Vritual gurney flap

[manchild]

Q: Now you’ve been quoted as saying you’re still not happy with the Ferrari wings. Can you just clarify the situation?

Geoff Willis:... We’ve seen wings that bend in one way, flaps that bend in another way, wings that aren’t bonded together. I think we’ve even seen an inflatable wing, which I must say I was very impressed with...

[Ciro Pabón]

Well, what a sinchronicity. I can imagine new excuses: "we suffered a puncture of the rear wing and we lost pole position"...

Seriously, you could also "modulate" this kind of wing by changing pressure. FIA would have a hard time classifying it under "movable wings"...

[flynfrog]

well as i said ealier one layer of carbon or fiberglass doesnt have enough stiffness for our needs once you start to add mutiple layers, everything starts to get heavy. as it is now, a layer of carbon is about equal to weight of the foam. And we also have a carbon tube spar running down in the foam that also adds a lot to our strenght which is being redesigned over the summer. Our wing has to be able to support almost 40 pounds at the moment. we do currently use a molding process for the fuse. its essentially made in two halves which are joined later as you said. the materail uses is honeycomb nomex sandwhich between two layers of fiber glass. its about 6 feet long and only weighs a pounds. its pretty incredible. we would use the nomex in our wings but the complex shape prohibts us from doing so. o yea, all the composite work do is cured under vaccum and in an oven.

you could do a two piece mold then pull vacum from the inside (bag whre you have foam now and pull to the negivte mold you could then add honey come but id guess that the shap would be pretty strong once its bonded to end plates but what a layup nightmare you could also dislove the foam out of there if you get the right kind

[R1ceboy32]

well the honeycomb/mold idea doesnt work since there is no way the honeycomb will conform the the curves of the leading edge. the foam isnt there for the shape, its acutally a strucually member so without it our wing has almost no stiffness since we only have 1 layer of composites on it. hollow wings have been tried but we still havent found a way to make it light enough (sub 2 pounds) while still having enough strenght to carry 35+ pounds.

[flynfrog]

well the honeycomb/mold idea doesnt work since there is no way the honeycomb will conform the the curves of the leading edge. the foam isnt there for the shape, its acutally a strucually member so without it our wing has almost no stiffness since we only have 1 layer of composites on it. hollow wings have been tried but we still havent found a way to make it light enough (sub 2 pounds) while still having enough strenght to carry 35+ pounds.

you can get honey comb to fit the leading edge you might have to use flexi core but tis easily done and you realy dont need to fill the whole wing with it you could do some strips in the flat sections

when resin system are you using if you have a good prepreg you could make that thing weigh ounces

the body i made for the 05 car weight less than 4 pounds total before paint

[zac510]

Maybe ciro or kilcoo would like to comment, but I believe that would be going against the lateral flow of air across the wing, and thus may be counterproductive.

[R1ceboy32]

we are current using the marine grade tap plastic resin system but probaly will change to west systems and we cant afford prepreg. the problem with our leading edge is that its about an 1/8th of and inch thick which is about the thick as the honeycomb. the whole aerofoil itself is only about half an inch thick at it's thickest point. we also dont have the budget to really exerpiment with the honeycomb and different types. we are currently living off a supply of honeycomb that was donated and only have a budget of about 2k from the school. thanks for the ideas dough. our current idea to ligthen the wing as of right now is to create a rotocell-carbon spar which should be lighter and much stronger than the carbon tube we have it in now. with a stronger spar we might be able to get away with using 2 mabye 1oz glass as oppsed to the 3 oz glass we are using now. (total wing weight now is about a pound and could stand at least 60lbft moment)
(sorry for hijacking the thread haha) but about the virtual gurney, wouldnt the "gurney height" become depenednt on speed. Therefore at higher speeds you have have a taller gurney and therefore more drag associated with it. Something you dont want on the straights?

[Crabbia]

i think something like this is not so far of from being introduced into f1, i mean if u look at the way the designers are starting to use warm air (from chimneys and flip up exhausts) to decrease the pressure over the wings.

about the carbon suspension strusts being possible and hollow wings not i think it has a lot to do with the shape, kinda like a straw being stiff if u try to bend it but if u flatten it it's into a thin profile it'll bend pretty easy.

also another thing (sorry it's my first post and i'm trying to catch up on years of non-postage) is that i think if u where to duct the air from the endplates say, i think u'd have to be rather careful cause generally holes in body work give up around twice the drag that solid surfaces do. and i'm not sure if u'd get the pressure differential needed.

i think its definately workable but u'd need something that could create and sustain pressure independent of the engine revs. maybe a blower feeding air through a non return valve. if your gaps in the virtual gurney flap are small enough and the wing can sustain a hefty pressure maybe it could release the flow needed in a more predictable fashion giving u a couple more seconds of downforce in the braking zones. (upshifts, as far as f1 goes, shouldn't be a problem)

but maybe i'm just talking out of my big brown one. actually i am. but balls, maybe it was of some use

[Crabbia]

Maybe ciro or kilcoo would like to comment, but I believe that would be going against the lateral flow of air across the wing, and thus may be counterproductive.

