DR

Hi Dave,

Great info, even thou Tom's minimal and smaller braces are not aero correct I had a feeling the smaller struts in the fashion he mounted them would be a lot less drag that some of the "X" bracing I have seen.

I haven't personally ran one that so high that I needed such thick supports and braces and your input is great info for future "higher" applications.

IF you don't mind, while you are crunching numbers give me your thoughts on these 2 different airfoil profiles. Sorry for the crappy photos, but I think you can get enough from them for your calcs. FYI, the lower one is the same as DL's so you probably already have the data.

mark kibort

Interesting stuff.
why the 50% greater cross section? was that due to the strength of round pole vs air foil shape? Still, the net result was 20% of the drag for an air foil shape even 50% larger is the main point here.

if you look at formula cars now, all struts are like the ones found on modern air planes. everything is covered, air foiled, naca ducted, etc.

Mk

worf928

YUP! I was using Tom's as an example because the picture was handy. But what I was really thinking of was the 'X-Wing' configuration we saw in an earlier thread.

I don't mind a bit. And yes, I do still have the profile from DL's wing. My concern with the aggressively cambered wing is that the picture is not a true profile. Once you get 'exotic' on the camber small changes (or errors due to perspective) can have disproportionate effects. Do you think you could get a true cross-section picture?

If you cannot I'll give it a shot but I may need to add so many caveats that a cursory analysis is not usable.

DR

Hi Dave,

>I don't mind a bit.

Somehow I knew that :-)

>And yes, I do still have the profile from DL's wing. My concern with the aggressively cambered wing >is that the picture is not a true profile. Once you get 'exotic' on the camber small changes (or errors >due to perspective) can have disproportionate effects. Do you think you could get a true cross->section picture?
>If you cannot I'll give it a shot but I may need to add so many caveats that a cursory analysis is not >usable.

That is the best I have at the moment, it will be a week or so before I can take a photo of the profile myself.

I know what the manufacturer claims about this profile, but I am really curious as to your un-biased opinion.

Thanks in advance,

worf928

Yup. A round pole has equal resistance to bending from all directions. Squash one axis down to make it more aerodynamic and you loose strength on that axis. In that particular example there was also a change in wall thickness of the support. But, too much of that and you get too much mass. In this case the car was solar powered so we had to optimize additional mass due to wall-thickness and cross-section versus the benefit of lower drag. I do distinctly remember that I was glad when that problem was done and I could go back to software

Now, if we were in F1 lala land we could have a component fabricated with non-uniform wall thickness over the cross-section, keep the mass down and keep the cross-section small.

worf928

I can tell that the upper surface of that wing is not straight. But the diagonal hash marks make it very difficult to see by how much it isn't straight.

If minimal thought was given to the profile (as opposed to just doing something that looks nifty) then it is quite possible that that wing is far more efficient than the original. It is however likely to generate less down-force overall and to have a narrower window of efficient angle of attack. BUT, if some real thought was given to the profile then all bets are off.

When you get something from a flat angle send it to me and I'll see what I can see.

Better yet is to have Pierre take it over to his buddy and see what he thinks.

blau928

Ahem,

Maybe the support for the wing could be nearer the roof where the hatch bolts to the body.. The extenders to support the wing would be on a slightly different plane, and would require a bit different support.. However, It could be sililar to the Rally Escort Cosworth cars that were in Group B racing..

It may allow the control of the variables while offering a better support point for the wing..

Oh, the supports could also be made from Carbon Fiber/Kevlar for strength and weight issues.. They could be laminated pieces molded to that compound shape, then glued and gel coated...

About cost, no comment there....

Good Luck Guys,

I'll just watch from the sidelines thank you..!

Stan.Shaw@Excell.Net

I don't claim to "know", and perhaps the splitter and wing I have just make my car slower, so more comfortable in the corners, but at least I have both. The wing is adjustable, the splitter is not. Of course a running motor would make it much quicker

Accusump did have metal shavings in it, so it was not working properly prior to the last motor's failure.....

DR

Hi Stan,

>Of course a running motor would make it much quicker

So it is safe bet that your BFW will not send you into the air like a bird any time soon, right?

>Accusump did have metal shavings in it, so it was not working properly prior to the last motor's failure.....

Interesting, did the metal shavings come from the old engine, or from the accusump itself? I know what accusump will say, but I am curious as to your opinion.

Stan.Shaw@Excell.Net

My (perhaps limited) understanding of the accusump would make me wonder how the accusump itself would generate shavings. Doesn't seem too likely it would fail, the piston movement would be relatively slow with only low pressure, right?

What concerns me is that the first motor failed due to a #8 rod bearing failure, and I really don't know why. If the accusump was in-operative before that point, wouldn't the #2/#6 bearings have been likely to fail? I did find wear on other rod bearings as well though. The motor only had 15 track days on it, about 90 minutes per day.

Perhaps I ran the last motor too long on non-synthetic for break in, resulting in it's eventual failure. Then I didn't identify the problem with the accusump which resulted in the second motor failure.

I haven't decided whether I will replace all my oil lines this time, as well as my System 1 filter.....

bcdavis

Are you drilling the crank on your new motor?

Don '85S3

Sorry Dave, but the wing looks more appropriate for a 19 year olds Rice Burner.

Stan.Shaw@Excell.Net

The motor I just rebuilt, and blew up, has a drilled crank, which I am hoping is salvageable.... Keep your fingers crossed for me.

ew928

Something like this?
Borrowed from the internet.
Supports running back from the hatch hinge area to join
with vertical to hold mongo rear wing in place.

Dennis K

There's a guy here in CA who's running an AABAUW (active aero big *** ugly wing) on his S2000. He has a button on the center console that he pushes to change the angle of attack. Push once while on the straights and it flattens. Push again on the entry to a corner and it flips up.

Most racing groups ban "moveable aerodynamic devices" but open track days and DE's don't care. It's pretty cool to see it in action, like wathcing Jim Hall's old Chaparrals.