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Old 12-25-2012, 07:08 PM   #1
Derago
 
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Default Request for comment on House Rule

I have a house rule I'm considering using regarding the aiming of large cannons. A little background: all of my players and I play World of Tanks. In this game, each gune has an aim time attribute that represents how long it takes to aim this gun before you reach maximum accuracy for the weapon; this is represented by a circle that grows smaller as you aim.

Back to GURPS: in a recent game, one of the players had a huge, short-barrelled gun that is relatively inaccurate, but inflicts large amounts of damage, while another player had more nimble, accurate cannon. We found that it was very strange that the huge gun could be brought to bear nearly as fast as the smaller gun.

Anyway, here was the proposal using the Rheinmetall KwK40 as an example:
Acc bonus will be totalled and the bonus spread across the total RoF time. That is very vague, but this is the idea in practice:

The KwK40 (HT p. 140), mounted on a tank (for +4 mounted bonus using TS rules) has an acc of 6 (gun) +4 (mount) +1 (sights) +2 (conditional: two additional seconds of aiming) for a total of +11-13. With this, I would have the acc build up as:
Sec 1: +7 acc
Sec 2: +4 acc (+11 total)
Sec 3: +2 acc (+13 total)

I got this following (roughly) a 50/30/20 split. This would simulate a gunner use coarse aiming to get the gun in the ballpark and continuing to finetune in the process.

Is this houserule doomed to fail? I know it will result in preworking the acc steps ahead of time (which I've done for many of our vehicles and just had them printed in the weapon's stat block), but I'm fine with that. I just don't want a huge howitzer getting full acc bonus in the same 1 second that a light cannon gets its own.
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Old 12-25-2012, 09:52 PM   #2
gilbertocarlos
 
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Default Re: Request for comment on House Rule

Tanks have a time to rotate the main cannon. Also, it could be represented by the bulk(but it isn't up to date).

My house rule is:
If you turn a weapon more than 30º in one turn or if you had run the last turn, you get a penalty equal to bulk that needs one turn walking or doing a mental action to be recovered.

For really huge weapons, like, Cannon size big I would put one second for each 4 or 5 points of bulk.
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Old 12-26-2012, 03:29 AM   #3
vicky_molokh
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Default Re: Request for comment on House Rule

Here's a simplified angular solution:

Find the turret's rate of turn. Find the angle between the cannon's forward direction before Aiming and the direction towards the target. Divide the latter by the former.
Multiply the ratio by Acc. This is the Acc reduction after a single Aim. (Round towards zero, otherwise you'll always have -1.)

If the ratio exceeds 1 / the penalty exceeds Acc, it is not possible to hit the target after a single Aim. If the target's angular velocity exceeds RoT, it is not possible to hit that target (IIRC this was a big deal at certain distances when faster tanks were deployed in WWII.)
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Old 12-26-2012, 04:20 AM   #4
Derago
 
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Default Re: Request for comment on House Rule

Quote:
Originally Posted by vicky_molokh View Post
Here's a simplified angular solution:

Find the turret's rate of turn. Find the angle between the cannon's forward direction before Aiming and the direction towards the target. Divide the latter by the former.
Multiply the ratio by Acc. This is the Acc reduction after a single Aim. (Round towards zero, otherwise you'll always have -1.)

If the ratio exceeds 1 / the penalty exceeds Acc, it is not possible to hit the target after a single Aim. If the target's angular velocity exceeds RoT, it is not possible to hit that target (IIRC this was a big deal at certain distances when faster tanks were deployed in WWII.)
While that may work when the problem comes from an issue of whether or not the tank turret can turn to the target in time, it's not a gameable solution without adding (probably significant) time to the combat (did I mention that two of my players are 8 and 10?).

I wanted a solution that would cover even the event that the targets are in the same direction, but different ranges or elevations. Consider a 155mm Artillery cannon being brought to bear in a direct-fire role compared to an anti-tank rifle - they both only take 1-second to get the full acc bonus!

