'template' in contemporary aerodynamic literature

[aerohead]

Originally Posted by JulianEdgar

Well I did ask you for links to threads where there had been proper testing of various different template style shapes for real car modification, but you didn't reply.

Yes, I think following a template in the mistaken belief that will get you a stellar outcome is wasting people's time. Far better that they do some testing and find out what is optimal on their cars.

As for your examples, as I've already said - if the extension has attached flow down to a smaller wake, I'd expect pretty good results... template or no template.

To make it categorically clear, I think posting a template for car shape on a discussion group and very strongly implying that it is the best shape for people to follow (no matter their car) is misleading and wasteful of people's time.

It might have been helpful in a past era when testing panel pressures, drag and lift were difficult, but that is not the case now.

Keep researching.

[JulianEdgar]

Originally Posted by aerohead

Keep researching.

Well that's the thing you see.

I don't just research, I also measure on the road (lift/downforce, separated/attached flow, panel pressures) and so I can see not only what is predicted to happen, but what actually happens.

It's very illuminating.

[MeteorGray]

Good point about the need to actually measure the aerodynamic effects of any modification on a particular car and its particular body design. With all the variables involved, how does one actually know what will happen with a particular modification unless its effects are actually measured?

Theory might get you in the ballpark, but it takes a lot more effort to win the game.

[California98Civic]

Originally Posted by MeteorGray

Good point about the need to actually measure the aerodynamic effects of any modification on a particular car and its particular body design. With all the variables involved, how does one actually know what will happen with a particular modification unless its effects are actually measured?

Theory might get you in the ballpark, but it takes a lot more effort to win the game.

Yes, I agree. And when I got here in early 2011, the emphasis was on testing. Aerohead was part of that. He has done quite a bit of testing, including working at a wind tunnel. We usually did these tests on the road using a variety of measurement instrumentation. A few years ago, testing efforts fell off. Take a look at MetroMPG's guide to testing for forum members from 2009. Still useful:
https://ecomodder.com/forum/showthre...tml#post147532

I'd reject a too hard distinction between theory and empiricism. Theories are the result of empirical examination and can themselves be tested further. Darwin's theory is not an invention of his imagination. It was an empirical investigation testing somewhat different concepts. Science is not just an accumulation of measurements. The aerodynamic qualities of the so-called template and similar low-drag bodies have been investigated empirically. The only controversy about them is whether they are appealing or practical as road cars.

[aerohead]

Originally Posted by MeteorGray

Good point about the need to actually measure the aerodynamic effects of any modification on a particular car and its particular body design. With all the variables involved, how does one actually know what will happen with a particular modification unless its effects are actually measured?

Theory might get you in the ballpark, but it takes a lot more effort to win the game.

The transistor was designed from theory.
Theory allows us to design aircraft and rocket ships inside a computer,within 1% accuracy.
All skyscapers are designed from theory.
All nuclear submarines are designed from theory.
The integrated circuit was designed from theory.
The upcoming Corona Virus vaccine will be derived from theory.
Theory allows capitalism to thrive.

[aerohead]

Originally Posted by JulianEdgar

Well that's the thing you see.

I don't just research, I also measure on the road (lift/downforce, separated/attached flow, panel pressures) and so I can see not only what is predicted to happen, but what actually happens.

It's very illuminating.

Keep researching.Full Navier-Stokes equation would be a good one.

[JulianEdgar]

Originally Posted by California98Civic

Yes, I agree. And when I got here in early 2011, the emphasis was on testing. Aerohead was part of that. He has done quite a bit of testing, including working at a wind tunnel. We usually did these tests on the road using a variety of measurement instrumentation. A few years ago, testing efforts fell off.

We must be seeing a different forum then. When I did my book, I asked people for examples of modifications that had been well-tested, so I could feature them. Lots of people contacted me but unfortunately I had to reject most of them because either:

• testing hadn't actually been carried out
• testing was done with poor methodologies (eg coastdown)
• their results were internally contradictory (eg claimed decrease in Cd didn't match actual increase in top speed)

As for Aerohead's wind tunnel testing, it was done in a such a tiny wind tunnel (with therefore such a huge blockage factor), I'd place zero credence on the results.

