Heroes Can't Jump

[TippetsTX]

Originally Posted by hcobb

Maximum length jump is at 45 degrees and reaches a quarter of the jump length in height. So rotate that vector and put all of jump into height instead.

So you're extrapolating... which is fine, but please don't claim something is RAW when it isn't.

Personally, I don't think real-world physics models are very useful in creating RPG rules. They can inform design choices, but they shouldn't be applied literally. The gameplay feel is more important than the formula IMO.

[David Bofinger]

Originally Posted by hcobb

Maximum length jump is at 45 degrees and reaches a quarter of the jump length in height. So rotate that vector and put all of jump into height instead.

The implicit assumption here is that the speed of the jump is independent of the angle at which it's made. Which isn't true: the forces required to jump up slow down the maximum speed.

The world high jump record is almost 2.5 metres, the centre of mass probably only rises about 1.2 metres, the ability to jump up levels would be somewhere in-between. The box jump record, which probably approximates better than these others what we might mean by jumping up a level in TFT, is almost 1.5 metres.

The long jump record is almost 9 metres and includes a little poking your feet out the front that might be unrealistic, I'm not sure. But that's not apples to apples because it's a jump with runup compared with a standing jump. The standing long jump record is only 3.7 metres.

There are some interesting tables in https://www.brunel.ac.uk/~spstnpl/Pu...Linthorne).pdf

I thought I understood this better when I started typing than I do now.

[Axly Suregrip]

Originally Posted by David Bofinger

The world high jump record is almost 2.5 metres, ... The box jump record, which probably approximates better than these others what we might mean by jumping up a level in TFT, is almost 1.5 metres.

The long jump record is almost 9 metres and includes a little poking your feet out the front that might be unrealistic, .... The standing long jump record is only 3.7 metres.

David, you collected some nice pieces of data. This is helpful. Comparing high jump record (2.5m) to long jump record (<9.0m) we can come up with the following: going up is about 1/3 that of going across. Maybe that can be used.

The box jump record is also useful.

Either way, it depends on how the OP intends to use it. I think you gave him the info here for him to figure out the rest as he needs it.

[Shostak]

Originally Posted by hcobb

Maximum length jump is at 45 degrees and reaches a quarter of the jump length in height. So rotate that vector and put all of jump into height instead.

For example, a one second duration maximum length jump is 5 m/s up and 5 m/s along the length and hence covers 5 m in that second. In the half second to reach maximum height you travel d = 0.5 * a * t^2 = .5 * 10 * (0.5)^2 = 1.25 meters in height (or a fourth the length as expected).

But doesn't that assume that the same energy is going into a vertical jump as a horizontal jump? It seems to me that standing still and jumping straight up will have a lot less energy than running at 5m/second and jumping.

[hcobb]

Originally Posted by Shostak

But doesn't that assume that the same energy is going into a vertical jump as a horizontal jump? It seems to me that standing still and jumping straight up will have a lot less energy than running at 5m/second and jumping.

Or Usain Bolt at 10 m/s. (MA 20, doubled for running in perfect unguarded conditions.)

[Drakenbow]

Oh, my!!!! Math is now in session. Let me pull out my sliderule!

I agree with the basis of HCobb's math even though I don't remember my high school and college physics class formulae. I do remember that 45 degrees with an initial velocity does yield the maximum potential distance. And that rotating the angle to 90 degrees will determine maximum height.

I do wish to point out that examples being used are top notch athletes trained for these feats of long and high jumps. Also, they are unladen by the boots, pants, belt, weapons, and other things carried by a character. But this is a fantasy game - it's magic! The characters don't have perfect running pitches and don't have time to make the perfect steps into the jumps (long or high).

So with that... Using reality and trying to mesh in the rules, what comes out to a workable game rule? The rules did use a progressive number of dice againt (ST+DX) in order to suceed for the distance attempted. Failure means falling short somewhere along the path. Same should be extrapolated for high jump, and a bit extra for the character's height and reach, yes?

[Axly Suregrip]

And let's not forget that jumping vertically will be more affected by how encumbered the character is. Running across you have more momentum with that extra weight then you do going up. Maybe for simplicity just go with MA.

I am going to assume you are trying to figure how far someone has to jump to grab a ledge. There are other reasons to want to know how far up someone can go, but that is the one that seems to make the most sense to me.

A big part of "how high can they reach with a jump" is going to be how tall are they and how long are their arm reach?

Average vertical jump is 12 to 20 inches. This fits nicely with it being MA * 2 in inches. Elves and runners in no armor going beyond the top average is good as there should be some outliers when using averages.

Now you just need a table of height & reach by race are you are all set.

[David Bofinger]

Originally Posted by hcobb

Or Usain Bolt at 10 m/s. (MA 20, doubled for running in perfect unguarded conditions.)

Also he's slower in his first turn and a little faster thereafter.

Usain Bolt also only steps in every second hex. His hundred metres record consisted of 41 steps, most of which were jumps over one intervening hex.