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Use of spoiler

Discussion in 'Exteriors / Body' started by pv_krish, Oct 23, 2014.

  1. pv_krish

    pv_krish Regolare

    Messages:
    418
    Chennai
    Grande Punto 1.3 90 HP
    Started this thread as I could not find any similar thread for a spoiler during my search in the forum.

    According to my understanding the role of a spoiler in a car is to reduce the drag and streamline the flow of air and improve performance and fuel efficiency.

    In a car like Punto/Linea, how helpful would it be to have the same or is it only for styling purpose? Does it really improve the efficiency of the vehicle?
  2. punto_emotion

    punto_emotion Esperto

    Messages:
    1,245
    Bangalore
    Grande Punto 1.3
    Its more to do with aesthetic value of passenger cars in India rather than technical help. Spoilers are used to 'spoil' unfavourable air movement and thus reducing the drag effect. Remember reading somewhere, its real usage would be felt at speeds of 170 kmph or above. Hence, its predominantly used in race cars or probably in a passenger car on Autobahn :p
  3. ghodlur

    ghodlur Esperto

    Messages:
    2,317
    Thane
    @pv_krish

    Heres the link to the details of spoiler used in cars.
    http://en.wikipedia.org/wiki/Spoiler_(automotive)

    In case of Linea to a certain extent the rear spoiler plays its role for what it is intended. In Punto its purely for cosmetic reasons only. The fuel efficiency becomes of importance when cruising at high speeds which is generally the case in moto sports. For the normal highways runs, fuel efficiency is negligibly affected due to drag force.
  4. GP_Freak

    GP_Freak Amatore

    Messages:
    240
    Chennai/Madurai
    Chennai
    Linea 1.3
    @pv_krish, This is an Ultra vast subject which involves kinetics and Fluid dynamics. Even the simplest right answer will take pages. These are forgotten subjects for me, but will try to explain in simple terms without any Jargons.

    Spoilers are used either to increase or decrease the drag by manipulating the airflow around the car( based on the position).In a passenger car, having a spoiler at the rear smoothens out the air from forming vortexes or turbulences behind the car. You may ask what the hell these turbulences created behind the car has got to with increasing the efficiency of the vehicle.

    Kinetically speaking, it’s not the Air which is moving, but it’s the car which is moving against stationery air molecules (If air is also moving, then we need to consider the relative velocity). Air being a very loosely packed fluid, it just moves to leave space for the car which is moving forward. So once the car passes, the Air behind the car rushes to occupy the empty space again. It this phenomenon which affect the efficiency of the moving object.
    Due to this phenomenon, a low pressure area is created behind the car.

    So now we have two areas in the car which majorly contribute to Drag.
    1. The Force required to cut through Air( High pressure area). Imaging walking normally and walking in water. Water is also a fluid, Air being loosely packed; we don’t feel it until enough speed is up. ( This is easy to understand for most )
    2. The Force required to move away from the low pressure behind the car ( Low pressure area). If the turbulence is more, the Air Molecules are moving hap hazardly and will not occupy the space immediately and creates more low pressure behind the car.
      Combined, they form a push pull effect. The High pressure area in the front tries to push the car back and low pressure area behind tries to pull the car back
    So a spoiler is used to ensure that the air leaving behind the car is smooth without any vortexes or turbulence so that the low pressure created behind the car is minimized. So less amount of energy is spent by the car to move away from this low pressure.
    Once again, another common misconception is, the vehicle with the least Drag will be the fastest car in the race. Never, most probably in a straight line, but never in a track.
    In race cars, the Huge wings generate down force to create enough traction to stick to the track and ensure the good speed through corners. There, efficiency of the car is looked in terms of road holding speeds in corners and Lap times and not in terms of Mileage.

    With more down force generated, more drag is also created since angle of attack of the wing increased to create more down force.
    So at 300 Kms per hour, an F1 car typically generates enough down force that It can go upside down example in a tunnel, but only at those speeds.

