Undocumented ("Hidden") Feature: DriverRotateHead
There is a neat undocumented (or "hidden") feature called DriverRotateHead that can be enabled via the iRacing app.ini file which enables a "yaw" effect that helps you to visually observe the amount of yaw the car is experiencing as the front and rear of the car begin to slide or drift.
This view effectively locks your in-car view car's direction of travel, while allowing the cockpit of the car rotate to the left and right in response to sliding and drifting, or yaw inputs -- the effect is like observing the slip angle of an airplane in a flight sim in chase view as it "crabs" sideways due to crosswinds, which cause the airplane to yaw left or right around its yaw axis, causing the nose of the plane to point in a different direction than the plane is actually travelling.
In iRacing, when you enable the DriverRotateHead feature, the camera point of view (or your virtual "eyes" in the game) will remain locked to your car's direction of travel, but the cockpit around you will become more active and you will see it actually begin to shift in a different direction (either left or right) when the car begins to drift or the back-end begins to come around. You will effectively be able to see the car's dashboard pointing in in a different direction than the car's actual direction of travel -- either more to the left or the right -- when the car's direction of travel and its yaw angle begin to diverge, much like watching the plane in the flight simulator example above "crabbing" from the effects of a crosswind. The effect in iRacing is fairly subtle, and many people feel that this makes the driving experience infinitely more immersive immediately, although some people with more sensitive inner ears (and thus more prone to motion sickness) report that this feature can have a negative effect.
Most people who enable the DriverRotateHead feature report that they can "feel" changes in the car's slip angle better because the alignment of the cockpit and the car's direction of travel provides a visual indication of the car's yaw angle, and, hence, the slip angle. This allows some drivers to catch slides more easily and helps prevent those situations where the back-end just seem to "come around unexpectedly," thus improving the overall driving experience.
In order to enable this function, you will need to edit the app.ini file -- just find the following value under the [View] section and set it to "1" to enable the DriverRotateHead feature:
DriverRotateHead=1.000000 ; Percent to rotate drivers head with slip angle. 0 to 1 with 1 being 100%
Note that if the effect seems to extreme to you, this value is adjustable from "0" to "1" -- at "0" the effect is completely disabled (or 0% yaw motion enabled), and at "1" the effect is fully enabled (or 100% of yaw motion enabled). On ovals, some people have reported better success with this value set to a moderate decimal percentage, such as 0.5 (or 5o% yaw motion), while for other the full value ("1" or 100% yaw motion) seems to work well.
If I'm coming out of a fairly high-speed right-hander (like T3 at Summit Point Jefferson Reverse) and my rear-end starts to kick out, that means that my rear-end will be stepping out to the left as the car tries to rotate in a clockwise direction. If I have my head locked to the front view with the DriverRotateHead function disabled, I end up looking where my car is pointed, but NOT where I want to go, and NOT where my car is actually going -- at that point in time, the car is still drifting in more or less the right direction, at maybe the wrong angle.
With the DriverRotateHead function disabled, I can see that the car is starting to point in the wrong direction, and I can dial-in counter-steer to correct. That works well enough, and that's how we've all learned to sim race up until now.
With DriverRotateHead function enabled, my view will show the car's direction of travel (e.g., the direction it's drifting towards), and at the same time, the vehicle/cockpit will begin to rotate, shifting to the right away from the center center of the screen and towards the inside of the turn, showing the clockwise direction and the rate of rotation for the car itself as the rear end steps out to the left and the clockwise spin begins. This allows me to dial-in dial-in counter-steer to correct, but with this function enabled I now have a total of THREE (3) additional pieces of information (visual cues serving as physics cues) that I can interpret and react to:
1) The view on my monitor reflects the vehicle's trajectory (e.g., the direction the vehicle is drifting towards, which is my basic trajectory at that point in time), and;
2) The amount of rotation (amount of yaw) that has occurred (where the vehicle/cockpit has moved away from center, and where the vehicle/cockpit is currently pointing), and;
3) The rate of rotation (yaw rate) (how fast is it moving away from the center of the screen.
Beyond the limit, or when you have the value cranked-up to a level that is too exaggerated, there really is no info being conveyed -- you just get the "washing machine" effect that seems wrong. Below the limit with the value dialed-in to give you info that your brain can properly interpret and integrate, these three additional inputs can be invaluable, and also incredibly immersive (more so than even force feedback, IMO).
Most of us have years and years of sim racing experience under our belts, and this information is completely new -- it's never been presented in this form in any previous sim as far as I know. Given that, learning to integrate it and use it is literally a learning experience, and there is a learning curve. I'm not immediately faster using the DriverRotateHead function, but I feel like I am more in control, and I now better UNDERSTAND what is happening when something goes wrong, and I am beginning to see the RATE of how it all happens -- which means that my envelope of control is actually increasing; I'm not faster, but I'm already starting to catch things that were previously unrecoverable for me given my reflexes and my skill set. This means that I'm already beginning to learn how to react to these new inputs, and as I integrate them into my responses I'm getting smoother more in-control as a result -- and this tells me that, ultimately, I will begin to get faster, too.
This is a lot like "learning" how to adapt to force feedback cues, IMO -- if you've never used force feedback, the first time you sit down with a FF wheel, you don't intuitively know what all the feedback cues mean, or how to react to them. As a result, you might be slower to begin with, but once you learn to "read" all the cues and react accordingly, you typically find yourself getting faster. I think ultimately this DriverRotateHead function may be like that -- in fact, I think it's ultimately going to be more powerful and more useful than any kind of feedback we'll ever get through a force feedback wheel, at least in terms of immersion and realism.
If you simply dismiss this feature and say "that ain't how it works in real life," and if you just consider how it works at the extreme when you're already past the limit without paying attention to how it works in the "subtle" range when you're still within the envelope of control, you'll never realize that having these three new data points (vehicle trajectory, amount of rotation, rate of rotation) to interpret and react to can be very, VERY valuable.
I was using 0.38 for the DriverRotateHead value in the app.ini file; this is the percent the driver's head will rotate with slip angle (the range is 0 to 1, with 1 being 100%, so 0.38 which would correspond to 38% rotation. When I set the value to 1.00 or 0.50, both values seemed too high and I got the "tank-slapper" effect that Mark mentioned -- for me, 38% seemed about right.