Aero

External options and variations: rear end mods, side vents, doors, cage mods, wings(!), etc.
Poboy
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Re: Aero

Postby Poboy » 18 Feb 2010, 18:42

Midlana1 wrote:The trouble is that the rear wing, in an accident, could partially break free and rotate up and over whatever's between the wing and driver. Also, extending the partition higher will have to be tested out to see its aero effects.

Right. But you've already got your harness bar and the diagonal across the main hoop partially blocking that. If you had sheet metal blocking out more of it, at head height of the driver, then a)the wing would be very unlikely to fit into the smaller opening, and b) pass over the driver's head and not into it.

wrymind
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Re: Aero

Postby wrymind » 21 Feb 2010, 12:30

It occurs to me that a lot of development has already happened on this in the Brit Clubmans cars. The Clubmans Register is a good source for these, that range from Lotus 7's up to mid-engined sports racers, but a lot of usable material somewhere in the middle. These Mallock examples show one of the simpler front-end fixes:
http://www.race-cars.com/carsales/mallo ... 2706wc.jpg, http://www.race-cars.com/carsales/mallo ... 2706wb.jpg
Apparently, extending the front fenders down very low in the front helps as well. As for the back, how 'bout a big, movable wing a la Chaparral - it's not like we have rules against "movable aerodynamic devices" :D

Midlana1
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Re: Aero

Postby Midlana1 » 21 Feb 2010, 17:47

wrymind wrote:... it's not like we have rules against "movable aerodynamic devices" :D

And that, potential builders, means other cars should be very scared when we show up an a trackday event, lol.

Midlana1
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Re: Aero

Postby Midlana1 » 17 Nov 2010, 11:55

On LocostUSA, someone posted this very interesting image of airflow over a typical Locost. Note how the air whips around the ends of the windscreen instead of up and over the top. (Though, whoever generated this must have purposely removed a lot of the airflow lines going up and over the car due to it obstructing the desired view.) Anyway, it very graphically illustrates why Locost drivers get pummelled by airflow. My brother runs into this exact issue, and confirmed that all the air hitting him in the head seemed to be coming around the end of the windscreen instead of over it.

Midlana will have similar issues though it shouldn't be as bad due to a much more angled (leaned back) windscreen. Due to the roll cage acting as the windscreen frame, it would be easy to add triangular corner windows to mitigate the wind. If that's not enough, front-hinged doors/windows would certainly work and seems like the most straightforward fix if things get too windy.

In addition, it looks promising for where radiator air exits the body, down below the headlights and inboard of the front wheels. It also confirms that air does indeed pile up ahead of the rear fenders, making it easier to get it to flow into the engine compartment without large ducts, but we'll see how that turns out in practice
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Jagmandave
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Re: Aero

Postby Jagmandave » 17 Nov 2010, 14:31

Re: wind and buffeting in the cockpit - isn't that what these are for?

Image

Midlana1
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Re: Aero

Postby Midlana1 » 17 Nov 2010, 14:52

Yes, but with Midlana's much more angled windscreen I'm wondering if permanent quarter windows could be added instead of these that have a tacked-on look. Adding the little windows also deals with some concern about the top forward corners of the cage getting crushed down in a roll-over. (Note that, drawing a line from the front chassis to the top of the main hoop shows that while the corner can get compressed downward, it's can only do so about 6".) Adding an additional tube to support it would serve nicely as the back tube to frame triangular windows.

The trick is making them small enough that they don't interfer with occupants' feet when they get in and out.

Marcus
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Re: Aero

Postby Marcus » 17 Jan 2011, 21:55

I haven't seen the latest pictures of Midlana. The higher sides should be a help with the flow into the cockpit. The whole depicted flow in that diagram is below the sides on Midlana. Of course there's plenty more where that came from. The folks in that thread on Locostusa reported that those little flexible side panels people attach for sevens made a huge difference.

Getting air from in front of those rear fenders into the engine compartment should work well. I have thoughts of putting the car's radiator against the back of the rear of the car and trying to get the air from in front of the fenders thru there. Sort of thinking there may be less drag if you can supply air to the rear, probably not so simple an issue though...

Midlana1
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Re: Aero

Postby Midlana1 » 18 Jan 2011, 06:32

True, and having it there might work just fine - I just can't guarantee it. Since all sorts of engines might be used (with a wide range of heat output), putting it up front is the only way to be sure to keep it cool. If someone wants to give it a try, I look forward to the answer!

7ishNZ
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Re: Aero

Postby 7ishNZ » 18 Jan 2011, 11:16

Surely having the radiator at the front will help with the f/r weight distribution....
7ish

Midlana1
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Re: Aero

Postby Midlana1 » 18 Jan 2011, 11:50

That too! :)


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