2018 Aerodynamic Regulations Thread

[godlameroso]

Maybe. It takes some imagination and creativity to be able to adapt your environment to your needs. With modern CAD and CFD it's easy to invert or manipulate shapes, run them backwards, or inverted. It's getting to the point that you can design on the computer and use the wind tunnel and track to validate, YMMV.

[CBeck113]

I've tried to stay out of this for as long as possible, but you are missing a very important point: a living creature's anatomy is not there for a single purpose, unless you consider existing a purpose. The feathers on a bird help it fly, but also keep it dry and warm, two things not all too important for the exterior of an F1 car.
Back to my original post here, the one asking about the diffuser on the bird: the shape of the bird is for aerodynamic efficiency, and fit to each species flying and or hunting habits (birds of prey have long and wide wings for more control and lift, while seagulls long but thin wings since they fly in regions with high winds. Which of these concepts has anything to do with a diffusor on an F1 car? The appendages in the diffusor are there to help maintain the flow, increasing its effectiveness in creating downforce. The secondary effect of creating vortices is used to separate flows, which also supports their first job: create downforce. A bird, on the other hand, is "built" to avoid vortices, since they are bad for efficient aerodynamics, and make it harder to fly (aka less efficient). The aero regulations in F1, on the other hand, are so stipluated and have the result that creating voritces to manipulate and control air flows around the car are the best way to create the optimum on downforce.
Summary: birds are great for showing efficiency, but not for downforce.

[godlameroso]

I've tried to stay out of this for as long as possible, but you are missing a very important point: a living creature's anatomy is not there for a single purpose, unless you consider existing a purpose. The feathers on a bird help it fly, but also keep it dry and warm, two things not all too important for the exterior of an F1 car.
Back to my original post here, the one asking about the diffuser on the bird: the shape of the bird is for aerodynamic efficiency, and fit to each species flying and or hunting habits (birds of prey have long and wide wings for more control and lift, while seagulls long but thin wings since they fly in regions with high winds. Which of these concepts has anything to do with a diffusor on an F1 car? The appendages in the diffusor are there to help maintain the flow, increasing its effectiveness in creating downforce. The secondary effect of creating vortices is used to separate flows, which also supports their first job: create downforce. A bird, on the other hand, is "built" to avoid vortices, since they are bad for efficient aerodynamics, and make it harder to fly (aka less efficient). The aero regulations in F1, on the other hand, are so stipluated and have the result that creating voritces to manipulate and control air flows around the car are the best way to create the optimum on downforce.
Summary: birds are great for showing efficiency, but not for downforce.

I'll just quote myself.

"Isn't that a bit contradictory? Birds have active aero, these cars are fixed, there's no comparison. My point this whole time is that there are areas on these cars that are sensitive and big performance differentiators, and seeing the resemblance in nature pays off in these areas."

If you could see CFD of birds in motion you see they shed plenty of vortecies. Also I can't believe you missed a basic fact such as aero induced drag is more efficient than skin induced drag, if you have to have one or the other everyone will choose the former. That's partly why bird feathers are tiny vortex generators. Not just birds but sharks also have tiny vortex generators on their skin. Why would sharks have vortex generators if vortecies cause drag?

[Just_a_fan]

So, an F1 car should be wrapped with feathers? Because that's what birds have.

They're getting there, if it was allowed by the regulations they would, all those little appendages are trying to emulate feathers, granted they're nowhere near as effective as actual feathers.

Aircraft aren't prevented by regulations from having feather type appendages. If they were so good, gliders would have them to improve their performance - no engine to overcome drag of course. But look, gliders are designed and built to be as smooth as possible. Long thin wings - not because the Albatross has long thin wings but because physics directs it to be the best shape. They don't have chunky bodies like birds do though. They have long thin fuselages instead. What gives?

[Just_a_fan]

Why would sharks have vortex generators if vortecies cause drag?

Vortices do cause drag but they cause less drag than flow separation does. In the case of a shark, of course, that separation would be seen as cavitation. The use of vortices to help keep flow attached over highly curved surfaces is well known in man made stuff. Sharks don't use vortices in that way, however. Are we wrong?!!

[godlameroso]

So, an F1 car should be wrapped with feathers? Because that's what birds have.

They're getting there, if it was allowed by the regulations they would, all those little appendages are trying to emulate feathers, granted they're nowhere near as effective as actual feathers.

