Monash wing data? or anyones for that matter

[Rob Davies]

OK you may not want to tell me to keep your secrets etc... but its worth a try

im doing a project on wings and ive done some simulation with an NACA airfoil (single element) front cl=2.2 , cd = 0.4area =0.3m2, cd=0.4, rear cl=1.6 cd=0.4 area=0.5m2, i pretty much made all that up from some naca data then played about for ground effect of front wing and increased drag of endplates (pure guessing)

i want to try some multi-element stuff to put in my simulation and i really like your stuff

ive heard you car has 50kg downforce at 50kph so i can work back to get a total cl.a of the whole car and assume its aerodynamically balanced. but my question is what is your cd.a ? im gonna assume its a third of cl.a unless youd like to tell me otherwise.

thanks, rob

im not even working on the car just doing a third year project which im gonna conclude get our car finishing the endurance before we attempt wings so no worries of us being another winged competitor

[Jarrod]

we have released a bit of info in the past, but aren't too keen on just releasing a lot of detailed stuff, but may be persuaded to trade data.
If you try a program called javafoil, it can simulate multi element wings, ground effect, boundary layers, all in 2d, its free on the web. should give you more than enough. None of our data includes good ground effect for the front wing, so we are still guessing a bit anyway. I'd personally love to see more wing cars out there.

Jarrod Hammond
www-personal.monash.edu.au/~fsae

[Rob Davies]

making wings is a little beyond us at the moment. we had people testing caron fibre this year and they found it hard to make simple flat pieces to test let alone a comlex wing shape.
ive put in my report that monash are gonna win formula student and prove wings work so you better do me proud.
i would like us to work on a shaped undertray tho - easier and more effective than wings i think

[Jarrod]

To get full effect out of an undertray, it has to be floating like UTA's or else you need to run very stiff, to maintain ride height and pitch attitude. Floating floors are real tricky. Worth it if you get it right without too many other compromises. We are certainly hoping to prove our car in the UK, we'll see how it pans out. Which school are you from?

Jarrod

[Rob Davies]

Im from Lancaster University

[ozzy]

why was it so hard to make flat sheets? i have never tried to make a flat sheet, but i would just lay a sheet of mdf or something down flat, put a layer of plastic on top of it, perform the layup and vacuum bag the layup and mdf to ensure that it is perfect

[DOHCside]

Ozzy and Rob, (and anyone else that is interested):

The MDF and bag trick is an OK way to get the flat sheets of CF, but there was a techniques we used that worked pretty well (maybe we were just lucky???). We went to the local Home Depot, and picked up a 4'x8' sheet of some white siding material (looks suspiciously like a dry erase board), waxed the hell out of it, spread some epoxy, lay down a ply of CF, pour some more epoxy on top, lay a plastic liner on top and squeegee to a uniform thickness. The dry erase boards leaves an excellent finish on one side and the liner/bag leaves a reasonable finish (definatley good enough to be seen from inside the car. Variations on that theme: use low-temp cure, pre-preg material to assure that you get a "perfect"� ratio of epoxy & CF, and coat only the visual side with some epoxy to get a "gel-coat"�. Or instead of squeegeeing the sheet by hand (lot of work) we had some luck using a huge metal roller used the roll radii in metal sheet, tubes, plate, you name it...(metal fab shop next door (Metalmorphosis, thanks guys)). We set the clearance to what we needed, rolled a sheet of CF in between 2 sheets of dry erase boards, and let cure. Bingo.

[Kirk Feldkamp]

Try a sheet of glass next time. It gives you a flat and super shiny surface. Plus it sounds like it'd be a tad cheaper than a big-ass whiteboard.

-Kirk

[DOHCside]

I agree the glass is "the" way to go for the perfect finish, and you can clean any excess epoxy/resin with a razor, however, the price of the 4x8 sheet white boards was only like $8.50 per 4x8 sheet. The were so cheap we bought a bunch, some were used for the carbon panels, and a couple made it to the walls of our design room for use as dry erase boards. Worked like a champ for sketching stuff and leaving messages, and for <$10, you can't beat it.

I don't think you could get a piece of (gl)ass for that... http://fsae.com/groupee_common/emoticons/icon_wink.gif

[NJM.]

Rob,

I wrote a paper on formula cars and wings. I wrote a very basic lap simulation to determine optimal downforce vs. drag for a fsae car and to use on other types racing cars. It may help you with your project. The paper is "The Effects of Wing Aerodynamics on Race Vehicle Performance" and is available at sae.org. Send me your email and I may be able to get you a copy. I'm always up for talking big wings.

I use Xfoil for single element airfoils and I use Mfoil for multielement and ground effect. They were written by Mark Drella of MIT and are good programs available on the internet.

If you are looking for drag numbers, look at induced drag (ie the drag induced by the creation of lift), profile drag is negligible. By the way, for an fsae course you can probably neglect drag altogether as a consideration. Low speed downforce is everything, as aerodynamics are conscerned.

Hope this helps.

Noah
nmckay@rcrracing.com

[Rob Davies]

Thanks NJM I sent you an email

I wish Id have spoke to you guys earlier. I bought a piece of software called DesignFOIL for like 50 bucks, and then I hear about all this better software out there like JavaFoil for one and now MFoil. Not sure if MFoil is free yet but even if I have to pay for it the ability to work on multi-element wings is better than designfoil i have

Cheers guys, Rob

[Rob Davies]

oh regarding the flat sheets of carbon - I wasnt refering to the flatness of it - lol - they put it on glass as you recommend! they just cant make carbon fibre period to any degree of quality and when theyve used a simple mould it turns out pretty bad.
Its my mate thats working on it and hes blaming lack of equipment so I hope he gets it sorted when he buys some stuff to vac bag etc..
He's gonna get a tour of a company called aerovac who make carbon fibre so Im sure the learning curve will be steep.

Cheers for the replies,

Rob

[wingman]

Hey Rob,

Do a search for wings, there were two threads in particular that had a lot of good info.

By the way, has anyone besides Cal Poly Pomona got a 1st place under their belts with a winged car??