Thank you

[JulianEdgar]

Originally Posted by jjackstone

Mr. Edgar was writing about posting facts in there somewhere. I suggest that the facts should be posted with all references and the references qualifications if not already being done.

That's been tried.

It became impossible when Aerohead posted references to textbooks that actually don't support what he was saying.

When challenged, Aerohead said that was because he (Aerohead) could see special things in the references that other people (eg I, AeroMcAeroFace and Vman455) couldn't see.

When people are just making up stuff, it's impossible to have a normal discussion.

Here's an example: there are no textbook references that support The Template being used to to guide the aerodynamic shape of extensions to cars, to guide the heights of spoilers, to assess the 'aerodynamic purity' of shapes, to determine where there will be attached and separated flow (etc).

None!

That's pretty stunning when the above stuff has underpinned an enormous amount of advice given on this group over many years.

[JulianEdgar]

Originally Posted by Isaac Zachary

If I ever did an engine again I'd want access to a dynanometer. But would it be worth the $700 for just one testing session?

I have a chassis dynamometer. I very rarely use it because road testing (eg with a stopwatch or accelerometer) gives me better information. Cost - under US$25.

[oil pan 4]

Yeah he just makes stuff up.
He will make up a reference, then say a 10 minute youtube synopsis of a study based on 10,000 hours of observation is useless and can't possibly contain anything useful.
And I have a reference.

Originally Posted by aerohead

contextual.
manipulative.
inaccurate.
not only cherry-picked, but a 'paid to publish' paper, simply to imply to the audience, the appearance of consensus and validation within the broader scientific community.
extreme confirmation bias.
audacity to attempt to reduce a required 10,000-hours of study, down to a 10-minute sound bite.
completely lacking in scientific rigor.
failure to defend premise.
easy to understand why broadcasts would repeatedly come under fire.
I don't see any real science demonstrated, only effective marketing attempts towards an audience which is more uninformed than the author.
an un-regulated, non-juried internet is a double-edged sword.
caveat emptor.

Pretty much anything he doesn't agree with is always wrong, or the person who wrote it is stupid or lives in a trailer park. He spends more time digging up dirt on the messenger than the what's in question.

[JulianEdgar]

Originally Posted by freebeard

But you can dodge the question. I can't explain your conceptual leap from no-template to mock-up.

The Template is a predetermined shape that has been stated here many times to be able to do the following:

guide the aerodynamic shape of extensions to cars, to guide the heights of spoilers, to assess the 'aerodynamic purity' of shapes, to determine where there will be attached and separated flow (etc)

Test and development, including the use of mock-ups, does not start with the above premise.

So for example, attached and separated flow is not determined by overlaying The Template on a profile of a car and making judgements. It is ascertained by tuft testing the car.

So for example, a rear hatch extension does not start with an angle determined by The Template. It starts with the angle horizontal and then inclines it downwards, with flow separation and drag being measured at the different angles.

So for example, the height on a rear spoiler on a three-box car is not determined by overlaying The Template on a profile of the car and extending it upwards until it reaches The Template line. It starts by tufting to see if there is attached or separated flow on the trunk lid (etc).

The Template is not the starting point for anything.

[Isaac Zachary]

Originally Posted by JulianEdgar

I have a chassis dynamometer. I very rarely use it because road testing (eg with a stopwatch or accelerometer) gives me better information. Cost - under US$25.

How much for shipping? How does a stop watch give you better info? Mine must not be as accurate as yours because that's what I've been using. I tried the accelerometer and didn't find the results consistent and repeatable.

[JulianEdgar]

Originally Posted by Isaac Zachary

How much for shipping? How does a stop watch give you better info? Mine must not be as accurate as yours because that's what I've been using. I tried the accelerometer and didn't find the results consistent and repeatable.

How much for shipping what? Neither the stopwatch or accelerometer cost much, shipping included or not.

A stopwatch gives better info than a dyno because, unlike a dyno, it takes into account:

1. Real aerodynamic flows

2. Real rotating inertia within the driveline (ie unlike a dyno, ramp times precisely match gearing).

The only thing I find impossible to achieve on the road is ultra low-load tuning of ignition timing - whereas that is quite easy on the dyno.

You've repeatedly said that you can't get consistency in testing. I'd suggest that's because your testing techniques aren't very good - either in the way you do the tests or the tests you choose to do. For example, with accelerometer testing, I can easily get results that match within a few percent on consecutive runs. The tests that I suggest doing (that don't include trying to hold a constant MAP value) are highly consistent and repeatable - if they're done with care, anyway.

[Isaac Zachary]

Originally Posted by JulianEdgar

How much for shipping what? Neither the stopwatch or accelerometer cost much, shipping included or not.

A stopwatch gives better info than a dyno because, unlike a dyno, it takes into account:

1. Real aerodynamic flows

2. Real rotating inertia within the driveline (ie unlike a dyno, ramp times precisely match gearing).

The only thing I find impossible to achieve on the road is ultra low-load tuning of ignition timing - whereas that is quite easy on the dyno.

You've repeatedly said that you can't get consistency in testing. I'd suggest that's because your testing techniques aren't very good - either in the way you do the tests or the tests you choose to do. For example, with accelerometer testing, I can easily get results that match within a few percent on consecutive runs. The tests that I suggest doing (that don't include trying to hold a constant MAP value) are highly consistent and repeatable - if they're done with care, anyway.

Low load ignition timing was one of my main goals to test. No aero, all engine related tests. So maybe that was the problem.

I do find it hard to test around here because there are no flat roads. And straight stretches longer than half a mile are hard to find too.

[JulianEdgar]

Originally Posted by Isaac Zachary

I do find it hard to test around here because there are no flat roads. And straight stretches longer than half a mile are hard to find too.

No flat roads and no straight roads = near impossible to test. I currently drive 30 miles to my test location.

Example of on-road accelerometer testing:



Effectively shows the on-road engine torque curve. Note how before the turbo comes on boost, there's no change before/after. I have a whole book on on-road car testing.

[Isaac Zachary]

Originally Posted by JulianEdgar

I have a whole book on on-road car testing.

Cool!

Originally Posted by JulianEdgar

No flat roads and no straight roads = near impossible to test. I currently drive 30 miles to my test location.

Sounds like I need to give up. It's about 300 miles (west, east or south) to where it's flat and straight.

[freebeard]

A hundred-foot circle averages out the crosswinds.

So for example, a rear hatch extension does not start with an angle determined by The Template. It starts with the angle horizontal and then inclines it downwards, with flow separation and drag being measured at the different angles.

It drives me nuts when people say 'angle' when they mean 'tangent' but I don't burn what little social capital I have trying to get people to change.