Random Wind Tunnel and Smoke Pictures Thread

[kach22i]

Originally Posted by aerohead

Historically,each maker has run a long-tail variant specifically for the conditions of the Le Mans course.
Any speed liability in the corners was more than compensated for by top speed capability on the Mulsanne Straight.

Good point, sort of like the Ford GT40's of the 1960's, later versions specific to LeMans were longtails. Even the Porsche 917 went with longtails for that race to stay competitive.

Here is what I'm thinking now that Aerohead reminded me of the historic aspect, McLaren longtail is a nod to this history, and it includes one of their own in the mid and late-1980's

https://cars.mclaren.com/featured-ar...s-le-mans.html

Our famous win at the 24 Hours of Le Mans in 1995 was unprecedented: not only was the McLaren F1 GTR essentially a road car competing against purpose-built prototype racers, it was also the first entry by McLaren in one of the toughest endurance races in the world. Against all the odds, McLaren took the chequered flag, finishing 1st, 3rd, 4th, 5th and 13th. We remain the only manufacturer to win the race at the first attempt.

Notice the tail got longer from 1995 to 1997 in image attached.

Image link:
https://www.ebay.com/itm/McLaren-F1-...-/254052100347

Oct 2018
https://www.hotcars.com/mclaren-reveals-speedtail/

A released teaser image shows a car that certainly seems to take from McLaren’s “longtail” heritage, showing an engine panel that seems to flow into a rear-fascia that seems extended beyond the normal bounds of a McLaren.

This would be the third vehicle after the McLaren F1 GTR Longtail to receive a similar design, with the 600LT and 675LT Super Series cars being the other two.

Read under "1997" for aerodynamic race stories.
https://en.wikipedia.org/wiki/McLaren_F1_GTR

[freebeard]

Absolutely spectacular first-ever air-to-air images of supersonic jets' shockwaves interacting

https://boingboing.net/2019/03/06/ab...r-first-e.html

Technically not a wind tunnel picture.

While NASA has previously used the schlieren photography technique to study shockwaves, the AirBOS 4 flights featured an upgraded version of the previous airborne schlieren systems, allowing researchers to capture three times the amount of data in the same amount of time.

[kach22i]

Originally Posted by freebeard

Technically not a wind tunnel picture.

Very cool.

I was only able to copy the images by going to the NASA website as linked to in your article.

https://www.nasa.gov/centers/armstro..._aircraft.html



https://www.nasa.gov/centers/armstro...teraction.html

[Vman455]

Originally Posted by freebeard

It doesn't really show much beyond the Gurney flap/spoiler. They think we won't notice no airflow into the radiator.

I will bet money that's just because they never put the smoke wand low enough. The real giveaways that this is for publicity are: no rolling road, no spinning wheels, and the car is on the ground (elevating it off the tunnel floor is one means of correcting for the first two).

[kach22i]

https://primotipo.com/2018/06/21/skin-deep-beauty/

Inperial College wind tunnel in 1967 (unattributed)

[freebeard]

Puts me in mind of the 'coke-bottle' rule that is a supersonic protocol. Don't the reliefs between the fender-tops give somewhere for air going around the top to equalize?

[kach22i]

Originally Posted by freebeard

Puts me in mind of the 'coke-bottle' rule that is a supersonic protocol. Don't the reliefs between the fender-tops give somewhere for air going around the top to equalize?

I noticed that as well, you have an artistic eye.

https://blog.toyota.co.uk/toyota-pri...r-design/img02


The Aerodynamics of Today’s Cars – Speed Carz

Up until now, designers and engineers have mainly concentrated on visible surfaces, giving us car designs that are attractive and streamlined. However, car shapes have changed as theories evolved about how best to manage airflow. Now other car surfaces have come into play, such as the undercarriage.

https://global.toyota/en/


https://www.digitalengineering247.co...ing-the-prius/

[kach22i]

https://www.motoringresearch.com/car...new-cars-2018/


https://www.wardsauto.com/technology...odynamic-gains

[COcyclist]

Thank you for posting. These are fascinating.

The smoke on this one looks fake to me. The lower streamline goes right through the spoiler at the edge of the roof.


I have been reading Julian Edgar’s book. He states that the counter-rotating vortices start at the A pillar. This view would seem to support that. Thanks.

[aerohead]

Originally Posted by freebeard

Puts me in mind of the 'coke-bottle' rule that is a supersonic protocol. Don't the reliefs between the fender-tops give somewhere for air going around the top to equalize?

I think that this is exactly what they were going for.
Area rule.Whitcomb-wasting.Coke-bottling.(after Richard Whitcomb of NASA, who invented the technology,albeit,for supersonic flow).
As the air is attacking the bonnet and fenders it encounters the greenhouse erupting out of the body,then the plan-taper of the aft-body.
By not allowing the cross-section from altering any more than a certain percent,as a function of change in body length,they can control pressure spikes,transverse flow contamination,local velocities and their separation effects due to local Reynolds number.
And I also think it's extremely aesthetically pleasing.
Good call!