Downforce

[jhawkins]

As I now have a car with slicks and wings, can someone enlighten me a bit (excuse my ignorance!)....I notice a few people I race against have filled in all gaps around the front splitters and other downforce aids.....how much difference does it really make to do this....is it noticeable when diriving the car or will a bit of turbulence not matter that much?


I dirve radical Prosport, if that helps anyone!

Thanks

[Oaksnaf]

This is the category you are talking about??

And they have filled all gaps around the splitters, does this mean they have moulded a new front spliter, or just filled it with what??

And what other downforce aids??


Generating the necessary downforce is concentrated in three specific areas of the car.

1. Front wing assembly (in your case splitter)
2. Chassis
3. Rear wing assembly

Downforce is necessary for maintaining speed through the corners

A road course with low speed corners, requires a car setup with a high downforce package. A high downforce package is necessary to maintain speeds in the corners and to reduce wear on the brakes. This setup includes large front and rear wings. The front wings have additional flaps which are adjustable. The rear wing is made up of three sections that maximize downforce.

There are a lot of books and articles on the internet (i prefer books) which can aid you in reading up on downforce.

[richard_sykes]

Sorry to steal the thread, any good books you can recommend?

Lots around but, some are very outdated.

Rich

[Oaksnaf]

Originally Posted by richard_sykes

Sorry to steal the thread, any good books you can recommend?

Lots around but, some are very outdated.

Rich

Competition Car Downforce. UK.
Aerodynamics for Racing & Performance Cars. UK.
are two that spring to mind.

[jhawkins]

Thanks for the reply Oaks, that is the car.

They haven't moulded a new front splitter, but have filled all gaps in the bodywork and the small wings on the front corners with I guess silicon to smooth the airflow.


I was also wondering what I could do to smooth the flow under the front and rear of the car as there are some large gaps, particularly under the front. I thought of constructing some form of ply-wood until to fit under front spoiler to meet up with the floortray of the car.

I'll try to get hold of the books you mentioned as this is a whole noew area that I have no understanding of!

Thanks again for your help.

[Oaksnaf]

Originally Posted by jhawkins

Thanks for the reply Oaks, that is the car.

They haven't moulded a new front splitter, but have filled all gaps in the bodywork and the small wings on the front corners with I guess silicon to smooth the airflow.


I was also wondering what I could do to smooth the flow under the front and rear of the car as there are some large gaps, particularly under the front. I thought of constructing some form of ply-wood until to fit under front spoiler to meet up with the floortray of the car.

I'll try to get hold of the books you mentioned as this is a whole noew area that I have no understanding of!

Thanks again for your help.

The underbody is shaped to create an area of low pressure between the underbody and the track. The shape of the tunnels under the car should resemble an inverted wing.

The following piece of an article i just read should help you.

The sidepods of the car housing the radiators were designed to allow airflow under the car through tunnels. The tunnels narrowed in the center and expanded toward the rear of the car. As the air moved through the tunnels an area of low pressure was created between the underbody of the car and the track. This resulted in the car being forced down to the track. As testing continued designers found that minimizing lateral airfow under the car improved ground effects. Formula One designers included skirts on the cars to reduce lateral airflow under the car. Skirts were attached to the sidepods and were vertically adjustable to seal off lateral airflow. This proved to be a major aerodynamic improvement but was soon regulated out of Formula One racing for safety reasons.

its all about angeling the air and creating low pressure under the car. As i can see in the picture the rear is slightly higher than the front meaning you would create a V shape like suction under the car. Perhaps as you mentioned with ply-wood or this can even be done with alluminium.

[richard_sykes]

Thanks for the titles, Amzon UK stocks both

Competition Car Downforce

Aerodynamics: For Racing and Performance Cars

http://www.indiacar.com/index2.asp?p...s/dirtyair.htm


Jhawkins this may be useful for a little understanding in the meantime until the arrive.

[Oaksnaf]

Originally Posted by richard_sykes

Thanks for the titles, Amzon UK stocks both

http://www.indiacar.com/index2.asp?p...s/dirtyair.htm

Jhawkins this may be useful for a little understanding in the meantime until the arrive.

Yeh i read that article too whilst looking for some info on downforcing. There are better technical articles out there though. That one is pretty general.

If you wanted a quick read on what aero can do. Just go here http://www.ceintl.com/nov2004/images...20dodging2.pdf

[jhawkins]

Thanks guys.....I can see a lot of reading and head scratching coming on! I really appreciate your help.

[marcush.]

The radical comes with setup instructions regarding ride heights .The ride heights are measured under the rear bulkhead(in front of the engine) and front bulkhead(below drivers knees) .Interestingly the floor of the car is a bit rised under the drivers knees ,so the measured ride height front is bigger front than rear.

[Oaksnaf]

Originally Posted by jhawkins

Thanks guys.....I can see a lot of reading and head scratching coming on! I really appreciate your help.

its really trial and error. Just when you make changes put them into a log book then after the practice sessions and races just write down the noteable differences and whether it was a plus or a negative. You will soon work out what does work and what doesn't.

[richard_sykes]

Some pictures of the areas might be an idea for more suggestions.

www.photobucket.com will store them and give you a link to put the on here.

[Oaksnaf]

There are two options you can go for here, or you can try and mould them into one.

A perfect example of the venturi affect is taking place under this DTM



Notice that he does not even have a front splitter as the lower portion of the spoiler curves back in towards the car, instead of pointing outwards.

This way they could maximize the venturi effect underneath the front of the vehicle. The front spoiler region of the car forms a "mini ground-effect tunnel". In the "throat" region of the venturi, the air flow speeds up and hence the pressure goes down. This creates downforce. The longer the throat region is, the more downforce that can be created.

Or you can try and get your downforce from a front splitter seen above.

You can go into a long haul of maths and terminology, but in the end they basically say the bigger the splitter is, the more downforce it can create.

[maddogf3]

J&P Rose used a rake of only 10 mm front to rear . I got that off Julian when he worked for Paul I dont know where they measured it from I thought they had a flat bottom on the radicals but that all I know
Best advise is read the books probably a couple is better see if there are varying views Downforce is very interesting stuff .Get them as low as possible at the front and keep them there i.e zero droop and stiff springs . We run our f3 reynard at about 12mm rake and its stiff with zero droop front and rear .That works best on the lap speed .
In the long run any air has to be speeded up underneath and then re introduced at the rear ( diffuseses job) at the same time as running air under the bottom of the wing quicker( low pressure) and thus forces car to the road Mr Oaksnaff knows plenty. I have not dissagreed with anything that they said .You need to read the books . make your own mind up . Look at F1 shapes they all have different shapes to get the same effect .It makes you realize why saloon cars are not very sure footed above 100 mph