Fascinating stuff. You may end up with a wing design to patent. 
Ya, und zee von Karmann vortex ve'll getchoo und de end!
Sorry, I just couldn't help being a smart a$$. Sometimes you've just gotta go with your strengths!
Very nice work Jack. But you always do nice stuff in that garage. One of these days I need to stop by and get an idiot's guide lesson from you on your lighting and motion activator wiring. I've gone back and read it & read it and I'm a hardhead I guess.
Jack,
Not all of these sensors will work for CFLs, Dan. Some of the older ones are SCR-based (Silicon-Controlled Rectifier) and only work with incandescent lights. The SCR converts the signal to DC (direct current) and CFLs and regular fluorescent lights will burn out their ballasts when given DC. Some of the newer controllers, however, are Triac-based. Triacs can be used for fluorescent bulbs as the signal is kept as AC (alternating current). When buying such a controller, dimmer, or switch, make sure it says that it's ok to use for fluorescent bulbs. If so, you're good to to.
That's how mine works. It knocks down a step at a time.
No need to apologize. The wings are called all sorts of different things. A picture is usually the only way to sort it out.
The ducktail is probably working in my favor. I say that not with a whole lot of knowledge to back it up, but because it's the way the factory is doing it on the current 911 race models.
And I apologize for the off-the-garage-topic stuff eating up space, but I love this stuff, and there actually are some ways to test what the wing is doing -- even when wind tunnel rental time is not in the budget. I use wool tufts to track where the air is moving -
- but the more-useful tool is a pair of 1995 Lincoln Continental ride-height sensors, scored for $5 each on Ebay and attached to my front and rear suspension components. They let me track differences in the ride height of the car with the little computer in my car's data logger.
Here's a graph from the data logger. This was when I found a very remote stretch of empty highway where I could bring the car up to a set speed (100 mph) for a few seconds -- then exit at the next exit and do the same thing in the other direction. So the graph shows two 100-mph pieces (the top section is car speed, the lower two sections are front and rear ride height), and also some not-useful data in between where I'm speeding up, slowing down, or turning around at the exit. But I repeated this with the wing set at different angles, so I could see if the wing was changing the car's ride height with the different wing angles at the 100-mph test speed.
Here's a detail segment where I've labeled the different wing angles.
Once I get the support structure issues worked out again for these new uprights, I want to go out and do the same type of testing with this newer wing and the four different angles it can run at.
But back to the new uprights.
I think it might make sense to add some cables, so that the allthread will really only be asked to work in tension (not compression), and a horizontal cable will also eliminate any squat-and-spread between the rear 'legs' of the uprights when the wing is pushing down the most.
Any stuff I can put right behind the ducktail would (I assume) come with less of a drag penalty. So one idea is to try and keep the new diagonal on the lower part of the upright, like this:
Option A
But that might mean too much of a compromise in terms of strength. So another way to go would be to take the drag hit and run it in the strongest position.
Option B
But then, that gets me thinking that maybe I eliminate the allthread and its weight, and just go with two cables, each providing strength in tension -- and crossed over each other so that compression is less of an issue.
I like the idea of using a tape wrap to create something like an aerodynamic shape for the cable, but in thinking about it I also imagine it could flap like crazy in the wind and actually produce more drag. But then, I don't actually know very much of this stuff. Maybe the drag from a 1/8" (or thinner) wire rope would simply not be worth worrying about.
Opinions?
Hey Jack - What's the sum of the aero profile of all the cross braces, vs the aero profile of thicker uprights? I'm wondering if there's a break-even point at which you'd be better off with thicker uprights.
Better yet, stamping a subtle ridge into the upright would give it some strength in the third dimension without adding weight, though it would add slightly to the aero profile.
My gut tells me (without anything to back it up) that the aero impact of those cross braces is going to create a bit of turbulence behind you. But then, this is a subject where laypeople such as myself generally know much less than they think they do.
It's held up great so far. That Scotch-Weld stuff is pretty amazing. The aluminum wing I made about seven years ago didn't have any fasteners in it. Just $50 worth of aluminum and about $100 worth of that adhesive -- and it held up to six years of hard use with no issues.
I agree. I'm always amazed (and a little humbled) by the generosity and knowledge that shows up in these forums (and sometimes in my email in-box).The amount of knowledge and skill floating around this board is truly amazing. I can only imagine what world problems could be solved should they be stated in a thread on the GJ
The across braces are needed because of the way I attach the uprights to my car, not because of the strength of the uprights themselves. I have to bolt the things to the underside of my deckled, which just rules out any good way to provide lateral reinforcement -- without damaging the paint on the visible part of the car. I kept making the uprights thinner only because I wanted to save weight. Oddly, I've now made slightly heavier uprights that have much lighter cross braces.Hey Jack - What's the sum of the aero profile of all the cross braces, vs the aero profile of thicker uprights? I'm wondering if there's a break-even point at which you'd be better off with thicker uprights.
Better yet, stamping a subtle ridge into the upright would give it some strength in the third dimension without adding weight, though it would add slightly to the aero profile.
