The online racing simulator
VHPA v3.1.4 [updated 26/03/10]
(613 posts, started )
sorted didn't need to move the file just selected the compataibility option like you said and it worked a treat

thanks again Bob
Thanks for making the simplified dampers automatic Bob
Quoting from another thread:

Quote from tristancliffe :Bob's setup tool is too complicated for it's own good (I've tried using it on my Reynard, but you need to know about 300 parameters I'll never be able to find out or measure

Which can't you measure? I'd have thought most of them could be measured (directly or indirectly) or estimated to a useful degree of accuracy.

(It's about 50 parameters btw, excluding the setup - though I realise you were exaggerating)
Vista sorted
Hi,

Just thought I'd let people know that I got the Vista registration issue sorted out. What was causing the problem was that even though I was running in Admin mode I also had User Account Control turned on. Seems this was blocking the registration process.

All working now!

thanks,
Andrew
Quote from Bob Smith :OT but:


Which can't you measure? I'd have thought most of them could be measured (directly or indirectly) or estimated to a useful degree of accuracy.

(It's about 50 parameters btw, excluding the setup - though I realise you were exaggerating)

CoG Height
Motion ratio of suspension (certainly not 1:1!)
Unsprung Mass (not without a complete stripdown of each corner)
Cd
Cl
Position of aero centres.
Brake torque (you be much better off with bias bar position, master cylinder diameter, wheel cylinder diameter, pad area and Cf, but maybe that's asking too much).
Roll bar stiffness - diamater, length and arm length would be better. If you could include blade type ARB adjustments even better
Ackermann - pffff, I dunno. Whatever it had when designed.
Damping. I think we have some figures for what the dampers should be, but the numbers are something like 300/8, which is nothing like the values in LFS and/or your units. I don't know what units ours were.

And after putting in 'best guesses' it says the top speed is 113mph, about 20mph down. My excel one is accurate to +-2mph, and requires less data (admittedly it doesn't work out times to speed/distance, or cornering ability, or aero stability etc, but I wouldn't believe yours anyway as it would be too simplistic to rely on anyway).
Tristan, damper values you talk about are valving, for example Bilstein uses 350/150 that is 3500 (3.5 lfs units) rebound and 1500 (1.5 lfs units) bump, I think it was at 0.150m/s rate, but can't remember that for sure. Anyway those values are probably not too difficult to decode to values used in LFS, now what is bit more challenging is to define rates before and after 0.150m/s.

Pic is to illustrate how damping behaves and it will explain how some value is not very useful alone we need to know what is test speed also.

What I can tell from my trip to dark side, it is very big factor how car feels, so this is something one have to get right as it affects so much to feel and handling.

Well, many of you know this already, but maybe some can get something out from this.

EDIT: Oh yes, motion ratio should be easy to get from F3 car, measuring with tape and bit of calculator work should do it
Attached images
shock_comp02.gif
CoG Height - can be estimated by comparing roll during cornering, assuwing you can measure that on your car, and that you have spring and anti-roll bar stiffnesses correct before-hand. Admittedly not easy.

Motion ratio of suspension (certainly not 1:1!) - latest versions allow your to enter the motion ratio. I have found guides online on how to measure it. Not a quick task though.

Unsprung Mass (not without a complete stripdown of each corner) - Rough estimate, remove wheel and tyre, weigh that, add 40-50%? Does that sound reasonable?

Cd & Cl - yep, completely understandable. No easy solution there.

Position of aero centres - not too hard for the wings, if you assume centre of the wing (front to back), that can't be far off? As for undertray and body, agreed, same as above.

Brake torque (you be much better off with bias bar position, master cylinder diameter, wheel cylinder diameter, pad area and Cf, but maybe that's asking too much).

Roll bar stiffness - diamater, length and arm length would be better. If you could include blade type ARB adjustments even better - I'll look into adding a calculator for that at some point.

Ackermann - pffff, I dunno. Whatever it had when designed. - Can't you measure the angles of the steering arms (maybe incorrect term) when the wheels are pointing straight ahead?

