WRC 2015 season

Please discuss here all your remarks and pose your questions about all racing series, except Formula One. Both technical and other questions about GP2, Touring cars, IRL, LMS, ...
User avatar
itix
2
Joined: 16 Mar 2015, 11:09
Location: Göteborg, Sweden

Re: WRC 2015 season

Post

More WRC (and Hyundai in particular) spam :)
New Hyundai test video has emerged!



It dipping quite a lot under cornering and braking. More so than I would expect. Here's to hoping they can finally end VW's dominance!
Massive rally fan... have fallen out of love with F1 yet again and have thus migrated

MadMatt
MadMatt
125
Joined: 08 Jan 2011, 16:04

Re: WRC 2015 season

Post

For those interesting I have posted an article about being a rally engineer on my blog (link in my signature). We can discuss things here if there is any interest! :)

User avatar
itix
2
Joined: 16 Mar 2015, 11:09
Location: Göteborg, Sweden

Re: WRC 2015 season

Post

MadMatt wrote:For those interesting I have posted an article about being a rally engineer on my blog (link in my signature). We can discuss things here if there is any interest! :)
I'll copy my comment to here... as there might be interest elsewhere in the forum:

Very interesting reading. I can see that you worked for RK at least from the blurred document (on the one event where he didn’t end up in a ditch or something broke on the car). How much of the car is set up from statistics and how much of it is from driver input? …and how on earth can you gather over- and understeer from sensors? Wheel speed sensors? Load sensors on the dampers? That one got me. Maybe that's also confidential :?

Looking forward to the post about the event from your perspective!
Massive rally fan... have fallen out of love with F1 yet again and have thus migrated

User avatar
Scorpaguy
6
Joined: 04 Mar 2010, 05:05

Re: WRC 2015 season

Post

Hyundai testing....

Still seems a bit slow on corner exit compared to the others. I dont know if its down on HP,have tranny/transfer case issues, or suspension woes. I suspect the first and last.

I'm convinced that the VW is able to get power to all 4 wheels better than the others...and they dont slide as much (which doesnt suit Jari's style). Citroen is close...and M-Sport just tries harder :D

User avatar
Scorpaguy
6
Joined: 04 Mar 2010, 05:05

Re: WRC 2015 season

Post

Hyundai testing....

Still seems a bit slow on corner exit compared to the others. I dont know if its down on HP,have tranny/transfer case issues, or suspension woes. I suspect the first and last.

I'm convinced that the VW is able to get power to all 4 wheels better than the others...and they dont slide as much (which doesnt suit Jari's style). Citroen is close...and M-Sport just tries harder :D

MadMatt
MadMatt
125
Joined: 08 Jan 2011, 16:04

Re: WRC 2015 season

Post

itix wrote:
MadMatt wrote:For those interesting I have posted an article about being a rally engineer on my blog (link in my signature). We can discuss things here if there is any interest! :)
I'll copy my comment to here... as there might be interest elsewhere in the forum:

Very interesting reading. I can see that you worked for RK at least from the blurred document (on the one event where he didn’t end up in a ditch or something broke on the car). How much of the car is set up from statistics and how much of it is from driver input? …and how on earth can you gather over- and understeer from sensors? Wheel speed sensors? Load sensors on the dampers? That one got me. Maybe that's also confidential :?

Looking forward to the post about the event from your perspective!
Statistics help the engineer to remove settings or parts that you know won't work in advance, to narrow the setup range to propose to the driver. You cannot rely 100% on data of course (I heard some teams few years ago used to not pay attention to the driver's feeling as what they could see on the computer was enough which I think is wrong, but out of topic). I cannot estimate the driver to data ratio of information to make the car faster as it depends on how skilled your driver is basically. I have seen cases where driver was only responsible of the settings to a proportion of 20%, but also 80 or 90%!

About the understeer and oversteer behavior of the car, you only have access to a limited set of sensors (these are homologated), including steering angle, yaw rate, car speed, etc. so if you know what makes a car understeer or oversteer you can evaluate the sensors in that sense. If you have got GPS it makes things even easier, but its not a sensor that is used by everybody. Also we do not use load sensors on the dampers, but more like accelerators or linear pots, but this isn't needed to see if the car is oversteering.
Scorpaguy wrote:Hyundai testing....

Still seems a bit slow on corner exit compared to the others. I dont know if its down on HP,have tranny/transfer case issues, or suspension woes. I suspect the first and last.

I'm convinced that the VW is able to get power to all 4 wheels better than the others...and they dont slide as much (which doesnt suit Jari's style). Citroen is close...and M-Sport just tries harder :D
True, VW always seem to be able to put the power down better than others, which rose the question few times about using some kind of disguised TC. What is for sure is that you need to have the wheels STRAIGHT to put the maximum power down, and it seems that VW drivers are able (better than others) to have their front (and rear) wheels pointing straight when exiting the corners, unlike some others which are sideways, so there is for sure a part of driving style, but also on car setup! :) This requires extensive testing tho in order to get it right IRL.