Something seems wrong about this - that, I guess, is what I'm trying to correct in the houserule. By the way, it was the 8 year old who pointed out this strange state of things, and I have to admit he seems right.
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Old 12-26-2012, 04:32 AM   #5
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Default Re: Request for comment on House Rule

There isn't a need for a new house rule. The tank descriptions in High-Tech all provide the number of Ready maneuvers it takes to rotate the tank's turret by a facing, generally 3. So if the target isn't in the same facing as the turret, you can't fire at it at all.
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Old 12-26-2012, 05:50 AM   #6
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Default Re: Request for comment on House Rule

Make a simple house-rule, like, you can turn the turret 30º or 60º per turn, vary that by each turret, that way, heavy cannons will take longer to aim.
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Old 12-26-2012, 06:51 PM   #7
Derago
 
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Default Re: Request for comment on House Rule

The problem isn't with turret movement.

Consider this: a heavy artillery piece (acc 5), a soldier with a rifle (acc 5), and a WWII-era tank (acc 5) are all facing the same general direction (out the same 'facing' of their hex, so no major movement of the weapon's mount is required).
A wild enemy appears.
All weapons take one second of aim.

At this point, at the end of one second , they all have the full acc 5 despite the fact that some of the weapons a huge and are being aimed by coarse and fine adjustment via handwheel. This can't be right.

I could see the weapons using Gunner (Cannon) at TL7 and below getting some sort of stepped accuracy (which is what my houserule is trying to cover) to cover their aiming method.
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Old 12-27-2012, 06:32 AM   #8
fifiste
 
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Default Re: Request for comment on House Rule

Your houserule seems pretty ok. Need some playtesting. For some reason I would like to add bulk statistic in somewhere in those deliberations :D.
Etc. Acc/Bulk if your bulk is 1, you get your full acc in one sec. If 2 then 2 secs. (this probably is too limiting but you get the gist)
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Old 12-27-2012, 06:23 PM   #9
Derago
 
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Default Re: Request for comment on House Rule

Quote:
Originally Posted by fifiste View Post
Your houserule seems pretty ok. Need some playtesting. For some reason I would like to add bulk statistic in somewhere in those deliberations :D.
Etc. Acc/Bulk if your bulk is 1, you get your full acc in one sec. If 2 then 2 secs. (this probably is too limiting but you get the gist)
Bulk could be a nice to determine some parts of this, but looking at HT I see that bulk is -10 for a 3.7 cm PaK (a gun known to be nimble) and -13 for the RIA M2A1 (an artillery piece).

Maybe bulk/3 could be used to determine how long it take for full acc, but I would only have this rule apply to weapons aimed using handwheels or relatively equal mechanical means.

I ran two small combats last night to playtest this rule. Two players were in tanks, one was a Panzer III Ausf. J with a 5 cm L/60 main gun while the other was in PZ IV with a 10.5 cm howitzer for a main cannon (not exactly historic, but think of it as a german version of what we did with the Sherman and a 105 mm). They fought two other players, one with a 7.5 cm anti-tank gun and the other in a T-28 Soviet Tank.
I put the acc steps as part of the weapons stat line so the 5cm line looked something like this (btw, we use decade scal for damage):

5 cm KwK 39 Range: 1500, acc: +7/11/13, Dmg: 3d(2), follow-up: 1d-3, RoF: 1/2

The 10.5 cm gun had its acc spread over 4 steps: +5/8/10/12. Written this way the player knew right away what his bonus to hit was. I made a ruling on the fly that an IQ-based gunner(Cannon) roll would allow an additional +1 to be gained per turn of aim, but the maximum could not surpassed (+12 in this case) without going into Precision Aiming rules. The players said they all liked it and that it made them feel like the weapons were working as they ought to.

Since we're mostly playing with vehicles of RoF 1 to 1/4 and that have similar acc values (they have maybe 3 or 4 points difference), it would be easy to make a couple tables that will lay out the acc steps given a RoF and acc value. Since the table would only be referenced once to make the weapon's stat line, it won't (and didn't) add any additional time to the combat, and in fact saved time since some of the bonuses (mount, sights, and aiming time) are already accounted for.
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