Damping. I think we have some figures for what the dampers should be, but the numbers are something like 300/8, which is nothing like the values in LFS and/or your units. I don't know what units ours were. - Yeah, dampers are like ARBs, very difficult to actually find numbers with units on them. Damper response is also very different between typical real dampers and the LFS dampers modelled in this app.

Quote from tristancliffe :And after putting in 'best guesses' it says the top speed is 113mph, about 20mph down. My excel one is accurate to +-2mph, and requires less data (admittedly it doesn't work out times to speed/distance, or cornering ability, or aero stability etc, but I wouldn't believe yours anyway as it would be too simplistic to rely on anyway).

Another problem is that you can only pick aero devices from LFS, a major limitation to recreating cars like yours. While being able to create your own will happen at some point, I doubt you'll have any data with which to build one with anyway.

Edit: JTbo's post was not there when I started typing.
With regard motion ratio, that will vary over the travel of the suspension, as the rocker arms pivot. That is what preload on springs is all about on single seaters (apart from ensuring the springs don't unload on full droop) - you set the preload so that the static condition as the rockers in the right position to acheive the correct rising rate (rocker movement) in bump.

Hence mine can't be 1:1, even if it is at one point.
Quote from Bob Smith :CoG Height - can be estimated by comparing roll during cornering, assuwing you can measure that on your car, and that you have spring and anti-roll bar stiffnesses correct before-hand. Admittedly not easy.

Could estimate it from photos I suppose, and use that angle for the calcs, but still not easy.

Quote :Unsprung Mass (not without a complete stripdown of each corner) - Rough estimate, remove wheel and tyre, weigh that, add 40-50%? Does that sound reasonable?

Bit of a dirty hack though isn't it!

Quote :Cd & Cl - yep, completely understandable. No easy solution there.

One day, at a test session, if I have nothing left to do, I'll attempt coast down tests on the car in various levels of downforce/ride height. Won't be any time in the next decade though

Quote :Position of aero centres - not too hard for the wings, if you assume centre of the wing (front to back), that can't be far off? As for undertray and body, agreed, same as above.

Hmmm, could do I suppose. The rake of the car (either by static setup or dynamic load transfer) will very the body/floor/diffuser values as well as move them. Pffff

Quote :Ackermann - pffff, I dunno. Whatever it had when designed. - Can't you measure the angles of the steering arms (maybe incorrect term) when the wheels are pointing straight ahead?

It's got fabricated uprights, with no easy provision for measuring that angle. I could possibly measure the wheel angles on full lock, and derive the ackermann from that.

Quote :Damping. I think we have some figures for what the dampers should be, but the numbers are something like 300/8, which is nothing like the values in LFS and/or your units. I don't know what units ours were. - Yeah, dampers are like ARBs, very difficult to actually find numbers with units on them. Damper response is also very different between typical real dampers and the LFS dampers modelled in this app.

Yeah, ours are something like 300/8 or thereabouts, and JTbo has expanded on those numbers a bit. Thanks. Not sure if those units can be used in your prog though.
I think F3 car uses pushrods? Those make things bit more complicated as you need to calculate leverage of pushrod so you can get wheel rate.

There was bit more into this on RSC rTracktor board but it is rather hard to find. Anyway easiest way to find natural frequency is to have only spring in and count how many bounces there is in second. But with F3 car that could be bit tricky as spring without damper is just not possible, I think?

Anyway, it is possible, just need bit more calculations than road car suspension.
Quote from tristancliffe :CoG Height
Motion ratio of suspension (certainly not 1:1!)
Unsprung Mass (not without a complete stripdown of each corner)
Cd
Cl
Position of aero centres.
Brake torque (you be much better off with bias bar position, master cylinder diameter, wheel cylinder diameter, pad area and Cf, but maybe that's asking too much).
Roll bar stiffness - diamater, length and arm length would be better. If you could include blade type ARB adjustments even better
Ackermann - pffff, I dunno. Whatever it had when designed.
Damping. I think we have some figures for what the dampers should be, but the numbers are something like 300/8, which is nothing like the values in LFS and/or your units. I don't know what units ours were.

