Race car aerodynamic help?

[Bennett_Racing]

I am after some help, please can you see our website,

www.bennettracing.co.uk

I am after some aerodynamic advice on our race car, we simply want to reduce drag and were open to ANY ideas or suggestions.

Thanks

Luke

[MetroMPG]

Hi Luke -

For which car? Can you post a link & photo?

[Bicycle Bob]

Put light fairings on the roll cage and wing support tubes and any similar bits cutting air. A simple tail of folded cardboard and two wraps of hundred-mile-an-hour tape can cut the drag of those parts to a third. Light, well-shaped fiberglass wraps could be much better still. You might even get to laminar flow in clean air, if the vibration isn't too bad.

A thin metal wrap on those headers could give both streamlining and downforce, especially if the pipe angles are adjusted with that in mind.

[Bennett_Racing]

Photos are all on site under the gallery

also some photos here

Feature: Bennett Racing

Thanks

[Daox]

Well, with how aerodynamically dirty that thing is, you'll need to start from the front and work your way back. Everything will need to be enclosed in a fairing. Avoid any abrupt angle changes. I'd try to tilt the windshield back to reduce the angle there. Once everything in enclosed, add a boat tail to the end. Tuft testing is really going to be your friend on this one.

[Bennett_Racing]

Got that book just reading through it now.

Really after things we can add without hugely changing the look of the car.

But to help it through the air a little better.

The rear wing struts we are going to change to the aero tubing which is basically tear drop shaped rather than round.

I was thinking of making an undertray for the front section too

[aerohead]

Luke,is it the AA Fuel Altered that you want help on? Your all-up weight would be useful ( wet ).Are you at full lock-up with the clutch at the timing light? Is there any horsepower to spare? Is the body of the car already carbon-fiber epoxy? Does the rule-book allow any enclosure of the body/chassis for that class? Are the wrinkle-walls slipping presently at speed ( roof-top negative-lift airfoil )? Can the driver see around the engine/blower/bug-catcher at present time? Do you have your front/rear axle weight bias ? Do you have a sense of the car's dynamic weight distribution at upper speed. Do you have a time/velocity table so we can see your residence time through a velocity regime? Can you show us where the center-of-gravity of the car is. Have you ever put a model of it in a windtunnel to determine it's aerodynamic center-of-pressure. Does the car do a wheel-stand,with chassis-flecture at launch? If so,at what distance and velocity does the front wheels touch down? Do the small outboard winglets at the front axle keep the wheels firmly planted near top-speed? Can you say how much the cabin raises as the drag slicks grow to full sidewall height? Is the length of the car at it's maximum or could it be any longer? Can the wheelie-bars be enclosed? These are some considerations one would need to appraise where you presently are,and potentially where you could get to.We don't have to tell you how dynamic a dragster is,from launch to the finish line,and your driver's safety is paramount.If your going to "experiment" with the "real thing" you sure want to be safe about it.

[Bennett_Racing]

Originally Posted by aerohead

Luke,is it the AA Fuel Altered that you want help on? Your all-up weight would be useful ( wet ).Are you at full lock-up with the clutch at the timing light? Is there any horsepower to spare? Is the body of the car already carbon-fiber epoxy? Does the rule-book allow any enclosure of the body/chassis for that class? Are the wrinkle-walls slipping presently at speed ( roof-top negative-lift airfoil )? Can the driver see around the engine/blower/bug-catcher at present time? Do you have your front/rear axle weight bias ? Do you have a sense of the car's dynamic weight distribution at upper speed. Do you have a time/velocity table so we can see your residence time through a velocity regime? Can you show us where the center-of-gravity of the car is. Have you ever put a model of it in a windtunnel to determine it's aerodynamic center-of-pressure. Does the car do a wheel-stand,with chassis-flecture at launch? If so,at what distance and velocity does the front wheels touch down? Do the small outboard winglets at the front axle keep the wheels firmly planted near top-speed? Can you say how much the cabin raises as the drag slicks grow to full sidewall height? Is the length of the car at it's maximum or could it be any longer? Can the wheelie-bars be enclosed? These are some considerations one would need to appraise where you presently are,and potentially where you could get to.We don't have to tell you how dynamic a dragster is,from launch to the finish line,and your driver's safety is paramount.If your going to "experiment" with the "real thing" you sure want to be safe about it.

