F'ing fast.

[jimk]

The windscreen on the 02 is quite vertical and I would expect more turbulence up and over the roof.  There is a goodly separation bubble at the lower edge of the windscreen, enough to lift the hood about halfway up the windscreen at 70 mph.  Easy to test, unlatch the hood and slowly increase the speed, you won't miss noticing.   Hood hovers there.

[visionaut]

3 hours ago, jimk said:

The windscreen on the 02 is quite vertical and I would expect more turbulence up and over the roof.  There is a goodly separation bubble at the lower edge of the windscreen, enough to lift the hood about halfway up the windscreen at 70 mph.  Easy to test, unlatch the hood and slowly increase the speed, you won't miss noticing.   Hood hovers there.

True the amount of windshield rake does make a difference. But not enough to fundamentally change that diagram.

 

The diagram I showed is not for a smooth low-angled aero vehicle (think 911 shape, where flow doesn’t even separate going from hood to windshield to roof).  It’s representative of our two-box body style - with multiple separation and reattachment points. (the 02 windshield sits ~44 deg from airflow).

 

At steep windshield angles (more perp to airflow) the airflow creates a small stable air ‘bubble’ at the front of the roof but then quickly reattaches to the roofline. Cabriolets show this ‘stable air bubble’ past the windshield which for them extends to where it reattaches on the trunk.
 

Tests of cruising semi-trucks (steeper windshields than 02) showed reattachment before the end of the cab. Notice how aero semis have these giant ramp devises trying to get the flow to go over vs into their trailers..

 

A nice aero feature of our windshields is the roundness of the side-to-side profile. Center front sits 6” forward of the edges, so a nice curved profile in that direction. In fact the side-aero of an 02 ain’t bad…

 

yessir - that hood WILL rise. Windshield base aero effects at work (the completely open bottom of the engine bay doesn’t hurt either).

 

Edited February 13 by visionaut
typo tom

[visionaut]

I always think of stuff after posting.. 😆 

 

You can see for yourself how quick the airflow reattaches to the roof - just open your sunroof while cruising. Reach up to the forward edge of the opening, slowly extending your fingers upward into the airflow. You won’t go far - It’s RIGHT there already.

 

and I had a semi-truck aero pic…

 

Tom

 

 

 

[TobyB]

...and then there are the mirrors...

 

...and the wheel wells...

 

...and what happens to the air that's displaced laterally off the sides of the nose AND the windshield...

 

t

it all adds up.

[JQ02]

Prolly way off topic, but maybe close enough. superfastmatt has a great video on aerodynamics and the use of airshaper 

 

[chargin]

On 2/12/2024 at 10:47 AM, TobyB said:

You read that the 0-60 is something like 3 seconds, but until the 2,5 ton bugger turns into a little red dot in front of

you, you don't really twig what that means in the real world.

 

Maybe, but lets see a Neurenberg lap time?

 

Honestly we got a Model S Ludacris at our office, after 2 pulls we never used the mode again, as fast as it is there is just no Opera about it, the same guy sold his Ferrari last year, after the "Pulls" he said "It's as fast as hell but it's just NOT my Ferrari" 

[Son of Marty]

2 minutes ago, chargin said:

Maybe, but lets see a Neurenberg lap time?

 

Might not be so bad, putting the main weight of the car below the axle centers does wonders for handling.

[visionaut]

2 hours ago, TobyB said:

...and then there are the mirrors...

 

...and the wheel wells...

 

...and what happens to the air that's displaced laterally off the sides of the nose AND the windshield...

Mirrors are overall trivial, unless mounted oddly.

 

Wheel wells are fun — LOTS going on.

 

Side aero vortexes are big, and they extend your aero effects even past the end of your car (and help my rear wing work.. lol). The 02 greenhouse, sitting inboard vs flush with the lower bodywork nicely aids these side vortexes wrapping onto more of the trunk lid from both sides..

 

[chargin]

2 hours ago, Son of Marty said:

Might not be so bad, putting the main weight of the car below the axle centers does wonders for handling.

 

The reason they don't do a lap is that after a few high power pulls the battery gets hot and the car goes into a Limp mode until the battery cools to a safe temperature.

 

really good for stop light races or Instagram posts, track time not so much 

 

Edited February 14 by chargin

[NickVyse]

I did 132mph in my old s14 powered Touring - obviously the more laid back windscreen made it easy 🙂 I'm in no hurry to repeat that speed.

 

I was in Vars the other week where a local set the World record last year - 159mph, on skis, feck, and no horses involved.

 

 

 

[Dudeland]

On 2/13/2024 at 9:25 PM, JQ02 said:

Prolly way off topic, but maybe close enough. superfastmatt has a great video on aerodynamics and the use of airshaper 

 

Love this guy.  He has some great views on stuff. 

 

[Dudeland]

On 2/13/2024 at 10:03 PM, chargin said:

Honestly we got a Model S Ludacris at our office, after 2 pulls we never used the mode again, as fast as it is there is just no Opera about it, the same guy sold his Ferrari last year, after the "Pulls" he said "It's as fast as hell but it's just NOT my Ferrari" 

I agree. I am about the analog experience.  The roar, the smoke, the rattles, the ride.   We all know that 02's are slow by modern standards.  Even doubling the HP won't be faster than my family friendly daily. 

 

The fun, the drama, the seat of the pants feel.  That is my gig.   I often think about replacing my daily, but new cars aren't that great, and I don't feel like spending 50-80K on something that really isn't fun or exciting. 

 

 

 

[Dudeland]

I wonder how these things help.  Kinda cool.  The guy that makes them was super nice. 

 

[visionaut]

14 minutes ago, Dudeland said:

I wonder how these things help.  

Airflow control for greater stability in high speed turns…

[visionaut]

On 2/13/2024 at 6:26 AM, Ian said:

Tom, it would be fascinating to see your calculations for the 2002.  Most of us won't be able to do much about it, but it would make for interesting reading.

 

I went looking through old files (on the old computer) and found some of my prior 2002 aero studies stuff. Thought I’d share this graphic.

 

Still looking for the rest… I remember doing piecemeal calcs for most of the aero elements and comparing with wind tunnel data... but some was just relative analysis.  I suspect some of it’s only hard copy stored who-knows-where.. lol 

 

Tom