I'd assume it is yaw. So if you calculate one you can probably use the same multiplier for the other inertias as well. So if the yaw dynamic index is too low then raise it and raise the other 2 as well using that same multiplier?
I just spent the time I could be calculating those dynamic indexes to post a rant on the ac forum about the topic. 
Anyways, it is a simple math problem.
http://en.wikipedia.org/wiki/List_of_moments_of_inertia
For box you have
and so
Now we know that
Ix=1737,6
Iy=2130,9
Iz=469,6
For reasons z is forward, y is up and x is sideways...
Solve h, d and w:
http://i61.tinypic.com/2ry6101.jpg
http://en.wikipedia.org/wiki/List_of_moments_of_inertia
For box you have
and so
Now we know that
Ix=1737,6
Iy=2130,9
Iz=469,6
For reasons z is forward, y is up and x is sideways...
Solve h, d and w:
http://i61.tinypic.com/2ry6101.jpg
I calculated in on paper
I can get you photo!
I can get you photo!
Lol I calculated the box dimensions.
What I have now in ac: INERTIA=2.4,1.5,5.2
What I should use according to my calculations: INERTIA=1.89,0.56,3.75
I think I've made a mistake... The actual inertias for the car were 2130 yaw, 469 roll and 1738 pitch. With mass of 1450kg.
You can't explain that.
What I have now in ac: INERTIA=2.4,1.5,5.2
What I should use according to my calculations: INERTIA=1.89,0.56,3.75
I think I've made a mistake... The actual inertias for the car were 2130 yaw, 469 roll and 1738 pitch. With mass of 1450kg.
You can't explain that.
Well, this is odd. Yesterday I did steam integrity check for ac and now for me the car seems to have a lot more bouncyness. Before the bouncyness was not an issue for me but now I'm getting oscillations which causes the car to jump around. In the nordschleife the parts which used to not be problems (the early part of the track where you use those concrete/tiled runoffs to cut corners a bit. Or the super fast left hander into schwedenkreutz. Before I noticed there was alot of bodyroll and some bouncing but never so much I'd miss my lines. Now I'm bouncing off the track...).
Also I think I have solved the numb steering issue in the center. Scrub radius. I never assumed it would make such huge difference! First I moved the whole suspension sideways 10millimeters. A lot heavier in the center. Reduced to 6 millimeters and now it feels better I think. There is more weight and resistance in the steering. Which of course makes sense considering what the scrub radius does but I never assumed even 6mm can make such big change. I also moved the steering arms a tad.
If you want I can share the files.
Next I need to go back and double (quad-something-check actually...) those inertias. This time I'll go all out and decide that box system so I can get as accurate as the positioning of the individual parts on my calculator.
Also I think I have solved the numb steering issue in the center. Scrub radius. I never assumed it would make such huge difference! First I moved the whole suspension sideways 10millimeters. A lot heavier in the center. Reduced to 6 millimeters and now it feels better I think. There is more weight and resistance in the steering. Which of course makes sense considering what the scrub radius does but I never assumed even 6mm can make such big change. I also moved the steering arms a tad.
If you want I can share the files.
Next I need to go back and double (quad-something-check actually...) those inertias. This time I'll go all out and decide that box system so I can get as accurate as the positioning of the individual parts on my calculator.
And that steering of yours is antiackerman 
. Basically the outside wheels turns more than the inside wheel. Why it feels more stable and wonders less is because you have several degrees of toe and even more in corners.
eI found the car dimensions in various ways. First I just took the stock xj12c. Then in blender after I had finished the model so the exterior dimensions should be fairly close I then measured it in blender. I did lots of cross referencing to get the blender model correct so I now I have measured most of the stuff from that. Frontal areas for aero, dimensions of the car...
. Basically the outside wheels turns more than the inside wheel. Why it feels more stable and wonders less is because you have several degrees of toe and even more in corners.eI found the car dimensions in various ways. First I just took the stock xj12c. Then in blender after I had finished the model so the exterior dimensions should be fairly close I then measured it in blender. I did lots of cross referencing to get the blender model correct so I now I have measured most of the stuff from that. Frontal areas for aero, dimensions of the car...
Last edited by Hyperactive, .
Well the box method is not supposed to be the exterior dimensions of the car exactly. But you also need to take into consideration the location of the cog (box becomes longer, wider or taller if the cog is further away from the geometric center). And also like phil said how much is the mass centered near the cog or more towards the edges. So the jag has more weight on the outer edges than the v8sc. Thicker steel (maybe), more heavier bodyshell, heavier windows, bonnets, doors etc.
in reddit I also saw a mention of BMW M235i Racing
lambo diablo SE30 Jota would be a nice car. Apart from the countach are those all awd? (I don't know much about modern lambos)
Meh. I just drove around vallelunga and noticed the wheel holes show through. For some reason ac doesn't show the bits behind the wheel but shows what's behind the car...
