The next-gen MX-5 Miata thread

[CodeRedR51]

 

[The Vanishing Boy]

Why would they have a focus group for a retractable hard top? When they want to save weight, they don't even have a powered soft top.

The new ND compared the the NA.

^ The NA looks like a Crossover roadster (dat ground clearance, yo) next to the ND. Maybe because the NA is so light, the shocks/springs doesn't need to compress as much.

^ Thank you for the share! 👍

 

[Eunos_Cosmo]

Saw the new MX-5 today at the Paris Auto Show. It looks utterly fantastic. Perfect size, great shape, and just the right amount of presence. The interior also looks really special and high quality. Can't wait to drive one.

 

[niky]

http://www.topgear.com.ph/features/...at-a-mazda-mx-5-hardtop-coupe-would-look-like
So the article finally ran... Get to post this outside the infield.

Sucks we're stuck with non-dynamic sizing on the site, as the pics came out terribly compressed...


Still... yay! Yeah... Photoshop would give a more realistic surface look, but I wanted to doodle.

Also did a quickie with an Alfa nose... and by quickie, I mean I only drew on top of the car for an hour or so, and didn't bother to render surfaces... basically, raised the nose, added a grille, (lazily) copy-pasted headlights.

 

[Tornado]

On the one hand I'm glad about the commitment to not making a gun emplacement for a cockpit.







On the other hand why so humpback shaped?

 

[CodeRedR51]

Roof is too round I think. Think flatter, bring the quarter windows down to the fender line like so:

 

[Dan]

Roof is too round I think. Think flatter, bring the quarter windows down to the fender line like so:

Now THAT looks good. Much better than the pics before.

 

[niky]

I was going for the Ginetta look.

http://www.classicandperformancecar.com/front_website/octane_interact/modelpicture.php?id=960

Which means the taller rear end was a conscious decision, too... to accomodate more blistered rear fenders.

 

[CodeRedR51]

I'm a fan of the sleek, fastback look as shown with the NB above and below. You should try your hand at doing something similar.

 

[ProjectWHaT]

How about a Shooting Brake Miata?

 

[CodeRedR51]

No.

 

[05XR8]

Will be interesting how Mazda play this out. Must be llightweight and aesthetically pleasing.

it'll come down to how they treat the rear glass. Will it be extra thin? Will it be plastic? Will it be like a Targa and bubble glass?

 

[Grandea GTR]

If the ND MX-5 gets a SKYACTIV engine, does that mean it can take regular gas now?

 

[niky]

The problem is, the new Miata has no ass.

Try to make a fastback with a flowing tail, and you end up with a notchback instead... which is basically a hardtop on the roadster. Or you make the tail longer, which is extra weight, all out past the rear end. Not ideal.

Was looking at making something realistic... but doing it differently... and trying to follow the Kodo shape. A straight shoulder line isn't Kodo...

What would match the styling language is something more flowing, so I tried to extend the slashing swage line up into the greenhouse. The taller roof and trunk, I originally made lower,

But I figured I'd leave some extra headroom for people who don't fit.

And, according to my templates, this shape is a bit more aerodynamic than a flatter roof. One pet peeve with the NC is that aero sucks. Even with the PRHT, top speed pales in comparison to my Protege. A 21st Century sportscar should, given 165 hp, be able to hit 220 km/h, at the very least.

 

[Omnis]

How about a Shooting Brake Miata?

Bledwagon?

 

[Keef]

And, according to my templates, this shape is a bit more aerodynamic than a flatter roof. One pet peeve with the NC is that aero sucks. Even with the PRHT, top speed pales in comparison to my Protege. A 21st Century sportscar should, given 165 hp, be able to hit 220 km/h, at the very least.

This is almost right. The highest point of the roof should be right over the driver's head like here...but immediately behind that it's still too high. It's nice to have a shelf behind the seats but it doesn't need to be that big. More fastback, less bubble canopy.

EDIT: As for "more aerodynamic", it depends on your goals. This bubble canopy will be low drag but will promote lift. something you don't really want on such a small, light, neutral car. I still think have a faster back would be better.

 

[Eunos_Cosmo]

Just do this:

 

[Cale]

Mad paint skillz incoming

 

[niky]

@Keef , that's basically following the ideal template. Could drop faster, but that would create more wake vortices... drop off more gradually, and you'll need to raise the butt even more... sort of like this:

 

[Keef]

@Keef , that's basically following the ideal template. Could drop faster, but that would create more wake vortices... drop off more gradually, and you'll need to raise the butt even more... sort of like this:

No, no, no.

You don't want it to drop faster, you want it to drop sooner.

I think we can both agree that the lift component of such a design is unavoidable. What we can change is where the center of lift is. What you've drawn is basically a bubble. The center of lift will be quite far back along the greenhouse, probably at least halfway back. You need to move it forward by shaping the roof more like a typical airfoil. That way the lift component won't directly effect the rear end as strongly and you'll have more time to deal with it via a ducktail or something.

