Developing a sports prototype

[minimangler]

But the Nascar and IRL etc would take precedence, especially as sponsors will partly pay for tunnel time.

[ss_collins]

Porsche tunnel and stuttgart tunnel - dunno which is which

[AU N EGL]

1% of the race teams use 99% of the wind tunnel time.

We have two wind tunnels( not counting the Penske Racing tunnel) here in my state, Moorsville NC, about $1500 / hour for use.

Or for smaller teams that require less computer time, $345 / hour for first two hours ( miniumum) then $490 hour ( two hour mininum)



Not my car.

[dj choc ice]

Originally Posted by JAG

How does that compare to a Group C/IMSA GTP car, and currently an IRL/Champ Car?

i know nothing about downforce amounts, but a high downforce spec zytek must be getting pretty darn close or similar downforce to a champcar in a balance downforce setting.

[MulsanneMike]

Originally Posted by minimangler

Should that say 400?

No, at their peak (1992), GTP cars were in the region of 10,000 lbs @ a theorectical 200 mph. But that's always a bit of a misnomer to an extent. in that kind of high downforce configuration you'd never see 200 mph. So in reality its better to compare downforce at 150 mph. 10000 lbs @ 200 is 5625 @ 150 mph.

[MulsanneMike]

Originally Posted by ss_collins

To add to Mikes answer

Audi - thier own (full scale)
Porsche - thier own (50%?) + university of stuttgart (Full scale)
Courage - (ACE 50%)
Lola - (Lola 50%)
Lavaggi - not sure but 1/3rd scale
Creation - Teddington
Zytek - not sure
Acura - not sure
Pesca - they dont!
Radical - MIRA 100%
Pilbeam - Don't know
WR - somewhere near paris
Lister - MIRA 100%
Dome - Dome 50%
Zulltec - ACE
Embassy - RUAG

The most advanced 50% tunnel in the world is probably Dome, followed closely by Toyota F1.

Most advance 100% will be Windshear I think.

Audi and Porsche use the Dallara tunnel for their scale development work. The Audi full scale tunnel is only used for basic fine tuning and well, marketing (those pretty images with the smoke wand). Porsche's in-house scale facility has been described to me as "quiant" and certainly wasn't used for the current RS Spyder (it doesn't have a full rolling road, only a belt between the wheels). Over the Petit weekend I had it confirmed to me that Dallara's tunnel was used for the RS Spyder. That's a natural given Pfadenhauer did all his Audi work there. Acura is at ARC Indianapolis, per Nick Wirth at Sebring.

And a full scale facility is pretty useless these days for a number of reasons. Other than the new Windshear tunnel and a facility in Germany that escapes me (perhaps Audi's full scale tunnel), none have a full rolling road. Additionally, you'd never start out a development program in a full scale tunnel for the reason of economies of scale. Too expensive to build in full scale (tooling; patterns, molds, etc.) for what is a development item that 9/10 times will be discarded. So you can guage an effort by the type of facility they are in. The top dogs like Porsche, Audi, Peugeot are spending weeks in the scale tunnels. They aren't bothering with their full scale facilities.

[old man]

Please forgive questions that show my ingnorance and fascination:

How reliable in practice is data collected from a tunnel with a static floor?

Do most tunnels have rolling roads (or rollers) under the wheels and does this reliably give data on turbulance and other effects?

Do some tunnels have full moving floors to simulate the progress over the ground and how is this influenced by cornering?

I am told that the top F1 teams have full simulation rigs that work in parallel with cars when on the track using live data from sensors on the cars, is this true and if so I imagine that these rigs must also be wind tunnels. I am told this is because of the limited track time in practice and enables factory based engineers to try alternative setting solutions for the benefit of the race team. I do not quite trust this information but assume that it is technically feasable....fantasy land? Any sportscar teams with access to such facilities?

[AU N EGL]

Originally Posted by old man

Please forgive questions that show my ingnorance and fascination:

How reliable in practice is data collected from a tunnel with a static floor?

Do most tunnels have rolling roads (or rollers) under the wheels and does this reliably give data on turbulance and other effects?

Do some tunnels have full moving floors to simulate the progress over the ground and how is this influenced by cornering?

I am told that the top F1 teams have full simulation rigs that work in parallel with cars when on the track using live data from sensors on the cars, is this true and if so I imagine that these rigs must also be wind tunnels. I am told this is because of the limited track time in practice and enables factory based engineers to try alternative setting solutions for the benefit of the race team. I do not quite trust this information but assume that it is technically feasable....fantasy land? Any sportscar teams with access to such facilities?

many tunnels the car sits on a turn table with scales under each wheel.

As the wind speed increases, the change on each scale is noted. The turn table can rotate the car to simulate a corner.

Plus most of the bigger tunners do have highspeed cameras and super computers to measure fluid dynamics.

[ss_collins]

See what mike says - take that as gospel - if you don't know hes the man on this stuff

[ss_collins]

I am told that the top F1 teams have full simulation rigs that work in parallel with cars when on the track using live data from sensors on the cars, is this true and if so I imagine that these rigs must also be wind tunnels.

No but we were going to write that as an April fool once... The rigs you are thinking of are 7 posters (google 7 post rig) the teams send data to hq who then run scenarios on therigs and feed the data back to the guys at the track.

I wonder if an LMP has ever been to Laurel Hill

[rcarr]

Cranfield's tunnel was used now and again for WSC back in the day.

Goldsmiths or was it Imperial was used by TWR with the Jaguars.

MIRA has a 30% tunnel which they use a Mazda 767b lookalike for "demonstration purposes" they told us it was just left there in the 90s. MIRA main tunnel is fairly flawed, it is static ground and may cause strange lift/drag ratios. It is fine for cars without underbody aero devices.

When I used the Coventry Uni the technician told me that the only car to ever produced negative drag was the Thrust SSC 1/10th scale model. That was also a static ground and produced lift induced drag for my LMP1 car model.

[Tim the Grey]

How do you get NEGATIVE drag? That sounds like Perpetual Motion to me...

[old man]

Originally Posted by Tim the Grey

How do you get NEGATIVE drag? That sounds like Perpetual Motion to me...

I am glad you said that!

[old man]

Originally Posted by ss_collins

No but we were going to write that as an April fool once... The rigs you are thinking of are 7 posters (google 7 post rig) the teams send data to hq who then run scenarios on therigs and feed the data back to the guys at the track.

I wonder if an LMP has ever been to Laurel Hill

Thanks for the Google tip, fascinating stuff in the Nascar and Viper links

[AU N EGL]

NEGATIVE drag? is that like the Bernoulli principle on sails? the low pressure PULLS the sail, not the wind pushing the sale.

[minimangler]

Yeah, that makes vague sense?

Kinda like lift not pushing but pulling something upward?

[AU N EGL]

a big part of the aero design of cars is to move as much air over the car, and not under.

This cause the negative pressure under the car and a high positive pressuer flowing over the top. This pushes or sucks the car to the ground.

[minimangler]

i knooow that!

basic ground effect principle.
which is created using a vacuum, by sweeping the floor up, pretty much.
And yes, sucks not pushes; i said that already

[class4v]

As written hereabove, manufacturers are using scale windtunnels and full ones. We used to go to the ACE with our models and to Saint Cir for the full testing. And yes, smaller manufacturers spend less time in the windtunnel. +/- 300 hours max (scale tunnel) before the launch of a model and some more to fine tuning things in the 100% one. Don't underestimate aero tracktesting, a lot have been found also during these tests. Nowadays with the new softwares and IT hardware a lot is pre tested

[ss_collins]

The Pesca is mainly developed using straight line testing