Drive Shaft (and Steering Column) Angle and Phasing

[BillCobb]

See ? And this is just a simple SIMULATION of the ISO On-Center (Weave) test. It uses approximate lateral acceleration computed as the
product of yaw velocity and forward speed.Strsimv6.jpg

Now, it really make not make a hellofa lot of meaning to a FSAE car, but so few of you will be racing professionals and so many may try to
become engineers in some field (Kubota, John Deer, Mahindra, ???) that this kinda of work is the foundation of a hiring, a career, and a retirement.

[Swiftus]

Excluding the actual lash, placing the slowing peaks out at the extremes of steering might actually have the effect of linearizing the relationship between degrees of a turned input and degrees of output because of the sin-connection in the tie rods.

[BillCobb]

Except that the provisions for Ackermann, negative Ackermann or parallel steering makes that suggestion an unlikely possibility. (It's a
mistake for teams not to know which way to go in this case.

Here's a sample (again) from the real world of competitive analysis. BTW: given a database full of the fitting coefficients for these tests, it's pretty easy to know who knows what.
SR_Example_B.JPG

[Claude Rouelle]

Out of the box observation here.

Many race cars, especially single seater should use pro (positive) Ackermann. You know that just looking at their tire models (expect is some specific case like some Michelin racing tires that do require Anti Ackermann).

However they don't for a simple reason: aerodynamics. Negative Ackermann could give significant aerodynamic downforce in corners that will more than compensate the little loss of mechanical grip.

[Swiftus]

@Bill - In the case of a single seater like an FSAE car which has a total of ~180º of steering, a lot of wonky behaviors are possible to implement which would otherwise be wacko in a more standard type of race car.

Putting a single u-joint in the steering shaft doesn't an effect on Ackermann, simply a scaling effect on the driver's feel of the steering - the geometry past the pinion in the rack would be identical in all cases.

It seems to be something which would be much more about driver feel and less about vehicle performance outright. For instance, on a circle track car which always has a 1/4 lock of steering on, one might want a dulled steering ratio when turning left compared to when turning right so they are better able to catch themselves from too much oversteer with some fast countersteer.

I'm thinking useful implementations of varying speed ratios, not what is appropriate for most situations.