Zac the flow drawn laterally to the wing is inside the wing so it doesn't affect the air going over the wing. If i'm picking up what manchild's putting down.

[Ciro Pabón]

Hi, I'm back from a meeting. Zac, I think Crabbia is right. Actually, MC idea is to use the fact that the lateral flow would put more pressure on the intake opposed to the turn (if you turn left, for example, the right side intake would have more pressure), so you would increase the downforce on the right side of the wing, helping the more loaded wheels. If you use the exhaust as a source of compressed air, you could do this using a simple valve system.

As I said before: once you think that you can get downforce, not by altering the shape of the wing, but altering the flow over the wing, you enter (I think) a new territory. This is what I think is really interesting of MC idea. And the inflatable beam suggestion is cool too...

Of course, one thing is having an idea (physics) and a very different one is to make it work within a budget and a time limit, with the current construction methods and materials, and somehow, thinking on the deleterious side effects on other parts of the mechanism (what I call engineering), as the wonderful posts from R1ceBoy32 show.

[zac510]

Sneaky bugger - Ferrari should hire him!

I totally misunderstood the whole concept.

[manchild]

Yep, I guess zac misunderstood my sketches. Air that is picked by duct is not directed on top of the wing but inside of it to exit trough slot on top of the wing.

[kilcoo316]

I should have said this yesterday, but all fluid Thrust Vector Control designs (which is effectively what this is) that I know of are about 5% less efficient than mechanical means at their (fluidic) optimum, this would rise at off-design point conditions.

While my knowledge is mainly from nozzles, the basic fluids problems should carry over.

The other problems are of course:

- pressurising the air
- ensuring even/optimal distribution across the wing span
- making ejection rate larger at lower speeds and reducing at higher speeds
- keeping the air cool
- keeping the weight down



I doubt its achieveable (to the point where it is advantageous over conventional gurney flaps) to be honest.

[Mikey_s]

I like the innovative thinking. I can see a few issues arising though, and I'm typing as I think, so forgive me if I ramble a bit;

1. Should the inlet venturi not be reversed? That way air would be compressed and speeded up, rather than slowed down prior to entering the wing internal.
2. In order for the venturi to collect air the Rear wing endplate would have to be thicker than it normally is, adding frontal area and increasing drag... but some sort of scoop, like a brake duct ought to work well
3. The device would clearly work better at higher air speeds, which is not really where you need the d/f - but it might also help to deflect the training edge down and reduce drag... not a bad idea now I think about it (flexy wing anyone??)
4. I wonder whether one could consider taking air from somewhere else in the vehicle (e.g. radiator exits??) and playing with different temperature/density air on one, or other side of the wings... in order to increase the actual, or relative mass flow over the different surfaces....

hmmm, must think about this (but must also do some work....)

[manchild]

I like the innovative thinking. I can see a few issues arising though, and I'm typing as I think, so forgive me if I ramble a bit;
1. Should the inlet venturi not be reversed? That way air would be compressed and speeded up, rather than slowed down prior to entering the wing internal.

Thanks M. If you're talking about shape of duct that is out of the question because that is NACA duct used for over 40 years I think, from fighter planes to F1 cars. Its design is optimized to enable intake of air with minimal drag and turbulence.

2. In order for the venturi to collect air the Rear wing endplate would have to be thicker than it normally is, adding frontal area and increasing drag... but some sort of scoop, like a brake duct ought to work well.

I don’t think that endplate should be thicker since NACA duct could be applied even on several millimeters thick plate. Also, use of brake-like duct would mean reduction of wing span since duct would extend overall width of rear wing assembly. To make it function well, duct should have to be able to feed wing with more air than what slot would let out. For that reason wing could be divided transversally in two sections but when I've put it originally that whole wing should be fed with air I had in mind positive ram-air effect (air reserve - more air in wing than what slot can consume so shortage never occurs).