Porsche 911 Ducktail - Study/Alternate - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

freebeard · 03-10-2018, 07:09 PM

I hope you didn't miss my edit four minutes later. The forum is so busy it's hard to keep up. I'm trying to build a metal kitchen cabinet to replace my plywood one. I'm hitting it hard for one hour a day.

kach22i · 03-10-2018, 07:31 PM

Quote:

Originally Posted by freebeard

I hope you didn't miss my edit four minutes later. The forum is so busy it's hard to keep up. I'm trying to build a metal kitchen cabinet to replace my plywood one. I'm hitting it hard for one hour a day.

Oh, yes I did catch that but the Trans-Am image I found just happened to coincide.

What you described is similar to a "Super Ducktail" (my term not an official name) I have on my old computer of a racing Porsche 911. It raised the Ducktail, widened it past the engine lid, and fluted it along the sides. Way to aggressive for what I had in mind, but marvelous in it's own right.

I'll try and find an image of it, worthy of inclusion.

Oh, and I found a wind tunnel for a model by happenstance.

https://www.rctech.net/forum/electri...ricks-103.html

I found the "Super Ducktail", but the car I was thinking of was white. It's similar to the below in any case.

http://germancarsforsaleblog.com/category/race-cars/

I'm not looking for all that down-force, nor all that bodywork.

http://germancarsforsaleblog.com/mot...acing-replica/

Looks like they taped them on and liked the results before they glassed them in.

http://www.racingsportscars.com/phot...-05-13-009.jpg

freebeard · 03-10-2018, 10:49 PM

That's what I was thinking, wider to catch more air and with the horizontal fillet.

kach22i · 03-11-2018, 10:41 AM

Different car from an old 911, same issue of disrepair for me, engine not running full tilt thereby drawing in air during wind tunnel testing - so what's the point if not simulating real world conditions?

REPOST:
http://ecomodder.com/forum/showthrea...d-26678-3.html

Quote:

Originally Posted by kach22i

We have talked about this car before, but I don't recall ever seen wind tunnel and smoke pictures of it before.

Does this last image indicate that attachment os air flow is not everything?

Seems to look like the air knows what to do and is not tumbling away in a disruptive manner.

EDIT-1: The wheels do not seem to be turning in the wind tunnel photos, therefore the draw of the engine fan does not seem to be entering the equation. Making the air flow even more flattering for this design, or less so?

The messy air and pressure discharge under the car's engine bay would undo any gains topside though the rear engine intake?

kach22i · 03-11-2018, 10:53 AM

Quote:

Originally Posted by freebeard

That's what I was thinking, wider to catch more air and with the horizontal fillet.

I sort of looked in a similar direction a while back trying to figure out a cold air intake system using ram air. This is done on some of the later 993 models incorporating intake inlets into the wing, popular in the more garish aftermaket offerings as well.

https://www.total911.com/porsche-993...sport-raw-993/

My thoughts on that line of exploration was to blend or flute the inlet into a sugar-scoop tapered into the body just under the rear glass belt-line. Just so that it wasn't hanging out there like elbow macaroni.

Sooooooooooo.........blending a "chime" (jet aircraft term) onto some kind of aft aero-device has been of interest. Even thoughts of reusing the roof wing on my pickup truck or the similar contraption as seen above my hovercraft duct have been sketched up.

In most of my schemes there is an air-gap between the car body and aero-device so that the engine lid can be raise and there is no disruptive joint in the assembly. In essence, just want to keep the wing/spoiler simple and in one piece.

Right now I'm thinking a foil or spoiler with an open bottom drainage slot in the location shown on the last model photo composite image is one last possible direction before this line of thought dead-ends.

Gotta take a thought until it dead ends.

I can't help myself.

EDIT:
What I was trying to describe as my last design attempt in this direction is perhaps an adaptation of the 993 basket hoop third brake light.

https://www.ecklers.com/porsche/993-...iABEgI3R_D_BwE

Only bigger, better and of different function.

The hoop above was to work with work with the adjustable grille.

https://www.luxsport.com/1998-porsch...rera-c-317.htm

http://pilotesanciens.blogspot.com/2...er-dealer.html

Quote:

basket-handle hoop

I'm going to cut up another business card, it's the right paper stock weight.

kach22i · 03-11-2018, 02:57 PM

Having more fun with my model and aerodynamic concepts.

When I first put it on it was level flat, and realized it was under the aero-template too much, plus could not open the engine lid. I curved it up to resolve both issues - could be a bit smaller/thinner in retrospect.

Also posted below if you need to see them a little larger.

random pics that YOU have taken....... - Page 606 - Pelican Parts Technical BBS

Now look again at the below image, how the flow sneaks under the air-slot under the rear spoiler much as it does on the roof wing of my pickup truck.

aerodynamics? - VW GTI Forum / VW Rabbit Forum / VW R32 Forum / VW Golf Forum - Golfmkv.com

I know that many of the images regarding my truck were lost to Photobucket's 3rd party BS including the CFD images, but the long and short of it is, the air getting under is accelerated and this draws the air above it downward.

In this case the backside of the wing/spoiler engages the airflow, causing a build-up of pressure, this pressure can escape downward and into the cooling vent, or attempt to fight the flow above and probably lose and end up as a vortex aft, which in turn would once again cause down-force and downward airflow on the engine lid.

All just my imagination at work currently, but this is much closer to being worthy of testing in some manner - in my opinion.

If I had to say this design reminds me of most, I'd say the New Beetle hoop wing.

FS/WTT: retro new beetle - NewBeetle.org Forums

I'm wondering if that would fit my car now.

kach22i · 03-11-2018, 04:14 PM

I had the camera too close to the car/object on the top overhead views and this was distorting things.

Here is a better aerial true view.

freebeard · 03-11-2018, 06:28 PM

At the Darko wind tunnel, a wire mesh screen moderates airflow 40ft away around a corner. Perhaps there is application here?

If you're going to publish correct geometry you should put a Creative Commons bug in the corner.

kach22i · 03-11-2018, 07:03 PM

Quote:

Originally Posted by freebeard

At the Darko wind tunnel, a wire mesh screen moderates airflow 40ft away around a corner. Perhaps there is application here?

You mean to straighten out the air flow off a swirling fan?

I looked at a couple of PDF's and a website on the subject, not sure that you mean exactly.

I have cardboard, mirrors, drinking straws and cigars.......................maybe I should blow some smoke?

freebeard · 03-11-2018, 10:15 PM

Thanks for asking

I hadn't posted these pictures from Darko:

The story is that after they finished the coke-bottled test section it had attached turbulence which reduced the effective cross-section. The solution was the (double-pass) 2" welded wire mesh wall. It had a wire mesh man-door in it.

Somehow it moderated the flow through the test section. Crazy world or what?