translating vehicles from 3/e to 4/e: Maneuver Rating

[whswhs]

Originally Posted by Rupert

For this alternate I would suggest a penalty of something like -2 x TR/Move (rounding away from zero), for -0, -2, and -4. This gives similar penalties to 3e in this case at least.

It seems to be respectively 10/10, 22/15, and 40/20. Multiplying by -2 gives -2, -3, and -4, not 0, -2, and -4. Or am I misunderstanding you?

[Kallatari]

Just providing an idea designed more around gaming simplicity than any realistic physics, but what if you used the 4E rules as is (Turning Radius that set the threshold of when a control roll is required and give a penalty based on your Move/Base Move) but then added an additional modifier of -1 per 10% you cut the distance between a safe turn.

So if you performed your turn at 50% of the distance you needed to travel for a safe turn, that's an additional -5 penalty to your roll.

If you turn more than 60 degrees, that counts as two turns, with a second turn happening at a distance of 0, thus a -10 penalty on the second roll (and possibly third and fourth rolls for really tight turns). I can see this coming up with trying to do a 90-degree turn from one street to another. Realistically, it's probably 60 degrees - go forward a bit - 30 degrees, but at high speeds, that might still be enough to require the second turn roll at -8(ish), which is still dangerous enough without being catastrophically dangerous -20 or -30 I saw in some of your other calculated examples.



The other thing that I noticed wasn't mentioned in any of your posts is the 4E stat of Stability Rating (SR) for the vehicle. Remember that to actually crash you have to fail your roll by more than the SR of the vehicle; a lesser failure is just a "close call" (GM's interpretation as to effects, but a default I believe is that they automatically slow down by the maximum safely allowed deceleration on their next turn to recuperate). So while Handling gives a bonus (or penalty) to the roll, the SR is just as important as it's almost equivalent to a bonus to prevent a crash, but does cost you something. If you do come up with an equation for safe turns/penalties to try to match a 3E approach, should it not also be a part of that equation? I am not saying it should - I really don't know - I'm just stating it's a another number that is related to what you are working with that you can attempt to plug in somewhere... if it makes sense.

[whswhs]

What I would really like is something based on realistic physics; I just would like it to be simple to figure out in play. The alternate rule in 4/e isn't that simple, and if I adopt Varyon's original proposal to have -1 when TR increases by an amount equal to the denominator (10 in the 4/e rule), then I get really huge penalties. I don't think turns should be quite that hard. But I'm not looking for a handwavy rule that departs from realistic physics; if I wanted that I could use the standard 4/e rule.

Your rule might be fine for someone who wanted a more cinematic campaign . . .

[whswhs]

As for SR, I'm aware of it and intend to use it. But it looks to me as if I can just say that SR (4/e) = SR (3/e). Easy peasy.

[Kallatari]

Originally Posted by whswhs

What I would really like is something based on realistic physics; I just would like it to be simple to figure out in play. The alternate rule in 4/e isn't that simple, and if I adopt Varyon's original proposal to have -1 when TR increases by an amount equal to the denominator (10 in the 4/e rule), then I get really huge penalties. I don't think turns should be quite that hard. But I'm not looking for a handwavy rule that departs from realistic physics; if I wanted that I could use the standard 4/e rule.

Your rule might be fine for someone who wanted a more cinematic campaign . . .

Fair enough. In that case, I concur with your previous conclusion that you are probably better off converting a 4E vehicle's Handling into an MR rating (or just dropping Handling it and determining MR the way GURPS Vehicles did) and applying the 3E rules for maneuvering instead of GURPS 4E's Turning Radius.

[the-red-scare]

Let me preface this by saying as someone who posts weird technical stuff that I hate seeing people respond this way to these sorts of posts, but I’m genuinely curious: why not just use 3e MR and maneuvering rules as is? That’s what I do. MRs are extremely easy to calculate even for otherwise 4e vehicles.

[whswhs]

Originally Posted by the-red-scare

Let me preface this by saying as someone who posts weird technical stuff that I hate seeing people respond this way to these sorts of posts, but I’m genuinely curious: why not just use 3e MR and maneuvering rules as is? That’s what I do. MRs are extremely easy to calculate even for otherwise 4e vehicles.

Some things about vehicles are essentially the same in 3/e and 4/e. For example, Acceleration turns into Basic Move, and Speed turns into top speed with Enhanced Move. And some things are different: 3/e hit points are a function of body surface area, which is proportional to the 2/3 power of volume, but 4/e hit points are proportional to the 1/3 power of mass.

When I started this out, I didn't know if Handling was essentially the same as MR. And for that matter, I didn't have that firm a grasp of MR. MR gave bonuses or penalties, just like those from Handling, but I didn't know if they scaled the same way. So I wasn't sure if using MR or something based on it would be the same as using Handling, or different, and if it was different, if MR was better or worse. I thought I might want to have a way to calculate Handling from MR, so that I could figure out a table of vehicle stats in 4/e; and, in fact, that's what I've ended up with, after a lot of thrashing around. But I needed to do the thrashing around to figure it out.