Searching for the "best" underbody construction

[Aceofspades]

@ wesley123
There are no limits in the Budget
I think you can imagine the look of an 65´ Mustang.
Here is a pic an Mustang underbody, just an I-net pic, not specificly my build:
http://67mustangblog.com/wp-content/upl ... tebody.jpg

@Jersey Tom
Planning on running the car mainly in the European Hillclimbing Series(Germany and Austria), occasionally on Track Days and Open road racing.
The car was build from ground up,
Suspension: Unequal long, anti parallel double wishbone pushrod suspension in front and rear (IFS and IRS)
I think my suspension could handle the stress of the extra load.
You know, all i want to do, is getting the aero thing done right.
Choking the venturi tunnel by a front splitter
could be prevented i think by using a splitter shaped like this: ____------____ ???

Just a quick drawing of your idea, would really help me out and getting my thoughts focused on whats really necessery. Maybe you have got a min and a old sheet of paper

@RH1300S
There is gonna be no prob. with engine cooling, i am sure about that.
Weight is reduced to max. because it was built from ground up, using alot of CF/GRP parts.
Also Replacing Roof by aluminium.
Titan Whisbones
etc...

Thanks to all and hoping for further suggestions
regards,

[wesley123]

Well, as i see the underbody it will be a though job, if you want a really good underbody you must build it behind the car or you have to build it compact.
Maybe it is possible to build the suspension more compact or make it have an aerofoil shape. You cant make a really big diffuser, you can but you have to change the whole rear. But only a flat panel that covers the suspension and other things under the car will make a big difference.

You need to find out if its possible to make the suspension raise higher, which is possible by using 26 inch wheels(?). Any way, to make a big Group C style diffuser you have to change the whole rear suspension and bodywork.

What also could help is making it lighter by using lightweight panels.

[Aceofspades]

-edited-

[Aerodynamicist#1]

Hey,

I reckon that a fan is probably the best way to go and has been proved successfully by the brabham. As far as I can remember I think Gordon Murray said that the fan used in that case was ran separately from the main engine, but you could easily run it from the main engine in a similar way to the F35 JSF 'dog' +ve locking clutch mechanism. (If you don't know what i'm talking about check out the jet fighter in Die Hard 4!!!!).

With the absence of a fan, it is best to accelerate the flow under the length of the car to a high velocity. This is why you see 'diffusers,' on lots of cars. These work by rapidly expanding the underbody airflow. You are essentially trying to create a 'vacuum,' under the car, which will suck the car down onto the track. This is where the use of skirts came in because air was being bled into the 'vacuum' from the front and sides, causing an increase in pressure hence skirts were used to seal the underbody.

I also think it could be possible to increase the underbody mass flow rate by the injection of an energising flow into the underbody directed aft.

Let me know what y'all think of my ideas!!!

[bettonracing]

With the absence of a fan, it is best to accelerate the flow under the length of the car to a high velocity. This is why you see 'diffusers,' on lots of cars. These work by rapidly expanding the underbody airflow. You are essentially trying to create a 'vacuum,' under the car, which will suck the car down onto the track...

Diffusers are there to slow down the air after it has been sped up by the throat area of the underbody. Speeding up the air lowers the pressure, slowing down the air raises the pressure. The 'expansion' of the air in the diffuser is slowing it down.

Regards,

H. Kurt Betton

[timbo]

I think Gordon Murray said that the fan used in that case was ran separately from the main engine, but you could easily run it from the main engine in a similar way to the F35 JSF 'dog' +ve locking clutch mechanism. (If you don't know what i'm talking about check out the jet fighter in Die Hard 4!!!!).

As I said earlier in this thread that direct link between the fan and engine would be a problem because air pressure (and downforce) would depend on engine revs. E.g. when you shifting gears you would have different grip. I read that mcLaren used to blow the exhaust through diffuser to get more downforce but abandoned it partially because of instability of such setup.

[Aerodynamicist#1]

kurt, you are absolutely right about the diffuser, i was getting too excited when writing the post and started talking rubbish! Yes you use the diffuser to reduce the pressure and it is essentially the pressure difference between the top of the car and the underbody, which causes the 'downforce'

Regarding the transmission of using a fan mechanism, John Watson who drove the Brabham fan car told me that it is a matter of driving the car differently to get it to work, apparently the faster you take the corners the better the suction force and so it is proven to work as the Brabham illustrates! You could however use some sort of constantly variable transmission (CVT) which could adjust the fan speed accordingly perhaps??

[duckrutt]

It think it would be easier to look at GTO or GTU cars for inspiration rather than gunning for GTP cars but that's just me.

Ducky

[flynfrog]

I think Gordon Murray said that the fan used in that case was ran separately from the main engine, but you could easily run it from the main engine in a similar way to the F35 JSF 'dog' +ve locking clutch mechanism. (If you don't know what i'm talking about check out the jet fighter in Die Hard 4!!!!).

As I said earlier in this thread that direct link between the fan and engine would be a problem because air pressure (and downforce) would depend on engine revs. E.g. when you shifting gears you would have different grip. I read that mcLaren used to blow the exhaust through diffuser to get more downforce but abandoned it partially because of instability of such setup.

the chapareall used a snowmobile engine to run the fans to is made the same downforce all the time