Thats a few questions ! I will try to answer them the best I can.


is it the AA Fuel Altered that you want help on?
Yes the black Relentless fuel altered

Your all-up weight would be useful ( wet )
2200lbs race ready with driver

Are you at full lock-up with the clutch at the timing light?
Do you mean top end finish line? Or the start line?

Is there any horsepower to spare?
How do you mean?

Is the body of the car already carbon-fiber epoxy?
No fibreglass but its fairly lightweight, we were concious of this when we made it.

Does the rule-book allow any enclosure of the body/chassis for that class?
Pretty much do what we want...thinking an undertray?

Are the wrinkle-walls slipping presently at speed ( roof-top negative-lift airfoil )?
Don'y get this one...sorry

Can the driver see around the engine/blower/bug-catcher at present time?
Yeah has about an inch over the injector

Do you have your front/rear axle weight bias ?
It is around 800lbs over front and 1400lbs rear end

Do you have a sense of the car's dynamic weight distribution at upper speed?
None

Do you have a time/velocity table so we can see your residence time through a velocity regime?
Not sure what you mean...

Can you show us where the center-of-gravity of the car is?
Not sure how can I find out?

Have you ever put a model of it in a windtunnel to determine it's aerodynamic center-of-pressure?
I am currently trying to get it sorted, have someone ready to put a model in there but need a CAD drawing done first.

Does the car do a wheel-stand,with chassis-flecture at launch?
Yes, chassis must flex to enable it to put the power down

If so,at what distance and velocity does the front wheels touch down?
Front wheels come down at around 60 feet out or about 100mph

Do the small outboard winglets at the front axle keep the wheels firmly planted near top-speed?
So far yes, we have only tested the car so far but at 160mph the car was very stable.

Can you say how much the cabin raises as the drag slicks grow to full sidewall height?
The tyres grow about 8-10 inches in total

Is the length of the car at it's maximum or could it be any longer?
We are restricted by wheelbase (centre of wheels) which is 125 inches. Everything else we can do what we want.

Can the wheelie-bars be enclosed?
Yeah


I agree safety is paramount its my dad in the car so I'd like it right.

Even if there are some little things I can do/make it might be the difference between a 6.200 and a 6.1999

Thanks again all appreciate your time.

Luke

[trikkonceptz]

I am watching this with interest as I feel that aerodynamic changes can give you the improvement in times you are looking for in a field where everyone just tries to increase horsepower.

My only question is, would an undertray be safe on a vehicle that already does wheelies? That aspect seems to present a problem IMO.

- more surface area to cause drag while in the wheelie, which will strain those wheelie bars even more, thus actually slowing you down. But I will other those that know break that down better.

BTW, without altering the wheelbase can you change the shape of the cab. Imagine a dragster with a boat tail ...

[Bennett_Racing]

Originally Posted by trikkonceptz

I am watching this with interest as I feel that aerodynamic changes can give you the improvement in times you are looking for in a field where everyone just tries to increase horsepower.

My only question is, would an undertray be safe on a vehicle that already does wheelies? That aspect seems to present a problem IMO.

- more surface area to cause drag while in the wheelie, which will strain those wheelie bars even more, thus actually slowing you down. But I will other those that know break that down better.

BTW, without altering the wheelbase can you change the shape of the cab. Imagine a dragster with a boat tail ...

Very good question, only thing I can say is that we will be trying to contain and 'tune' the wheelie bars this year to reduce the height of the wheelies.

While a 12 inch wheelie looks good, going up means your not going forward...

An inch is plenty...but the point it def to do a small wheelie as it transfers ALL the cars weight over the rear slicks which aids in traction.

As for the boat tail, could you post a simple drawing please? We made the body and added the arches and also the part for the parachutes to go onto, as any lower its just dead air.

We can make and fabricate anything so any ideas are very welcome.

Thanks