Want low drag? Don't follow a template.

[Stubby79]

Originally Posted by JulianEdgar

I've spent too many thousands of hours modifying cars to be cavalier in such a manner.

That's why I don't put you down for spreading your view on the matter, and count on you to keep the rest of us straight on it.

[AeroMcAeroFace]

Originally Posted by Vman455

What are you all afraid of? Are you afraid your previous beliefs about aerodynamics will have to be rethought? Do you think you'll "regret" learning something new, as someone threatened in another thread...

[or are your beliefs] now so entrenched that you all truly believe it and no contrary evidence will be tolerated let alone investigated? What is it?

I think you are right, they don't want to admit that they have dismissed credible evidence because it doesn't fit their prior beliefs.
Scientists generally enjoy being proved wrong or that their conclusions are wrong or there is another way, it gives them more to think about and test and improve.

What is the problem with being wrong? You (and all of us) can now get better results and conclusions as a result. Dismissing evidence because it doesn't fit your prior beliefs is not scientific, and is a disservice to the community here.

[Vekke]

I find it really not nice how you try to sell your book here by saying things you say on the video.

Basic manners should mean something. If you claim something to be not true then you should show the results. I did not see any results showing otherwise in your video.
Sure those new cars have low drag figures, but is it due to to the roof taper or whole car being shaped in the windtunnel to match manufacturers idea of that current car model is and looks or is it modeled to have the lowest drag coefficient? I bet you dont know that so you cannot assume nothing just by looking at some tufts tests you have done. You say you have easy method to measure the pressure coefficients at the wake. from those you migth be able to see something already can you show your test results here on all of those tuft tested cars?
- Sure the old car has low drag figure but its not lowest it can go. Cars drag coefficient does not tell nothing about the potential how low the drag coefficient could be if everything is done to get lowest drag.

Aeroheads template shows the shape which leads to lowest drag.
- I have understood there can be attached flow with even steeper curves, but the the lowest drag is achieved if you follow the template.

Julian I would appreciate rapid answer with pictures and measurements to point out your argument true.

Here is a link which you should also read. https://ecomodder.com/forum/showthre...uel-15251.html
I dont want to hear answers it can be found at the book. For me it seems you have created your own truth on many topics here which are not true this topic especially.

I hope the wind will be with you on this, but my hopes are not high.

[Vekke]

On the honda legend tail. If you want to follow the template you make the current tail lid longer. No ecomodder would build there a spoiler you describe on the video.

- You make a spoiler which reaches backwards to meet the shape of the template. That means about half a meter extension.

[ME_Andy]

I agree 100% with Vekke. BTW I'm also a mechanical engineer.

The original description of the template was very clear:

Those with more advanced aerodynamic toolbags will will no doubt venture out into some of the more exotic shapes,but for amateurs,I believe this form can serve us well.

There's no reason to be rude on the forum.

[AeroMcAeroFace]

Originally Posted by Vekke

I did not see any results showing otherwise in your video.
Sure those new cars have low drag figures, but is it due to to the roof taper or whole car being shaped in the windtunnel to match manufacturers idea of that current car model is and looks or is it modeled to have the lowest drag coefficient?

But isn't that his point entirely? That low drag can be achieved without the/a template?

It is irrelevant whether it was for styling or drag, it achieves low drag, and doesn't follow the template.

"I have understood there can be attached flow with even steeper curves, but the the lowest drag is achieved if you follow the template." where is the evidence for this claim?

The template, I am pretty sure, without wheels, theoretically has a drag coefficient of 0.09.

Many solar cars with wheels, that are real, have drag coefficients around and lower than 0.09. But also none, of the many papers I have read about solar car design, say "we used an arbitrary template as the starting point".

I don't see what is relevant about being a mechanical engineer, mechanical engineering and aerodynamics are completely different things.

(I am not saying the template is useless, but it has many claims, and I have seen contrary evidence elsewhere in scientific research papers (not just in Julian's videos))

[freebeard]

No you're quite right - Freebeard is not obliged to correct misapprehensions.

Again with the gratuitous capitalizations. Way back when this started I offered this as elucidation:


https://xkcd.com/386/

I stopped correcting other people on another forum in the mid-2000s.

Originally Posted by Stubby79

He is in no way morally or otherwise obliged to correct people. His choice what and when he decides to speak up about. You - and everyone else - don't get to decide for him.

Thank you.

[Vekke]

Originally Posted by AeroMcAeroFace

But isn't that his point entirely? That low drag can be achieved without the/a template?

It is irrelevant whether it was for styling or drag, it achieves low drag, and doesn't follow the template.

"I have understood there can be attached flow with even steeper curves, but the the lowest drag is achieved if you follow the template." where is the evidence for this claim?

Its about what claims Julian has made about the template. not the drag coeffiecient figures of any cars.

First you need to read all the 19 pages of that aerotemplate topic and after that all the other topics that are related to using that I can say there are many. Details are in this forum for those questions, because I have learnt them from here. That information is not put to one page, but its spead here and there on the forum.

You can reach low aerodynamic drag coefficients by not using the template I am not saying that is not true. What I am saying that template leads to lowest drag coefficient. 0,22 is not a real low drag car. Its just a low drag production car which has certain limitations to designs it can use and what manufacturers want to use in their products.

I remember testing my first kammback in my Seat cordoba TDI 2008 with tuft testing. I think the final angle where I left it was around 17 degrees and tufts were attached with that angle. Sure it was better than no spoiler at all, but without any wind tunnel or CFD simulation softwares available. Then was no templates to be used just huchos book knowledge on these kammback angles and lengths.

If someone clearly says current template is so wrong he should have real data to back those claims otherwise its just noise in the water and clearly against the forum rules.

I have also looked these super aerodynamic concept and production cars and noticed they dont meet the template, but that does not prove nothing unless you have actual data of the cars development process how and why have they used the shapes they have used.

If no more real data is shared I still recommend using the template in your projects in correct way, unless you have the windtunnel or cfd simulations loops to prove your data.

The basic shapes is possibly to be simulated in basic solidoworks even in 1D and I believe results should be pretty accurate. So there is no sense to make any other claims which you cannot back up.

Of course you can say what you have found out, but with your own testing, but then you dont have any need to say bad things about other people who have studied and shared their knowledge here for years for free for others. and other is just trying to sell his books.

[AeroMcAeroFace]

Originally Posted by Vekke

I have also looked these super aerodynamic concept and production cars and noticed they dont meet the template, but that does not prove nothing unless you have actual data of the cars development process.

"What I am saying that template leads to lowest drag coefficient"
it just doesn't though, low drag yes, lowest, no.

A solar car having drag coefficient of 0.08 is evidence that lower drag coefficients than the template are possible.

The development process is irrelevant if they get a lower drag coefficient.

[Vekke]

That solar car is exellent example lets use it with the template:



Sad there is not clear picture the roof head cover at their pages, but with quick tilt of the picture is fills the template form pretty nicely to my eye.

Coincident? I dont think so. If you have time and find better pictures that test is pretty easy to do be anyone. If the most aerodynamically efficient test cars use the template where they can what is the reason if not lowest drag?.

Other forms are dictated by the need to have surface area to those panels. also the covers for wheels are probably designed with that teardrop shape. That solarpanel shape creates more skin friction as is not best but its needed.

Do also notice that not all pictures are in correct proportions what you find in the internet. If you take close picture of some part and try to model it same with your computer there will come errors depending on the lense that was used how ball shaped it is. Trust me I have tried.

Form follows function.