FR Aero Test Project

[Detrick]

Background
The question has been nagging me for quite some time - to aero or not to aero?  Generally speaking, I'll take every aero bit available and bolt it on without thinking.  But why?  I flinch whenever I see the speed rating take a huge hit but I generally ignore that initial reaction on go right on bolting up that Forza wing.....

Fender's PI Project fanned that flames of curiosity for me even more (see some testing results below).  I plan to use these results as a starting point to build from.  I'll move on to a couple other FR test mules before I start on other drivetrain configurations (FF, MR, etc.).  Stay tuned for regular updates.  Feel free to leave your observations or discuss.

All Testing done at Suzuka Full

Test Mule #1
Honda S2000 without Aero (A744 at 2,481 lbs)
Best Time - 130.694
Benchmarks
0-60  - 4.140
0-100 - 10.746
Top Speed - 165.6
60-0 - 102.7
100-0 - 278.9
G's 60 - 1.10
G's 120 - 1.07

Track Notes

• Car had a tendency to oversteer with the default race suspension settings and is an acceleration dog.  I lowered tire pressures to 29/29, adjusted Rear Toe to -0.2, upped Front Caster to 5.5, and adjusted the Final Drive Ratio to 4.50.  Seemed to improve both conditions dramatically
• Raced 10 laps with my best lap finally coming on #9.  Tire wear at the end of those 10 laps was 54.5% front and 48.6% rear (averaged L / R)

Honda S2000 with front and rear Forza Aero and Forza Bumper (A731 at 2,528 lbs)
Best Time - 131.192
Benchmarks
0-60  - 4.228
0-100 - 11.227
Top Speed - 149.3
60-0 - 103.3
100-0 - 271.7
G's 60 - 1.11
G's 120 - 1.12

Track Notes

• Same suspension settings just to be consistent.  Front aero set at 50 lbs.  Rear aero set at 100 lbs.
• Much sharper turn-in response, better braking, more consistent lap times (no surprises here).
• Raced 10 laps with my best lap coming on #5.  Tire wear at the end of those 10 laps was 54.6% front and 47.0% rear (averaged L / R)
• Much more comfortable car to drive but the "aero penalty" on acceleration and top speed was too much for this car to overcome.

Honda S2000 with front Forza Aero and Forza Bumper (A742)
Best Time - 130.506
Benchmarks
0-60  - 4.184
0-100 - 10.928
Top Speed - 162.1
60-0 - 103.8
100-0 - 276.4
G's 60 - 1.10
G's 120 - 1.10

Track Notes

• Without the RR Forza Wing the car was very prone to oversteer.  To help counter the imbalance I increased the front springs 100 lbs., F. Rebound +0.5, F. Bump +0.5, RR Toe -0.1 from the full aero tune.
• Even with the tuning adjustments the car was not as "tossable" and required smooth driver input to achieve consistent results.  It was just a 5 minute tune session after all......
• Raced 7 laps with my best lap coming on #7.

Test Mule #2
TVR Tuscan S (A848) Forza Bumper only

• A favorite of mine in-game and a car I race online considerably.  I had been running the car with full aero since I bought it.  First off was to strip the front and rear Forza wings but I left the RR Forza bumper.  I'll use this build as my base for this car.
• My previous best hotlap time set in the Fairlady Custom for my test track (Suzuka) was 126.102 - I will beat my previous best with the Tuscan.

Best Time - 126.307
Benchmarks
0-60  - 3.954
0-100 - 8.646
Top Speed - 201.5
60-0 - 106.3
100-0 - 287.3
G's 60 - 1.01
G's 120 - 1.00

Track Notes

• Car seems to understeer and oversteer at the same time.  Well, this should be fun.....
• I won't go into all the tuning details but made some changes to springs, ARB's, and dampers to try and balance the car better.  All in, I ran 7 laps to get my best time but spend the better portion of the first 4 laps making tuning adjustments.

More testing tonight......

[Fit4aking]

Just to interject some experience on this test.  While I was/am going through and testing the TVR's I found that addind aero to the Tuscan R actually INCREASED the PI of the car.  I was definately taken off guard by that because I was hoping to add more parts to the car to meet 850 but ended up having to lose some tire to do it.  So far that's the only car that has done that for me.

Interesting thread and test as I have some cars that are off balance with aero and others that require it.

