Different Gyroc Designs

[Ulzgoroth]

Originally Posted by Anthony

Oh, you want it to recognize the movement of the weapon before firing? I guess that's probably technically possible (it's essentially a form of coordinate guiding) but it doesn't seem at all easy, because the bullet has to know its own position with sufficient accuracy.

Tracking the motion of the firing platform as input to a gunnery calculator is a solved problem, seen in gyroscopic aircraft gunsights. (Obviously not hand weapons, but we're talking at least 2 TL later.)

In addition to the issues with a gyroc that guides by blind dead reckoning, I wouldn't really want to trust the sweep of the muzzle to be perfect and smooth enough to be on target at long range.

Also, if you're skipping having a ranging step, so the gyroc has to fly along the arc traced out by the moving bearing across all ranges, that's not going to be a super efficient flight path at long ranges.

Originally Posted by Varyon

If bullet drop is such a minor factor, rangefinders (or other methods of knowing exact range) shouldn't give such a massive bonus (+3), at least against targets without significant lateral velocity. If the rangefinder bonus is appropriate, the straight flight of a gyroc should be useful. Of course, having sights mounted parallel to the path of the bullet (rather than intersecting it at some range, as with conventional firearms) does mean you'll always hit a bit below your point of aim, but only by the difference between the location of the sights and the location of the chamber; if you want to hit someone in the eye, aim at their eyebrow.

The rangefinder bonus is way out of line at short ranges. It's probably appropriate at genuine long ranges. Remember in the real world it's most likely to apply to cannons and sniper weapons.

[Anthony]

Originally Posted by Ulzgoroth

Tracking the motion of the firing platform as input to a gunnery calculator is a solved problem, seen in gyroscopic aircraft gunsights.

I was more concerned with the smarts required in the bullet, not in the gun (the gun also needs an acceleration sensor, which is harder for something handheld than something mounted, but probably within the capabilities of modern hardware, let alone TL 9).

[Varyon]

It occurs to me my curving gyroc idea would probably be better served getting its input from a rangefinder, which should be able to calculate the target's velocity to determine the angle at which the gyroc needs to curve to stay on-target. That's going to be more reliable than expecting the shooter's aim to be stable enough.

Originally Posted by Ulzgoroth

The rangefinder bonus is way out of line at short ranges. It's probably appropriate at genuine long ranges. Remember in the real world it's most likely to apply to cannons and sniper weapons.

At what point do you feel the full bonus (+3) is appropriate? If we have a decent value there, we could come up with the ranges at which it would get +1 and +2. For example, if +3 is appropriate at 2000 yards, that's normally -18 to hit, indicating a +1 for every -6 is appropriate. Of course, now that I think on it, there's probably no range at which the +3 bonus is appropriate - an SM-6 target 10 yards away looks the same (in a featureless plane) as an SM+12 target 10,000 yards away, and indeed both are at -10 to hit. It's kind of hard for a rangefinder to give you better hit chance than a same-size (by perception) target that's close enough that time-to-target doesn't matter. If may be more realistic to only allow a rangefinder to reduce any penalties due to the target's speed (or introduce a rule that gives time-to-target penalties, and let rangefinders reduce those).

[Anthony]

Originally Posted by Varyon

It occurs to me my curving gyroc idea would probably be better served getting its input from a rangefinder, which should be able to calculate the target's velocity to determine the angle at which the gyroc needs to curve to stay on-target.

If you have an integrated rangefinder, you'd just have the gun aim so the gyroc doesn't need to curve at all.

[Ulzgoroth]

Originally Posted by Varyon

It occurs to me my curving gyroc idea would probably be better served getting its input from a rangefinder, which should be able to calculate the target's velocity to determine the angle at which the gyroc needs to curve to stay on-target. That's going to be more reliable than expecting the shooter's aim to be stable enough.

You're still depending on the shooter's aim being stable to calculate the target's velocity. They've got to keep the rangefinder laid on the target to collect the datapoints! And their aimpoint even wandering around the target's surface will complicate the plot a bit.

Originally Posted by Varyon

At what point do you feel the full bonus (+3) is appropriate? If we have a decent value there, we could come up with the ranges at which it would get +1 and +2. For example, if +3 is appropriate at 2000 yards, that's normally -18 to hit, indicating a +1 for every -6 is appropriate. Of course, now that I think on it, there's probably no range at which the +3 bonus is appropriate - an SM-6 target 10 yards away looks the same (in a featureless plane) as an SM+12 target 10,000 yards away, and indeed both are at -10 to hit. It's kind of hard for a rangefinder to give you better hit chance than a same-size (by perception) target that's close enough that time-to-target doesn't matter.

It looks like you've demonstrated that it's not right for the size and range penalties to exactly cancel out that way for ballistic weaponry without rangefinding, rather than that there's a problem with bonuses for range information.

(There is, frankly, overwhelming evidence from real-world military practice as well as basic theory that range information is important in gunnery.)

Originally Posted by Varyon

If may be more realistic to only allow a rangefinder to reduce any penalties due to the target's speed (or introduce a rule that gives time-to-target penalties, and let rangefinders reduce those).

