2015 Aero Rules - Interpretations and Ideas

[paul_mh]

Hello, I am Paul from the TUG Racing Team and I am currently doing some concepts for a 2015 car and there are some things that are not really clear yet:

Firstly rule T9.3.1 b) says that

"In plan view, no part of any aerodynamic device, wing, undertray or splitter can be: Further forward than a vertical plane through the rearmost portion of the front face of the driver head restraint support, excluding any padding, set (if adjustable) in its fully rearward position (excluding undertrays)"

Now what is the rules commitees definition of "undertray"? Has someone already asked the rules committee about that? My personal definition would be: "An undertray is the aerodynimic surface that can be seen from the bottom of the car and lies between the bottom surface and XX,X mm from the ground. Parts of the sidepods or wings that can be seen from the bottom of the car are not considered parts of the undertray"

That being said I have already done a concept of a FSAE- version of a "wing car" like the Lotus 78 but I am not sure if this could be considered an "undertray" since this is essentially a big wing profile attached to the side of the car (altough there are sidepods on top of it) including some flaps at the end and in front of the rear tyres.
Also if you cut some slots into an undertray and generate "forward facing edges" by doing so you will have to round the edges and in the end this will look like an airfoil, but is it still considered part of the undertray?

Secondly rule T9.2.2:

"When viewed from the front of the vehicle, the part of the front wheels/tires that are more than 250
mm (9.8 inches) above ground level must be unobstructed by any part of the aerodynamic device, with
the exception of any vertical surfaces (end plates) less than 25 mm in thickness."

What is the definition of "vertical surface"? Can there be Gourney flaps or vents in the endplate as long as the whole part is less than 25mm thick? Or must the enplate be one flat part with a max. thickness of 25mm?

Thank you for answers

[Pat Clarke]

Paul,

You are not going to get a definitive answer, only opinions.
You need to direct your enquiry to the Rules verification site at whatever event you intend to attend,

Pat Clarke

[Kevin Hayward]

Paul,

I think there is enough clarification in T9.4 to allow the Lotus 78 style sidepods. The confusion comes from front and rear mounted devices without having clear definitions of where the rear and the front begin.

The titles give a clue to what each section T9.2 to T9.4. Unfortunately A3.9 states that the headings are only used to facilitate reading and do not affect the paragraph contents. Read objectively that means that T9.3 prohibits the use of any aerodynamic device forward of the headrest mounting front plane. No text in the paragraphs actually states that this is limited to the rear mounted aero devices.

I think the intent of the rule is reasonably clear, but as Pat mentions should be checked.

If you do have clarification from the RC please post the results here. What you are thinking about is likely being considered by many teams. I know the students at ECU have run the sims.

Kev

[JT A.]

Another good question is, "What is an aerodynamic device?". An argument could be made that anything that touches the airstream will affect the aerodynamics of the car, and could be used to improve the aerodynamic performance.

[JulianH]

JT has a point.

If I had to guess the intent of this rules, then an aerodynamic device is a part that has "the improvement of the aerodynamics of the car (e.g. reducing drag / increasing downforce) as one of it's key(!) functions. E.g. a wishbone affects the aero but it's main purpose is to link the wheel assembly with the chassis.

The keep-out zones prevent the positioning of "such devices". Therefore a tire, the upright and so on are "legal". An Aero-cover not.

The whole thing gets interessting if the wishbone (or a brake duct for example) is "aerodynamically shaped" to reduce drag. Then, in my opinion, it is an aerodynamic device and should be illegal because it is inside the keep-out-zone....

[Kevin Hayward]

Julian,

I would suggest an aerodynamic device (as suggested by the rules) is something that uses the flow, or pressure of air (external to the car) towards some designed goal. This would include, but not limited to:

- Brake ducts
- Radiators
- Intake system
- Wings
- Undertray
- Shaped body

Your example of the brake duct is a good one. It is very clearly designed to be an aerodynamic device, and as you say is in the keep out zone.

I think that what the RC intends is any device that is designed to produce a downwards force from relative air motion. The wheel pods throw a spanner in the works as they are primarily a drag reduction device (although they help keep temperature in the tyres). Unfortunately once you introduce devices involved with drag then the issues of aero section wishbone tube etc becomes problematic.

Kev

[Rory Hourihan]

It's my understanding that brake ducts would still be legal because they are on the inboard side of the tires. I'd also assume most teams wishbones lay below the max height rule and would also be legal. What I think is more of a blurred line is what the RC considers bodywork. There is a rule stating nothing to be above 19.8" between the wheels except bodywork. Is bodywork only something to separate the driver and the road? or can I place any item permanently affixed to my side panels to the car, between the two wheels, at any height I deem fit? so long as it isn't more than 15.75" outboard from the centerline of the car?

[mech5496]

Totally agree on the brake duct issue. As far as I understand it, you are allowed to put anyhing from 500mm upwards as long as it li withn of 400mm on each side of the car. For instance, I cannot see why you could not mount an 800mm wide sprint car style wing on top of your MRH as long as it is under 1200mm...

[Rory Hourihan]

I think there are some other rules that prevent that, something with driver egress and the new front vs. rear mounted confusion.

[mech5496]

Not sure... I mean yes, driver egress would be tricky but I cannot find anything that excludes it. Or a bi-pnae front wing with the upper plane above 500mm...