Aerodynamic Inquiry

[marlin]

Hi all,

Looking for some help to clear up some aerodynamic issues in my mind. I have a GT Zero under construction. I have been told the diffuser makes a big improvement for handling and plan on installing one. My understanding is the smoother the flow of air into the diffuser the better it will work. Not sure if this is true?

 

I have also heard that putting a belly pan under the car would help evacuate heat out of the engine compartment. I can place one from the nosecone back to the oil pan. To improve the evacuation of heat it was suggested that putting a bend downward at the tail of the belly pan would disrupt the air flow and extract more heat. I would think the belly pan would increase front end lift and with the down fold, to increase heat extraction, this would disrupt the flow to the diffuser.

 

I know everything has trade-offs. Was looking for correction if my thinking processes are wrong. Any information welcome. Willing to read informative information if pointed in the right direction.

Thanks,
Marlin

[tractor]

Rear defuser makes the back end look finished it has no aerodynamic purpose and at the front best way for heat flow is keep engine compartment open at bottom and as many vents on top and sides to encourage air flow

[Mrbarry]

A zero is too high off the floor to get any ground force effect, but the diffuser wont make things any worse. Will keep laminar air flow smoother than not having one so will reduce drag, its not going to be noticeable to a driver in a million years however. A totally flat bottom is the ideal with a diffuser and canyards and a chin lip.... The zero is still too high for real noticeable effects of the diffuser tho. Unless youre doing track work and suffering with control its not even worth worrying about.

Looks wise, diffuser all the way

[brumster]

https://www.lotus7.club/forum/techtalk/aerodynamics

 

I used to know Claire Kendall - she lived locally and we were both members of Shenstone & District Car Club - and her dad was the chap who arranged the visit to MIRA to use the wind tunnel. She used to sprint a Rover Metro with some rather serious aerodynamic mods (unsurprisingly!).

Edited November 27, 2017 by brumster

[knights_templar]

Zero was taken to MIRA, deffuser looks better and does keep the back of the car cleaner, but had very little effect on airodynamics.

 

As others have said, makes little difference to shape of a brick, to many flat surfaces facing the air flow, to many holes and surfaces to break the flow up.

[theduck]

Whatever happened to the splitter design they tested at Mira? Always thought it looked interesting.

[marlin]

Not to mention the bonnet vent that you can just barely make out on one of GBS's blog posting, related to their testing. It shows a vent similar to what CAN-AM cars had right behind the radiator. Looks very interesting.

Thanks to all who have replied to my question. Will continue with my brick building.

Edited November 28, 2017 by marlin

[WallerZ]

Aerodynamics of a 7 as said are shocking....but doesn't mean they don't still look good! It would take a serious amount of work to get the car to benefit to any appreciable difference.

Best option I found for keeping bonnet temps down was no bonnet

[agent_zed]

open wheels are one of the worst offenders for causing drag. Was reading about this in F1 cars.

 

From what i've read the 7 shape has a drag coefficient of about 0.7 (1 being a brick - 0 being super slippery) which compared to the sierra which is about 0.33 is pretty awful. Modern cars are even better than this. My peugeot 3008 is 0.296 which is great for such a bit car.

 

Most of the time though under 50mph most of the problem is other factors e.g. weight and transmission losses etc So just drive slowly and you'll not have a problem