Aerodynamics of a bug

[judgie]

have plans this winter for the race car.
front spoiler and spliter leading to a flat floor pan into a rising rear diffuser,deep side skirts to stop air going into the low presure area under the car.
vented wings,grills on top of the fronts and holes in the bottom rear edge of the rears.
there will be 2 naca ducts in the floor pan to feed cold air to the bottom of the engine, header and gearbox.also two vents in rear 1/4 like remmele style ones to feed the air boxes on each carb.
to fiinish it all of i have a f3000 lola bi-plane rear wing which will be mounted as high and far back as the regs will let me.highest piont of the wing can not be higher than the roof line and rear most part can not over hang the rear of the car by 400mm.
this the car at the moment

will post pics when this work is compleat and let you all know if it works.
cheers rob

[lazylongboarder]

I'm impressed so far...Keep us posted on the improvements.

[beetle1303]

Very good choices i must admit. One issue for me though ( im going the same way for my street 1303)

The position of the front ing vents
A: the J-sports racing bug has 2 cuts on the back side of the wings

B: F40 used a huge vent on the back plane(vertical) of the front wings

C: DTM Audis and 935 have vents on top of their front wings. From what i have read on the DTM cars is that the vents on top of the wing help the above the wing ( low pressure) get filled with the vented air from the wheel wells...

D: the best i believe would be the 911 gt1 design


I also agree with the front bottom closing every posible gap (air trap)

Chris

[judgie]

the DTM Audis and 935 have vents on top of their front wings. From what i have read on the DTM cars is that the vents on top of the wing help the above the wing ( low pressure) get filled with the vented air from the wheel wells...

yep thats why im going for the vents on top of the wings to try and "pump" air in to the rear wing,also its to try and have the low presure air in the wheel wells sucked out by the high presure air flowing across the top of the wing.vents must face to the rear to do this or will just force air into the wheel well.
cheers rob

[beetle1303]

yeah thats what i meant
very nice bug ( you actualy partly realise my ideas )
Im going to build two different kits for by 1303, one like a 935 and one like a gt1 with the fender extending all the way back ( both in 3d models first and then from alu)

Chris

[judgie]

this is the sort of thing i had in mind

will just have to try and do it all before the season starts.
cheers rob

[beetle1303]

Try and do something to the place around the transmission. Its a big gap that engulfs much air...In one of my designs im using a fake bottom and very square wheel wells for the back since rear wheels dont turn and their movement is minimal in a yaw manner.

Chris

[judgie]

Originally Posted by beetle1303

Try and do something to the place around the transmission. Its a big gap that engulfs much air...In one of my designs im using a fake bottom and very square wheel wells for the back since rear wheels dont turn and their movement is minimal in a yaw manner.

Chris

yep going for a compleate flat floor pan gentaly rising to the rear leading into a defusser.
cheers rob

[beetle1303]

In a few hours im flying back home so i could get some measurements. I believe that with "gently" you mean from the rear of the floor pan towards the back... otherwise it will be too low -the front clearence-(if it goes from the front to the rear directly)

Also one of my other considerations is: Would the side skirts be more effective if they have a small lip at a 90 degree angle towards the cetreline of the car? this would improve stractural rigidity and make it a bit more difficult for the side skirt to break if it touches the ground in a small radius u turn with high altitude difference...just a thought

Another thing for you jugie and every other racing: in the case that the regulations permit it... Have you thought of putting ribs on the top-outer end of your wings? (like the K3 935) they are supposed to improve the flow over the end of the wing. (like the small lip that goes on top of the rear window, but on the longitudinal plane) it could improve the airflow to the rear fenders...and any air intake around there

Chris

[judgie]

floor will rise from just behind the front axle line to just behind the rear axle line,or as far back as i can before curveing up to the defusser.rise only needs to be a degree or so.
the wing vanes that you refur to i'm trying to confirm if i can run them or not.regs are prety free as long as the work is below the axle line or does not alter the side profile of the car.
cheers rob

[beetle1303]

in order to get the best of the ground effects i would go with parallel bottom instead of inclined. See both pics to understand what im saying. Also i would go for the same depth for the venturi and the difuser (side view). From what i understood the rules doesnt give you enough space to play with ground effects... so i dont know if the venturi would have enough meaning...

Chris

[judgie]

in hill climbing and the class that i'm in i can pretty much do what i want,apart from fans and the wing angels have to be fixed.also have to have a min of 40mm ground clearance. will be a learning curve in what will and wont work on the humble bug but it will be fun trying.
cheers rob

[Bebobug]

This thread is awesome!! I have an idea for the street. If you do the mods under the car, subtle vents on fenders, slight front chop & a little rake with both front & rear lowering of the suspension. You could have near sports car aero but still look pretty much stock. Just an idea.

[jimby]

I have picked trhe brain of gavin, he's a mate that is an aerodynamic engineer on the currnt F1 Renault team, yes the ones that are winning
he reckons the first thing is the flat pan, second is slice the rear of the front wings so you can see the rear of the front tyres. get the car as low and flat as you can. kill the lift on the front with louvers on the wing tops and even ducts on the bonnet, a bit like the elise.

[DORIGTT]

Hey Jimby,

Ask your mate to look at a Ghia and make a couple recommendations as to improving it's aerodynamics.

Thanks