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Old 06-04-2012, 06:28 PM   #11 (permalink)
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Quote:
Originally Posted by drmiller100 View Post
Note the back is "behind" the front - so I add the frontal area of the hood plus the frontal area of the "greenhouse" - windows and above.

Any guesses on Cd?

Aero?

under .20????? (I am hoping?????)
Al's gonna close the store in 7-minutes so I'm out of time basically.
Like the others,I'm concerned with the flanks,aft of the fenders.Your source flow at the nose is good,but the fender truncation will destroy the rectilinear flow to the tail,which can't 'sink' unless the onset flow is exceptional.
I've gor the same issue with the mini-hypercar.I will enclose this entire area with 'pod' for storage and side crumple zone to provide the gentle plan taper to the rear which the tail needs to function.
Your foundation is real good.Wish you didn't have the short deadline.

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Old 06-04-2012, 08:40 PM   #12 (permalink)
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Aero, Thanks for your comments.

A few things. The 4 dimensional model is interesting. Yes, I have some stagnation area behind the front wheels, and yes I'm curious to find out what cut outs do.

If you look at the windshield, it is actually well behind the front fenders. I expect high energy air to flow off the hood, spill around the cockpit, and add adequate energy for the back of the car.

I'm pretty confident of that.

i'm so confident I put the goofy air scoops on the back to make ti look cool, but now that the car is outside, I hate the goofy air scoops at the back, and they are getting changed or removed.

as for covering the wheels, am I better to cover the wheels and close behind the fenders, or am I better off to leave the wheel wells open, open behind the wheels, and let air flow in the wheel wells and out the huge openings behind the fenders - basically make the back of the "fender" look like a fender, but not at all functional?
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Old 06-04-2012, 08:41 PM   #13 (permalink)
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Quote:
Originally Posted by skyking View Post
If you want to get anything out of this site I suggest you quit taking things personally.
It would be a piece of cake, so to speak, to fair in the area in question during testing. Reach out the window and close a second panel, etc.
Then you'd know for sure the cost/benefit. I could make it faired off and still use that door and still have it all work if you are interested.
Is that how you built your car?
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Old 06-04-2012, 08:45 PM   #14 (permalink)
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Kach, thanks for the photos, and apology accepted.
Yes, I'm a bit sensitive about my baby.

FWIW, the rear I purposely didn't take photos of. It is about 12 inches wide, has a 2 inch rim around it, and is already on the edge of functionally too long.

So when you really add up the frontal area, it is the hood, plus the cockpit above the hood, right??????
And you don't think air will spill "down" the sides as it goes around the windshield?
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Old 06-04-2012, 09:18 PM   #15 (permalink)
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I don't think air will rush into the wheel wells to flow out the back, the cover suggestion is to smooth the flow across the rotating wheels. Also, having it open at the back will be quite messy in rainy weather. The wheels would toss all that grime right up on the side window and corner of the windshield.
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Old 06-04-2012, 09:55 PM   #16 (permalink)
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Quote:
Originally Posted by drmiller100 View Post
And you don't think air will spill "down" the sides as it goes around the windshield?
Keep in mind that I'm not pretending to be an expert. I'm just trying to use my imagination, and think this one through.

Although at this late stage in the game a complete re-design or even modest modifications may be enough to stall you from getting on the road indefinitely, and I don't wish to do that.

This is what I think will happen now:
Automobile 2 - Odds and Ends pictures by kach22i - Photobucket


This is what a tightly curved or deep split vee windshield may do.
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Old 06-04-2012, 10:08 PM   #17 (permalink)
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it doesn't show in the pic, but the windshield is pretty curved.

Thank you for your excellent work on the pics - I have NO idea how to go about that kind of stuff.

I envision the B pic is what I have now, with turbulence from the sides.

If I had a FREE rein to do what I wanted, I would have dived the fenders at a 20 degree angle behind the center point of the tires downwards, and made the back of the fenders shorter.

But I needed to use an existing template as I don't have the skills to do the hood from scratch.

Does anyone recognize the hood?
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Old 06-05-2012, 01:00 AM   #18 (permalink)
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The front clip reminds me of a Lotus.
It is looking good !
My suggestion, (eh gad not another one) is to round the front fenders ends off in a ergonomic type curve, something like the edge of remote control only bigger, for instance, where Kach22 suggest a curve back i suggest a curve forward and back.
Esthetically speaking that is.
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Old 06-05-2012, 10:13 AM   #19 (permalink)
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The air flow is probably going to be a combination of the to flow diagrams that George posted. If you know that an ideal vehicle has air flow that is first accelerated outward in all directions by the front of the vehicle, and then smoothly closes back into place after the vehicle has moved past. To achieve this, the air pressure must be as even as possible all over the vehicle.

If there are areas of low(er) pressure, then they will pull the air away from the higher pressure areas. The largest areas of low pressure on this vehicle will be behind the truncated front fenders. Some air will flow through the front grill, through the engine bay and past the spinning front wheels (I am assuming) and then will exit into this area, and will partially "fill in" this zone, but this exhaust air flow itself will be turbulent, and may not form a trapped pocket, similar to the bed of a pickup for example.

The result will be, I think, that there will be both a lot of turbulence and a lot of air will be pulled down from the hood and lower windshield, as well. Maybe this turbulent area will allow the air flowing off the fender to "bridge" to a point on the rear of the vehicle and reattach? The only way to "know" is to tuft test it.

Here's a vehicle called the Trev that addressed this issue by having a really "fat" door, hinged at the back:




Trev (two-seater renewable energy vehicle)
Image archive

Ideally, the sides would be slightly convex; not slightly concave.
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Old 06-05-2012, 10:25 AM   #20 (permalink)
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Quote:
Originally Posted by drmiller100 View Post
Does anyone recognize the hood?
It's not the GF3 Mark Smyth Performance front end, which was my first thought.

JLP's Smyth Performance G3F Build - GO GREEN, GO FAST


The trendy Porsche GT3 style openings at the lower front corners (dual split radiators) makes me think it's something fairly current.

The Trev is cute, I like it. However, they stopped short of their full potential - tail wise.

http://s184.photobucket.com/albums/x...%20and%20Ends/


I modified one of their images found here:
http://w3.unisa.edu.au/solarcar/imag...ve/default.asp

More images of car here;
http://www.nvntrs.com/mpg-trikes.htm

My latest mark-up:


I still would not dare to guess the Cd, it's just such an unusual vehicle.

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Last edited by kach22i; 06-05-2012 at 11:05 AM..
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