Hmm, I think I'll send a pm to aris to see if he responds. As far as I know he was one of the guys doing tires and physics for the gtr2 power&glory mod so he should have good bit of info about the tires these suckers have.
I'll check that reducing dy0 but again I just don't want to it blindly. So I need to figure out if it works why it works.
I did check some rf mods. And nope. I don't see such pattern.
It is odd because on my car I can pretty much change the dx1/dy1/xmu values in a major way without causing big difference to the car handling. What I have found is that my tires seem to be (or were at one point) somewhat camber sensitive.
Those peak values come from my only source of info about the tires. Historix mod. Comparable tires (3.0 csl) which raced same times (in the same races even: http://touringcarracing.net/Pages/p%201977%20Zandvoort.html). The csl in rf had something like 1.5lat, 1.3long.
nope
Wide. 345 front, 365 rear! (yolo) Maybe I should try just making the tires skinny to see what it does to the car.
Maybe this is a wheel issue because for me I don't really notice any wandering. Some people are saying it does it but personally I only seem to notice it when I drive with keyboard (testing stuff) or with a wheel braking into a corner where it does get a bit squirrelly. But with a keyboard I notice the car has a tendency to keep its rotation. Like if you make a turn on the straight the car kinda keeps going to that direction. But I don't notice it with wheel (fanatec 911 tbo s).
Hmm, maybe I should tripple check the steering arms. Does the problem go away with more toe-in? Sinbad also mentioned light feeling in the center.
The model and sounds are borrowed.
I'll take a look. What was wrong? Too little unsprung weight, tires..?
I don't think there are any hidden driving aids in the car physics files, boris. I've turned off everything I have found.
I get what you say phil. I don't know what it is that makes the car almost tankslapper free. How it is so effortless to drive out of corners. How it stops so well. I get it there is something wrong with how well the car rotates. The inertias are there and they are big. It has mass. Mental front weight distribution. Huge wide tires all around. Relatively neutral aero in the sense the car basically makes 0 lift. But it has lift on front axle and downforce in the rear. And high cog of pretty much half metres. 0.48m Iirc.
TOTALMASS=1450
INERTIA=2.4,1.5,5.2
The way inertias work in ac is that you just try to create a box that matches the dimensions the car. Then make the box longer if the cog is far away from the geometric center. For example a 4 metre long porsche would have inertia of something like x,y,4.5 meaning its yaw (and pitch) inertia is bigger than the car dimensions would produce. The jag length is 4.8metres. The inertia for the box is 5.2. I have not calculated the reverse of the 3 dimensional box kunos uses so I could use the inertias I've calculated for the jag. Maybe I should do that. But I don't think the problem is there. The tires have inertias and weight as well. Those are probably the heaviest parts in any ac apart from the race truck.
I'm thinking the dampers need more work. But also in the tires there could be something that makes the super wide tires handle too well. But I don't know what it is. The tires are not easier than the kunos tires. The xmu, load sensitiveness, camber gains. All those are very close to the 312t tires that I used as a base. Same make (dunlop), same construction (biasply) and same era. I've tried 90s slicks. The car handles even better. I tried the grpA tires from m3. Handles really really well.. On the first version of the car I made a mix of those 3. I did try contacting the historix guys too but their response was pretty much they don't want the car (I basically offered the model in exchange for help with the tires). I tried contacting the historix physics guy but he did not respond.
I won't just start changing things randomly to make the car drive harder. I want to understand what is wrong. This is the best I can at the moment.
I get what you say phil. I don't know what it is that makes the car almost tankslapper free. How it is so effortless to drive out of corners. How it stops so well. I get it there is something wrong with how well the car rotates. The inertias are there and they are big. It has mass. Mental front weight distribution. Huge wide tires all around. Relatively neutral aero in the sense the car basically makes 0 lift. But it has lift on front axle and downforce in the rear. And high cog of pretty much half metres. 0.48m Iirc.
TOTALMASS=1450
INERTIA=2.4,1.5,5.2
The way inertias work in ac is that you just try to create a box that matches the dimensions the car. Then make the box longer if the cog is far away from the geometric center. For example a 4 metre long porsche would have inertia of something like x,y,4.5 meaning its yaw (and pitch) inertia is bigger than the car dimensions would produce. The jag length is 4.8metres. The inertia for the box is 5.2. I have not calculated the reverse of the 3 dimensional box kunos uses so I could use the inertias I've calculated for the jag. Maybe I should do that. But I don't think the problem is there. The tires have inertias and weight as well. Those are probably the heaviest parts in any ac apart from the race truck.
