Perhaps no one else on here is old enough to remember them.
In the UK, maybe mid 70s (?), I think they featured on the back windows of some Ford Capri’s. Couldn’t find any pics to support that, but here’s something similar on, …er…a Camaro.
The idea, AFAICT, is that vision in-line with the louvres is essentially unobstructed, but someone looking downward, and sun and rain ditto, will be blocked.
Seems like it’d be a good thing on a hatchback here. My rear vision isn’t good at night, especially in the rain, and if something like this allowed the removal of the tinted film, it might be better (though of course it still wouldn’t be a Camaro)
[quote=“sulavaca”]That would seem like a very good idea.
The only issues I imagine might exist could be wind resistance, and resilience under the elements.[/quote]
Yeh, I wondered how it would affect the aerodynamics on a modern, slippery car, though that description doesn’t really apply to mine.
The commercial product described on the URL has louvres of anodised alloy, so should stand up to UV ok. Bit pricy for something apparently so knickable, though.
I think the UK ones were plastic/FRP, though I’m not certain.
That link you provided was to a product for a specific vehicle. As yours isn’t that vehicle, you must be then talking about fabricating something I presume.
Now a simple, single sheet flat horizontal plate extending from the roofline which covers the entire rear window would create a vacuum beneath it and thus drag. You would have to create your own multi-louvre rear window cover I imagine.
One method of analyzing your present drag would be to tape short pieces of string to the roof and upper side ‘C’ pillars as well as rear glass. Drive the car at speed and have someone in an adjacent vehicle record your car. The string will lay flat to the body or flap to indicate turbulence or lack of it. This data will help in producing a suitable rear louvre system. You can then record your car after any modification and judge the results against the original data.
Psch, aerodynamics… just go ahead and start making your own! It will be ugly, though.[/quote]
Wot, no Ford Capri’s?
Yeh, I’m not too worried about aerodynamics personally. I don’t drive very fast so it’d have to be very bad to have much impact on fuel consumption. Likewise ugly is what I do.
If you wanted to market such a ting in Taiwan you’d have to consider it seriously, but the merits would be then much less important than the herd perception.
Unless it got to be a ‘fashion’, getting Taiwanese to fit something that isn’t on everyone elses car would be even more difficult than it would be elsewhere.
I wonder (a) if what you save on aircon might compensate for any increase in drag. (b) Whether, with that kind of roofline, a combined spoiler/louvre might be a possibility.
I suppose Priui/Priux/etc (?) aren’t big on downforce requirement, though.
(Unless the owners feel a need to overcompensate, of course. )
My aircon costs me 20% fuel consumption in the height of summer, which makes a big difference on a very frugal car. I get 6.2 litres per 100km in the hottest months in city driving only, using no overhead or high speed roads, compared to around 5.3 litres per 100km at this time. In the winter it will improve slightly further.
On the highway I can achieve a maximum 3.2 litres per 100km stuck at 86kph with the aircon off. It makes only little difference with aircon on at that speed however.
With climate control fitted to the Prius I notice a considerable ramp up in fan speeds and engine starting whenever I enter sunny areas during the hottest months. Sticking to the shade will make a considerable difference. I feel therefore that a louvre system could potentially make quite a difference when under the sun’s direct burn.
[quote=“sulavaca”]My aircon costs me 20% fuel consumption in the height of summer, which makes a big difference on a very frugal car. I get 6.2 litres per 100km in the hottest months in city driving only, using no overhead or high speed roads, compared to around 5.3 litres per 100km at this time. In the winter it will improve slightly further.
On the highway I can achieve a maximum 3.2 litres per 100km stuck at 86kph with the aircon off. It makes only little difference with aircon on at that speed however.[/quote]
Seems quite likely that the saving on aircon would be significant then, especially if one mostly did city driving, which I’d guess is the case with many people.
Fairly major extension of the topic/basic idea, but I wonder if it would be possible to design a relatively aerodynamic version of the “safari” style double roofs, as seen on some Landrovers. Could be bad aerodynamics is inherent to thier function, though.
I’ve heard of people doing that on sailboat decks, the idea being that the black mesh is stretchy enough that you can still walk on the deck, without losing much, if any, grip/non-slip quality. Drag isn’t such an issue on sailboat decks, though I’d guess its still a consideration.
I suppose one would have to consider possible consequences in an accident, especially given that this is likely to be an illegal modification in Taiwan.
I’ve seen scooterists bouncing thier heads of the back of cars a few times here, at least one of those times without the benefit of a helmet.
That might rule out metal versions like the commercial one linked to above.
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