Aeromodding a Yugo (Zastava Koral)

[GRU]

my art skills are not as good as yours

[GRU]

these pictures should help you because the rabbit was a big influence on the design of the Yugo
Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - diesel_john's Album: aerorabbit2010

[yugomodder]

Thanks for the ideas GRU!
Yeah I figure as long as I can prevent the car from funneling the air directly underneath the car/at the ground I should get a sizable benefit. Even just a simple grill block can be 5% so I'd imagine a nose redesign should give at least a 10% reduction in drag. Yeah I figure that I'll get a lot more benefit streamlining the underbody, adding a diffuser, and adding a Kammback. That being said, if I can reduce drag by 10% that's nothing to scoff at. I will be adding smooth wheel covers to all the wheels, and probably wheel skirts on the back. Did you mean to also add wheel skirts on the front? I'm not sure exactly how to do that.

I really like your lawn edging idea. I don't think I'd want to put it on the front like an air dam though because I should have nice linear flow under the body instead of just blocking the airflow off because the area is so turbulent. On the sides though it would allow me to keep flow attached after each wheel without ruining ground clearance. Do you think it would help to place them after the back wheels? I think I could design some sort of boat tail after the wheels out of lawn edging so that if it hit anything it would just deform and then go back into shape. Should I do this on the sides also? Like making a square pipe of lawn edging to go between the wheels(with the ends capped off) so that flow on the outside but also the inside by the diffuser is streamlined, but if it hits anything the square cross section would just deform to a rectangle with bulgy sides.



Here is a quick model of my interpretation of what you're saying being made as modifications to the design just before. It now has the wheel covers which I'd neglected to add, as well as the lawn edging in the shape I described. This is with 3inches of ground clearance btw(that thing at the bottom is supposed to be ground). I'll have more pictures with a better model shortly.

[yugomodder]

Here are several different angles. Haven't added wheel covers on the other side yet. I'll get those on.









I've got to say I'm actually starting to like how this looks. It's certainly a lot better than a stock Yugo.

[aerohead]

Originally Posted by yugomodder

Thanks for the input Aerohead!
I went ahead and modeled what I think you are describing as far as a nose extension.

Here is at 16 degrees from the ground.


Here is shortened up a bit


The 16 degrees looks a bit long, but it shouldn't really give any problems. It looks to me like I could lower the whole thing a bit and get rid of some frontal area where the tires are, but still build a good nose extension.

This last picture is of another design I was playing with before.

I'm not sure exactly how much aerodynamic benefit this design would have, but it seemed to give more room for batteries. Obviously building a nose extension is going to provide far more room though.

As far as wheel skirts, yeah I'm planning on outfitting it with wheel covers and rear wheel skirts. I don't think it'd be worth it to put front wheel skirts on it before it's more streamlined. Also yes all of these sharp edges would be rounded off significantly, it's just difficult to model that in google sketchup and still be able to change around the nose design.


Next thing would be to lengthen the boattail if I'm lengthening the front end.

The blunt nose is plenty good.If you have softened leading edges with a radius of around 80mm you should be okay separation wise.Laying
'back' the grille will direct air over the hood.The soft edges on the sides will let air bleed around there without separation.
Staying above the 16-degree line protects a wrap-around airdam/chin spoiler.
You can lengthen the boat tail without altering the front at all.You're just mimicing the fusiform design of fast fish,shark,dolphin,falcons,etc.,where the stream is deformed within the 1st 1/3rd of the body,then the last 2/3rds is used to settle it back down.
The further back you go,the closer you get to ideal flow.
Lookin' good!

[Sven7]

That Sketchup model is pretty crude (for instance, it has no tumblehome or radii). If you look at real blueprints of it you'll see that the windshield to roof transition is curved well enough that you don't need that roof modification.



When you get down to the final planning and measuring stages, I would recommend using these accurate drawings to avoid surprises later on.



The-blueprints.com has a high quality vector version as well (under "various cars") but you have to pay a subscription fee to download it. It might be worth it if you're as serious as it appears.

Keep up the good work but don't forget that the car is a lot more complex than that model!

[yugomodder]

Thanks for the input!

Yeah the model is fairly imprecise. The top has a rectangular cross section rather than trapezoidal, the edges aren't curved, there are no mirrors, etc. I was just using the model to help visualize the mods I'm going to make.


Thanks for digging up the blueprints for me. Yeah the roof transition doesn't look too terrible. The idea of the top for me was about transitioning into the boat tail better. The images earlier showing the template lined up with the top vs lined up 2in over the roof were to show the difference in how much each reduces the wake area.



So the roof transition is no Prius, but it's not nearly as bad as in the model. I figured that smoothing out that transition would just be more of a fringe benefit of an aerodynamic top, whereas the transition into the boat tail would be the main benefit. If I weren't going to put a boat tail on, I would definitely not put a top on it.

Those blueprints really show how so many under-body parts stick out into airflow and can cause turbulence, as well as how the nose directs airflow underneath the car/at the ground. The first aeromods I'd make would definitely be a nose extension, full bellypan, and diffuser. A boat tail and aerodynamic top would come later on. I'm pretty sure I want to do the boat tail, as I would probably see the greatest benefit from it, and I'm fairly certain that an aerodynamic top would help the boat tail work better, but if this isn't the case then I'll just stick with a normal boat tail.

What are your thoughts on this?

[aerohead]

Originally Posted by yugomodder

Thanks for the input!

Yeah the model is fairly imprecise. The top has a rectangular cross section rather than trapezoidal, the edges aren't curved, there are no mirrors, etc. I was just using the model to help visualize the mods I'm going to make.


Thanks for digging up the blueprints for me. Yeah the roof transition doesn't look too terrible. The idea of the top for me was about transitioning into the boat tail better. The images earlier showing the template lined up with the top vs lined up 2in over the roof were to show the difference in how much each reduces the wake area.



So the roof transition is no Prius, but it's not nearly as bad as in the model. I figured that smoothing out that transition would just be more of a fringe benefit of an aerodynamic top, whereas the transition into the boat tail would be the main benefit. If I weren't going to put a boat tail on, I would definitely not put a top on it.

Those blueprints really show how so many under-body parts stick out into airflow and can cause turbulence, as well as how the nose directs airflow underneath the car/at the ground. The first aeromods I'd make would definitely be a nose extension, full bellypan, and diffuser. A boat tail and aerodynamic top would come later on. I'm pretty sure I want to do the boat tail, as I would probably see the greatest benefit from it, and I'm fairly certain that an aerodynamic top would help the boat tail work better, but if this isn't the case then I'll just stick with a normal boat tail.

What are your thoughts on this?

After looking at the blueprints Sven7 posted,I agree that the roof is okay as is.There's ample radius and some camber up to the max camber point.And there is the mandatory,almost imperceptible beginning downward curvature.
If you haven't seen the Crisis Fighter Pinto,you could borrow some ideas from it.
A short nose extension with integral grille block,covered headlights/indicator lights, and wrap-around airdam would buy you some insurance at the front.I would wrap the airdam all the way around to fair in ahead of the front wheels.
The black portion of the rocker panels could be extended straight down even with the future belly pan at the bottom.The sides would help keep the flow parallel to the plane of the outer tire faces.
Rocker panel extensions behind the rear wheels would help cleanup the flow onto the sides of the future tail.
Full-coverage wheel covers will help smooth flow in those areas.
Rear wheel skirts will help ensure quality onset flow to the tail.
You will see the most benefit from the tail.All the initial mods will be an insurance policy to guarantee the performance of the tail.
Can you tell us anything about the Yugos cooling system fan? I've never seen under the hood of one.