[Detrick]

Well, I moved on too test mule #2 - the Tuscan S.  We'll see if I experience the same.  Initial test results posted in the OP.

[gs shyner]

Det,

I had the same under/oversteer problem on the Cobalt. Build C
I have a feeling the R bumper adds unadjustable downforce and weight to the rear. (even if it doesn't show in the ARB/SPRING/DAMPER numbers)

Hence the rear pushes the car under momentum and braking then transistions to a bit loose as the weight is shifted to accelerate.
I'm gonna remove that from all my cars that have it and go to the "wings" build if the weight difference/HP gain continues to trend on other vehicles. 
I no longer trust the S/B/H #'s that the R bumper contrives .

Geo

[Blooze]

I have been 'sperimentin' with the aero on R1 cars in the last few days and am continually coming up with surprizes of sorts...

• The Aero settings are the same for all of the R1 cars initially, and to their extents - no matter the drive type or weight bias.  For this reason, I am very reluctant to alter the f/r bias of the aero dynamics.
• Running Aero to the maximum improves the accelleration benchmarks.
• Laps times on Sunset Infield Short are faster with full aero.    This conclusion was reached during races and needs to be tested on an incremental level.  I just ran all on, and all off.

Right now the most serious hit I see for turning the aero all the way up is a rather serious hit in the accelleration rate above 100 mph.  This can be compensated with gearing.

Some examinations that need to be run...

• Find the Terminal Velocity (TV) for various percentages of aero... Max, 90%, 80%, Initial...Min
• Translate the TV into Transmission adjustments that can be somewhat automated cut down on tweakage time.
• Look into tire wear/heat issues with full aero.
• Look into suspension travel ramifications with full aero.

For right now, I am cranking the aero all the way up and adjusting the transmission to compensate, and then asking questions later.  This combination is producing the fastest laps for me at this time.

$

[gs shyner]

Timing is impecable

I started a 'perimentan with the C-Class Fairlady Z in Exhibition and just for grins ran the car with and without aero keeping the same HP and weight.
(well, the aero one was 1 lb heavier).
With apologies to Spiny, my stock powered, aero'd (I only ever use the front bumper and rear wing unless not avail) Fairlady Z was QUICKER than my non-aero Fairlady Z in those 4 laps.

On a related note,
I have been using Blooze's Gear calc to find the Forza (and I hope) real world tranny ratios.  As such I've been doing high speed runs on the straight
of Nordy with a couple of C and B class cars. The Fairlady Z, I think, with @ 45-50 F and 70-85 R DF showed a reduction of about 7mph top speed.
I too was noting the TV of the aero car and adjusting 5th or 6th to just about red line at that speed.

[gs shyner]

Final EDIT done  3/22/08
Smokey, if you wanna move it to a MA thread you don't need my permission   LOL


more aero data along Bloozes query.
Ran my next B class project at Nissan prior to the b-class professional series.

Proto Spirra  320 hp, 295 tq, 2294 lbs
All runs made at same stock engine HP/TQ and curb weight at Nissan speedway for 4 complete laps.
Only using adjustable aero (front bumper, rear wing).
Blooze gear calc Spirra tranny & street tranny default Final Drive.
Virgin BT4274 tune.

neat                             Min aero                         default aero                    Max aero
top spd 167mph              top spd 158mph               top spd 153mph               top spd 148mph
tire pres/temp °F            tire pres/temp °F              tire pres/temp °F             tire pres/temp °F
32.7/173°   33.2/183°        32.7/172°   33.1/189°       32.7/172°   33.1/188°       32.7   33.1
33.3/184°   33.9/196°        33.3/184°   33.8/193°       32.7/185°   33.1/193°       32.7     33.1


12 lap Free run (I hope FM3 let's us generate a race cause no tire wear in free run).
highest heat in replay during lap 12

neat                             Min aero                        default aero                    Max aero
BM tspd 170.8mph           BM tspd 159.7mph           BM tspd 154.5mph            BM tspd 149.9mph
top spd 167mph              top spd 158mph              top spd 153mph               top spd 149mph
tire pres/temp °F            tire pres/temp °F             tire pres/temp °F             tire pres/temp °F
32.8/174°   33.3/184°      32.7/173°   33.1/182°      32.7/173°   33.1/181°       32.7/173°   33.1/181°
33.3/185°   33.9/197°      33.3/185°   33.8/196°      33.4/186°   33.9/196°       33.4/187°   33.9/196°