Aircraft aren't prevented by regulations from having feather type appendages. If they were so good, gliders would have them to improve their performance - no engine to overcome drag of course. But look, gliders are designed and built to be as smooth as possible. Long thin wings - not because the Albatross has long thin wings but because physics directs it to be the best shape. They don't have chunky bodies like birds do though. They have long thin fuselages instead. What gives?

I bet having feather appendages is probably more efficient, guaranteed, but it's a cost issue, to replicate the complexity of nature isn't easy, so you make compromises. It's a lot cheaper and easier to make draggy gliders and compromise by using thin bodies. There are always constraints, you wouldn't be able to sell any gliders if you try to mimic the complexity of nature, no one would be able to buy them, nor would you have the budget to develop it.

[Just_a_fan]

I bet having feather appendages is probably more efficient, guaranteed,

I'd like to see some evidence of this. You keep stating it but there's nothing to back up your position.

[3jawchuck]

I bet having feather appendages is probably more efficient, guaranteed,

I'd like to see some evidence of this. You keep stating it but there's nothing to back up your position.

This is a good "question". You've been making a lot of big assumptions with nothing backing you up. If you could show evidence of your claims then this discussion could be more than just empty text and nice pictures and become something worth reading.

[godlameroso]

I bet having feather appendages is probably more efficient, guaranteed,

I'd like to see some evidence of this. You keep stating it but there's nothing to back up your position.

No just 10 F1 teams putting more and more feather like appendages on their cars and the corresponding increase in performance. Correlation is not causation you say, but if correlation is nearly 1:1 then you can be fairly sure there's some relationship. Plus do you really need me to prove flexible aero can be better than fixed? There's just no pleasing some people.

[johnny comelately]

So, an F1 car should be wrapped with feathers? Because that's what birds have.

They're getting there, if it was allowed by the regulations they would, all those little appendages are trying to emulate feathers, granted they're nowhere near as effective as actual feathers.

Aircraft aren't prevented by regulations from having feather type appendages. If they were so good, gliders would have them to improve their performance - no engine to overcome drag of course. But look, gliders are designed and built to be as smooth as possible. Long thin wings - not because the Albatross has long thin wings but because physics directs it to be the best shape. They don't have chunky bodies like birds do though. They have long thin fuselages instead. What gives?

Blasphemy

[Vyssion]

Okay... lots of comments to read here - gonna add my two cents worth to the argu.... errr I mean discussion!!

I dug out one of the papers in my archive which relates to this type of thing. It was a paper called "Bionic Research on Bird Feather for Drag Reduction" where they performed a micro-scan of toucan feathers and then manufactured 3x surfaces (with 1x smooth surface) to kind of "replicate" the micro-structures.

Here is the scan below for you to see what they were based off:


What they decided to do was essentially push a sheet of metal through two rollers with one of them having tiny little riblets which would dig into the sheet metal to form little channels similar to what they scanned. This was then placed in a wind tunnel and tested against a smooth plate. Here is what they found:


Between a Mach Number of 0.4 and 0.9, there was indeed a noticeable drag reduction efficiency gain of the ribletted plates vs. the smooth plate with the most noticeable effect being dependent on the surface geometry vs. speed. You can see that at higher Mach Numbers, the effect actually ends up having a negative effect vs. a smooth plate. Similarly, you can see that as the Mach Number drops away from 0.8 to 0.4, the gains of some of the surfaces are less substantial.

This is important as far as this discussion because F1 cars at Baku (372 km/hr top speed as I recall seeing) still only just hit a Mach Number of ~0.3 (plus or minus some amount due to temperature/humidity, altitude, etc.) and so I feel kinda confident that, at least with a toucan feather microstructure, there wouldn't really be any significant gains to be had by implimenting this type of surface. It is made worse by the fact that the flow structures over the cars as they drive in a straight line are not always perfectly aligned with the direction of travel - let alone when they are cornering!! This paper doesn't go into yaw effects with aerodyanmics, but I feel okay saying that your benefit would probably drop off at least by some amount.

My guess as to what is happening is that the little vortices which are induced within these channels have a "reduction" effect on the shear stress within the airflow. They probably induce a tiny increase in pressure though, simply due to there being more churning about on a surface with more surface area etc. Both of these would reduce the skin friction drag by a fair bit.