Look at the BMW again. Its roof begins curving down over the driver's head. But your Miata roof doesn't begin curving down until the headrest - probably 6 inches aft of the BMW. That's just unnecessary because nothing is back there that needs any headroom.

@Cale design is more like what you want.

EDIT: Make it look like this http://m-selig.ae.illinois.edu/ads/afplots/defcnd2.gif

Then you'll have plenty of room on the decklid to put a useful ducktail spoiler to plant the rear. But having the greenhouse's center of lift right over the rear wheels is the worst spot. Try to move it as far forward as possible.

EDIT 2: And don't forget about the option of a double bubble either.

 

[mustafur]

Car needs lower Seating position so it can be more sleek, otherwise its going to look like crap.

 

[CodeRedR51]

Car needs lower Seating position so it can be more sleek, otherwise its going to look like crap.

You already sit lower in it than the NC, that was something Mazda had announced.

 

[niky]

@Keef - well, coulda... but it's done. Still... I would have gone for the flatter top if I had more space (must say, the Z4 has worse space than the NC, from the time I sat in it) or if the base of the windshield and the seats were further forward.

 

[Keef]

but it's done.

Make another one!

Also, link me to or send me this template thing you're talking about. I'm curious.

 

[niky]

Make another one!

Also, link me to or send me this template thing you're talking about. I'm curious.

Knock yourself out!

http://ecomodder.com/forum/tool-aero-template.php

Granted, this is a 1930's template, but I find that mix-and-matching parts of it to modern cars shows a lot of them following the lines... especially around the rear bumper and the greenhouse.

But as many modern cars have shown, it's possible to get under 0.30 cd without really following this template, all through detail optimization... so it's more of a rough guide, than anything.

 

[Keef]

Knock yourself out!

http://ecomodder.com/forum/tool-aero-template.php

Granted, this is a 1930's template, but I find that mix-and-matching parts of it to modern cars shows a lot of them following the lines... especially around the rear bumper and the greenhouse.

But as many modern cars have shown, it's possible to get under 0.30 cd without really following this template, all through detail optimization... so it's more of a rough guide, than anything.

Ah, the 1930s. Before we knew much about aerodynamics. And speaking of streamlining, the B24 used a laminar flow airfoil by accident because they didn't know what laminar flow was yet. It basically looked like a "streamlined" car. Obviously, depending on what speed you're going, streamlining can be anything from totally unimportant to so important you end up with a super wonky airfoil design. Here is the B24:

Here's another laminar wing. We'll ignore the fact that it's designed for high lift. For our purposes, the fact that it has a low Reynolds number is more important. The lower the number, the more laminar the flow, the less likely the flow is to separate.

That's even steeper an airfoil than the B24's yet the top surface is still laminar.

You already know that flow separation generally begins at the back and moves forward. As the boundary layer gets thicker the shear between it and the laminar flow gets stronger, eventually resulting in turbulence. These laminar wings attempt to delay that as long as possible by having smooth trailing edges with almost no arc at all. Compare these smooth trailing edges with the rear hatch of your Miata roof. Whereas these arc early and taper off smoothly, your roof continues an almost constant arc basically from the base of the windshield to halfway down the rear window when it finally starts to taper. At high speed this roof's turbulent flow would reach probably reach halfway up the rear window, rendering the small ducktail pointless. You'd be left with both high lift on top the roof and high drag at the rear. You can do better!

Taper that rear window a little more. Start the arc downward about 6 inches in front of the headrest, down to a virtually flat rear window which meets the decklid a couple inches forward of your drawing. The tiniest change will make a crazy big difference.

Yes, I know this is a much longer car but your Miata roof still has room to be optimized. I'm just trying to help you make it perfectly awesome!

 

[05XR8]

Are these designs taking into account the double humps in the roof like the RX7 above? Would that be a design study Mazda may be trying?

 

[Keef]

Are these designs taking into account the double humps in the roof like the RX7 above? Would that be a design study Mazda may be trying?

It looks like Niky's designs do as you can see in the 3/4 views.

From a side view, you can only see the shape of the humps anyway, not the trough in between them. If you want to view the lowest point of that trough as a separate arc, you'd basically have a wing shape with lower camber which is Better for aeros. If you can make it work with a single hump it'll work even better with a double hump or double bubble, whatever you wanna call it. Not only will it reduce the camber of the roof arc, reducing the likelihood of turbulence, but it will also reduce frontal area and help control flow over the roof, directing it toward the center of the rear spoiler which will become more effective.

EDIT: @niky, I probably should have read the article yesterday. Just looked at it and you did a wonderful job with the wire frames and whatnot. I was wondering how you made the design look so proper. Is that some special software or is that all PS work? And is this PS stuff your secret hobby or what? You should probably concentrate on doing that haha. Developing renderings for these publications seems to be a decent gig. Not sure how much money is in it but they all do it so somebody is getting paid.

 

[CodeRedR51]

Was searching Google for something and found this. I like this more. The roof line is nearly spot on, but I think the lower window line could be tweaked some.

 

[ProjectWHaT]

That is the best thing I've ever seen!