260DET Posted February 21, 2014 Share Posted February 21, 2014 Where to start, OK, APR Performance for one do a carbon fibre job but $$$$$$ for us amateurs. Plus shipping So what I'm thinking, using Simon McBeath's Competition Car Aerodynamics, is to make one up using a pair of elements/blades from a cheap Ebay job but set up properly in relation to each other and to ground level. McBeath is pretty good on this particular aspect of wing design so with suitable elements I'm thinking, yes, this should work. So, anyone played around with this sort of thing? Because, a serious 'off the shelf' rear wing for the Z is not something very common. Or available at all. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 21, 2014 Share Posted February 21, 2014 (edited) I've looked at it and considered various options. The Ciro Design wing is popular here for autoxing and it uses two of the old APR aluminum extrusion elements. The second flap is the same size as the wing, which is not what McBeath recommends at all, yet it is pretty popular and obviously it does work. I've seen one of these on an Evo where the AL wing had cracked around the mount after a few years use, just a warning. You don't want your wing to exit without warning. The problem is that it is hard to find a chord deep enough for use with a second flap. Most of them are 10" and McBeath suggest that the flap should be 30% of the overall chord length (wing + flap), so that would be about a 4" chord on the flap. It's hard to find a good wing that small. APR did have an aluminum two element with a 7.5 inch main and I think it was a 3.5" flap (I think this is the one used in the wind tunnel testing), so that flap would be close to the right size flap for a 10" wing, but as I recall it only came in one relatively narrow width. The other problem in my particular case is that I can have 8 square feet of wing, so optimized I think I had it figured with a 14" chord on the main, and it's hard to find wings that big. FWIW, I don't believe APR makes that AL dual element wing anymore. One option is to make your own aluminum wing. There was a guy on the pegasus porsche site who built his own AL wing. There is another thread on that forum where he made another, bigger wing too: http://forums.pelicanparts.com/porsche-911-technical-forum/294153-poor-mans-aero-wingin.html I was thinking that I would buy a standard wing from Kognition or G-Stream or one of the other quality budget makers, and then make my own flap. Already have all the aluminum to do the flap, in fact. The idea would be to put the flap on for autox, and then take it off for track days, just by changing the end plates. I have a bit of hesitation with the idea of running a HUGE dual element at track speeds because I don't think I'll have the front downforce to match. In autoxing, the forces are low enough that you can't really get too much from any one area. There are quite a few sites out there that talk about making your own CF or FG wing too, with vacuum bagging and the whole deal. Usually involves a hot knife and foam core. Look around and you'll find some. I'm still apprehensive about composites so I didn't look into this that deeply. McBeath wrote a book on composites, FYI. If you use an off the shelf main plane and then make a flap, the main wing isn't going to be optimized for the flap, but I don't think that makes it a losing proposition, at least it's not in the case of the Ciro wing, which is far from optimized and still works. The nice thing about rear wings is that you can always go bigger. I wonder if it wouldn't be easier to just get a larger single element wing than to go through the hassle of the dual in your case. Are you exceeding the capability of your existing wing and can't find a larger single to replace it with? Edited February 21, 2014 by JMortensen Quote Link to comment Share on other sites More sharing options...
260DET Posted February 22, 2014 Author Share Posted February 22, 2014 Good points and ideas Jon, as usual, thanks. My motivation is a personal dislike of really wide single element wings on a Z, and, to get to a situation where by adjustment the rear wing can be tuned to balance front end grip. Which is not the situation now. Going by McBeath a dual element has a wider range of adjustment and of course for the same downforce won't be as wide as a single. Quote Link to comment Share on other sites More sharing options...
mmendes Posted February 22, 2014 Share Posted February 22, 2014 I also want to run a dual element wing for that exact reason. Flap on for AutoX off for the track. I wouldnt be too scared of making an element yourself. These is a huge database of profiles online. You are shooting in the dark though. On my fsae team we would usually start with a high lift airfoil and then modify its shape in 2D CFD until we got an airfoil with good flow attachment. Theres a company that can make the make the profiles out of foam with a CNC hotwire. Lay CF or fiberglass around the foam core place it back in the block it was cut out of, vacuum bag the whole thing and voila. They re relatively cheap so you could experiment with a few different designs. https://www.flyingfoam.com/ Theres also an APR option that you KNOW will work. The only thing you would have to optimize its the overall height. This was designed for a time attack mitsubushi eclipse. This is the whole write up and has other good info in it. http://www.amb-aero.com/files/APR004_public.pdf Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 23, 2014 Share Posted February 23, 2014 This would be a good start, http://nissanroadracing.com/showthread.php?p=65055&highlight=eppler+wing#post65055 Also take a look at the Selig 1223, it seems a number of people use that too. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 23, 2014 Share Posted February 23, 2014 I have a side view of the profiles for some wings McBeath designed for someone else too... Quote Link to comment Share on other sites More sharing options...
