Want low drag? Don't follow a template.

[JulianEdgar]

Originally Posted by 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.

I would sell more books by agreeing with what everyone here says, rather than arguing against it. Pretty obvious.

In this, and the other posts you have made on this topic, you are not arguing against what I have actually said. So I'd better say it again. Note that I am talking about how I have seen the template being used here in the last 12 months, not what it was originally intended to do (or anything else for that matter).

The template is claimed to allow you to:

- Show where there is separated and attached flow on existing cars

This is very much yes/no - is the flow attached or separated? The template definitely does not show this on cars.

- Guide the shape of rear extensions

Absolutely not. The best shape rear extension will depend on a whole lot of factors, and following a preset template is no guide at all to gaining the best outcome.

- Show how rear spoilers on sedans should be positioned and shaped

Completely wrong. This confusion shown by Aerohead when describing how rear spoilers work is based on his belief in the template (and how rear spoilers worked on old cars), and following that advice will give terrible outcomes on any modern sedan. (And in answer to your point - I have seen it stated here that the spoiler should reach up to the template line.)

- Allow the assessment of the ‘aerodynamic purity’ of cars

The idea that, if only car makers followed the template they would get so much better results, is complete rubbish. Therefore, overlaying a car and 'measuring it' against the template (to purportedly see how good the car is) is equal baloney. After all, why not pick one of the other five low drag shapes with which to do the comparison?

The template is just one of a bunch of different, low drag, theoretical shapes. If it were presented as that, then that would be quite correct, and I'd have no issues.

I don't know, maybe it started off like that - but it's certainly gone into crazy land since!

[JulianEdgar]

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?

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))

No current professional car aerodynamicist uses the template for anything.

In fact one such aerodynamicist, who has worked for major car companies including leading car aero development (ie a real car aerodynamicist, not amateurs like us) told me how he very much enjoyed my video that debunks the template.

He didn't say: "Oh my gosh, don't you realise that the template is fundamental to all we do."

For those who think the template is so important, just read any current car aero textbook. "Optimal shapes" (all of them) are typically given only a few pages in the whole book - they're just not that important.

[freebeard]

Upthread or elsewhere I mentioned blisters and canopies. That solar racer is at one extreme.

Mid-range would be your bubble-top coupe. 1964½ Mustang, etc.

The other extreme IMHO — the Volkhart Sagitta.



The cabin is well integrated with the two pontoons.

[JulianEdgar]

Originally Posted by AeroMcAeroFace

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.

This needs repeating! (My bold).

[ksa8907]

I've been watching from the sidelines and that's where I'll return. From what I understand of all these points is that the "template" works as it sits.

If you change things, other forms may work as well. It is not a perfect shape that must be followed or adhered to, many other shapes and combinations of features can yield similar or better results through enough testing.

Is that a sufficient summary? Can we move past this all now?

[freebeard]

Can we move past this all now?

I will never lose my affection for the Volkhart-Sagitta and it's 25hp VW engine.

[elhigh]

Originally Posted by JulianEdgar

Well, since you ask: yes.

On a discussion forum I would have thought it normal behaviour to speak out when you know that there is misinformation being put forward in a post.

Or he has a job and can't be expected to spend all his time refuting every assertion. That's possible. We've had some nutty statements fly around here.

[freebeard]

Or he doesn't have a job, but still can't be coerced into 'caring'.

Originally Posted by JulianEdgar

On a discussion forum I would have thought it normal behaviour to speak out when you know that there is misinformation being put forward in a post.

Please understand Internet culture is at odds with passive-aggressive normies. It's a hall of mirrors. When you point a finger, you see it pointing back at you, back at you, back at you....

[JulianEdgar]

Originally Posted by ksa8907

I've been watching from the sidelines and that's where I'll return. From what I understand of all these points is that the "template" works as it sits.

If you change things, other forms may work as well. It is not a perfect shape that must be followed or adhered to, many other shapes and combinations of features can yield similar or better results through enough testing.

Is that a sufficient summary? Can we move past this all now?

No it is not - perhaps you need to do more than just watch from the sidelines.

There are (at least) four uses to which the template is often put here where the template simply does not 'work as it sits'.

It cannot be used to decide any of the following with any more accuracy than basically closing your eyes and guessing:

- Show where there is separated and attached flow on existing cars

- Guide the shape of rear extensions

- Show how rear spoilers on sedans should be positioned and shaped

- Allow the assessment of the ‘aerodynamic purity’ of cars

Therefore, when it is used in just these ways, it is massively deceptive and misleading.

[JulianEdgar]

Originally Posted by freebeard

Or he doesn't have a job, but still can't be coerced into 'caring'

Please understand Internet culture is at odds with passive-aggressive normies. It's a hall of mirrors. When you point a finger, you see it pointing back at you, back at you, back at you....

I am sure all that means something to you. I reiterate my point, which I would have thought so obvious as to not need to even be stated in the first place:

On a discussion forum I would have thought it normal behaviour to speak out when you know that there is misinformation being put forward in a post.