Just made these. feedback required... (Miata/MX-5 front tire deflectors)

[caferacer51]

Hi Guys/Girls...

Fuels finaly hit £1.30/litre. A*se.

My MX5 (Miata) has really exposed front tyres, so yesterday I made a pair of these (see before and after photos...)

I would like to tidy the fixings up a bit ie, make them smaller/lighter.

Before...



After...




I used a store bought clear material labelled as 'polystyrene'. It was certainly flexible enough, but produced tiny cracks when cutting. It was 2mm thick.

What other products/materials would suit this application?

Have I made something worthwile?

Thanks in advance, Ian

[Joenavy85]

i'll give you an "A" for the concept of deflecting the air around the front tires and a "C" for execution of concept. I've dealt with polystyrene alot (i built tons of plastic model cars growing up) and i have to say it is likely too flimsy to suit your needs in this case. i would suggest finding some 1/16"(1.5mm) Plexiglass to use instead of the styrene. I'm sure the guys on here know of a few other materials you could use. it's a good start for what your looking for and it's a good thing to look at (i'm going to put something similar on the side of the airdam on my Jeep) since it should reduce drag caused by the tires

[lunarhighway]

you may want to have a look at (what toyota calls) 'aero corners'

they have recently appeared on a lot of aerodynamics cars like the new prius, iq, citroen ds3, and some others.

basically the corners before the wheels are squared off, sometimes by agresively styled daytime light, what looks like air scoops or just add-on like bumps in case of the IQ.

but all designs seem to create a sharper corner and a more flush pannel leading up to the wheels.

this aero corner thing seems fairly new and appart from a general description i don't have much info on it, but the fact it's on cars like the prius sugests there's something good about the design.

it may also explain why some olders cars managed to get a very good Cd with relatively square fronts... perhaps 'making the front as smooth as possible' is not always the best strategy

[jakobnev]

I think the material you are looking for is polycarbonate. It doen't crack like an addict when bent or machined.

[Joenavy85]

^^That's one of the one's i couldn't think of^^

[fidalgoman]

What you've done reminds me a little bit of NASCAR air dams. There is a lot that can be learned from racecar aerodynamics. Smooth contours, diverting airflow away from dirty parts of car (like undercarriage), not making the airflow to bend any more than necessary and eliminating extremes in pressure gradient distributions, etc. However there are things that do not pertain to those of us on the street doing under 150 MPH.

First racecars are obsessed with down-force to create high cornering loads. Many rules today are there just to eliminate that technology thereby slowing down the cars. Most racecars are so overpowered that just getting the power to the pavement is a real problem. One that we don't have. Also racecars (that resemble street cars) have quite a few restrictions on what they can and cannot do as far as changing vehicle profile and airflow around the car. Again that's mostly not a problem for us.

For us it's all about eliminating drag. Drag comes from changes in flow, both directional and pressure distributions. Anything we can do to create equilibrium and smooth contours only helps us. Anytime the airflow has to work through changes in direction, slowing down or speeding up, it extracts energy from the airstream. That energy (often called drag) has to be made up through our propulsion system. That in turn requires fuel which we all know is something we are trying to avoid.

[aerohead]

Originally Posted by caferacer51

Hi Guys/Girls...

Fuels finaly hit £1.30/litre. A*se.

My MX5 (Miata) has really exposed front tyres, so yesterday I made a pair of these (see before and after photos...)

I would like to tidy the fixings up a bit ie, make them smaller/lighter.

Before...



After...




I used a store bought clear material labelled as 'polystyrene'. It was certainly flexible enough, but produced tiny cracks when cutting. It was 2mm thick.

What other products/materials would suit this application?

Have I made something worthwile?

Thanks in advance, Ian

Ian,you're doing a good thing.Ideally,as in solar race cars for example,complete shielding of the tires from the airflow cuts drag.
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At say,100 km/h,the forward face of the front tires are travelling downward at 100 km/h and impacting the air perpendicularly at 100 km/h.It's a situation which makes it impossible for attached flow.
Your shields will kick the air out and around the tires where it can flow to the rear.
If you were to do likewise for the entire sides of the Miata you'd gain even more.GM measured improvements this way with its Trans AM Firebird.

[caferacer51]

Thanks all for the replies and info.

Think I'm gonna make a more polished version from better materials.

Will have a think what I can do with the rear wheels? Not sure I fancy fully faired in. But something similar to the front?

[MorphDaCivic]

Great Idea. I was wondering is Lexan a trade name? I saw some Lexan on sale at Lowes and it says it 10 times stronger than plexaglass.

Does anyone have experience with using Lexan?

[fjasper]

Lexan is a trademarked name for polycarbonate sheet. It's softer & scratches more easily than Plexiglas (a trademarked name for acrylic sheet), but it has much better impact resistance than plexi.

On a different note, I'll be interested to see how the Miata project goes. I think there's some real potential for hypermiling the Miata.

I'm planning to put a grill block and belly pan on mine, and maybe some removable fairings around the wheel openings. Maybe I could justify buying a Speedster tonneau cover on fuel efficiency grounds.

There are so many options for body kits, it might be possible to find some that are aerodynamically good, or that could be used as foundation for good shaping.