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Old 05-02-2015, 01:19 PM   #11 (permalink)
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45-50-mph

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Originally Posted by BabyDiesel View Post
With more weight reduction, LRR tires, a Cd of 0.19, a drivetrain efficiency of .90 for a manual swap, and 77* air puts me at 70-80 mpg for my usual drive speeds of 45-50 mph (theoretically)

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The Cd 0.19 GM Ultralite was rated at 100-mpg @ 50-mph.You're frontal area wouldn't be much different,and at cruising speed you're weight wouldn't slay you.
GM did have tires with something like 60% less rolling drag than conventional steel radials of the day.I suspect that this gap has closed since 1991.

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Old 05-02-2015, 11:30 PM   #12 (permalink)
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Here is a picture shoing how the deflector fits on my car. It is rigged pretty badly lol. I plan on having a more permanent one soon.
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Old 05-02-2015, 11:57 PM   #13 (permalink)
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Quote:
Originally Posted by aerohead View Post
Eiffel and Hoerner both tested reversed streamline bodies ,and while the drag was higher,as half-bodies,and with wheels attached,I guestimate that you could see Cd 0.13 for a perfectly smooth wind tunnel model.
What we don't know,is if we can cheat on the windshield.If we can't,then the angles of the glass would make it impossible to see out of the car.
'Elliptical' bodies have the same drag as teardrop bodies,for the same fineness ratio,so I don't think you can hurt anything by extending the front.The pro's might say that you're creating undue additional skin friction.
Testing would tell.
0.13 Cd?!?!?!? That is crazy talk!

I have thought about doing a second windshield similar to what basjoos did on his aerocivic. He said in another thread that while he didn't have exact numbers, it did help improve his coasting distance. With a car as light and as aerodynamic as his, I am guessing randomly that his Cd key have dropped close to 0.15.



What exactly do you mean by cheat the windshield?

I do plan on extending the front. I need to lower the stagnation point so air can flow over the Top, rather than under my car. I probably won't extend it to match the template... If I did, LOL
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Old 05-03-2015, 12:05 AM   #14 (permalink)
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Quote:
Originally Posted by aerohead View Post
The Cd 0.19 GM Ultralite was rated at 100-mpg @ 50-mph.You're frontal area wouldn't be much different,and at cruising speed you're weight wouldn't slay you.
GM did have tires with something like 60% less rolling drag than conventional steel radials of the day.I suspect that this gap has closed since 1991.


That is great news, aerohead! So I could be looking at having a 100+ mpg car if I max the aero out. Just the motivation I need

It is good to hear that my frontal area will not differ very much. I was concerned that it was already a penalty to overcome. What I do have planned to help lower FA is the give the ZX2 a Probe IV treatment. I plan on lowering just the front, and maybe lifting the rear 0.5-1" ONLY if it would help aero.

I suspect the same as well. Sounds like they had RE92s haha. I plan on going with them as my next set of tires, unless there is another tire with lower LRR.
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Old 05-03-2015, 01:33 AM   #15 (permalink)
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I had not seen the windshield aerocivic added. It looks hard to see through. Here's my own attempt at kicking out a windshield:

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Old 05-04-2015, 07:49 AM   #16 (permalink)
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I find your attempt rather awesome freebeard! Was it just an "attempt" or did it have permanent merits?
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Old 05-04-2015, 02:25 PM   #17 (permalink)
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I've gotten this much further. But the drawing and that picture don't show the boattail very well.



The boattail is full length to the reverse camber, or could be truncated to a 45 angle at the solid bulkhead or the original vehicle length at the open bulkhead.

The redwood strip version could be made with flexible sheets in simple curves. The sides flat but twisted and the center one bowed with curved edges.

If I built the photoshopped front end instead of a bubble (as suggested by the highlight), there would be three flat pieces like the Shalaho or Grumman post office trucks, but the center piece would be a hexagon with the side triangles following a line that sort of folds over the edge. I should document that. Here is is before being 'hexagonized':



Can you see how the angles on the hexagon would be about where the quarter panel ends? With the bottom edge the width of the spare tire, it could fit on an unchopped front valance.

The current plan is to leave the front as-is with a flat aluminum bar bridging across the two horns that are what's left of the quarterpanels, with headlights hanging from it. It will have a Superbeetle gas tank where the back seat used to be. I'm backing off from the electric motor conversion.

The next round on the boattail will be in a material called Omega-Panel. The pontoon fenders are also further defined but not documented.
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Old 05-05-2015, 12:12 PM   #18 (permalink)
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Simply awesome, freebeard I can't wait to see what this thing looks like when finished!
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Old 05-05-2015, 01:40 PM   #19 (permalink)
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We talked about me again. I'm sorry.

So, '57 Mercury Turnpike Cruiser style rear skirts? Have you seen bubble skirts?
https://www.google.com/search?q=bubble+fender+skirts

What about the front? skirts or air curtain?
https://www.google.com/search?q=bmw+air+curtain

Edit: Just found this on http://ecomodder.com/forum/showthrea...rts-28821.html

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Old 05-05-2015, 06:05 PM   #20 (permalink)
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cheat

Quote:
Originally Posted by BabyDiesel View Post
0.13 Cd?!?!?!? That is crazy talk!

I have thought about doing a second windshield similar to what basjoos did on his aerocivic. He said in another thread that while he didn't have exact numbers, it did help improve his coasting distance. With a car as light and as aerodynamic as his, I am guessing randomly that his Cd key have dropped close to 0.15.



What exactly do you mean by cheat the windshield?

I do plan on extending the front. I need to lower the stagnation point so air can flow over the Top, rather than under my car. I probably won't extend it to match the template... If I did, LOL
When Walter Lay did his wind tunnel research,he found that the drag of an 'ideal' form could be duplicated with an 'optimized' windshield.Both gave Cd 0.12


-------------------------------------------------------------------------
With respect to 'reversed' bodies,there is zero wind tunnel studies performed with 'mutilated' forebodies.So we don't have any knowledge about what happens if we disturb the contour of a reversed body to create a 'working' windshield.
If it turns out that we can't,without raising drag,then Hucho would say 'fuggetaboutit', 'cause,the distortion of the radically-raked windshield would be too great to see through.
This Citroen Karen would be impossible to see out of

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