TLDR; too complex to impliment in a way which works for all flow conditions/directions which doesn't have some amount of flip-flopping between working and not, and the fact that most gains to be had are outside of the speed ranges of F1 cars. The other thing is that all of this skin friction drag reduction etc etc would pale in comparison to the drag reduction of something like a DRS system..................... oh right!! We already have those

[johnny comelately]

Okay... lots of comments to read here - gonna add my two cents worth to the argu.... errr I mean discussion!!

I dug out one of the papers in my archive which relates to this type of thing. It was a paper called "Bionic Research on Bird Feather for Drag Reduction" where they performed a micro-scan of toucan feathers and then manufactured 3x surfaces (with 1x smooth surface) to kind of "replicate" the micro-structures.

Here is the scan below for you to see what they were based off:
https://imgur.com/APRRhBl.png

What they decided to do was essentially push a sheet of metal through two rollers with one of them having tiny little riblets which would dig into the sheet metal to form little channels similar to what they scanned. This was then placed in a wind tunnel and tested against a smooth plate. Here is what they found:
https://imgur.com/XhFo1Ty.png

Between a Mach Number of 0.4 and 0.9, there was indeed a noticeable drag reduction efficiency gain of the ribletted plates vs. the smooth plate with the most noticeable effect being dependent on the surface geometry vs. speed. You can see that at higher Mach Numbers, the effect actually ends up having a negative effect vs. a smooth plate. Similarly, you can see that as the Mach Number drops away from 0.8 to 0.4, the gains of some of the surfaces are less substantial.

This is important as far as this discussion because F1 cars at Baku (372 km/hr top speed as I recall seeing) still only just hit a Mach Number of ~0.3 (plus or minus some amoutn due to temperature/humidity, altitude, etc.) and so I feel kinda confident that, at least with a toucan feather microstructure, there wouldn't really be any significant gains to be had by implimenting this type of surface. It is made worse by the fact that the flow structures over the cars as they drive in a straight line are not always perfectly aligned with the direction of travel - let alone when they are cornering!! This paper doesn't go into yaw effects with aerodyanmics, but I feel okay saying that your benefit would probably drop off at least by some amount.

My guess as to what is happening is that the little vortices which are induced within these channels have a "reduction" effect on the shear stress within the airflow. They probably induce a tiny increase in pressure though, simply due to there being more churning about on a surface with more surface area etc. Both of these would reduce the skin friction drag by a fair bit.

TLDR; too complex to impliment in a way which works for all flow conditions/directions which doesn't have some amount of flip-flopping between working and not, and the fact that most gains to be had are outside of the speed ranges of F1 cars. The other thing is that all of this skin friction drag reduction etc etc would pale in comparison to the drag reduction of something like a DRS system..................... oh right!! We already have those

You have used toucans in this great analysis, but they cannot fly very well

[Vyssion]

Looks like they fly okay to me...? Not like I was suggesting an emu or penguin feather structure Are you really going to try and invalidate this paper based on the fact that a toucan isnt a hawk or eagle?

[johnny comelately]

Looks like they fly okay to me...? Not like I was suggesting an emu or penguin feather structure Are you really going to try and invalidate this paper based on the fact that a toucan isnt a hawk or eagle?

http://notesfromthewildside.com/wp-cont ... 5-copy.jpg
https://upload.wikimedia.org/wikipedia/ ... posite.jpg
https://c1.staticflickr.com/9/8239/8541 ... 1af5_b.jpg

No, not at all that is why it was with a wink at the end.
As I said it is a great piece of research, very interesting.
I suppose the next step for investigation is the structure now that the surface behaviour has been shown.

[Vyssion]

Looks like they fly okay to me...? Not like I was suggesting an emu or penguin feather structure Are you really going to try and invalidate this paper based on the fact that a toucan isnt a hawk or eagle?

http://notesfromthewildside.com/wp-cont ... 5-copy.jpg
https://upload.wikimedia.org/wikipedia/ ... posite.jpg
https://c1.staticflickr.com/9/8239/8541 ... 1af5_b.jpg

No, not at all that is why it was with a wink at the end.
As I said it is a great piece of research, very interesting.
I suppose the next step for investigation is the structure now that the surface behaviour has been shown.

Okie doke

Yeah, I'd say thats a fair shout... Spacing between channels, sharp vs. soft channel geometry, depth, etc... VERY science project-y!!