellant?

In any event, if your rocket exhaust is some non-condensable vapor, you won't get much of a trail. Take one of those hypothetical (or merely fictional) high nitrogen fraction substances and its combustion could give you mostly nitrogen and carbon dioxide, with water below the saturation level. Ta da! No exhaust trail.

Something like this could give results something like you see with Star Wars blasters - a bright streak of light (from the glowing portion of the exhaust plume) and then an explosion where it impacts. Relatively low speed rockets makes it look even cooler, with projectile speeds not much more than that of an arrow. The low accuracy of rocket rounds could explain the storm trooper's notorious inability to hit anything.

Luke

[Varyon]

Traveling Charge sounds like a conventional/gyrojet hybrid. Skimming, it sounds like it uses a relatively small amount of powder to throw the bullet, and once it exits the barrel its rocket ignites for a brief time to add additional velocity without the recoil you'd get by producing that in the traditional way. If the burnout issue referenced by Rupert is a solved problem (necessary for gyrocs to continue on a ballistic trajectory once the fuel is extinguished), they'd be doable at TL9. From what I understand, however, the rocket will inherently add some instability to the bullet (and I suspect rockets deal poorly with spinning munitions, so it may have to be smoothbore), so it will probably have fairly poor Acc.

Personally, I don't see it as being particularly worth it. You've got all the problems of gyroc (bulky, relatively inaccurate round) but lose the benefit of the flatter trajectory and long range. The weapon itself would also probably be heavier to be able to handle the initial charge (the round may be lighter, if gunfoam gets better energy per unit weight than gyroc fuel, but I don't think that's a guarantee).

[Phantasm]

Are these gyroc rounds solid rockets or liquid fuel rockets?

[AlexanderHowl]

Most likely solid fuel because of the simplicity of the designs.

[Anthony]

Originally Posted by Phantasm

Are these gyroc rounds solid rockets or liquid fuel rockets?

They're something that remains shelf stable for long enough to be practical as small arms ammunition. There might be liquid propellants like that, but far more likely solid.

[Fred Brackin]

Originally Posted by Anthony

They're something that remains shelf stable for long enough to be practical as small arms ammunition. There might be liquid propellants like that, but far more likely solid.

I believe that space probes that need signifcant thrust long after launch rely on hydrazine and nitrogen tet. They might be "shelf stable" but you're not going to want to put them in your pocket. They are rather toxic.

The very small size and short burn time of the UT gyroc also favors a solid motor. The faster you need to burn liquid fuels the more powerful a fuel pump you need.

[Hide]

Originally Posted by Daigoro

You can see some gyrojet test shots in this video, although they're using vintage ammo (...)

Originally Posted by lwcamp

It's probably largely inspired by the real-life gyrojet
(...)

Originally Posted by evileeyore

The Taofledermaus boys at their best (...)

Thanks, I got it!

Originally Posted by lwcamp

Chemtrails? (...) In any event, if your rocket exhaust is some non-condensable vapor, you won't get much of a trail (...) something like this could give results something like you see with Star Wars blasters (...)

This sounds very nice.