Poor Man's Aero: Building Your Own Wing (many pix)

[JohnJL]

The cord length should be exactly the same as yours, I used yours as a template. My spacings are around 10", the total width is 60" to fit within the narrow-body max-width requirements.

Yes, its 1-piece.

Do you still have yours on?

[armandodiaz]

Originally posted by Eric Coffey
+1

For front end aero treatments, you might try experimenting with different winglet configurations ala DTM/LMP cars. Here are a few examples to offer inspiration:

Any idea on where these would be available?

[Jack Olsen]

Originally posted by JohnJL
The cord length should be exactly the same as yours, I used yours as a template. My spacings are around 10", the total width is 60" to fit within the narrow-body max-width requirements.

Yes, its 1-piece.

Do you still have yours on?

You might be using stronger materials than I did, so it might not be an issue. But with the aluminum skin I was using, I think 10" would have been too far apart. I had a rib every 5.5-6 inches. However it looks like your rib metal is a little thicker than mine, so your skin might be heavier gauge, too.

I'm still running mine every track day. Last Wednesday, I beat my previous record at my home track five times over (with narrower and less sticky tires than I'd set the previous best with), so I can't say that the wing is slowing me down.

[911pcars]

"Any idea on where these would be available?"

Armando,
Open up the pages of any sport compact magazine and you should find many canards in FG and CF from several manufacturers. The mounting contour might be different. Those exact ones in the photos are probably custom built.

Sherwooe

[armandodiaz]

Thanks, I'll have to stop by a rice burner shop. I'll hide my face.

[Chuck Moreland]

I thought I'd have a go at this too. Noting Jack's comment about the AL flashing being flimsy, I had an idea.

Fill the cavities of the wing with this expanding foam stuff. It shoots out as liquid, then foams up to several times the size. Sticky stuff, I it should help bond everything together making the glue less important.

And it cures to a styrofoam consistancy, providing support to the backside of the thin AL skin.



You can see the core of the wing in the background.

Feeling proud of myself for coming up with a good solution that was a sure winner, I dutifully spent many hours cutting the ribs and other piece parts of the wing. Then several more hours gluing up the whole assembly. Then some more fitting the AL skin (not so easy to do, even the thin flashing material is difficult to get to conform fully).

I drilled holes in each cavity, then shot in the foam till it started oozing out. I was concerned that the pressure of the foam might split the wing, but it didn't.



At this point I'm thinking "Awesome. I love it when a plan comes together".

Now it's just a matter of trimming the excess foam and go flying low to the ground.


Not so fast, flyboy.


After breaking off the beautifully-cured excess foam, I could see nothing but darkness in the fill holes.



Probing into the holes, I found no foam - only gooey residue. The AL skin was unsupported. The foam did not cure properly inside the wing, only the stuff that oozed out into free air.

I think the contained foam takes longer to cure, and while it remains soft longer the bubbles are popping. The foam breaks down into its liquid state. At least that's what appears to have happened.

I've seen similar expanding foam used as packaging material. The foam is in a bag that would similarly contain it. Yet that stuff seems to cure just fine. However the packaging products I've seen require heating.

Maybe the heat accelerates the cure, and prevents the foam from breaking down? Maybe I can fill my wing with foam, then put in a warm place? Maybe there is another product that would work better?

Anyone with experience in this area?

[randywebb]

there are things made with Al foam - it's pretty high tech stuff

there is also Al hex cel material

Back to the - ah - foam foam... did you use the slow set or the fast set type? if the slow, then the fast might work -- it WAS a good idea...

[pieterk]

Chuck,

I'm not sure if that brand is similar to the other brands I've used. I wouldn't say the stuff comes out as liquid, more like compressed shaving foam if that makes sense. I've used three difference densities of the stuff extensively in all kinds of situations, including sealed cavities with only a drilled access hole, and the stuff's always worked well for me. If I was doing this, I'd probably have used it here too.

I can't remember the brand name, but it comes in three different colored cans--blue, red, and I think yellow or black--and is readily available in any building supply or hardware store like Home Depot, Osh, or whatever.

