Why don't vehicles have aerofoils to partially take the weight of the car?

[Ecky]

Originally Posted by aerohead

* If we can agree to analyze a specific vehicle, the math will answer our questions.

I'm not in immediate possession of enough data on any particular vehicle. Would you care to suggest a modern one? One made in, let's say, the last 20 years, which is relatively common/popular?

[aerohead]

Originally Posted by JulianEdgar

In a nutshell, this is why I really dislike "thought experiments" on web discussion groups. (Not just this thread - all of them.)

Anyone - anyone at all - can come up with ideas that might possibly work. But does an idea alone have any value? I'd suggest that in the field of modifying cars, no, it doesn't.

What has value is coming up with the idea then proving (through actual testing) that it works.

Maybe I have a different perspective because, as a magazine editor, I used to get maybe one or two of these a week sent to me for my thoughts. Someone, dreamily looking into space, said "But what if we did...? Wouldn't that be great? I know, I'll send it to that bloke Julian Edgar for his thoughts." I have one in my in-box right now.

Is it a good idea? Who knows? Who cares? I don't, much. Unproven ideas are easy. I'd go so far as to say: trivial. Only two of those hundreds of ideas that I have been presented with over the last 30 years, have, to my knowledge, ever been commercially successful. And not serendipitously, both had been well tested before being presented to me.

But the real reason I dislike thought experiments is this: they spread likely falsehoods. The idea may have been a mere postulation, but soon it takes root. The idea initiator has plausible deniability ("I didn't say it was true or would work!"), but they're the one who initially promoted it. Just look at US politics for many classic examples.

Suggesting that lift is a good idea in road cars - and 99 per cent of this website is about modification of road cars - is an especially bad idea to spread... there is literally truckloads of evidence against it.

* those who dislike them are in no way obligated to participate.
* personally, I've never heard a stupid question.
* the world's being destroyed by people who don't ask any.
* the value of a question could only be quantified 'after' the exploration was complete.
* the job of the engineer is to solve the idea on paper or in a computer, without testing, using theory, and all extant data available.
* some commercial successes of ideas have ruined the world.
* I'm quite confident that commercial failures of the past are what will save us from the successes.
* bad ideas will not survive the light of day. They're not a threat.
* In the United States of America, citizens are free to believe all the bad ideas they can contain.
* politics would be a poor analogy. There's no such thing as political 'science.'
* 'good' and 'bad' are subjective terms. They cannot be quantified. There's no acid test for them. There never will be.
* perhaps, the data which emerges after a full investigation, will be enough for an interested participant to draw their own conclusions.
* I for one, am not interested in thought police. I don't need EcoModder.com to be sanitized for my own protection.
* the only stupid question is, the one that was never asked.

[aerohead]

Originally Posted by JulianEdgar

If you reduce the effective weight of the car by half through aerodynamic lift, you will decrease the unloaded car's suspension static deflection by half. If the car has a static deflection of (say) 3 inches, and you have 50 per cent lift, the car will ride 1.5 inches higher. That will increase CdA, and may well in fact cause further lift.

(The opposite happens when you lower a car* - Cd, CdA and Cl all tend to decrease. *Road cars, with normal ground clearance.)

I know of at least one University study at MIRA in which the opposite was found to be true.
I'd lose the word 'will' and replace it with something about 'statistically significant.'
Exceptio probat regulam

[aerohead]

Originally Posted by JulianEdgar

Anyone can come up with ideas - and people very often do. I've had three this morning.

- I wonder if I put cabin outlet vents on the roof whether that would energise the boundary layer and reduce flow separation?

- I wonder if the sky is blue above my house today because someone is holding up a big blue sheet?

- I wonder if I pressurised the frame of my bicycle at say 100 psi whether I could run tubes with paper thin wall thickness?

My classic story of an idea is the probably apocryphal one of WWII. Someone wrote to the UK government saying they had an idea for finding all the German Wolfpack submarines in the Atlantic.

Yes, asked the government, what is your idea?

Oh, said the correspondent, we should just boil the ocean dry.

Ideas are ten a penny - like opinions. Everyone has them. Ideas alone are worthless.

I am also amazed how people have, and I can only describe it as the arrogance, to believe ideas they come up with are worthy of consideration... without their having done even an hour of research or any testing at all. For example, I would never, ever suggest how solar race teams could do better. They are so far ahead of anything I could come up with that it's just not funny. We've had a person in this group suggest that the head of Porsche aerodynamics knows little. He knows so much more than any of us about car aerodynamics that to think otherwise is to be completely deluded.

I am currently (ie this morning) working with a suspension expert as I write a book on the history of car suspension. He knows so much more than I do about suspension that, even if I spent every minute between now and when I die studying suspension, I could never catch up. So yes, I am indeed happy to be guided by experts suggesting ideas. And you can be sure that in every case, they will have plenty of evidence to support the ideas they suggest - otherwise, they wouldn't have suggested them.

