The Fastback bloc

[aerohead]

Originally Posted by freebeard

My recollection is that the blunt nose and rear taper from Mair, minus the constant-section center approximates [one instance of] Thee Holy Template.

I've met with aerohead on The Salt and at Darko.

On Internet it is customary to post a wrong answer. That how you find out the right one. I documentated the pushback against the Template that was available before you started posting.

My intent really was to draw out the Morelli design that was all forebody with max camber at the C-pillar and a 45° chamfer instead of a wickerbill.

The closest I can find is this [Honda?] concept:

It's a pretty amazing concept. The Cd was published, and remarkable for such a short vehicle. Like the Aston Martin Cygnet/ SCION iQ.

[aerohead]

Originally Posted by JulianEdgar

No, I think you have it quite reversed. Using a template of any type makes us think in 'the box' that the templates creates. Far better to test a variety of approaches and see what works, rather than have the template already directing us in a certain direction.

Concrete example: when I made the roof extension to my Skoda Roomster, I tested many different angles until I found that which gave the best results. The final design therefore took into account everything happening on the car - boundary layer thickness, wake pattern, etc. I didn't have any preconceptions as to what would work - which I would have had, if I'd thought a template (any template) would be a guide.



That's OK. Templates (and Aerohead's endless discussion of ideal shapes) I see as relevant only if we were all developing cars from scratch. If we are working with an existing car shape (ie modifying it) I think templates - any templates - are worse than useless.

It's Hucho's shape. I just took the archipelago of dots he shared and put it all together, plus my own trick which has escaped detection so far.
If you're taking issue with me, you're taking issue with Hucho.

[aerohead]

Originally Posted by JulianEdgar

1) Calling something a law gives it no further credibility

2) A Wiki - an editable body of knowledge - is nothing like a discussion group. Here people don't edit out their mistakes, misunderstandings, etc. All the material stays present to cause confusion as people further down the track try to follow threads.

3) To be successful, the approach that you suggest requires a very large number of people knowledgeable about the topic. In car modification, it also helps a great deal if people have actually done a lot of testing and development of what is being discussed.

I reiterate: I think suggesting that posting incorrect information is a good idea is really dumb.

I couldn't agree more! So why don't you stop?

[freebeard]

Can't we all just get a bong?

[aerohead]

Originally Posted by JulianEdgar

This is Aerohead's normal mix of irrelevancies, errors and half-truths.

If Aerohead believes the rear active spoiler on the Porsche Taycan is a bandaid put on a mistake, he appears to be suggesting he knows more about car aero than Porsche.

Mind-boggling.

Someone 'styled' the Taycan.
Aerodynamicists at Porsche may have made recommendations about the general architecture of the Taycan, citing weaknesses aerodynamically. That's all fine an good, however, the stylist, manufacturing engineers, bean counters, and marketing people might have the final say in the matter. Hucho went up against this at VW AG. Any modification had to be 'stylistically acceptable.'
Adding a rear spoiler would be a rather simple matter, considering a complete overhaul of the shape.
Since the 1998 911 GTR was primarily a race car, without upsetting devotees of the 911, Porsche was in a better position to throw the template at that car. As a 'halo' car, Porsche had it's reputation riding on the aerodynamic advantage of the lower drag, then throwing as much downforce-induced drag as they dared, in a delicate dance of speed versus cornering ability.

[aerohead]

Originally Posted by JulianEdgar

You write absolute rubbish - and your fake attributions are disgusting.

Hucho has never written anything about the Taycan, let alone the statement you attribute to him.

Hucho wrote about spoilers. And he said that simply lofting the rear of the body contour, up to the height of where someone intended to end the spoiler, would not only be better for spoiling lift, it would be better for drag as well.
I gave you the exact page number many months ago.
You're like my cat. Once she learned to speak, all she wanted to do from then on is to argue.

[aerohead]

Originally Posted by JulianEdgar

Just what I said Aerohead would do! Tuft testing showing attached flow isn't really showing attached flow if Aerohead doesn't agree with it.

Spare me the mental contortions to attempt to justify the unjustifiable.

You're confusing downwash for flow attachment. They are completely different animals. The vortices which are inducing the downwash cannot be visualized with tuft testing.
Again, all provided to you specifically, months ago, yet you cling to your folk knowledge.

[aerohead]

Originally Posted by JulianEdgar

Just the normal mix of Aerohead irrelevancies and misunderstandings.

And, I am starting to realise, quite breathtaking arrogance - Aerohead obviously thinks he knows far more about car aero than Jaguar, Porsche (etc). Amazing.

I've constructed vehicles with lower drag than them. I didn't have a committee telling me that I couldn't. That's as far as I'll go. They haven't cornered the market on cardboard and duct tape.

[freebeard]

You're confusing downwash for flow attachment. They are completely different animals.

Porsche exploited downwash for air intake.

edit:
I know, not a good example. The firewall is modeled incorrectly and they took 'boxer' engine too literally.



Better? Smaller? It's all I've got.

No lift in the rear, all it needs is a rake.

[JulianEdgar]

Originally Posted by aerohead

Someone 'styled' the Taycan.
Aerodynamicists at Porsche may have made recommendations about the general architecture of the Taycan, citing weaknesses aerodynamically. That's all fine an good, however, the stylist, manufacturing engineers, bean counters, and marketing people might have the final say in the matter. Hucho went up against this at VW AG. Any modification had to be 'stylistically acceptable.'
Adding a rear spoiler would be a rather simple matter, considering a complete overhaul of the shape.
Since the 1998 911 GTR was primarily a race car, without upsetting devotees of the 911, Porsche was in a better position to throw the template at that car. As a 'halo' car, Porsche had it's reputation riding on the aerodynamic advantage of the lower drag, then throwing as much downforce-induced drag as they dared, in a delicate dance of speed versus cornering ability.

What does all that mean? Nothing much.

The Taycan uses a active rear spoiler to achieve a low rear coefficient of lift when it is deployed, something that is needed because of the car's relatively high coefficient of rear lift.

Obviously, Porsche would have not fitted it if they could in fact have achieved a similar low level of lift and drag by other means, while retaining the packaging (etc) requirements for the car.

Aerohead writes as if the combination of low lift and drag is just a pen-stroke away, when in fact all the shapes he nominates are high-lift shapes. (High lift in the real world, not in a world that uses models of non-viscous flow, etc.)

Basically, Aerohead's theory of lift on modern car shapes is quite wrong, so he needs to invent weird reasons to explain the actual outcomes we can see on cars like the Taycan.