slate blue

I read some interesting quotes from the late Dr, Harvey Postlethwaite who mainly worked for Ferrari F1 I believe. He was a very well regarded aerodynamicist, the following are his quotes from 2005.

This also fits with the early 2009 season problems that beset the McLaren F1 where extensive work was done on the diffuser "to turn the floor on."

It certainly is an interesting subject, clean airflow, fast moving air and great diffusers make good downforce, easier said than done of course.

Greg

slate blue

I'll try and post some drawings.

slate blue

Not much of an artist I'm afraid

nc_growler

A shark with gills... Love it.

Going to be a very unique vehicle.

svp928

Nice, Greg, but you seem to missing a few other parts....

slate blue

By svp928
The whole car does exist but it just doesn't move It is also on stands as such the wheels are drooped.

I also have had some thoughts on further downforce enhancing changes, I have read some studies that deal with the front wheels and cooling. Very clever solutions one used by Porsche the other Ferrari. Porsche achieved an almost zero drag cooling system. Where that could be relevant is for oil coolers on HiPo engines. The Ferrari uses a blowing system to lower drag around the front wheels. Much like a blown rear wing used in F1. They were used to lower drag.

slate blue

It will be interesting whether it wins 928ers over in the end, I conducted a poll and 39% liked it 33% hated it and the remainder accepted it on the basis of a functional body mod only.

The front splitter has been designed but not made, it is much larger than the earlier one at the start of the thread, it is functional and it will be the largest that can be used on the street, hope the wife doesn't wipe it out! It does take a bit getting used to driving with low slung bits. It is safe for now on stands and with no seats.

thal

i really like what you're doing Greg. those side vents look great.

now you just gotta become friends with someone at your national aeronautical and space administration so you can use their big-*** wind tunnel to test mock ups before you finalize.

then you gotta become friends with someone at your department of transportation to make sure all your roads are flat as glass.

Landseer

You do amazingly cool stuff, always well planned and executed.
Kudos. The body mods are subtle and attractive.

mark kibort

should have been apart of the stock design. Nice work!

slate blue

Thanks very much, given the rather harsh words we have exchanged in the past it take a pretty big person to overlook that. So

By mark kibort

Hopefully the design keeps going down that sympathetic path, that is enhancement not overt change, thanks also.

By Thal
Appreciate your words. Still got some more good stuff to come.


So another update, in one of my magazines there is a study on the DBS Aston Martin, I know the sides are not the same but I thought this was at least interesting hence the post.

Can you see how the area behind the front wheel (where the vents are now located) appears to be a low pressure area? Even on the 928 there is a distinct change of direction of the wooly tufts. Where the pressure changes happen on the Aston it appears to roughly correlate on the 928, look at the window back of the guard, door etc.





So the vents depending on what they are used for may work quite well if we have a high pressure zone feeding a low pressure zone.

Comments on the CFD?

Greg

Lizard928

Greg,
Put a canard behind the wheel to add downforce!

slate blue

Thanks for that I will consider it carefully. What is clear from the cars I have actually looked at down at the Porsche dealer and the areo studies where photos have been available, I have seen diffusers in front of the tyres or blown areas.



You can see the diffusers in front of the rear wheels quite clearly, on some of the Formula One cars I have looked at, in front of the rear wheel has the guide vanes directing a certain amount of air right at the tyre and the rest around it and over the top of the diffuser. Now we aren't concerned with over the top of the diffuser but certainly underneath it is important to us.

What I think they are doing is directing a certain amount of quality airflow, that is fast laminar air to the downforce parts of the car. The rest is sacrificed and hits the tyres.





When McLaren built their 2009 car when the rules changed it was a complete disaster, three seconds a lap off the pace. What this was put down to was their front wing was directing too much air to the floor of the car. Normally you would say with a car with flat floor and diffuser you can't have too much air but it was the quality of the air they had was the problem.

The McLaren philosophy was alway direct as much air as possible away from the wheels (to lower drag) however when the rules changed and the wing became much wider the same thinking didn't apply successfully.



So they directed more air at the tyres and cleaned up the flow to the floor and the car immediatley improved. So I think there is some lessons there don't try for too much and stick to quality.



This is the back of the Ferrari wing, basically the back of these wings looks like a diffuser, for some reason when I see the underneath I always get a bit of a surprise. Thinking about it in relation to what we have gone over, the top of the wing is the high pressure area and the underside the low pressure area much like what Ferrari did with the Enzo in the top pic. That is run low pressure air into the tyre.

When they further developed the Ferrari FXX, they used a blowing system from the radiators and exited the air in front of the tyres (full width of the tyre) this along with the change in the front bumper dramatically changed the CFD study of the floor. The low pressure area under the car was greatly improved with this change. The image below is not in my book so I will have to compare it to what is there just in case Ferrari is having a fiddle with the colour pallete. Seems to have a lot of red for a car that produces so much downforce. Maybe it is just different pressures and we shouldn't read too much into the actual colours?



The other car and maybe we can get others to chime in here that are much better qualified but what Porsche did with the 997 Carrera was basically build a zero drag cooling system that again had the air exit around the tyres. Slight twist on that though. They used the pumping action of the tyre, i.e the low pressure zone created in part of the wheel well to exit the air and as such the system was essentially drag free. This was one of the main reasons the 997 had such a low cd, 0.29 from memory.

So if anybody was to add coolers into the front guards there will be a right and a wrong way to go about it. Something to think about anyway.

Here's a bit more just a few lines from Ferrari about road cars and aerodynamics.

http://www.ferrari.com/English/GT_Sp...odynamics.aspx

Interesting comment on the 599's B pillars, I think the shape of the rear area around the glass is similar to the rounded 1/4 window glass on the 928. Maybe somthing in our favour? The other thing that is related is the GTS rubbers that fit the front windscreens. I was told by a GTS owner that the water now tended to flow over the side windows but without them it now flowed presumably over the roof. Is it better for the air to go down the sides?

P.S for those who didn't see the wet practice here's a youtube clip with the Renault's front exiting exhaust. You can see the water spray and how the air goes back under the car.


There is a couple of stills on this page

http://www.f1technical.net/forum/vie...187&start=1260

and how it works on this page.

http://scarbsf1.wordpress.com/2011/0...fee-explained/

Randy V

So what's the goal of this project?

Mongo

Side exhausts and making your shark look like a 550 Maranello apparently.