Has anyone seen how vehicles stats were created?

[Chaldfont]

I am going to stat up some vehicles for an adventure I am writing and I would like to be accurate. Has anyone seen a "behind the curtain" type of write-up on how they came up with the vehicle stats for d20 Modern?

 

[kreynolds]

I'm not sure about all the other stats, but the top speed is easy. Just convert the top miles per hour to feet, divide by 60 to get your feet per minute, divide by 10 to get your feet per round, then divide by 5 to get your 5-foot squares per round (character scale).

For example, take a car with a top speed of 200 miles per hour. 200 miles converts to 1,056,000 feet. So, this car can move 1,056,000 feet per hour. Divide by 60 and you get 17,600 feet per minute. Divide by 10 (there are 10 rounds in a minute) and you get 1,760 feet per round (every 6 seconds). Finally, divide by 5 and you get 352 5-foot squares per round (at character scale). To get your chase scale, just drop the last number, which in this case, the car would move 35 squares per round at chase scale.

You can also do the same thing in reverse (multiply) to see if the top speeds in the books are accurate.

 

[tetsujin28]

One kooky thing I've noticed (unless I interpreted the section wrong), is that all vehicles have the same rates of acceleration, deceleration, and ability to turn.

 

[kreynolds]

One kooky thing I've noticed (unless I interpreted the section wrong), is that all vehicles have the same rates of acceleration, deceleration, and ability to turn.

Yup. The driver is what increases or decreases acceleration and deceleration, and the ability to turn. However, the Maneuverability rating of a car can also increase or decrease the difficulty of such tricks. Not all vehicles have the same maneuver rating either.

 

[tetsujin28]

Still, it's kooky that a Harley and a F1 bike have the same acceleration.

 

[kreynolds]

Still, it's kooky that a Harley and a F1 bike have the same acceleration.

It's only kooky depending upon your point of view. I really like the vehicles. Instead of making the vehicles rules overly complicated, they put the vast majority of the performance of a vehicle into the hands of a driver. Just because you have a nice car doesn't mean you know how to drive it. You might have a Camaro Z28 and I might have a stock v8 Mustang, but if you don't know how to drive a Camaro, or you're just not a great driver, then I'll beat you off the line. Even though the Z28 should woop up on the Mustang, its your driving ability that holds you back. Besides, it gives players something to do while they're in the car.

Also, initiative has a lot to do with "acceleration" when you think about it, and some vehicles have no modifier, as opposed to others with a -1 or even a -4.

 

[Moonsword]

And somebody at Wizards needs to do their homework. The idea that a Bradley or an Abrahms has less ability to detec an opponent and react quickly than a BMP... That's crazy! I won't argure with the manuverability, but the Initiative ratings are nuts! I used them when I posted up some military helos, but that's based on speed. An idiot in a Chvette can outrun a tank, but the tank's fire control system will give him a better ability to react to evolving situations.

 

[Chaldfont]

Here is what I have so far for a Semi. One can work from the Moving Van in d20 Modern or the Motor Coach bus in the web enchancement (though that isn't open content, so I won't put its stats here). I also use the semi stats from Spycraft.

These stats are for a Semi truck w/ trailer.

In the examples of vehicle sizes, they list a semi as Colossal size. That gives a whopping -8 to Init, Maneuver, and Defense. This matches up with Spycraft pretty well.

Spycraft's vehicle wound points seem to be about 2.5-3x higher than d20 Modern, so I suggest about 55 hp for a d20 Modern Semi.

Spycraft lists a semi's top speed at about 90MPH, so, using the math described in kreynolds' post we get 158 (15).

According to various web sites, I find that a semi can be between 60-70 feet long, no more than 102 inches (8.5 ft.) wide, and its maximum load can be 34,000 lbs.

So I say:

Mack Truck w/ trailer
Crew 1
Pass 2
Cargo 34,000 lb.
Init -8
Maneuver -8
Top Speed 158 (16)
Defense 2
Hardness 5
Hit Points 55
Size Colossal
Purchase DC 34
Restriction Lic (+1)
Face: 2x12 squares

 

[kreynolds]

And somebody at Wizards needs to do their homework. The idea that a Bradley or an Abrahms has less ability to detec an opponent and react quickly than a BMP... That's crazy!

What's a BMP?

EDIT: Ah. Nevermind. Found it.

An idiot in a Chvette can outrun a tank, but the tank's fire control system will give him a better ability to react to evolving situations.

Perhaps, but you're talking about a whole different ball game. Firing a cannon has little to do with driving a vehicle. I understand what you're saying though, but when it comes to maneuverability, a tank is not that graceful, but you must keep in mind that the Initiative modifier of a vehicle is based purely on size.

You could always change it though.