x838nwy

^The double-deck wing on this example I'd guess is somewhat ineffective due to its proximity to the rear windscreen.

Is this assumption correct? Can any of you aero guys enlighten me on this?

trinydex

iTrader: (12)

well there is the normal force of the air commoing down and hitting that spoiler, i don't think that part is primarily a wing but primarily a spoiler and secondarily a wing.

do you know what i mean? like they made it to get hit by air and made a wing shaped to get some of the wing characteristics in case.

x838nwy

I think I do, kindda. So it's not really a double-deck wing as such. Not a proper one anyway.

BTW:

Just to fill in those who don't follow F1, basically some teams have been accused of having their wings designed so that at high speeds, the gap between the top and bottom element close up. Now I'm no expert but I suspect that theis system is more easier implemented on cars with a centre column support on the rear wing (where they can just get the top element to deflect down towards to bottome element).

There's even talk that some teams are even getting their package to stall at high speeds.

I'm pretty sure other people can explain the physics of these thing better than I can - just thought this news is pretty interesting to this thread.

trinydex

iTrader: (12)

any link to this talk? i'm not quite following.

x838nwy

I subscribe to Autosport.com (and the magazine). There are rumours going around the F1 press that some teams - I don't know who - are deliberately stalling their wings at high speed. Apparently this vastly reduces drag.

Finally!! found it!!! http://www.gp2006.com/news/controlle...&news_id=19235

It's not actually on autosport, but was a link from one of the threads!!

I don't know how it works and was hoping someone could explain!!

p.s. the gap thing I can just about understand, the stalling of the wing is a little beyond me. I thought you stall if you go too slowly?

trinydex

iTrader: (12)

this is interesting to hear.

wing stall happens can happen in many ways, it's simply a situation where the flow across the top and bottom of the wing is seperated and or not longer creating/maintaining a pressure differential and hence stability in aero flow.

it can happen when you're going too slow, you're right. this is when you're not "powering" the wing with enough air flow and the air is not making it to the rear of the wing but is accelerated and then "flitters" off.

it also happens when the angle of attack is too great, the under flow is usually not able to rejoin with the upper flow and you just get a mess of drag and no pressure differential with only the benefit of SOME normal force downforce. basically turns your wing into a spoiler.

angle of attack is what you usually see in air planes, when they stall, it's cuz they started moving in a direction or contorted in a way where the wings aren't seeing air flow anymore.

how would a stalling wing reduce drag??? i'm not sure.

a wing can also stall if you're going too fast. the underflow is now over accelerated and you get break off flittering flow which increases drag but whill maintains some pressure differential.

x838nwy

Thanks for the info, Mr.trinydex.

Yeah, how stalling reduces drag I don't really know. At least it is possible to stall when you're going too fast which is what they said they're try to do. I could well be that it's just a journalist getting a little confused but I've seen it mentioned in more than one place. Unfortunately, neither of these locations mention it in any detail.

I'm chatting to a prof. on aero eng. this evening and will prolly ask him about it. Wouldn't guarantee he'd know but I guess that's why Adrian Newey and co. gets paid 3million pounds a year for doing what they do...

trinydex

iTrader: (12)

see... there could be a caveat here... setting their wings "flat" with little angle of attack will definitely lower their drag and will definitely cause wing stall at higher speeds... but this reduction in drag due to lack of angle of attack may be greater than the drag induced by high speed flow seperation.

JasonS

iTrader: (1)

now, regarding the effectiveness of a rear diffuser for the Evo...
The Evo 9 has pretty much just a cosmetic rear diffuser, but what do you think about this voltex piece?



I've been thinking about it for awhile to help with keeping the rear planted at higher speeds without going to a John Force type rear wing.
I've currently vented the rear bumper to help with the so-called parachute effect, although it may be mostly cosmetic as well..

trinydex

iTrader: (12)

venting the rear bumper is a great idea, however your setup right now while cosmetically appealing is only partially complete. to really vent the rear you need to have ventilation everywhere. of course some is better than none. thumbs up.

the rear diffusers are useful but only as an antiparachute if you're (still) so far off the ground. what you can see of the voltex piece is promising, it seals off the sides as many other pieces don't. however what's really important is not shown. the under part of the "diffuser" must be seen in order to reveal how much antiparachuting it does.

otherwise... any finning they have inside is mostly useless but will give minor drag benefits.

JasonS

iTrader: (1)

ok, here's the underside......


what do you think?

trinydex

iTrader: (12)

looks like a great antiparachute piece. it doesn't do too much for the turbulence but doesn't matter, you're minimizing losses, not optomising anything.

it's well thought out. it even curls up where it can to help the bird tail flow.

nvr2fast

iTrader: (1)

Who sells this piece?

trinydex

iTrader: (12)

do you not see the big bulletproof automotive watermark?

wrcwannabe

iTrader: (1)

I occasionally crew on Marc Walker's Sportsracer2000 2005 SCCA national champ. I can tell you that all the top racers use seam tape on the body work, even on fasteners at the back of the body around wings etc. According to the McLaren folks it works "rather well" to reduce drag.

Milburn