The Vitesse spoiler article sparked discussion on "SD1Online" forum which calls into question the original premise. With no hard evidence of the original design, it leaves things open to opinion.

* Good reading Ramon, The SDI's a very aerodynamic shape to start with. Wonder how much less drag is yielded by the front spoiler? TWR developed the later Vitesse type in a wind tunnel to reduce drag on the Grp A racers. Robert Thornton.

* Having had experience in these things the spoiler's job is not to decrease drag, but to increase it. The wind tunnel testing was to decrease the lift generated at the back by 'spoiling' the airflow and thus destroying the lift, in effect increasing the drag. They would see how little drag they could add while killing the lift. Whatever the reason for the better fuel economy, it's not decreased drag, maybe lift at speed is so great the wheels are loosing grip and slipping! Stewart Weller.

* Fair input but you are probably wrong in this case. It's well known that some spoilers increase drag for exactly the reasons you say yet improved aerodynamics will allow designers to reduce drag. Into which category does the Rover Vitesse spoiler fall? We are not in either Aircraft or Race-car territory here. Could not the Rover designers have found a way to improve the aerodynamic behaviour of the car by clever design of the spoiler in question, in direct relation to the existing SD1 body shape?If Rover's particular design increases drag as you suggest, how does the identical body shape with the added spoiler have a lower measured drag than one without? (0.36 and 0.405 respectively). It is not wheel spin/lift at motor-way speeds on a car as heavy as the SD1. Even without a spoiler, in a straight line a Rover SD1 sticks to the road like glue at 70mph. Ramon.

* But what if the slab-like rear panel of our SD1's was promoting turbulence behind the car, would that not generate drag (low pressure area trying to hold the car back)? If the spoiler "smoothed" the airflow off the back of the car this would decrease the turbulence in that area thus improving the airflow and lowering the drag factor. I believe this is the principle behind most of the aerodynamic elements (excepting the actual horizontal elements of the main wings) on a modern F1 car. They are there to "direct" and "smooth" the airflow over critical areas - you don't want turbulent air entering radiator ducts or the airbox for example. Even most helmets now have a small spoiler like flap moulded into them. It's not for downforce. Roy ?

* The spoiler effectively makes the area at the rear of an SD1 larger, increasing the turbulance at the rear of the car. Actually most of the vertical surfaces on an F1 car are designed to maximise airflow to items such as brakes, radiators and air intakes not to decrease drag (they don't!) with the exception of those at the edges of the front and rear spoilers, these are to stop the air bleeding off the sides and thus causing a loss of downforce. As for the helmets, god knows what they are trying with those as the drivers head is in an area of turbulance anyway. Stewart.

* The basic profile of the SD1 is almost the perfect shape. The spoiler moves it away from that and does it ,almost certainly, for down force. Lets face it the standard car was tail happy so making the same car more powerful and faster it was probably wise to do something about this. Stewart.

* A rear spoiler creates downforce at the cost of drag (afraid I have to take issue with Ramon's article that the spoiler reduces drag - sorry Ramon but that's like saying holding up a board from the sunroof will reduce drag, because the spoiler increases the height of the 'slab' back end of the car, and it's the negative pressure area behind the car that causes more problems than the positive pressure in front of it, hence why NASCAR drivers tailgate and why aeroplanes are pointy at the back end.The combination of lower ride height, front chin spoiler and rear spoiler make a significant difference to the way the SD1 is planted to the road. The reduced drag comes from the lower ride height (reduces the amount of air getting into the wheelarches and airflow under the car where drag is horrendous) and front spoiler, either deep chin or the standard S2 version (both of which reduce the air going under the car). Lawson 5000se.

* As additional comment to the overall subject that has been rumbling along, I had this cute idea for an experiment! When summer ('08) comes and my TP comes out of storage, (as an alternative to removing my spoiler) I conceive it to be possible to strap an MDF board from the top of the tail gate to the high point on the rear spoiler to prevent the downforce generated by the spoiler itself. If the alternative viewpoints are correct, the MPG measured by trip computer over, say, a couple of miles should increase because of reduced drag compared with the anecdotal supposition (spoiler exposed) over the same track in the same conditions. None of the above experiment would emulate the original SD1 shape of course, but it would be fun to find out. On the other hand perhaps someone who is about to fit a factory spoiler might care to do some before and after measurements? Ramon.

You Decide! Further inputs welcome.

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