And after putting in 'best guesses' it says the top speed is 113mph, about 20mph down. My excel one is accurate to +-2mph, and requires less data (admittedly it doesn't work out times to speed/distance, or cornering ability, or aero stability etc, but I wouldn't believe yours anyway as it would be too simplistic to rely on anyway).

some of those things are pretty easy:

- motion ratio: 1. put a jack under one wheel and raise it 1" 2. take a zip tie and put it on the shock shaft up against shock body. 3. lower the wheel exacly 1". 4. measure distance between zip tie and shock body. that distance is your motion ratio (i.e. how much the shock travels for 1" of wheel travel).

- unsprung mass: (this only works as long as you're using rodends in the suspension and not rubber bushes and the rodends are reasonably free and are not binding up). 1. put the car up on jackstands 2. put corner scales under each wheel (or just one front and one rear) 3. disconnect the shock/spring and a/r bar link completely. the scale will read the approximate unsprung weight for each corner. depending on how tight the rodends are i'd add 5-10% for friction. it may also help to raise the wheel off the scale and put it back down a couple times and take averages.

- brake torque is not difficult if you can measure your deceleration (in g) and know your tire diameter.

the things that are hard:

- CG height. you won't get that without having a spreadsheet or CAD model with every component and its accurate weight and location. measuring from roll angle is very error prone as it requires knowing your exact roll stiffness front and rear, the exact cornering g, the exact longitudinal position of the cg (which is the easiest of the bunch) and to some degree chassis torsional stiffness although on a race car that's pretty minor. you might as well just eyeball it or use 13" for a formula car just because.

- CD, aero centers of pressure, etc. you need a rolling road wind tunnel or a good and accurate CFD model with sophisticated software and someone who REALLY knows what they're doing. eyeballing it is absolutely pointless. even good data acq with motion and force transducers can only get you in the ballpark, depending on how sophisticated your filtering is and how carefully you run the tests. best you can do is guess whether there's downforce or lift and whether center of pressure is forward or aft of CG by how the car feels at high speed vs low speed. even coastdown tests would need to be performed very carefully and the results are not at all obvious since you have to filter out rolling resistance and drivetrain drag. it's far easier to 'reverse engineer' the CD if you know your horsepower and frontal area by looking at your actual top speed and rpm and then calculating what the CD must be to achieve that. you can get to within 5% of the actual number that way if your top speed is high enough where drag is the overwhelming factor, say 150 mph or so. at lower speeds you need to account for mechanical factors more.
bob have my babies :P this is a awesome peice of software, and has help me get faster and set the car upa lot better, it should be integrated with LFS down the line, next just need a realtime data logging sort of thing to go with it
Quote from Bob Smith :You can find the option for 'LFS compatibility mode' in the attached screenshot.

As for the file error, the file 'COMDLG32.OCX' is included in the zip. I'm not sure what has made this want to happen now, but move that file into your windows\system32 folder. Then click Start, Run, and type in: 'REGSVR32 COMDLG32.OCX'. Click OK. Once that has executed, try loading the program again.

for all u guys getting this files is missing dependecies or similar issues with this file, right click on the executable, of this program, run as admin, and its fine after that
dont know if this has been said before, but when i try to open certain XRG setups, it gives me a runtime error.

Quote : Run-time error '383':
'Text' property is read-only

not sure what it means.
it will let me open any other setups.
just not these certain ones.
Please post the setup here and I will have a look.
Quote from Bob Smith :Please post the setup here and I will have a look.

i dont know if it matters, but both were made while in multiplayer.
they were intended for use in LTC servers so they arent too important
cant figure out whats going on.


if i find any more that dont work, i will upload them.






on another note, occasionally, when autospacing gears, i get an overflow error.
i think its because the gears are too close together.

another thing is that my "tire grip" line has disappeared from the gear analyzer screen.
i am talking about the red line that was so useful for powerful FWD cars (UFR) to prevent me from frying the tires all day long
Attached files
XR GT_sand saver.set - 132 B - 242 views
XR GT_towtruck.set - 132 B - 240 views
Thanks for the setups, will check them out.