    Air drag increases in squares. Simply put, if speed increases 10 times, then drag becomes 10^2 = 100 times.

    I have explained this for others who may find this topic intriguing.

    Coming to your exact question, Linea already has a very low drag coefficient. IMHO, for speeds these cars do, there will be very little advantage of the spoiler, May even have negative effects. We as a common man will never know unless the coefficient values are specified with and without spoiler.

    Sorry If I had bored you guys to death

    Edit:

    @ghodlur , Didn't notice your wiki quote, would have saved my time. :-(
    Last edited: Oct 24, 2014
  5. pv_krish

    pv_krish Regolare

    Messages:
    418
    Chennai
    Grande Punto 1.3 90 HP
    @GP_Freak, Thanks for the detailing about the spoiler use. I knew most of them, was actually checking on how this could actually improve in passengers cars that are not Ferraris or maseratis.

    So in essence, these seems to be just used for styling of the car with no other functional purpose.
  6. 5u3zEr0

    5u3zEr0 Regolare

    Messages:
    390
    Madras
    Linea T-Jet
    Krish, like you mentioned above, on any of our normal cars 99% of the time it is only for looks if not 100% of the time. There is no performance gain on our normal roads driven by normal people in a normal car :).
  7. varunrtr

    varunrtr Esperto

    Messages:
    1,256
    KL-01/ TO
    Grande Punto 1.3
    The main purpose of the spoiler is to redirect the flow of air outward, without allowing it to form vortices in the back of the car . More than sedans, hatchbacks benefit from the spoiler. If vortices are formed, it generates low pressure zone and sucks the air coming from the top of the car. a Simple spoiler in fiat panda 100hp reduced it drag co eff from 0.38 to 0.34.

    In sedans, a lip spoiler serves the same purpose by redirecting the flow of air outwards. When there is wing spoiler, it splits the flow of air, reducing its velocity, increasing the pressure and hence more downforce is generated in the rear.

    1620563_777766212262056_5913304058600520936_n.jpg
  8. Ganges

    Ganges Esperto

    Messages:
    3,121
    Driver Seat _/
    :
    Grande Punto 1.3
    varunrtr,
    How will be the figures on bumpy roads ? :D i think you have forgotten about the masterpiece so called Ritz ? :D
    Drive from kerala to Delhi at a cost and in return it will be free of cost [ boomerang... effect ]
    GP_Freak likes this.
  9. varunrtr

    varunrtr Esperto

    Messages:
    1,256
    KL-01/ TO
    Grande Punto 1.3
    The companies are struggling to make the designs more aerodynamic and even a reduction of 0.01 in terms of drag is considered big everywhere in the world, as it results in a significant reduction in carbon footprint , some try to integrate the elements with the design like lip spoiler in the boot while some others attach in separately as wings for their different purpose. I ve seen its testing and hence quoted the figures in my previous post. Any properly designed aerodynamic element will aid significantly in the handling characteristics in highway driving. Imagine someone doing only highway trips, like many i know of, it will be put to proper use, not just who drive it only in bumpy uneven roads. Thats why in ferarri 458 italia and all, the aero elements are all active elements, which open up only at higher speeds above 60, like spoiler, air passage in the front bumper, etc.
    Any inclination more than 5 degree in the rear (b/w roof and boot) is not good aerodynamically, for hatchbacks, hence they put up a spoiler to compensate for that, without spoiling the design of the car. Some cars like ritz and wagon R not fit for high speeds because of the tall boy design and hence higher roll. Do you think any car in the world is tested for aerodynamics in bumpy roads?
  10. Ganges

    Ganges Esperto

    Messages:
    3,121
    Driver Seat _/
    :
    Grande Punto 1.3
    You took my post up to extreme thoughts. I was comparing Ritz with Punto. Ferrari not my reach.I drive on Indian roads only and for me spoiler is just for aesthetic only.Seems like Kerala have good roads.

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