Ford Escort ZX2 Aerodynamics

[BabyDiesel]

Alright y'all! I'm getting ready to design a kammback and use the upper radiused edge as described above. I'm still in the preliminary stages of planning, but there is some things I've already got in plan:

- The overall design is to follow the Template as close as possible. The kammback will lead into the boattail later, so this is critical.

- The real world design I want to try and copy is off of the Toyota Prius' rear hatch, but with a more radiused end as is on Phil's CRX.

- It will be able to pivot so the rear hatch can open.

The biggest things I am encountering in opposition is the frame material, how to get the slope correct and how to securely attach it.

Here is a side view of a design. Ignore the bottom section of the incomplete boattail

[dirtydave]

wait why do you have two threads?

[freebeard]

Fwiw

Originally Posted by op

i'm starting a new thread here that will handle the aerodynamic aspects of my car exclusively

[BabyDiesel]

Dave, I started this thread as freebeard pointed out - to talk exclusively about aerodynamics with regards o the Escort. And it has worked because I have recieve some extremely valuable information from both freebeard and aerohead, and others too.

The things I mentioned in opposition to my build... Has anyone got any ideas how to go about working these out? There is not many people who have done this to a sedan, as it is harder than a hatchback. I'll look and see what I can find in the archive that may be of some use.

[aerohead]

Originally Posted by BabyDiesel

Dave, I started this thread as freebeard pointed out - to talk exclusively about aerodynamics with regards o the Escort. And it has worked because I have recieve some extremely valuable information from both freebeard and aerohead, and others too.

The things I mentioned in opposition to my build... Has anyone got any ideas how to go about working these out? There is not many people who have done this to a sedan, as it is harder than a hatchback. I'll look and see what I can find in the archive that may be of some use.

Take stock of your situation with respect to a work space,tools and equipment,your experience with fabricating and what you'd be willing to learn from scratch,and things you might outsource locally.
You could do it all in metal.You could do it all in wood.You could do it all in composites.Or mix some of the technologies.
There are some great books and DVDs out there on metalworking and everything else and now with YOU-TUBE you'll find DIY videos on all kinds of processes.
The learning curve is pretty fast with a lot of this stuff.
Check yard sales,estate sales,auctions,swap meets,Amazon,and flea markets for deals on power tools at a fraction of new prices.
Some metal recycling centers will allow you to buy salvage metal at whatever the Wall Street Journal says it's worth on any particular day.
It's nice to have a perfectly level concrete slab to work from,as it makes it the easiest for measuring critical dimensions.(I'm still driving 6-miles into town to do this in parking lots,so it's not absolutely essential).
And see if the car 'settles' when you and passengers get in.If so,you'll want to ballast the empty car with 300-lbs in the front seats for measurements,so when the car is loaded,she's at the proper inclination as far as the aerodynamics go.

[BabyDiesel]

Tuft testing and coastdown testing are coming soon I have to wait for our rainy conditions here to improve and tweak a few aero mods (seal the front gaps, form-fit the rear skirts, etc.)

I'm hoping for a Cd of 0.25

Aerohead, I have decided to make the boat tail out of all metal. The frame will be very similar to redneck's, but it will be covered with thin sheet metal. The back will have a plywood piece for mounting the new lights and license plate. I have decided to build the tail at 85% of the template length, which should give me over 90% of the effect that a full tail would.

[aerohead]

Originally Posted by BabyDiesel

Tuft testing and coastdown testing are coming soon I have to wait for our rainy conditions here to improve and tweak a few aero mods (seal the front gaps, form-fit the rear skirts, etc.)

I'm hoping for a Cd of 0.25

Aerohead, I have decided to make the boat tail out of all metal. The frame will be very similar to redneck's, but it will be covered with thin sheet metal. The back will have a plywood piece for mounting the new lights and license plate. I have decided to build the tail at 85% of the template length, which should give me over 90% of the effect that a full tail would.

We'll cross our fingers and toes and hope that the Escort's engine responds favorably to the load reduction.
After Darin's (MetroMPG) results with his boat-tailed CIVIC,I'm on pins and needles now,each time a member does a new tail.

[BabyDiesel]

I am hoping that it will have a big improvement! I have lean burn now, so that changes everything about loading the engine. I am seeing 10-15% greater loading on the engine at cruising speeds (40-50 mph) when I have lean on rather than off.

The rear of my car is far from optimized and much less so than Darin's Civic. With the quick sloping glass (24 degrees) and roundedness of the sides, there is much to be gained IMO. However, I will not know till I get there due to the CivicTail dilemma

Here is a quick mockup of what theoutline of the tail will look like. I increased the length to 90% of the template by adding a 3rd-gen Prii style extension on the end. I figured "Why not?"

[aerohead]

Originally Posted by BabyDiesel

I am hoping that it will have a big improvement! I have lean burn now, so that changes everything about loading the engine. I am seeing 10-15% greater loading on the engine at cruising speeds (40-50 mph) when I have lean on rather than off.

The rear of my car is far from optimized and much less so than Darin's Civic. With the quick sloping glass (24 degrees) and roundedness of the sides, there is much to be gained IMO. However, I will not know till I get there due to the CivicTail dilemma

Here is a quick mockup of what theoutline of the tail will look like. I increased the length to 90% of the template by adding a 3rd-gen Prii style extension on the end. I figured "Why not?"

If you'll add rear wheel skirts,I don't see how you wouldn't come in below 0.25.The CRX indicated 0.235 according to GM.

[BabyDiesel]

Oh, that is a very outdated picture of my car! It looks like this today!



My current setup is around 0.26-0.27 Cd. With making some fine tuning adjustments such as
-100% grill block, top and bottom
-front gaps sealed
-wheel skirts adjustment for a better fit
-something else small that I forgot

Im hoping to crack 0.25. With the boattail, im hoping for <0.20 Cd.