260DET Posted February 28, 2014 Author Share Posted February 28, 2014 Making progress, keeping in mind the DIY aspect of this thread. Which is motivated by the observation that any wing profile will work so for an amateur there is no point in chasing what we may think of as 'perfection'. Mainly because once a wing is mounted behind a car other influences apply so ultimate efficiency, for an amateur, is discernible only by trial and error. S-1223 profile below but my thoughts for a twin element are that the main should be be less aggressive than the 1223. Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted February 28, 2014 Share Posted February 28, 2014 I read one I think on pelican and there is another on a bimmer forum, one was cf and the other was aluminum wrap. the aluminum one the guy shows how he made the spars in the wing. both really cool diy jobs. I am looking into this as I think I can get more out of one of those than I can out of my old apr dual element wings. plus those on kognition and g stream were over 1k in $. yikes, I can make several for that price. may not look as pretty. jimbo 1 Quote Link to comment Share on other sites More sharing options...
duragg Posted February 28, 2014 Share Posted February 28, 2014 Several... Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 28, 2014 Share Posted February 28, 2014 Making progress, keeping in mind the DIY aspect of this thread. Which is motivated by the observation that any wing profile will work so for an amateur there is no point in chasing what we may think of as 'perfection'. Mainly because once a wing is mounted behind a car other influences apply so ultimate efficiency, for an amateur, is discernible only by trial and error. S-1223 profile below but my thoughts for a twin element are that the main should be be less aggressive than the 1223. RIchard, From my research the selig is a good single profile wing but isn't very good when you add another element. I think you'd be better off look at the Eppler 423 with a NACA 4412 element. This was close to the profile Jon showed me on Mcbeath's wing as I remember. The other option is to take a look at a program called Xfoil. In this you can pressure plot the element and see what it looks like. A good main element will have a pressure plot that drops towards the back of the wing and the second element is used to recover this pressure. On the Selig it still has a lot of pressure at the rear. Cary Quote Link to comment Share on other sites More sharing options...
260DET Posted February 28, 2014 Author Share Posted February 28, 2014 Yes, I'm familiar with the twin setup in McBeath's book and am presently chasing similar off the shelf elements. Will look at those profiles thanks Cary. There is a profile available which the maker says is off a Porsche GT3 which means nothing to me, anyone have any ideas about it? If there was time available then I'd get foam elements of my choice cut and go from there, fiberglass or CF wrapped. Quote Link to comment Share on other sites More sharing options...
260DET Posted February 28, 2014 Author Share Posted February 28, 2014 Moving right along, pic below of the two second elements that I have, which one would be best? Had a look at the Eppler 423 Cary, yes. Quote Link to comment Share on other sites More sharing options...
260DET Posted March 4, 2014 Author Share Posted March 4, 2014 To keep this DIY I'm pretty limited as to what main profiles are available. The profile below is different to the one in McBeath's book and to the Eppler 423 but I'm thinking it may work well with the second elements that are available to me. Without the Gurney of course. Quote Link to comment Share on other sites More sharing options...
260DET Posted March 4, 2014 Author Share Posted March 4, 2014 To keep this DIY I'm pretty limited as to what main profiles are available. The profile below is different to the one in McBeath's book and to the Eppler 423 but I'm thinking it may work well with the second elements that are available to me. Without the Gurney of course. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 4, 2014 Share Posted March 4, 2014 (edited) Images not working. EDIT--yes they are, it's just so faint I didn't see it. Clicked around and hit them though. Edited March 4, 2014 by JMortensen Quote Link to comment Share on other sites More sharing options...
260DET Posted March 6, 2014 Author Share Posted March 6, 2014 Decided to go ahead with a main element from the profile above. Cut templates out of cardboard of that element and the two secondaries I have to see how they look together, particularly concerning the gap shape. That and the overall shape of two profiles together to get a nice sweeping curve underneath. The secondaries are smaller than the two thirds rule allows but they are what I have and they do combine well. Probably use the fatter of the two secondaries available but that decision can wait until the main element arrives in a few weeks. Like doing this sort of stuff rather than buying off the shelf, when time and talent allows Quote Link to comment Share on other sites More sharing options...
260DET Posted March 14, 2014 Author Share Posted March 14, 2014 Main element has been ordered, should be able to finish it all before the Bathurst/Mount Panorama adventure over Easter. Z should be capable of 250kph or more down Conrod Straight, aero will be tested if the wussy driver does not lift off going through Caltex Chase. It's called backing yourself so they say Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 14, 2014 Share Posted March 14, 2014 How did you order the main element? Are you having it foam cut with the hot wire, or are you having someone build it for you? Quote Link to comment Share on other sites More sharing options...
260DET Posted March 16, 2014 Author Share Posted March 16, 2014 The supplier makes wing elements to order using the various profile moulds he has. The end user makes the mounts and end plates. As my supports will not go on the ends, the element will be drilled and tapped underneath where there is a moulded in aluminium member for that purpose. Will know more when it arrives. Quote Link to comment Share on other sites More sharing options...
260DET Posted April 11, 2014 Author Share Posted April 11, 2014 This is all on the backburner now, bloody engine problems again so the whole lot is coming out and being dumped. LS3 and a TKO600 going in. Plus something else is going to add to the delay, no real problem, just a 'temporary' situation. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.