Investigating exhaust aided diffusers

[DaveW]

Easy now Dave, what I meant to say is that among all this talk about vortexes, stalling and boundary layers,
it would be useful to repeat what it all is aiming for, namely speeding up the air under the car and nothing else.

I understand your point, X, but I can't help adding: ...so F1 vehicles generated no down force before Lotus "discovered" ground effect?

[autogyro]

When the logical development of a twin chassis car in the Lotus 88 was banned, the greatest F1 designer of all time, Colin Chapman lost interest.
Since then F1 technology has just been variations on the same stagnant theme.
If F1 is to survive this needs to change.

[xpensive]

Easy now Dave, what I meant to say is that among all this talk about vortexes, stalling and boundary layers,
it would be useful to repeat what it all is aiming for, namely speeding up the air under the car and nothing else.

I understand your point, X, but I can't help adding: ...so F1 vehicles generated no down force before Lotus "discovered" ground effect?

Actually, ground effect was "discovered" by Mauro Forghieri at Ferrari in 1972, when he compared the slim 312B2 F1 car with the 312P sportscar in a wind tunnel and found that the full bodied car generated much more downforce. He didn't quite understand it, but the result was the wide-body 312B3, which almost won the 1974 WDC with Clay Regazzoni, as well as the ultra-successful 312T-series with three WDC's in five years.

[DaveW]

Actually, ground effect was "discovered" by Mauro Forghieri at Ferrari in 1972, when he compared the slim 312B2 F1 car with the 312P sportscar in a wind tunnel and found that the full bodied car generated much more downforce. He didn't quite understand it, but the result was the wide-body 312B3.

Who am I to argue? But I did use quotes because my friends on the other side of the pond insist that Jim Hall of Chaparral was the pioneer of ground effect race vehicles. No doubt others will have alternative candidates. I don't think it matters too much because they were all working relatively independently and with differing levels of understanding. Anyway, you managed to sidestep my question rather neatly, I thought.....

[xpensive]

Easy now Dave, what I meant to say is that among all this talk about vortexes, stalling and boundary layers,
it would be useful to repeat what it all is aiming for, namely speeding up the air under the car and nothing else.

I understand your point, X, but I can't help adding: ...so F1 vehicles generated no down force before Lotus "discovered" ground effect?

So sorry Dave, of course there was downforce pre Lotus 77, both from wings as well as from under the car,
but I fail to understand the relevance of your question, please xplain?

[autogyro]

Most ground attack aircraft in WW2 could use ground effect to advantage.
Even long before that aircraft designers and builders were aware of the difference in wing lift in ground effect.
It is only F1 aero fan boys who think that motor sport has some sort of weird monopoly over something that pre dates their ideas by at least a century.

[DaveW]

...namely speeding up the air under the car and nothing else.

Just questioning the underlined "corruption" (apologies).

[xpensive]

As the higher speed of air under the car is what creates downforce, what other purpose would the xhaust aided diffuser have?

Yes, I know it looks kinda cool, but that's not a purpose in itself, is it?

[riff_raff]

Here's an old tech paper on using a piston engine exhaust ejector to improve air mass flow through a radiator cooling duct. It's not an F1 undertray diffuser, but the basic principles are the same.

http://ntrs.nasa.gov/search.jsp?R=47096 ... c1%26N%3D0

Have fun.