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Paul
A player of mine posted this:

QUOTE ("3278)
Check my figures, please. [Oh, please.] This is more about math than it is about Shadowrun, so I put it in SST. Plus, I don't care if it doesn't really belong here. Nyah.

If a vehicle has an acceleration of 36, that means it can accelerate 36 meters per combat turn, multiplied by the number of successes on a test with a target number of the vehicle's Handling.

With 12 dice - a car skill of 6 plus six dice from the Control Pool - and a Handling of 2, one could expect, statistically, to get 8 successes of 2. [12 dice > 66 percent chance of success = 8 successes.]

36 meters per combat turn multiplied by 8 successes would be 288 meters per combat turn, or 96 meters per second per second of acceleration. [288 / 3 seconds per combat turn.] That's about 9.8Gs. [96 / 9.8]

Here's the really mystifying part, for me. I'd like to figure out the amount of time it would take for a car accelerating 96 meters per second per second to reach 100 kilometers per hour. [I realize this computation can't be real-world accurate, since acceleration is never going to be linear like this in an actual car, but it's Shadowrun.]

100 kilometers per hour = 100,000 meters per hour = 1666.67 meters per minute = 27.79 meters per second

There's the problem. According to that, a car with an Acceleration of 36, a Handling of 2, and a rigger with a Car of 6 can do 0-100 kilometers per hour in 0.289 seconds. [27.79 / 96]

What am I doing wrong?


Any takers? Any view points we're missing from the other thread?
Austere Emancipator
In 3 seconds of acceleration Mr Rigger gets to 288m/CT = 96m/s. That means he's accelerating at 32m/s^2. It will take him 0.77 ((100/3.6)/32) seconds to get to 100km/h.

If Mr Rigger spent 3 actions per CT on accelerating, then the numbers would be correct.

My view point: The rigging rules are pretty screwed up. Try not to think about them too much.
Kagetenshi
What on earth do you have with 36 Acceleration?

~J
Fortune
With a TN of 2, wouldn't you expect to get 10 out of 12 successes, or 83%?
Aes
QUOTE (Kagetenshi @ Mar 26 2005, 08:25 PM)
What on earth do you have with 36 Acceleration?

~J

Sports car + jet engine power plant (was diesel in R3, corrected to jet in R3R) + smart materials will give you that.

With Drive by wire and a few other mods, you could press it up to around 40. If you think that's obscene, check out the acceleration on aircrtaft in R3R. For example, the Airbus A1570 with an accel of 80 or the Bac-Dessault-MBB EFA Variant (which the fluff states is a stock jet fighter for several militias around the world) with an acceleration of a whooping 150. An accel of 150 is also avialable in the Boeing "China Clipper" suborbital, bringing fatal G-forces to the masses. nyahnyah.gif

Scanning my R3 power plant list, I also note that the standard (no smart materials/mbw/turbocharging etc.) max. acceleration for a jet fighter with a jet turbine is 250. With 4 levels of improved handling or a level 2 VCR and a skill of 6, you'd be averaging at an acceleration of 2500m per combat turn per initiative pass. Hullo mr. redout/blackout.
Edward
Remember civilian applications rarely accelerate more than there base acceleration. So that suborbital is going to be accelerating at 16.666m/s/s. uncomfortable but not fatal.

My maths puts that 250m/ct/ct aircraft assuming 3 actions ant 10 successes at 7500/ct after 1 ct. giving an acceleration of 833.333 m/s/s or over 85g.

I concede that this is imposable speed for a human to survive but remember that the pilot dose not always need to be on board.

Edward
hyzmarca
I'm going to assume internal consistancy of units and say that acceleration is m/CT^2. So, the 288 would be divided by 9, not 3. Thats 32m/s^2. Its still fast, but it is much more reasonable than the other.
RunnerPaul
For what it's worth, I've always taken the view that multiplying the vehicle's acceleration rating by the number of successes that the rigger gets only really makes sense if you consider that those rules are an abstraction intended solely for vehicle to vehicle combat, and any distances/speeds/accelerations indicated by the vehicle combat rules are distances/speeds/accelerations measured relative to the other moving vehicle in the combat and not any stationary landmark.

Of course, I also have a houserule that any speed result is automatically capped at the sum of the two vehicles' max speeds, because the fastest two moving points can move relative to each other is if they're traveling flat out in opposite directions.
Edward
QUOTE (RunnerPaul @ Mar 27 2005, 11:55 AM)
For what it's worth, I've always taken the view that multiplying the vehicle's acceleration rating by the number of successes that the rigger gets only really makes sense if you consider that those rules are an abstraction intended solely for vehicle to vehicle combat, and any distances/speeds/accelerations indicated by the vehicle combat rules are distances/speeds/accelerations measured relative to the other moving vehicle in the combat and not any stationary landmark.