I don't get the thought-process that led to the conclusion that range-finding is irrelevant against stationary targets, but it really should be extremely obvious how wrong that is.

[Anthony]

Originally Posted by Ulzgoroth

I don't get the thought-process that led to the conclusion that range-finding is irrelevant against stationary targets, but it really should be extremely obvious how wrong that is.

It is typically less relevant against stationary targets, because at intermediate ranges it doesn't take all that much movement for it to create larger errors than bullet drop, and humans are taller than they are wide so it's easier to miss horizontally, but it's certainly not irrelevant.

I found an article I wrote on why rangefinding matters. Be warned of annoyingly written equations.

[Fred Brackin]

Originally Posted by Ulzgoroth

I don't get the thought-process that led to the conclusion that range-finding is irrelevant against stationary targets, .

It would be for lasers but not for any projectile affected by gravity.

The idea of these self-aware projectiles that cancel out known factors but aren't guided towards the target is almost certainly more complicated than one that homes on a laser desgnator.

Incidentally, UT doesn't have laser homing projectiles but they probbaly would be a superior TL9 solution to what UT does have.

[Varyon]

Originally Posted by Anthony

If you have an integrated rangefinder, you'd just have the gun aim so the gyroc doesn't need to curve at all.

True. Forget the curving gyroc idea, then. Looks cool, but ultimately useless.

Originally Posted by Ulzgoroth

You're still depending on the shooter's aim being stable to calculate the target's velocity. They've got to keep the rangefinder laid on the target to collect the datapoints! And their aimpoint even wandering around the target's surface will complicate the plot a bit.

The rangefinder may be able to compensate for the shooter's movements (or use a stationary rangefinder and let the vehicle pass its point of aim).

Originally Posted by Ulzgoroth

I don't get the thought-process that led to the conclusion that range-finding is irrelevant against stationary targets, but it really should be extremely obvious how wrong that is.

It shouldn't be irrelevant, but the GURPS rules - which as noted don't distinguish between hitting an SM-6 target 10 yards away and an SM+12 target 10,000 yards away - imply it's irrelevant. Realistically, there should be some additional penalty to hit based on bullet drop if you don't know the exact range to the target (with the penalty reduced the closer you are to properly estimating it), but that's not in the current rules, and would be finicky to work out. "Negates any penalty from target speed" is easy to work out - it's exactly what it says on the tin - and is probably closer to accurate than the +3 (which functionally treats the target as though it were 1/3rd the distance away it actually is, or 3x the size). Increasing the scope bonus (to a maximum of doubling it) might also work.

We're getting into a pretty serious digression from the topic of gyrocs at this point, however. My apologies for the derail.

[Ulzgoroth]

Originally Posted by Anthony

It is typically less relevant against stationary targets, because at intermediate ranges it doesn't take all that much movement for it to create larger errors than bullet drop, and humans are taller than they are wide so it's easier to miss horizontally, but it's certainly not irrelevant.

Interestingly, you don't actually need the range so much for deflection shooting if you have a good idea of what the target's speed will be. The lead angle to hit a target (with a perpendicular course) is arcsin (v-target/v-projectile), if you approximate projectile speed as constant.

Of course, if you don't have solid prior information about the target's speed then you really need that range information to figure things out.

Originally Posted by Fred Brackin

It would be for lasers but not for any projectile affected by gravity.

The idea of these self-aware projectiles that cancel out known factors but aren't guided towards the target is almost certainly more complicated than one that homes on a laser desgnator.

Incidentally, UT doesn't have laser homing projectiles but they probbaly would be a superior TL9 solution to what UT does have.

Laser designator homing has the rather huge problem that you have to keep laying a laser designator on the target. UT targets will likely detect the laser and trace it back.

[Ulzgoroth]

Originally Posted by Varyon

The rangefinder may be able to compensate for the shooter's movements (or use a stationary rangefinder and let the vehicle pass its point of aim).

You're trying to get the target's velocity. You need to get at least two separate datapoints with both range and bearing information (and time) to be able to do that.

Originally Posted by Varyon

It shouldn't be irrelevant, but the GURPS rules - which as noted don't distinguish between hitting an SM-6 target 10 yards away and an SM+12 target 10,000 yards away - imply it's irrelevant. Realistically, there should be some additional penalty to hit based on bullet drop if you don't know the exact range to the target (with the penalty reduced the closer you are to properly estimating it), but that's not in the current rules, and would be finicky to work out. "Negates any penalty from target speed" is easy to work out - it's exactly what it says on the tin - and is probably closer to accurate than the +3 (which functionally treats the target as though it were 1/3rd the distance away it actually is, or 3x the size). Increasing the scope bonus (to a maximum of doubling it) might also work.

We're getting into a pretty serious digression from the topic of gyrocs at this point, however. My apologies for the derail.

On a basic qualitative level, saying that artillery gunners, siege engineers, snipers, and tank gunners engaging stationary targets have no use for rangefinding is egregiously wrong.

Also, given GURPS speed/range penalty mechanics, there usually isn't any penalty for target speed in long-range shooting. Speed of sound at sea level is less than move 400. Basically, you've made rangefinding exclusively useful at short range.