[Rant] d20 Modern: square root of two = 3 (WotC mathematics).

[Gez]

I was readin the d20 Modern SRD, and found some rules that were just excellent (massive damage threshold=Constitution, here's what we all needed to stop getting all-elf parties !), but some just didn't made sense. For example, the vehicle combat rules.


From the d20 Modern SRD:

Sideslip: A driver might wish to move to the side without changing the vehicle’s facing, for instance to change lanes. This simple maneuver, called a sideslip, allows a vehicle to avoid obstacles or weave in and out of traffic without changing facing. A sideslip moves a vehicle 1 square forward and 1 square to the right or left, and costs 3 squares of movement.

I could understand 2 rather than sqrt of 2, because of the slight loss of maneuverability (and it's easier to compute mentally), but 3 ? Stupid.



Another stupid rule:

The DC for a sideswipe is 15. It's modified by the relative size and speed of the target.
Target Condition DC Modifier
Each size category larger –5
Each size category smaller +5
Each speed category of difference –2

On a failed check, both vehicles take damage as though the sideswipe attempt was a success. However, the other driver does not need to make a check to retain control.

So, if you drive a big car, you'll have a harder time sideswiping a racing bike than a tank. That would be OK if a failed check meant you didn't hitted the target. But no. Both vehicles take damage, so the collision happened. It's just that with the same vehicle and check result, you can make a tank driver lose the control of his tank, whereas a bike driver would not. Silly, isn't it ?



Have you noticed other rules that are in dire need of errating ?

 

[RangerWickett]

Pythagorean theorem:

The length of the hypotenuse of a triangle is equal to the square root of the sum of the square of both legs.

Thus, 5 ft. one way, 5 ft. the other way. 25 ft. + 25 ft. = 50 ft. The square root of 50 ft. is ~7 ft., or about two squares. Hmm. Yah, it doesn't sound quite right, but I'm not a stunt driver, so I wouldn't know. Making quick turns might slow you down a lot. *shrug*

As for sideswiping, do larger vehicles get a stability bonus to driving checks like this? If so, then even if you do hit the tank, you're not likely to budge it. Otherwise, it's no good.

 

[Ranger REG]

Well, a simple slip is the same as turning 45 degrees (1 movement), move one diagonal square (1 movement), and turn back in the same direction 45 degrees (1 movement). That's about three movements.

It's been that way since Star Wars RCR vehicle combat rules, as well as the d20 Modern preview of the vehicle combat rules spotlighed in the Thunderball Rally d20 mini-game in Polyhedron #152.

 

[Gez]

Pythagorean theorem:

The length of the hypotenuse of a triangle is equal to the square root of the sum of the square of both legs.

Thus, 5 ft. one way, 5 ft. the other way. 25 ft. + 25 ft. = 50 ft. The square root of 50 ft. is ~7 ft., or about two squares.

I know Pythagoras' theorem. If both legs have the same length, you can consider it's worth 1 unit. For example, 1 5-ft. unit. And then, 1²+1²=2, that's why I was talking about square root of 2. Square root of 50 is actually 5 times square root of 2. And actually nearer to 1 case than to 2 cases in length (7.07107... feet; lesser than 7.5 feet).

As for sideswiping, do larger vehicles get a stability bonus to driving checks like this? If so, then even if you do hit the tank, you're not likely to budge it. Otherwise, it's no good.

I havn't noticed any (maybe it's in the book but not in the SRD ?). The stability, or inertia bonus is totally forgotten, so the heavier lose. The simplest way would be to reverse the size modifier in this case.