Vehicle Dynamics Insights 004 | Ackermann Steering Geometry w/ Mike Law

Returning again for Episode 04, we are joined by expert dynamicist Mike Law to talk about Ackermann Steering geometry.
Covering the three main modes of Ackermann implementation, we explore what it's used for, how to arrive at the level of Ackermann you need in a given application, and some things to avoid in the process.
Enjoy!
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Mike has a book published called "Ace Thinking" which takes the skills and experience he's gained developing race cars to create a framework for approaching tasks, engineering and otherwise.
Many of the approaches to problems you hear in these episodes are communicated in the book, which you can find on Amazon at: www.amazon.co.....
All proceeds from the book go towards the Small Piece Trust.
This episode is also available on Spotify and Apple under the title "Wavey Dynamics Insights"

[@zzvyb6]

A proper & robust Ackermann geometry must be defined by at least 2 turn radii. Otherwise, there is an infinite number of solutions to produce the single only value, involving static toe, compliance and the steer arm geometry. Anti-Ackermann is an understeer REDUCTION technique. It also gets mixed up in mid-g_level steering gain issues, especially for a car that's slightly oversteering to begin with and you want to have a specified limit behavior. A higher Max_lat usually comes along with this too. But, like everything else, you can overdo it. The rear should also be subjected to mods to maintain your balance. Once you know the minimum turn radius and one other high speed turn radius (plus the tire data). The solution is fixed. Keep in mind that there are 3 types of tire properties that you need to be aware of: Peak Fy advancing in slip angle with increased vertical load, no change in Peak Fy slip angle with load, and Peak Fy slip angle reducing with Fz loading. The first is more common, but plenty of the other ones around... Oh, and you need to know your wheelbase, too. Sometimes BOTH of them....

[@WaveyDynamics]

Yeah right on! I like the framing of it as an understeer reduction technique 👌🏾. I’ve always held it as a tool to maximise a_y but that’s a more subtle and nuanced take on it. Mid g steering gain as in it increases gain when tyres aren’t saturated? Have never come across tyres which demonstrate peak Fy at reducing slip angles, in the linear range at least.. we’re talking radial ply? - Jahee

[@zzvyb6]

@@WaveyDynamics I sent you an email (theoretically) with a presentation on all of this subject. Did you get it ?

[@WaveyDynamics]

@@zzvyb6 Hey Bill. Yeah i got it, i sent you an reply back over the weekend - did it get relegated to junk? - Jahee

[@jesseadcock247]

@@zzvyb6Would you be willing to share the presentation with me by chance?

[@supersevenhead]

Curious what Ackerman Indycars run at Long Beach (Queens hairpin) and F1 at Monaco (Loew's hairpin).

[@WaveyDynamics]

Haha yes i would be too! 🙂 - Jahee

[@bigbothoee8617]

What would happen if you have a front rack steering system the rack is parallel to track rod ends, I'm getting anti akerman If I moved the rack behind the track rod centreline will this make a positive akerman?

[@WaveyDynamics]

Try and sketch it out in CAD and see for yourself 🙂