Physics investigations on Stunts

[Overdrijf]

Wow ones again. You really are good at this. So the drag really has nothing to do with it, and my kart has a very special unreachable powergear...

[Overdrijf]

By the way, I'm probably sounding spoiled now, but it appears you where so exited about the second set of dimensions that you didn't mention were the car-to-car set is located.

[Duplode]

I can not imagine you did not find this out in a dream.

Not quite, it was rather like one of those situations when lots of apparently unrelated informations suddenly start to make sense together when you stumble at the missing piece 

Only one distinction missing: speed difference between ACURA power gear and Indy power gear.

This distinction was, in a way, already pointed out - by you  Many years ago you wrote, and a few years later I read, a "Tips for Newbies" article in which the powergears of Indy and Acura were called "flexible", in opposition to the GTO and Vette ones. That is the fundamental distinction: "rigid" (or boring ) powergear, the most common kind, works exactly the same for all cars that have it - to reach it you have to be at/above 225mph and the car must not have enough engine power to keep accelerating on its own by then. Flexible powergear, on the other hand, can be reached below the flat track top speed, and the minimum launch speed depends on the balance of forces acting on the car (including engine power, gear ratios, aero drag, steepness of slope, etc.). The launch speed for flexible powergear can potentially be much lower than 225mph, a fact that is evident on any Acura/Indy lap... The speed of the car when in PG is the speed of the car at maximum rpm in the (final) gear, so that's why Acura and Indy are different. If Acura had a value for mass that would give it rigid PG, however, it would never reach it, as the top speed is below 225mph (that is exactly the case for Audi, by the way). I like "rigid" and "flexible" terminology, guess I'll stick with it 

So the drag really has nothing to do with it, and my kart has a very special unreachable powergear...

Drag does not affect the kind of powergear indeed, but it if the powergear is flexible it changes the minimum speed (higher drag leads to easier-to-reach powergear). You mentioned to be using mass=15 and drag=19. 15 is a flex-PG value (same as Indy), and 19 is quite low, so the minimum speed might be well above 156mph (have you tested going through a loop, though?  )

By the way, I'm probably sounding spoiled now, but it appears you where so exited about the second set of dimensions that you didn't mention were the car-to-car set is located.

Oh my bad, maybe I shouldn't have gone so far in skimming detail on that post  The range of interest is 0EEh - 0F3h, and values are in the usual x-y-z pattern. I will (try to) start writing some of this stuff (and more) to the Wiki now, so stay tuned 

[Overdrijf]

So the drag really has nothing to do with it, and my kart has a very special unreachable powergear...

Drag does not affect the kind of powergear indeed, but it if the powergear is flexible it changes the minimum speed (higher drag leads to easier-to-reach powergear). You mentioned to be using mass=15 and drag=19. 15 is a flex-PG value (same as Indy), and 19 is quite low, so the minimum speed might be well above 156mph (have you tested going through a loop, though?  )

Not 15, 5. That's actually just a bit on the heavy side for a "realistic" superkart. So that would make it rigid. But no, I haven't tested a loop yet, I should probably still do that. (But I'm too lazy to do that before getting the new dashboard to work, and that's gonna take a few days.)

[CTG]

Duplode, may I have a question? How do you have so much energy for this Stunts research plus high level racing in the same time? This work is amazing!

[Duplode]

Duplode, may I have a question? How do you have so much energy for this Stunts research plus high level racing in the same time? This work is amazing!

Thanks - in my case, I think one thing feeds the interest for the other, and vice-versa 

[Overdrijf]

O, I forgot to mention, I tried the loop. As predicted by your formula, it does not powergear (for having a rigid/boring powergear and limited top spead).

[Duplode]

You can already read full report on how to control PG when tuning a car at http://wiki.stunts.hu/index.php/Power_gear_bug ...

[CTG]

Daaaaaamn, I just realized that I use a bad theory for air drag limited top speed calculations. It worked for all my custom cars, except Veyron: it should reach 245 mph without powergear, but somehow it accelerated only up to 237. Problem solved. Sometimes I should read the instructions carefully...

[gagarin]

OFF: just found this spare account, forgot about it completely... (guests cannot see the memberlist)

ON:
Have you ever noticed that car size ratios are far from real life values? Duplode described the height anomaly and that some cars are just way too big. But their relative size is weird, too. Audi Quattro and Countach have almost the same length in real life - while in Stunts, difference is 22 units (>1.3 m).

Stunts Wiki says 1 pt = 0.2 ft = 6.1 cm (confirmed).

Lamborghini Countach
Real life size: 420/200/107
Stunts size: 104/38/18; which means: 634/232/110
Difference in %: +51.0 (!!!) / +16.0 / +2.8

Way too long and flat.

Lancia Delta Integrale
Real life size: 390/177/136.5
Stunts size: 79/34/25; which means: 482/207/153
Difference in %: +23.6 / +16.9 /  +12.1

Ratios are more or less fine.

Lamborghini LM002
Real life size: 490/200/185
Stunts size: 88 (without spare wheel)/34/31; which means: 537/207/189
Difference in %: +9.6 / +3.5 /  +2.2

The largest car from the pack in real life - very undersized in the game, compared to other cars.

[Duplode]

There is a correction to be made, minor numerically but conceptually relevant, to the discussion about tile length in the opening post here. It's something that has been known for some time, but hadn't been written down yet. Back in the day, I had talked about the tile to feet conversion in these terms:

And now for the interesting stuff, during which I'll use imperial units so the numbers get prettier. Since one mile is exactly 5280 feet, that means one tile measures 204.95 feet, very close to an integer number... since we should expect a slightly higher speed than 245mph due to truncation, it is perfectly reasonable to admit the developers made it so that each tile has exactly 205 feet, or 62.484 meters. That, in turn, triggers a cascade of interesting implications: [...]

There are two naive assumptions in the quote above. Firstly, there is no reason to expect a speed higher than 245 mph, as that is a hard limit which the game imposes by cutting off engine power when it is hit. Secondly, though the feet might feel like a more natural unit for describing the displacement of a car, it turns out the game goes directly from mph speed to displacement in internal units, without feet as an intermediate. The practical consequence is that the conversion factors 1 graphical point = 0.2 feet and 1 mph = 11/30 graphical points per frame are exact, and therefore 1 tile = 1024/5 feet = 204.8 feet. The Car Model Physics article in the Wiki was updated accordingly.

[Cas]

Track tiles measured in feet don't feel very natural.... They should be measured in wheels instead    Anyway... good to have the precise data now documented!