Originally Posted by California98Civic

Take a look at MetroMPG's guide to testing for forum members from 2009. Still useful:
https://ecomodder.com/forum/showthre...tml#post147532

I can't see anything there about throttle-stop testing, lift/downforce testing or surface panel pressure testing. Or eroding clay testing or even tufting!

Originally Posted by California98Civic

I'd reject a too hard distinction between theory and empiricism. Theories are the result of empirical examination and can themselves be tested further. Darwin's theory is not an invention of his imagination. It was an empirical investigation testing somewhat different concepts. Science is not just an accumulation of measurements.

Who has said testing should replace theory? Not me, anyway. The actual argument is this: if test results do not match theory, then the theory (or mostly in Aerohead's case) the application of it, is wrong.

Originally Posted by California98Civic

The aerodynamic qualities of the so-called template and similar low-drag bodies have been investigated empirically. The only controversy about them is whether they are appealing or practical as road cars.

That may be your belief; it is not mine. I agree that there is controversy about them in appeal and practicality as road cars, but I also have strong doubts about they way they are applied in developing modifications to existing cars - after all, what basically 99 per cent of people here are doing.

[freebeard]

We must be seeing a different forum then.

The scary thing is that everyone is seeing a different forum.

Urban Dictionary: Own private Idaho.
https://www.urbandictionary.com/define.php?term=Own private Idaho.
This is a phrase taken directly from the 1980 dance pop song, "Your Own Private Idaho" by the outrageous party band, the B-52's. It means "living inside an Idaho potato", or a very small space. Metaphorically, it refers to someone who is not paying attention because he is daydreaming, or under the influence, or otherwise wrapped up within his own very narrow sphere of interest or frame of ...

You make a positive contribution here, hopefully everyone can coexist.

Thee Template is a Procrustean Bed. Everyone slavishly follows the longitudinal section while ignoring the lateral section. And it fails to model the underbody.

Vehicles are a collection of parts, the Template can be applied to subsets, like pickup aerocaps and the bubble top coupes. Times past we've had discussions (like tears in the rain...) about blisters and canopies.

I actually think the boat tail looks ugly, and it would be illegal where I live.

Have you seen aerocivic?

[MHR1294]

Originally Posted by aerohead

The transistor was designed from theory.
Theory allows us to design aircraft and rocket ships inside a computer,within 1% accuracy.
All skyscapers are designed from theory.
All nuclear submarines are designed from theory.
The integrated circuit was designed from theory.
The upcoming Corona Virus vaccine will be derived from theory.
Theory allows capitalism to thrive.

Wouldn't normally chip in my 2 cents worth, but I think you're missing a few things from your post.

Nothing is designed from theory, things are DEVELOPED from theory. Design, production and testing, then going back to the design based on the physical testing results. It's an iterative process!

Otherwise we would never progress.

Theory AND development. Theory on it's own is useless.

Testing on it's own is also useless, if you don't know what to do with the results - you combine them with theory for an overall picture of what's actually happening.

Don't forget about all the failures with various buildings, nuclear reactors, transistors etc! because we only had a theory to go on when they were being designed.

[JulianEdgar]

Originally Posted by MHR1294

Wouldn't normally chip in my 2 cents worth, but I think you're missing a few things from your post.

Nothing is designed from theory, things are DEVELOPED from theory. Design, production and testing, then going back to the design based on the physical testing results. It's an iterative process!

Otherwise we would never progress.

Theory AND development. Theory on it's own is useless.

Testing on it's own is also useless, if you don't know what to do with the results - you combine them with theory for an overall picture of what's actually happening.

Don't forget about all the failures with various buildings, nuclear reactors, transistors etc! because we only had a theory to go on when they were being designed.

Yes indeed.

I do a lot of electronics (been writing for electronics magazines for 25 years) and one thing is for sure - you never, ever publish an electronic project without first testing it.

(I worked for years with a top electronics engineer - a brilliant guy who had developed literally thousands of electronic projects. He used to say: "When you test the circuit, it never works exactly as you had expected!")