Some More Pics

Wow!!! Superb. I don't normally get jealous about cars, but that's just awsome. One day, when I have a spare couple of months...

in article bqg03f$22dbi5$ snipped-for-privacy@ID-199813.news.uni-berlin.de, **-** at snipped-for-privacy@btinternet.com wrote on 01/12/2003 18:08:

Nevertheless a great achievement. Nice ride as well.

Paul

Thanks, much appreciated. Its still in development, been nearly 2 years in the making so far. Max speed would be accurate to about +/- 2mph. So it was either just under or well over ;-).

Matt

Try dropping the front skirt/air dam a bit -- maybe with a strip of metal attached to the bottom -- to cut down on the air going under the car from the front and the sides. It looks like there are some gaps on the sides of the bottom of the air dam. Try closing those. Air going under the car will lift the front a bit, particularly at high speeds. Lowering the air dam sends more air over the nose and forces the front down. You will gain some drag.

snipped-for-privacy@madmousergraphics.com

The front skirt is pushed out like that on purpose, the car runs a flat bottom and the thought of a largish bump leaving the front floating on a cushion of air isn't appealing to me LOL, those gaps are the getout as without them and due to the shape of the undertray theres a small chance of it getting a bit messy.

Its drag I'm trying to combat at the moment hence the use of a flat bottom on the car, its got a very very mild rake angle on it at the moment. I'm going to try and get some windtunnel time early next year so that should reap big rewards but I think with a slight adjustment to the setup it should be okay, we'll see ;-)

Thanks for the interest.

Matt

Yeah, and isn't it true that cars with the cleanest lines are usually the most elegant. Very nice.

BTW Matt, you mention lightness in the front end at speed. At the speeds you're doing (assuming high rate springs and smooth runway surface), have you considered a front air dam that reaches a bit lower (another 3-4 cm or so), and outwards?

That standard Aero air dam "tucks in" all the way down until the last 3 cm, which would cause some lift. For this particular application (on concrete runway), maybe you could get someone to fashion an air dam that flares outward only. Only issue is to brace it from the inside so it doesn't flex or collapse. Maybe it wouldn't look so good but I bet you'd get a very sure-footed 170 mph ;-)

Wonder what your fuel consumption is at that speed (heh heh).

Looking forward to the next diary entry, keep it going.

/Robert

in article bqg3g9$1v6k57$ snipped-for-privacy@ID-199813.news.uni-berlin.de, **-** at snipped-for-privacy@btinternet.com wrote on 01/12/2003 19:06:

What? Fookin' 'ell :) You're one hardcore m***********. LOL.

Paul

See my reply to LauraK re: the above. Its not so much downforce I'm after as anti-lift and the undertray on the car should prove sufficent if I can refine the setup.

Don't worry I will.

It's a subtle distinction, but it's *absolutely* the important one...

Good luck, mate.

Indeed! And rather worringly it seems to be the one that most miss.

Cheers chap.

;-) I know that Mira will be doing some windtunnel work for a contact early next year so hopefully I can sneak the Saab in for 10mins and get some idea and input from the chaps there.

The original poster's mail describes the problem being a too-light front end at 160+ mph. In his text there is no hint of top speed being reached (he rather implies that the only reason he's not going faster is because the car feels unstable at the front).

If this really is a true description, then he needs to counter the front-end lift. Drag, in this case, is a secondary issue. Power appears to not be in short supply here, especially when considering his previous postings on the engine mods done (drool drool).

A properly-shaped front air dam (not the cheesy stock version) will reduce the amount of air getting under the car (= lift force) at the cost of very little drag. If he refits the car accordingly, then I am sure that his next post on the subject will be "How can I get faster than 175 mph? Handling is fine ...".

Hard to understand his (and Adrian's) subsequent comments that some of us respondents are missing the distinction between negative lift forces and drag. We have answered according to the symptoms described.

When you have worked out what problem you really want to describe on this NG, then I am sure you will get responses that you will find relevant and hopefully useful.

Good luck.

Robert Sweden (have abandoned Saabs in favour of cars with much lower Cd [Audis] ;-)

-----8

Oops - apologies to Adrian and Matt for the final 2 paragraphs here. In fact no one has actually said that drag is the primary issue. My fault. Guess I better get back on them pills them thar voices makin me do it ;-)

But seriously folks - the air dam can be shaped to push air as much to the sides as upwards, which would result in minimal added downforce, yet counter the menacing lift issue.

Laura's still right on the money IMO, if you use the right shape on the air dam. Extending the current dam downwards 3-4 cm should reduce air under the car without increasing the front axle load. Just build it strong . . . /Robert

With the rev limit top speed is just over 170mph.

I'll have a play about and see what I can come up with. As it is at the moment I rely on the undertray to provide a touch of downforce but mainly to smooth airflow under the car and avoid areas of high pressure. What I might try and do is shape the front and rear sections of the undertray to increase airspeed and combat boundary layer formation. Don't know if it'll work as planned but I'll have a bloody good go LOL. As its not got to corner at these speeds downforce creation is not a concern minimising drag and lift is.

Cheers Matt