Question on GPL RA telemtry

GPL Replay Analyzer (which is marvelous) has the ability to graph "slip angle." My question is, is this really slip angle in the vehicle dynamics sense or is it actually yaw? From a physics point of view, they're two different things. I was just curious which one I'm actually looking at when I use GPL RA. If it's actual slip angle, which corner of the car is it? Thanks, Bill -- | "Instead of letting the moon be the Bill Mette | gateway to our future, we have let Enteract, Chicago | it become a brief chapter in our [email hidden] | history." - Andrew Chaikin

In article <[email hidden]>, Martin Granberg <no@spam> wrote:

Quoted text (13 lines)

>Hi Bill, > >> GPL Replay Analyzer (which is marvelous) has the ability to graph "slip >>angle." My question is, is this really slip angle in the vehicle dynamics >>sense or is it actually yaw? > >Well, you tell me! :) I've seen many definitions of slip angle, but >the one we use is(from the readme): > >"The slip angle available in the graph is defined as the difference >between the direction the car is traveling and the direction the nose >of the car is pointing. This means we don't (yet) take into account >the angle of the front tires."

Hi Martin, Thanks for answering so quick. Guess if I would have been thinking, I would've gone back and read the README again. Technically speaking, I think what you guys are grabbing is yaw. But from a pure engineering point of view, even that would only be true for the difference between the driection of the car's center of mass and the direction the nose is pointing. Slip angle (as I've read it) is basically the difference between the direction a tire is pointing and direction that the rubber at the contact patch is travelling. Caroll Smith's books do a really good job of explaining it. Anyway, as long you guys define it yourselves in the README it doesn't really matter. I was just curious about what information you're grabbing from GPL. Keep up the great work with Replay Analyzer! -- | "Instead of letting the moon be the Bill Mette | gateway to our future, we have let Enteract, Chicago | it become a brief chapter in our [email hidden] | history." - Andrew Chaikin

Hi Bill, > GPL Replay Analyzer (which is marvelous) has the ability to graph "slip >angle." My question is, is this really slip angle in the vehicle dynamics >sense or is it actually yaw? Well, you tell me! :) I've seen many definitions of slip angle, but the one we use is(from the readme): "The slip angle available in the graph is defined as the difference between the direction the car is traveling and the direction the nose of the car is pointing. This means we don't (yet) take into account the angle of the front tires." > From a physics point of view, they're two >different things. I was just curious which one I'm actually looking at >when I use GPL RA. If it's actual slip angle, which corner of the car is >it? It's for the rear, Cheers, /Martin

On 24 Mar 2000 19:58:59 GMT, [email hidden] (Bill Mette) wrote:

Quoted text (9 lines)

> Thanks for answering so quick. Guess if I would have been thinking, I >would've gone back and read the README again. Technically speaking, I >think what you guys are grabbing is yaw. But from a pure engineering >point of view, even that would only be true for the difference between the >driection of the car's center of mass and the direction the nose is >pointing. Slip angle (as I've read it) is basically the difference >between the direction a tire is pointing and direction that the rubber at >the contact patch is travelling. Caroll Smith's books do a really good >job of explaining it.

Yes, I read that too. But then I read the definition we use and a couple of others. > Anyway, as long you guys define it yourselves in the README it doesn't >really matter. I was just curious about what information you're >grabbing from GPL. Keep up the great work with Replay Analyzer! Thanks! BTW, the slip angle (or whatever) we use isn't stored in the rpy-file but has to be calculated from the driving lines and orientation of car (which is stored). /Martin .