I would probably choose the lowest density foam, as I think its expansion rate is about 1:2. The 1:4 stuff will probably be too extreme and might damage the wing. The stuff has been known to deform door and window frames so I wouldn't trust it to be gentle enough here.

[CBRacerX]

I have used "Great Stuff" foam inside wings on my FC and it worked fine. Good luck!

[pieterk]

"Great Stuff!" That's the stuff I was talking about.

Thanks.

[randywebb]

also -- maybe you can apply it as you go - so it would "get good air"

[smdubovsky]

I think the expanding foams are moisture cure urethanes. They require moisture from the air to harden them. An AL cavity isnt permeable to air. Maybe drill another hole(s)? Squirt in a small amount of water?

I dont think your foam is broken down, just uncured. Like the state it resides in while in the can.

SMD

[Chuck Moreland]

When I said "broken down" I meant the bubbles that make the foam had popped, leaving nothing but liqiud. Yes it is certainly uncured.

But in the can I think it is actually 2 parts. They are now mixed and inside my wing, however still liquid.

[smdubovsky]

Chuck,
http://greatstuff.dow.com/greatstuff/cons/howto.htm
Says to spray w/ water between passes in deeper cavities. Definately a moisture cure. The propellant "foams" it on the way out. It didn't cure fast enough in your case and resettled.

MSDS:
http://www.dow.com/PublishedLiterature/dh_02dd/09002f13802ddaf4.pdf?filepath=pusystems/pdfs/noreg/741-62847.pdf&fromPage=GetDoc

Polymethylene polyphenyl isocyanate needs water to react w/ the prepolymer.

FWIW, I dont see how you could deliver a 2-part resin/hardner out of one can (that isnt a moisture/air cure). All two part resins we use are in parallel tubes w/ a mixing tip/straw. Those will definately cure in a sealed cavity. I guess the door foams are technically 3-part (w/ the missing water being the 3rd)

It looks like acetone will disolve the uncured stuff. You might be able to wash the old stuff out and try again. THough, Id be temped to buy a two part external mix and figure out how to pour/squirt it in before it foamed. I think some of the styrenes will do that.

SMD

[lateapex911]

Great stuff will work, I have used it in similar applications.

Perhaps you could spray a mist of water...or steam...just a little in there before foaming, and foam in "lifts". A little at a time, in two passes? Also, choose the low build stiff, as you might find the high build stuff distorts the al skin.

In any case, I would experiment first with a mock up.

[JohnJL]

Hey Chuck, you sure you didn't read that idea before...early on in the thread, search on the word "foam"

I'm surprised to see it didn't work...i bet there is another formula that would work...or if it was baked or warmed while curing...

More about your construction...what bonding material did you use?

[FinallyGotOne]

With Porshes body alreay created for aerodynamics, is a wing like that any more beneficial than a tea tray type tail? Or is it better that the little wing on it already? just logical questions from me on that/

Besides those questions, quite an amazing job for sure!!

[lateapex911]

Read backt through this thread and all others by Jack Olsen concerning aero for your answer to that question. The "Search" feature and "wing" and/or "aero" and "jack Olsen" will give you answers that might surprise you.

[Chuck Moreland]

JohnJL, great minds think alike

Unfortunately we don't always get the results planned

I'm going to try some different products.

[Jack Olsen]

Originally posted by Iwantone
With Porshes body alreay created for aerodynamics, is a wing like that any more beneficial than a tea tray type tail? Or is it better that the little wing on it already? just logical questions from me on that/

The Porsche body (especially the pre-1990 one) has good aero in the sense that it doesn't generate very much drag. But the same teardrop shape is pretty lousy in terms of generating lift. The ducktail/teatray/whaletail spoilers were there to interrupt airflow over the car (all of them except the ducktail also came with a penalty -- increased drag. But a true wing is much better in terms of both drag and its ability to create negative lift, which fights the 300# or so of positive lift that the basic body creates at 150 mph. Wing's aren't very practical on street-driven cars, but they've been a fairly common item on track Porsches for decades.