My gut tells me (without anything to back it up) that the aero impact of those cross braces is going to create a bit of turbulence behind you. But then, this is a subject where laypeople such as myself generally know much less than they think they do.
But aluminum is dirt cheap compared to Porsche engine work.
Thanks. I can see the value to rolling the edge(s). With these new uprights, I don't think I'll need it. (But then, I've said that before and been wrong.) And I wonder if the way the wing is cantilevered out back makes it actually improve its rear-axle downforce numbers even as it passes (or flirts with) stall. The reason I'm wondering about that is that I took the thing out and tested it, and I definitely get the best downforce from the wing at a pretty ridiculous angle (around 20°). Now, according to the numbers, my airfoil shape should be at its best at right around 15°.
You mean the decorative wings you see on Hondas and such? Well, I have learned from them. But the knowledge is mostly about how ridiculous I look when I'm running a wing at all. But on the track, I'll take the ridiculous look if it makes me faster.
Again, it's because of my odd way of mounting the whole assembly. There's very little 'ankle' strength, so I have to make the whole thing rigid.
Yes. I'm not poor, but I'm frugal to a fault. It pained me to spend $80 on this new aluminum alloy, and it further hurt me to spring for a $29 piece of carbon fiber to save a little weight over allthread. This is low budget work, here. That's what I like about it.
Thanks! Keep us posted on your progress. I'm happy to have provided some inspiration.Hi
A little hello from France across the pond
read most of this amazing thread
Flabbergasted is the word
congratulations for your workmanship, attention to detail and result - bravo
Myself ,
I managed to organize my garage with a workbench found when I bought the house and around it, I arranged it mostly with cabinets and drawers found in the street ! ( in France, quite often , once a month the town clears junk - old appliance etc... so people put stuff on the pavement )
but its not a good looking organization !
Unfortunately it is a small garage and is now more and more cluttered, as
It is used to park all the family bicycles and all my parts as I never buy a new bicyle and am mostly rebuilding bikes with parts found in France, quite often in the UK and sometimes even the USA ( mostly MTB's from the nineties as I don't like "can or plastic" frames ! and road and city bikes)
and I have got too many bikes ! fortunately less expensive than a porsche ;-)
reading your post, you gave me courage to be more "pro" and I am now willing to improve it and will work on it ;-)
Unfortunately
apart from good vices, good quality equipment does not come cheap in France !
stuff like you lista cabinet are more at the tune of 600 USD or more for one !
Keep the good work
Now there's another valuable lesson. You should be racing in a honda.
Are your two drawers still orphans? If not, where are they living now? Inquiring minds want to know.I actually DID have a plan to use at least one of the two extra drawers -- since I believe in using the whole buffalo and all of that. In shortening the top of the desk to allow the cabinet to fit, I reduced the space where I sit to the exact width of one of the drawers. So it seemed a no-brainer to put a shallow drawer under the main bench, right where I sit.
But as soon as I started filling the drawers, it seemed like a shallow one would be more useful in the stack. So I rearranged it. Now I could still fit a 3" drawer there -- I checked the clearance. But I'm on the fence about it. I've got the parts set aside. But it may be that both drawers end up as donors to the drawer swap thread that someone else organized. We'll see.
They're currently sitting in a stack of stuff ready to go out for scrap. I know there's a drawer swap thread somewhere, which I keep meaning to check. But these are older drawers -- I'm not sure of their compatibility with the newer Lista units.
I've done some wool tuft testing that pointed to 11° for the incoming airflow. But I suspect my data is not giving me a clear look at the whole picture -- and that what you're describing is probably what's actually happening.
QUOTE]
The wing can affect airflow direction a significant distance upstream at low speeds (and 130 mph is low speed, only about Mach 0.2). Since, by eye, your tufts are only about 1/4 chord in front, there may be some turning to the flow caused by the wing at that point. Yarn tests are good, but there are two issues: 1) you cannot put yarn tufts everywhere you would want to, and hanging them out in the flow does change the flow, and 2) it is hard to get angles accurately with them when your cameras are at funny angles too. I would not be surprised to find a 2-3 degree error in angles based on the compound camera angles I am seeing there (and where I would think you could mount a camera on a 911, it appears the camera may be both below and in front of the tufts--makes the geometry more difficult and small changes can make a difference). It really would not take much to put you nearer the 15 degree AOA, and since you do not have that specific airfoil, we would have to figure out which airfoil you actually have (you may have posted that, but I am too lazy to read back through all the pages of this thread to find it, and I do not have all the airfoil tables at home anyway, I would have to find a University library to get the data, if it is a NACA airfoil). The AOA I cited is only for a specific airfoil, others will reach max lift at different angles.
Overall, if you are maxing the lift at the angle you are running, then you have maxed out the downforce, and what the actual AOA is, just doesn't matter. Love to see people try out the aero stuff, and your work looks good to me. Remember, the Wright brothers made their first airplane on testing much like what you are doing, and a lot of guess and check.