In the United States they are called U.S. PATENTS, for 17-years, just for coming up with a novel idea for a product or process, without ever testing anything.
The field of study, which is a requirement for the patent application, is a tip-off the the patent examiner, as to whether or not due diligence, and a thorough research of the appropriate patent fields have been undertaken by the applicant.
The Small Business Administration and Defense Advanced Research Projects Administration offers $ 425,000 ( US ) for ideas.
Check your premises.

[aerohead]

Originally Posted by Ecky

Intuitively, this is tough for me. If you're displacing air in order to provide an upward force on the vehicle, my intuition says that energy is lost. But, it's been proven many times that what is intuitive often isn't reality.

* Technically, energy is always conserved.
* It may take on a form which is essentially useless to us, which is at the heart of the 2nd-Law of thermodynamics. Entropy.
--------------------------------------------------------------------------------------
* Using and internal combustion engine, with an overall thermal efficiency of 15% to power a wing ( which has it's own losses ), to generate lift, to reduce rolling-resistance, has some overall thermal or mechanical efficiency footprint.
* The gain from the pain quotient must be examined to decide if the concept is a non-starter.
* There's enough existing information available that, actually building and testing could all be done virtually, with a high degree of certainty in the results.
* The days of physical prototyping R&D are fast disappearing.

[aerohead]

Originally Posted by JulianEdgar

Aerohead deliberately misinterpreted by post, by pretending that what I wrote ("As far as I am aware, there has never been a road car of any type, ever created anywhere, where aerodynamic lift was a positive.") was somehow saying that no cars had lift.

I couldn't be bothered explaining "a positive" (i.e. something good) isn't the same as "positive" (i.e. the mathematical sign opposite to negative).

So I doubt the point is worth pursuing.

I am not interested in discussing Buckminster Fuller; I've said everything I have to say on him in my aero history book.

Exactly! And the the very reason why there's so much consternation surrounding your posts.
And stop with the 'deliberately' language. I've warned you time and time about this! It's completely unacceptable!
Those of us who possess critical thinking capability will continue to struggle with your loose use of the English language.
If you'll learn technical writing skills, it will save us all a lot of grief.

[aerohead]

Originally Posted by Ecky

I'm not in immediate possession of enough data on any particular vehicle. Would you care to suggest a modern one? One made in, let's say, the last 20 years, which is relatively common/popular?

I was hoping that a member or guest, with a larger database than my own, might step forward with a well-documented example.
In the meantime, I'll set up a gray matter sub-routine and see if I can isolate a candidate.
Hucho had the VW 1500 notchback, but that's going way back.

[aerohead]

If any member or guest, that wants to become a member, and has a subscription to CAR and DRIVER Magazine, they may already have data for a candidate car on the pages of some present or past issue.
Periodically, C & D road warriors will descend on the A2 Wind Tunnel, and do a complete test of some car, including lift and drag data. Somewhere I have one for a Cadillac CTS Coupe.
The vehicle itself doesn't matter. It's the test data we'll be able to use for the lift/ R-R table-top discussion.
Thanks in advance.

[freebeard]

Originally Posted by Julian Edgar

Ah yes. I forget your propensity for disappearing down rabbit burrows. All wonderful when we never actually do anything, personally, in modifying cars (caveat)

'Let aerohead answer my question' is a rabbit burrow? I've read Robert Aton Wilson. I'd prefer 'reality tunnel'.

I live on a fixed income (and I'm no Burt Munro), my efforts are modest*. Maybe they fly under your radar?

Over the years I've gone from a staunch air-cooled VW person, to driving a Geo Metro and holding an Arcimoto reservation number. Modifying cars is only one aspect of EcoModding, you nut behind your wheel. Mainly, I'm in it for The Lounge.

aerohead -- Thanks. I miss my old Notchback. I drove it when I lived in a geodesic dome. I guess I miss the 90s in general.

*Right now I'm 3D printing center caps for the Marathon wheels I just had powder coated. Their coming out more like bird's nests. So I'm learning all about stringing and first layer adhesion.

[JulianEdgar]

Originally Posted by aerohead

In the United States they are called U.S. PATENTS, for 17-years, just for coming up with a novel idea for a product or process, without ever testing anything.
The field of study, which is a requirement for the patent application, is a tip-off the the patent examiner, as to whether or not due diligence, and a thorough research of the appropriate patent fields have been undertaken by the applicant.
The Small Business Administration and Defense Advanced Research Projects Administration offers $ 425,000 ( US ) for ideas.
Check your premises.

As soon as Aerohead writes something here, you can be fairly confident it needs checking for its veracity. I've found it literally doesn't matter what the topic or subject is.

You cannot patent ideas, as a 30 second web search shows.

Here

Here

...and no doubt in plenty of other places.

Why can't you patent an idea? Because an idea without evidence is valueless.