Ford Escort ZX2 Aerodynamics

[BabyDiesel]

Originally Posted by aerohead

Technically,a trip strip is any device which acts like a turbulator to trip a laminar boundary layer into a forced transition to turbulent boundary layer,or energize a TBL over a 'fast' contour.
It can be sand glued on,a wire,a bright molding on a Landau roof,dimples,nubs,ribs,micro-vanes,vortex-generators.
The sharp edge on the Prius is a fix to a design problem discovered in the wind tunnel.The original body created bistable flow,buffeting,and noise generation.
The hard edge fixes the separation line to maintain a constant drag coefficient,rather than one which 'hunts.'
Since they extend the elongation of attached flow and pressure recovery,they contribute to higher base pressure and lower pressure drag.All good.
Don't expect any remarkable savings.

If I am reading this right, a trip strip can be the vortex generators that I have seen some fellow EMers put on their rear diffuser? I need to research laminar and turbulent boundaries, and a trip strip's simulated effect.

I would prefer a constant drag coefficient, rather than one that varies with every second. I have seen hard edges on several other cars, including a Volt. I am definitely going to work it into my build!

Every little bit will help me towards my ultimate goals!

Speaking of goals... Aerohead, do you think it is possible to get my car down to sub-0.15 Cd territory?

[BabyDiesel]

Originally Posted by freebeard

I'm a big fan of rooftop tailfins. This could adapt to a Kamm-back for your notchback:


http://jalopnik.com/meet-the-mitsubishi-pajero-evo-the-last-forgotten-homo-1704009601

I'm a fan of the old style ones, such as the Bel-Air. I can see how they would adapt over for a kammback. I'll have to figure out their exact placement.

[2000mc]

Originally Posted by BabyDiesel

Do tire splats really help?

Side panels will reduce drag, I have just got to figure out a way to attach them to the body! I really want to make a pair for each side, one flush along the outside edge of the car, and the other along the inside of the tires from front to back.

I think there are more new vehicles that have spats, than vehicles without. So i figured they were a safe bet, and made mine thinking it was matter of figuring out size, shape and position, based on what I'd seen done on newer vehicles. didn't test them, guessing best case secnario was that I'd find any difference at all.

If you were going to make inner and outer skirts, I would think it would be good to just box them in, and cap the ends

[freebeard]

If I am reading this right, a trip strip can be the vortex generators that I have seen some fellow EMers put on their rear diffuser?

My thought is that a 'trip strip' would be a strip. There is an example in the top row of this pic (labeled 'vortex strake'):



Can you provide a link to an example of an EM'ers diffuser with vortex generators? I spent some time on site search and came up dry.

My thought on side skirts was mud flaps behind the front tire and ahead of the rear, with an inflated tube connecting them. Or a bundle of four tubes is you want a flatter side and bottom.

Too bad about the color mismatch on the Bel-Air's door and rear quarter.

[BabyDiesel]

http://ecomodder.com/forum/showthrea...avy-28815.html

The last picture on the 1st post is what I mentioned. Vortec generators may not be the correct terminology.

Thank you for the useful picture! It makes more sense now.

I will draw up my ideas for my double side skirts. It is hard to put it in words what exactly I want to do.

And I think the color difference might be a lighting issue. Beautiful car nonetheless!

[aerohead]

Originally Posted by BabyDiesel

If I am reading this right, a trip strip can be the vortex generators that I have seen some fellow EMers put on their rear diffuser? I need to research laminar and turbulent boundaries, and a trip strip's simulated effect.

I would prefer a constant drag coefficient, rather than one that varies with every second. I have seen hard edges on several other cars, including a Volt. I am definitely going to work it into my build!

Every little bit will help me towards my ultimate goals!

Speaking of goals... Aerohead, do you think it is possible to get my car down to sub-0.15 Cd territory?

Hucho infers that we can get to Cd 0.08 if every trick in the book is used.Delft University is reporting Cd 0.05--- for their latest EcoMarathon car.
To get to Cd 0.15 or lower in the Escort will require an enormous investment in time and money.And it will require flawless execution,as Ford's Ghia Studios have done with their concept cars.
*You'll need active suspension.
*You'll need to move the AC condenser to the rear.
*You'll need to move the radiator to the rear.
*A completely sealed nose.
*Below 0.15, a camera system to replace the side-view mirrors.
Here is the 1983 Ford Probe-IV,Cd 0.152

Here is the 1985 Ford Probe-V,Cd 0.137

[freebeard]

I'd call those fences rather than vortex generators, as they appear to be longitudinal.

[BabyDiesel]

Originally Posted by aerohead

Hucho infers that we can get to Cd 0.08 if every trick in the book is used.Delft University is reporting Cd 0.05--- for their latest EcoMarathon car.
To get to Cd 0.15 or lower in the Escort will require an enormous investment in time and money.And it will require flawless execution,as Ford's Ghia Studios have done with their concept cars.
*You'll need active suspension.
*You'll need to move the AC condenser to the rear.
*You'll need to move the radiator to the rear.
*A completely sealed nose.
*Below 0.15, a camera system to replace the side-view mirrors.
Here is the 1983 Ford Probe-IV,Cd 0.152

Here is the 1985 Ford Probe-V,Cd 0.137

Is there a way to get around having an active suspension? I can tell the Probe IV & V are low to the ground, with the Probe IV having just over 3" of ground clearance. It looks like this measurement is at the air dam. I am trying to not run an air dam to keep my frontal area as low as possible.

I am deleting the A/C and all of its components soon, so that is not a factor. The radiator though... hmmm. I had the thought of integrating it with my belly pan, in such a way that the radiator would lie flat and make up a piece of the belly pan itself. This comes with the risk being hit by debris should I ever run over something. Cooling could be hindered, but that can be alleviated by the electric fan.

Sealing the nose will not be an issue. Of course I would do it in a material other than duct tape, but this cannot be so hard to do.

I can tell from the photos that I am going to have to lower the ZX2 if I have any hopes of achieving the Cd figures I desire! I want to simulate the front rake of the Probe IV, so my thought was to lower just the front. Or lower the car all the way around and get a professional to cut lowering springs for more than a 2" drop up front.

Thank you for the photos. Now I have a visual to work towards

[BabyDiesel]

Originally Posted by freebeard

I'd call those fences rather than vortex generators, as they appear to be longitudinal.

Gotcha freebeard!

What purpose do they serve other than directing the air to flow in a longitudinal manner in stead of tumbling?

[BabyDiesel]

Probe I



Probe II



Probe III



Probe IV







Probe V