Of course, I also have a houserule that any speed result is automatically capped at the sum of the two vehicles' max speeds, because the fastest two moving points can move relative to each other is if they're traveling flat out in opposite directions.

So under that system how long dos it take for a vehicle moving at speed 100 to cross the 1km bridge, and given that the bridge will be blown in 3 combat turns will the vehicle get across.

What quickenes, running multiplier and force spirit power of speed do I need to outrun a racing bike with an acceleration of 15 and a speed of 200 over a 2km race.

Dose my sports car go faster when it is racing a Harley or a motor scooter.

If the vehicle speed and accelerations are only meant to be compared with other vehicles speeds and accelerations what do you use when vehicles, ground distances and meta human speeds all need to be considered together.

Edward
Cain
*sigh*

Here's where you're going wrong. According to the rules on p132, BBB, the accelleration doesn't complete until the start of the next initative pass. So, assuming you have a rigger with a VCR 3 and structural agility 3, the maximum initative you can roll (15+ 4d6) is 39. That's good for 4 actions per turn. If we divide 3 seconds by 4 actions, we get an average time per action of .75 sec.

So, by the SR3 rules, the shortest interval of time a vehicle can accelerate in is somewhat less that .75 sec. Now, this is of course an artifact of averages, so it's not real-world accurate. However, it does put a limit on how quickly you can go from 0-100.
RunnerPaul
QUOTE (Edward)
So under that system how long dos it take for a vehicle moving at speed 100 to cross the 1km bridge, and given that the bridge will be blown in 3 combat turns will the vehicle get across.
In that case, I'm not even in the vehicle combat rules. I'm just doing a straight comparison between the vehicle's speed rating, the distance required to be traversed, and the time allotted. Although speed rating is one of the numbers that get plugged into the abstracted vehicle combat rules, there is a formula given outside of the context of the vehicle combat rules for converting speed ratings into kilometers per hour and such.


QUOTE
What quickenes, running multiplier and force spirit power of speed do I need to outrun a racing bike with an acceleration of 15 and a speed of 200 over a 2km race.
There are special rules for mixed interaction between vehicles and non vehicles, that are based off of the normal combat rules. Unlike vehicle to vehicle combat, I view normal combat as being referenced against stationary landmarks. I would treat it as a running "normal combat" played out over a 2km battlefield.

QUOTE
Dose my sports car go faster when it is racing a Harley or a motor scooter.
Your sports car can go no faster than its maximum speed (plus whatever the percentage over maximum allowed if you're willing to accrue stress points if you're using that rule), wouldn't you agree? And yet, under the vehicle to vehicle combat rules, it's possible, with really good dice rolls, to increase your distance from the opposing vehicle by more meters per combat turn than the vehicle's listed maximum speed. The only way I can see to account for this is to say that the driving tests you make during vehicle to vehicle combat abstractly represent any number of sneaky driving tricks like bootlegger reverses where one vehicle might be chasing another, but the vehicle in the lead makes a sudden 180 degree turn and heads in the opposite direction. Until the second vehicle makes it's own 180 degree turn, it's actually heading in the opposite direction it needs to be going, adding to the distance between the two vehicles. Unfortunately, to account for sneaky tricks, I had to ditch references to fixed landmarks.



QUOTE
If the vehicle speed and accelerations are only meant to be compared with other vehicles speeds and accelerations what do you use when vehicles, ground distances and meta human speeds all need to be considered together.
Like I mentioned above, at the end of the vehicle combat chapter, there's special case rules for combat that involves vehicles and non-vehicles.

And anyway, if ever there were a topic where the stock phrase "Your Milage May Vary" would apply, this would be one of them.
Edward
Although the mechanics are not that fine we can estimate acceleration over a much smaller range, as all vehicles have electronic fuel injection (or similar) acceleration rates can change instantly (for all intensive preposes). By knowing this and that the vehicle can accelerate to 75kph in .75 seconds and 150kph in 1.5 seconds we can state that after it reached 100kph in 1 second. A faster car that after 1 action (.75 sec) is travelling at 150kph can also be said to have reached 100kph in .5 seconds.

These numbers donít reflect the mechanical abstraction; they represent the observations of people within the world. The fact that the car reaches 100kph in .5 seconds gas no relevance to the mechanics but the mechanics provide enough data to work out that that is when it happened.

Edward
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