Quote from Zebediah_S2 :on another note, occasionally, when autospacing gears, i get an overflow error.
i think its because the gears are too close together.

I'll have a play but some example settings would come in handy. It's not something I've seen before.

Quote from Zebediah_S2 :another thing is that my "tire grip" line has disappeared from the gear analyzer screen.
i am talking about the red line that was so useful for powerful FWD cars (UFR) to prevent me from frying the tires all day long

That line is now optional, check out the graph settings to enable it. It should be noted the red line does not take either weight transfer or downforce into account, so isn't at all accurate (hence it is off by default).
Quote from Bob Smith :I'll have a play but some example settings would come in handy. It's not something I've seen before.

it usually happens when the gears are relatively close:
first = 3
fifth = 1
drop = ~ between 4.9 and 9.9


Quote from Bob Smith : That line is now optional, check out the graph settings to enable it. It should be noted the red line does not take either weight transfer or downforce into account, so isn't at all accurate (hence it is off by default).

i cant figure out how to turn it on tho...
i am slow.
the "show front/rear vertical tire loads doesnt do it, and thats the only thing relating to tires in the options menu
Quote from Zebediah_S2 :it usually happens when the gears are relatively close:
first = 3
fifth = 1
drop = ~ between 4.9 and 9.9

I tried with a few cars and gearing twice as close as that, no problems here.

Quote from Zebediah_S2 :i cant figure out how to turn it on tho...
i am slow.
the "show front/rear vertical tire loads doesnt do it, and thats the only thing relating to tires in the options menu

Tyres? It's part of the gearing analysis. "Gearing Analysis - Torque Plot Options" is the frame you want (towards the bottom of the page so you'll need to scroll). The option is called "Draw Static Traction Limit".

I'll look at the setup problem tomorrow when I'm more awake.
its possible that i have a bad version.

with the uf 1000, i have 1st set at 4.5 and 4th set at 1
with adjustable progressive, anything below 19 gives me an error.

i also cant find the tire torque option.

i cant tell what version i have, but i think its the second one you released

i am using lfs x 10

here are two pics
hilight the thing in red





edit:

all right.
i just downloaded the final version.
everything seems to be ok.
sorry for the confusion.
Attached images
grc1.jpg
grc2.jpg
Aha, sorted, I just opened those sets and they loaded fine, so that's good.

Note the latest version is RC Complete, not RC Final. The up-to-date link is always available from the first post.
Quote from dpcars :some of those things are pretty easy:

- motion ratio: 1. put a jack under one wheel and raise it 1" 2. take a zip tie and put it on the shock shaft up against shock body. 3. lower the wheel exacly 1". 4. measure distance between zip tie and shock body. that distance is your motion ratio (i.e. how much the shock travels for 1" of wheel travel).

- unsprung mass: (this only works as long as you're using rodends in the suspension and not rubber bushes and the rodends are reasonably free and are not binding up). 1. put the car up on jackstands 2. put corner scales under each wheel (or just one front and one rear) 3. disconnect the shock/spring and a/r bar link completely. the scale will read the approximate unsprung weight for each corner. depending on how tight the rodends are i'd add 5-10% for friction. it may also help to raise the wheel off the scale and put it back down a couple times and take averages.

- brake torque is not difficult if you can measure your deceleration (in g) and know your tire diameter.

the things that are hard:

- CG height. you won't get that without having a spreadsheet or CAD model with every component and its accurate weight and location. measuring from roll angle is very error prone as it requires knowing your exact roll stiffness front and rear, the exact cornering g, the exact longitudinal position of the cg (which is the easiest of the bunch) and to some degree chassis torsional stiffness although on a race car that's pretty minor. you might as well just eyeball it or use 13" for a formula car just because.

