Project: The Anal Probe

[Weather Spotter]

well the air would like you to build the tail at the yellow line, but if its just from the trunk back got with the blue line. Also the template and protractor should be level with the ground not the car.

[Sven7]

Thanks, it should be level- whatever.

Picked up about 8 sq ft of coroplast from the dumpster at work today. Yayy

Also went to the junk yard and pulled the headlight buckets from a '79 Cadillac. $10. Bringin' a touch of class to this shizz!

Got halfway through pulling some tail light plugs at the yard and realized they're all just spade connectors. I'll buy some spare connectors after work and just splice them in. No wires cut yet!

Once the lights are hooked up I can start laying out the angles in real life to get the boat tail frame started. If the angles and Photoshop are right it should be overall shorter than I'd anticipated For sure with the size of the lights (just as tall as the license plate) it is theoretically possible to have a wake of about two square feet.

So tired physically, mentally and emotionally right now. I need to keep myself busy to avoid thinking about certain things.

[Varn]

Sven
Perhaps the template isn't right for your car. The Probe is fairly smooth. Well very smooth, when you compare it to the folded paper design of my Jetta.

If the air flow looks good on the rear window, how much are you going to gain? As you increase the length you will be adding some surface area which may tend to negate decrease in wake that you will experience. Perhaps some mechanical changes might help more than working on the aero.

It will be interesting to see how you do.

[Sven7]

Even though the window is attached there is still a large wake from the beltline down. I am going to build it as long as possible while still fitting the license plate and tail lights on the rear surface. With 15* angles the skin friction should not be a problem, and wake reduction will be significant- perhaps a mere fraction compared to stock?

Remember, the stock Cd of this car is something like 0.30 or 0.31. Not spectacular- there's plenty of room for improvement. With a basjoos style nose cone it should be even better. With the full belly pan, boat tail and low nose I'm expecting something like 44mpg sustained 60-65mph highway cruising instead of about 38mpg now. That's a 16% FE increase, or 32% aero improvement.

The goal is to get low 40's without P&G'ing everywhere. It gets old, especially on long trips. I want to go to Duluth and back on $30 and when I have a girl in the passenger seat I'd like her to not be mad at me.

Also interested in what you're thinking for "mechanical improvement"? WAI could come in the future if I can bribe someone who knows what they're doing.

[Sven7]

Hellooo!

4X8 Plastic Cardboard 3 sheets

Hooked up the LED tail lights yesterday and they work great except don't come on when the headlights come on. Going to look into it.

Laid out some tape lines on the ground to get angles right, etc. Looks like the tail will be around 40" long.

[kach22i]

I paid $25 for one sheet, that's a good deal.

[JethroBodine]

The way I THINK I under stand the rear aero is as follows...

Any way you fill the wake will help reduce drag.
For better/best results the tail needs to start near level and gradually increase toward your final angle of 21/22 degrees, or in your case, start with attached flow on the rear window and build from there. If I were building the tail on your car with the testing you've already done, I'd start where the lowered template leaves the rear window, which will still afford you some visibility out the rear, and follow it to your preplanned ending. This will not strictly follow "template" parameters, but I "think" it will still help a lot.

This post is made by a complete novice in the aero world and should be taken with a grain of salt( with a hint of lime and tequila). YMMV

[Sven7]

I don't care if it gets me 30% better MPG- I'm not building crap over the rear window. Too much effort, not enough visibility (if it were a hatch it would be different).

Attached is good enough there- I'll do what I can with curves on the rear and see how it goes. Hopefully get something done today. Yesterday I went go-karting on a sweet outdoor track but it really took a toll on my upper arm muscles

[Smurf]

... Whoa. I just read this entire thread for the first time. My mind = sufficiently boggled.

You did so much, so quickly, so cheap, with so little hands-on experience. That sounds a lot like me, except the 'quickly' aspect, as I have yet to even decide which vehicle I will start with. Can't wait to see what you can do with something shiny as your budget increases, perhaps a late-90s Dodge Avenger? Any parts you can use on Eclipse/Talon will work on the Avengers, and they're quite sleek.

I think next time I'm in the Cities I'll have to swing thru the Menards lot and take a peek at this machine.

[sheepdog 44]

Originally Posted by Sven7

I don't care if it gets me 30% better MPG- I'm not building crap over the rear window. Too much effort, not enough visibility (if it were a hatch it would be different).

You could do a kammback over the top of the rear glass like BrucePick has on his civic that has good rear visibility. Not sure if it would help in your case with a boat tail. Whether attached flow off the stock glass leading to a boat tail, or a kamm off the top glass to conform to the streamlining template but then having an air gap in between that and the boat tail.