Underbody downforce vs. rear wing | FerrariChat
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Underbody downforce vs. rear wing

Discussion in '360/430' started by Brian C. Stradale, Dec 9, 2004.

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  1. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,615
    Dallas, TX, USA
    #1 Brian C. Stradale, Dec 9, 2004
    In another thread, Solly posted this about the F430:

    Yes, there is a very good reason for the racecars to have a wing... because they can... AND because the race series typically do NOT allow the underbody effects... those cars have the Venturi tunnels of the streetcar removed.

    So, the racecars not relying upon the underbody effects does NOT support your argument. Most modern racecars will use the underbody effects to great advantage in any race series that allows it.

    I wanted to pull this issue out into a separate thread as I think it is an interesting discussion to focus on...

    The 360 Modena and the 360 Challenge did experience some issue with the underbody effects... the underbody effects lose their effectiveness if the gap between the car and the road gets too great... the "suction" is released. Under heavy braking and/or at a bump in the road, the rear of the car seemingly would elevate enough that the suction would release. In the Challenge series, this was blamed for some of the wreckage... in the heat of battle, the cars would come into corners a little hot, tail up high, much turbulence from the nearby cars, and they would be surprised with less traction in the back than they are accustomed to... at the worst moment possible.

    With the Challenge Stradale, they addressed this problem by essentially mounting a rear wing in the Venturi tunnels. Its a huge wing they have down there... nobody would question whether that thing would produce downforce if mounted in the normal wing position... though its so big you wouldn't be able to see ANYTHING out the back window. In addition to the wing effect, it also has the additional benefit, along with the vanes on the underside, of reducing or containing the max distance from the ground under heavy braking and preventing/reducing the "release of suction".

    On the track, my CS rear end definitely does not get as twitchy under heavy braking as my Modena used to. Further, the downforce numbers on the CS were notably better. So, I feel like they've succeeded in addressing the issue... but that is FAR from conclusive. Far more conclusive would be if they let the Challenge series install the Stradale's rear underbody wing.

    Does anyone have any evidence or physics that would support or deny that the Stradale's underbody wing is highly effective and doesn't suffer problems under heavy braking?

    Interestingly, as best I can tell, they did NOT use the same underbody wing on the F430. (Anybody have a good underbody shot of the F430 from the rear?) I guess they figure that the track-day owners will be in Stradale's, so the F430 won't be as likely to be cornering hard under heavy braking??? Or did they decide it wasn't really all that effective?
     
  2. WCH

    WCH F1 Veteran
    Owner Rossa Subscribed

    Mar 16, 2003
    5,186
    #2 WCH, Dec 9, 2004
    I always felt that my 360CH had power on oversteer in the mid to high speed corners - a real limiting factor for me, to be sure. I didn't have the car very long, and never played with the suspension at all to try to address my handling concerns. Several people suggested adding a wing, but to me it's more fun to try to work on mechanical stuff before aero changes.

    As for the Stradale, I wish we had a choice of tires for track use. IMO, the street tires seriously limit the car's performance.
     
  3. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    #3 thomas_b, Dec 9, 2004
    Must be a rainy day – we have discussed this before – however I am biting

    I don’t buy Steven’s arguments anymore – I must confess some of the talk on FChat has made me nervous when I bought the 360 CH – however after having driven the car now on several tracks I don’t believe one needs a wing and that the its absence is not the root cause for all the crashes

    Paficic Raceway’s has a 150mph right hand turn heading downwards with a bump/pavement change and the car behaves beautifully but one has to set it up right

    Most of the problems for me occur in the braking zone – the 360M or CH rear toe-in causes the car to be extremely twitch under braking with the tail moving randomly left right – any corrections are asking for trouble - my favorite place is the front straight of Portland International Raceways braking into the chicane close to the wall; pointing into the wall/ pointing away from the wall/pointing into the wall/etc. ….

    The CS never showed that behavior and it has more rear toe-in – changing the CH to the CS spec solved the problem - voila – one major source of problems gone – changing brake pad type front/rear also helps

    The second class of problems I find is that if the car, cossing the limit of tire adhesion, goes it goes at minimum with my level of skills – with the Pcar I was able to catch the car but with the mid-engine configuration phh

    The third class of problems I have is the gear change of the CH – if one is not careful with an up/downshift under full throttle on slippery surfaces or under braking the cars will spin – been there done that

    So I am
    - wings are necessary for some of the race cars because some of the mentioned race series don’t allow the underbody style of the 360
    - that in most of the turns at turn-in the speed is too low to generate significant down force (<80mph) so wing or underbody will not contribute anyhow
    - that most of the problematic behavior of the 360 can be dialed out by proper alignment / setup

    F did the right thing with the 360 & 430 – a fixed wing is such a crude and ugly device - if F offers a 430 CS and I am in
     
  4. scud

    scud F1 World Champ

    Oct 2, 2004
    11,803
    #4 scud, Dec 9, 2004
    thomas b , can you or other cs drivers supply me with your toe in and neg camber settings?? I run a standard 360 spider with ( I think ) neutral toe and 1 degree neg camber on the front and 2mm toe in and 2.5 degrees neg camber on the rear. My ferrari club in oz hardly puts on track days so it's hard to find correct settings.I run my ferrari with my GT3 on porsche club track days but the porsche eats it due to superior suspension,better brakes and less weight. I am not saying the porsche is the better car as you can't compare the two. I love them both .I wish I had a cs but very hard to find.
    any info appreciated

    rock on
     
  5. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
    8,520
    Melbourne
    Full Name:
    Phil Hughes
    #5 ferrarifixer, Dec 10, 2004
    The 360C is one of the most tuner friendly cars you will find. They are super sensitive to all set up parameters and as such can be turned from oversteer into understeer in just a few small changes.

    They are CRYING out for decent shocks though....

    After racing 10 of them for nearly 5 years now, I still trim set up to suit different tracks/drivers/conditions etc.

    Braking stability without a wing is the hardest to achieve. Best solution is to increase rear toe in, but you need to compromise with your required tyre life. 10mm total toe in on the rear, yes 10mm will make it stop like it's on rails and you'll pass people on the brakes easily if you're racing. But you'll also gain rolling resistance on the straights. Less and less to suit tyre life/rolling resistance simply degrades stopping stability.
     
  6. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    #6 thomas_b, Dec 11, 2004

    in addition - comparison of Challenge & Stradale alignment specs

    360 CH

    Wheel Alignment Data

    Car height with static load
    - front 88 mm
    - rear 110 mm

    Wheel camber
    - front wheels – 3° 30' ±10'
    - rear wheels – 2° 30' ±10'

    Total toe-in (diameter size 495 mm)
    - front wheels 0 mm
    - rear wheels 2,2 ±0.5 mm

    Front caster (fixed) 6° 00' ±10'


    360 CS


    Wheel Alignment Data

    Car height with static load
    - front (A) 110±3 mm
    - rear (B) 130±3 mm

    Wheel camber
    - front wheels 1° 28' ±0°10'
    - rear wheels 2° 00' ±0°10'

    Total toe-in (diameter size 495 mm)
    - front wheels 2,5 ±0.5 mm
    - rear wheels 3,0 ±0.5 mm

    Front caster (fixed) 6° 16' ±0°10'
     

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