I'm thinking the dampers need more work. But also in the tires there could be something that makes the super wide tires handle too well. But I don't know what it is. The tires are not easier than the kunos tires. The xmu, load sensitiveness, camber gains. All those are very close to the 312t tires that I used as a base. Same make (dunlop), same construction (biasply) and same era. I've tried 90s slicks. The car handles even better. I tried the grpA tires from m3. Handles really really well.. On the first version of the car I made a mix of those 3. I did try contacting the historix guys too but their response was pretty much they don't want the car (I basically offered the model in exchange for help with the tires). I tried contacting the historix physics guy but he did not respond.
I won't just start changing things randomly to make the car drive harder. I want to understand what is wrong. This is the best I can at the moment.
Just be as anal as possible when going through the suspension setup. Calculate every bit, double check every measurement you have, try to understand what every term means, understand how and why it works and matters. Try to visualize everything you can in excel or in some other software. Then drive it. If it does odd things try to learn what is causing it. Don't adjust anything based on feel. Only use feel to find issues. Never try some random value. Try to use math to fix them. And accept good feedback If all else fails see what others are doing (kunos has all tires available so it is not full darkness labyrinth like in rf1 was at the time).
Apart from the tires I feel I achieved that. And with the tires nobody knows what the values actually do. Xmu is supposed to be the shape of the slip peak. But how exactly nobody knows. Stuff like relaxation length, speed sensitivety? Nope. Not that I would know even if I had the exact equations. I don't know much about tires.
I think I'll be doing one mre patch for the car. It doesn't seem to be particularly popular so doing the lods is probably waste of time. Once I fix the last issues (and get proper sound for the car) I think I move to lx8gtr.
Apart from the tires I feel I achieved that. And with the tires nobody knows what the values actually do. Xmu is supposed to be the shape of the slip peak. But how exactly nobody knows. Stuff like relaxation length, speed sensitivety? Nope. Not that I would know even if I had the exact equations. I don't know much about tires.
I think I'll be doing one mre patch for the car. It doesn't seem to be particularly popular so doing the lods is probably waste of time. Once I fix the last issues (and get proper sound for the car) I think I move to lx8gtr.
The new version of my car is out:
http://www.assettocorsa.net/forum/index.php?threads/broadspeed-jaguar-xj12c-1977-v01-is-out.12979/page-16#post-345808
https://www.youtube.com/watch?v=VZaqtLruCVk
Have fun.
http://www.assettocorsa.net/forum/index.php?threads/broadspeed-jaguar-xj12c-1977-v01-is-out.12979/page-16#post-345808
https://www.youtube.com/watch?v=VZaqtLruCVk
Have fun.
new closed beta version of the broadspeed jaguar:
http://www6.zippyshare.com/v/74508998/file.html
Tell me what's wrong.
http://www6.zippyshare.com/v/74508998/file.html
Tell me what's wrong
.It is ripped from lfs s4.
Maybe one day
(that is all scratch made by me)
(that is all scratch made by me)
I have managed T3 and further many times. Not many without getting wrecked though.
All the spa servers are useless for racing tbh.
It seems the 5s penalty has been tweaked a little bit? It's no longer an additional insult if you spin off but it seems to "understand" that if you run wide in a slow chicane and halfspin and lose time you don't get the additional 5s penalty. Dunno.
The ruf also seems to have the same hidden driving aid as the cobra. Once you get into big slide it suddenly stops rotating any more and the car almost like drifts itself. Maybe it is just the ffb being better following the path of the car with the front tires. Or maybe there is just some bug with the tires... compared to how hard it is to keep the car at the limit keeping the car at decent drift angle is super easy. Just odd...
All the spa servers are useless for racing tbh.
It seems the 5s penalty has been tweaked a little bit? It's no longer an additional insult if you spin off but it seems to "understand" that if you run wide in a slow chicane and halfspin and lose time you don't get the additional 5s penalty. Dunno.
The ruf also seems to have the same hidden driving aid as the cobra. Once you get into big slide it suddenly stops rotating any more and the car almost like drifts itself. Maybe it is just the ffb being better following the path of the car with the front tires. Or maybe there is just some bug with the tires... compared to how hard it is to keep the car at the limit keeping the car at decent drift angle is super easy. Just odd...
It can do every kind of oversteer.
And it is insanely fun wet sock to drive around nordschleife!
The yellowbird is available as free gift.
FGED GREDG RDFGDR GSFDG