Cold Fussion
Cold Fussion
93
Joined: 19 Dec 2010, 04:51

Re: WRC 2015 season

Post

MadMatt wrote:For those interesting I have posted an article about being a rally engineer on my blog (link in my signature). We can discuss things here if there is any interest! :)
I'm interested in knowing what sort of data analysis you do, and what you find important to aid setting up a car. At my FSAE team we had a datalogger connected to the car which collected data from a large variety of sensors, however the usage we got out of it was pretty low outside of people using specific outputs for thesis work. I'm interested in how you as a professional makes use of this data because right now, our car setup work would be based 95% on driver feedback.

MadMatt
MadMatt
125
Joined: 08 Jan 2011, 16:04

Re: WRC 2015 season

Post

Skoda presents their new Fabia R5. A Polo deguised basically, but it looks good. Notice the caster angle!

Image

MadMatt
MadMatt
125
Joined: 08 Jan 2011, 16:04

Re: WRC 2015 season

Post

Cold Fussion wrote:
MadMatt wrote:For those interesting I have posted an article about being a rally engineer on my blog (link in my signature). We can discuss things here if there is any interest! :)
I'm interested in knowing what sort of data analysis you do, and what you find important to aid setting up a car. At my FSAE team we had a datalogger connected to the car which collected data from a large variety of sensors, however the usage we got out of it was pretty low outside of people using specific outputs for thesis work. I'm interested in how you as a professional makes use of this data because right now, our car setup work would be based 95% on driver feedback.
You have to ask yourself the real questions. I am sure other race engineers on this forum could answer your question, but what you are trying to do is minimize contact patch load variation while maximizing car acceleration. There are hundreds of things you can monitor, but I will give you 4 basic good ones:

- wheel speed (with the difference you can check how your diff is working)
- gps (to evaluate the traction you have, and couple with wheel speed you can get your slip ratios)
- damper pots (to see where you are working on your curves and how the dampers are working)
- steering angle (check how stable the car is, understeer, oversteer, yaw rate)

If you are working on a FSAE team I am sure you have some laptime simulation lectures where all I am saying has probably been said. The wheel has already been invented, you just have to use it best :)

User avatar
itix
2
Joined: 16 Mar 2015, 11:09
Location: Göteborg, Sweden

Re: WRC 2015 season

Post

Forward caster angle? Never seen that before. I'm gonna go through this thread properly when I get home again. Out on travels right now.
Massive rally fan... have fallen out of love with F1 yet again and have thus migrated

User avatar
Tim.Wright
330
Joined: 13 Feb 2009, 06:29

Re: WRC 2015 season

Post

MadMatt wrote:Skoda presents their new Fabia R5. A Polo deguised basically, but it looks good. Notice the caster angle!
How are you seeing the caster angle from this view? Aren't focus' still using the control blade rear axle?
Not the engineer at Force India

MadMatt
MadMatt
125
Joined: 08 Jan 2011, 16:04

Re: WRC 2015 season

Post

Tim.Wright wrote:
MadMatt wrote:Skoda presents their new Fabia R5. A Polo deguised basically, but it looks good. Notice the caster angle!
How are you seeing the caster angle from this view? Aren't focus' still using the control blade rear axle?
Sorry Tim I meant the angle of the dampers, especially fronts! We cannot see the steering axis that is for sure, but it is a weird design. I would imagine the damper is clamped at the top of the upright in the middle and then a bracket at the bottom a bit like what you would have for a brake caliper! For comparison, here is the Fabia S2000:

Image

I don't have access to the homologation paper but we would find the answer we need in there!

They cannot have negative caster unless the road car has too because you cannot move the suspension top points much.

User avatar
Tim.Wright
330
Joined: 13 Feb 2009, 06:29

Re: WRC 2015 season

Post

Without knowing where they put the lower ball joint on the lower control arm its not really possible to judge the caster.

The steering axis runs through the top mount and the lower ball joint on a McPherson suspension but this is often NOT the same axis as the strut itself. The struts often have a different line of action for wheel clearance reasons and the the spring is occasionally fitted at yet another angle (not coaxial to the damper) in order to cancel out some of the bending moment imposed by the first misalignment which causes increased friction hysteresis.

If ever there was a suspension not built for racing use its the McPherson. It pretty much ticks every box of "how can I compromise grip"...
Not the engineer at Force India

MadMatt
MadMatt
125
Joined: 08 Jan 2011, 16:04

Re: WRC 2015 season

Post

Yes I agree with that. Fords have the damper going in front of the lower ball joint for example (opposite to Skoda R5). Either way you have to clear the driveshaft.

As you mentioned the friction in the damper due to the axis offset is important but the damper angle too as this can change the squat and dive properties of the car.

User avatar
Tim.Wright
330
Joined: 13 Feb 2009, 06:29

Re: WRC 2015 season

Post

MadMatt wrote:As you mentioned the friction in the damper due to the axis offset is important but the damper angle too as this can change the squat and dive properties of the car.
Yup, exactly why, in my opinion, it is a very compromised suspension for competition use.
Not the engineer at Force India