- CD, aero centers of pressure, etc. you need a rolling road wind tunnel or a good and accurate CFD model with sophisticated software and someone who REALLY knows what they're doing. eyeballing it is absolutely pointless. even good data acq with motion and force transducers can only get you in the ballpark, depending on how sophisticated your filtering is and how carefully you run the tests. best you can do is guess whether there's downforce or lift and whether center of pressure is forward or aft of CG by how the car feels at high speed vs low speed. even coastdown tests would need to be performed very carefully and the results are not at all obvious since you have to filter out rolling resistance and drivetrain drag. it's far easier to 'reverse engineer' the CD if you know your horsepower and frontal area by looking at your actual top speed and rpm and then calculating what the CD must be to achieve that. you can get to within 5% of the actual number that way if your top speed is high enough where drag is the overwhelming factor, say 150 mph or so. at lower speeds you need to account for mechanical factors more.

My motion ratio isn't fixed. As I have rising rate suspension, the wheel ratio varies from about 2:1 to about 1:1 depending on where the suspension is within it's travel. I can use an 'average' (about 1.4 I think), but it's not 100% ideal.

Unsprung mass - did this the other night. Basically 50lb front and 55lb rear (using proper units).

Braking peaks at about 1.7g with a static tyre diameter of 20.1" front and 21.4" rear. I am trying to work out (from the DL1 datalogger) what the dynamic circumferences are, but there is too much error in the speed/acceleration/rpm data to get it accurately. At times the RPM is too high, at times too low (for a given speed/gear). Been factoring it at about 0.3% increase, but I'm not convinced that that is correct.

Agree about CG height and aero stuff though. I think I'm using about 13" for CG height, because I eyeballed the car with a tape measure, and decided 13" looked about right!
Quote from tristancliffe :My motion ratio isn't fixed. As I have rising rate suspension, the wheel ratio varies from about 2:1 to about 1:1 depending on where the suspension is within it's travel. I can use an 'average' (about 1.4 I think), but it's not 100% ideal.

Unsprung mass - did this the other night. Basically 50lb front and 55lb rear (using proper units).

Braking peaks at about 1.7g with a static tyre diameter of 20.1" front and 21.4" rear. I am trying to work out (from the DL1 datalogger) what the dynamic circumferences are, but there is too much error in the speed/acceleration/rpm data to get it accurately. At times the RPM is too high, at times too low (for a given speed/gear). Been factoring it at about 0.3% increase, but I'm not convinced that that is correct.

Agree about CG height and aero stuff though. I think I'm using about 13" for CG height, because I eyeballed the car with a tape measure, and decided 13" looked about right!

how is your motion ratio not the same all the time?
you must be measuring it wrong or something

as for speed and rpms, if you have an automatic transmission, that would be why it is off.
put it in 1 or low, where you can feel engine braking, and try to get it as good as you can from there.

when i was calculating my rear end gear last year based on speed and rpms, i calculated it to be 3.00
the nearest gm rear end ratio to that was 3.08, which is what i assumed it was.
however, i forgot to account for transmission slippage.
turns out the actual ratio is 2.73, which is about 15% off.
bob before the latest version I prefered the one before it, in regards to the gearing analysis, you had the blue line for torque peak, green for HP peak and red for redline, now you only have the HP peak, or can I add the others somehow???

also when im adjusting the final gear say 6th in most, if ots .95 , and I want to change it to 1.0

when I change it it flips out, changing them all to .5, kinda weird to explain, if I can find fraps ill record it to show u what its doing, also is it possible to get the picture of the car, like in the pits of LFS so we can check sill rake ect,
the program is great, just minute improvments and it can only get better BOB thanks for making the program,

ppl dont relize that to make a program like this u have to be intimate with cars, how suspension, dampers, gearing. downforce all works, someone capable of this is at a engineer level, and should apply to ferrari for a job

VHPA v3.1.4 [updated 26/03/10]
(613 posts, started )
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