All testing was done with Tranny adjustments to get the max HP 320 at 6400ish rpm.
1st - the BM top spd calculation appears more reliable with aero than without and the error decreased with amount.
2nd - It would appear that the cursory assumption of tire pressure and temp are NOT AFFECTED by aero or the amount of aero
in this arena is verified.

unrelated interesting observation.
The braking line was left on from online racing and on the "'neat" car the line was a dim grey throughout the track.
I never had to lift during the above run but I did have to be very gentle in the turn input coming into the grandstand.
Once I did the min/def aero, the braking line was more noticable and had a dim yellow color throughout most of the track.
For some reason, the computer wanted me to brake a little on the slower car that NEVER had a tire squeal.
At max aero, the braking line returned to the dim greay throughout the track.
WEIRD.

[Blooze]

So basically what I see from your data is...

There isn't really that much difference based on Aero settings.

Tire heat appears to be directly related to Top Speed.

Is that how you see it?

$

[gs shyner]

bump
extended testing data added to my above Blooze post on the Spirra MR aero test.

[JG4tr]

Could it be that the differences in tire temp are due to how much the tires are slipping? It would seem possible that a car without aero might scrub the tires more, drifting slightly in a turn and generate more heat. Likewise, the version with aero might stay planted better and therefore, run cooler.

If you regeared the non-aero version to run the same speed as the aero version, you might be able to tell if it was that or, just the speed difference...

[gs shyner]

I think we'd all agree that the scrubbing is the difference in the tire temps in the non-aero car.
I could have tried to tune out the rear slippage but thought it advantageous to keep the variables to a minimum

"edit" I'd bet, that WITHIN ERROR and this track, the conclusion still remains that tire temps are unaffected by aero and the amount.

The allure of running non-aero is the lack of drag associated, so a de-tune of the tranny would seem to be a waste of the car's TV potential.
I could try it if some are interested.

[Spiny Anteater]

...Running Aero to the maximum improves the accelleration benchmarks...

Ok, this is about a week too late, but that's how long my thought processes take!

I think I'm right in thinking that you are just mentioning this in regards to the Benchmark screen, but back when I was running the Ferrari I noticed a similar thing while testing. I usually ran the same first gear ratio as that was my launch gear, but it was noticeable that the car launched much better with ful aero than with the settings at minimum. Even when no other settings were changed, the same thing happened.

I really can't think of a good real-life reason for this. The only possible explanation is that someone has sneaked a giant 'reverse-hoover' onto that R2 Ferrari in front of the rear wing. How else to explain the apparant additional downforce when stationary?

[feuerdog]

The same way a 100% rear split bias in an AWD is not a full 100% rear, DF might might still influence grip even at zero speed.  Unrealistic, but possibly easier for the programmers.  Hypothetically, of course.

[BarbecuePete]

Bit late on this one I guess but here goes....

I noticed the other day while trying to build a Ford GT to A-class car for the Speedway exhibition race, I was thinking about adding front Aero to stop the car drifting out into the wall on turn 4 but I noticed that if I added the rear bumper the top speed actually INCREASED... So I guess that the rear bumper improves a cars drag profile and allows a higher top speed, has anyone else noticed this?

Also Spiny's note about Full Aero giving better acceleration, I used to notice this on GT4 too, more downforce = better Acceleration, I belive that the figures we adjust in toonin' screen are the Maximum amounts of downforce at full speed, so (very basicly) if you put 100lbs of downforce on the car that can do 100mph, it will only give you 100lbs of Downforce at 100mph, at 50 mph you will only be getting say 50 lbs of downforce (Should be less really as downforce increases exponetially with speed IRL, but im not sure if it does in the game) So if you apply 200lbs of downforce to the same car then at 50mph you will be producing 100lbs of downforce...

Therefore if you have full downforce it will start to affect the car more, sooner and at lower speeds and push it into the ground more so the tires have more grip and you can accelerate faster up to the point where the extra downforce creates more drag and so the top speed is reduced...

[Spiny Anteater]

Damn, I was going to write something really clever here, with lots of equations and all, then I crunched the numbers and it turned out that Forza's aero-weight is calculated when the car is reversing at 8mph (and that was using a simple relationship - it would have been worse if I'd started using geometric curves!)

Something tells me I've missed out an ultra-important variable somewhere