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PostPosted: Thu Jun 23, 2011 2:10 pm 
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Champion Driver
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I have a few questions about the ride height variables in rFactor.

Variables from Stock NSCR HDV file.
Code:
[BODYAERO]
...
BodyDragHeightDiff=(0.31)       // drag increase with front/rear ride height difference
...

Does this variable increase the drag with rear ride height being higher than front ride height, or front ride height being higher than rear ride height?

Code:

[DIFFUSER]
DiffuserBase=(0.0, -1.5, 0.0)  // base lift and 1st/2nd order with rear ride height
...

I forgot the formula for this data set. I know it's something like "<first value>*<setting> + <second value>*<setting>^2 + <third value>*<setting>^3". How far off am I? Also, if I remember correctly, the second value is the change in lift/drag with setting, and the third value is the efficiency of the change with each setting.

Code:
[DIFFUSER]
...
DiffuserFrontHeight=(1.0)         // 1st order with front ride height
...

Does this affect the lift generated from the front ride height?

Code:
[DIFFUSER]
...
DiffuserLimits=(0.0, 0.13, 0.13)  // min ride height before stalling begins (0.0=disabled), max rear ride height for computations, max rake difference for computations
...

Can I have a more detailed explanation for this one? I'm especially confused at the word "stalling" as this is usually used to describe an aircraft that has insufficient lift under the wings and quickly loses altitude as a result.

Code:
[DIFFUSER]
...
DiffuserSideways=(0.0)              // dropoff with yaw (0.0 = none, 1.0 = max)
...

This is supposed to affect downforce, right?

I did do a search but I didn't come up with anything relevant.

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PostPosted: Mon Sep 19, 2011 10:38 pm 
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US Pits Crew
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Joined: Thu Sep 29, 2005 11:57 am
Posts: 400
Location: Menomonie, WI
TCR_500 wrote:
I have a few questions about the ride height variables in rFactor.
Many of the aero values in the hdv yield a constant, which I'll call C, used to calculate lift (downforce) or drag force.
F (lift or drag) = C*V^2
where F is force in Newtons and V is velocity in m/s.

Variables from Stock NSCR HDV file.
Code:
[BODYAERO]
...
BodyDragHeightDiff=(0.31)       // drag increase with front/rear ride height difference
...

Does this variable increase the drag with rear ride height being higher than front ride height, or front ride height being higher than rear ride height?
Rear higher than front.
Code:

[DIFFUSER]
DiffuserBase=(0.0, -1.5, 0.0)  // base lift and 1st/2nd order with rear ride height
...

I forgot the formula for this data set. I know it's something like "<first value>*<setting> + <second value>*<setting>^2 + <third value>*<setting>^3". How far off am I? Also, if I remember correctly, the second value is the change in lift/drag with setting, and the third value is the efficiency of the change with each setting.
The diffuser is fixed, it doesn't have a "setting".
The three values together produce a second order equation that describes the downforce as a function of rear ride height, at some velocity.
Total downforce is:
F = <first value>*V^2 + <second value>*(RearRideHeight)*V^2+ <third value>*(RearRideHeight)^2*V^2


Code:
[DIFFUSER]
...
DiffuserFrontHeight=(1.0)         // 1st order with front ride height
...

Does this affect the lift generated from the front ride height?
Yes. Force is calculated in the same way:
F = <value>*(FrontRideHeight)*V^2
Code:
[DIFFUSER]
...
DiffuserLimits=(0.0, 0.13, 0.13)  // min ride height before stalling begins (0.0=disabled), max rear ride height for computations, max rake difference for computations
...

Can I have a more detailed explanation for this one? I'm especially confused at the word "stalling" as this is usually used to describe an aircraft that has insufficient lift under the wings and quickly loses altitude as a result.
Stalling occurs when the air flow over a lifting surface detaches and becomes turbulent, it's no longer laminar (smooth). From the description, must be the diffuser can stall if the ride height is below some minimum.
I have no documentation on how the lift is affected when the max limits are exceeded.

Code:
[DIFFUSER]
...
DiffuserSideways=(0.0)              // dropoff with yaw (0.0 = none, 1.0 = max)
...

This is supposed to affect downforce, right?
I assume so, but I don't know what the function is.
I did do a search but I didn't come up with anything relevant.


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PostPosted: Tue Sep 20, 2011 9:36 am 
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Champion Driver
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Joined: Fri Feb 15, 2008 8:49 pm
Posts: 714
Thanks.

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