Elio Motors, The Next Big Thing?!!...

[kach22i]

It works because of low frontal area, not because the Cd is anything special.

[Xist]

Originally Posted by kach22i

It works because of low frontal area, not because the Cd is anything special.

How much does the taper help? The frontal area is small, but the wake should be tiny!

[NeilBlanchard]

The side taper would terminate the back in a "fishtail" and it would be much shorter than this.

[Ryland]

Friends of mine are already talking about plopping down $1,000 for one.
I can't wait till a year from now when they should be doing road tests and preparing to release the first few.

[NeilBlanchard]

Is that deposit fully refundable, or not?

[Ryland]

Originally Posted by NeilBlanchard

Is that deposit fully refundable, or not?

Nope, but it seems worth the risk, there are much worse things that we already throw money at without a return.
Elios seems to be making real headway tho, so as much as I'd like to see a better written investment plan in the company, I don't think it's going to happen.

[Swordsman]

They have a cheap reservation level of only $100. That's how much I put in. No way I'm gonna gamble $1000 on a risky company that has over a year to completely fall through. But a good bar tab? Yeah, I can part with that much. I'll be toward the end of the waiting list though. So, looks like I could be twiddling my thumbs for two years (1+ for final development, 1 year-worth of production)!!!

I'm thinking I may just have to go ahead and sell the Ural and pick up a scooter or something. 2 years is a long time to keep plowing through gas. We'll probably be hanging at a steady $4/gallon by then!

~SM

[brucepick]

Originally Posted by NeilBlanchard

The side taper would terminate the back in a "fishtail" and it would be much shorter than this.

I don't follow you here. In plan view I believe it tapers gently enough to maintain attached flow. So that air flows well I think. Roofline also tapers down some and I think that flow will stay attached.

Granted the front wheels aren't faired. So that creates maybe 5-7 sq ft frontal area. Trying to estimate towards the high side here. 2' tall tires + .5' fender height=2.5' high. Width 1' each x 2 wheels = 5 Sq feet front wheels. I think that will be the majority of its "effective" frontal area because the main body tapers down to maybe 1-2 sq feet I estimate.

Is there a significant aero situation I'm missing?

[NeilBlanchard]

The top and the sides can be tapered at about the same rate while the bottom has to be tapered much more gently (due the proximity of the ground), so by definition the two sides will intersect before the top and the bottom will intersect.

So, it depends on the proportions of the frontal area - it has to be a pretty wide and low rectangle in order to have the tapers of the top and bottom be the surfaces that intersect to form the tail; what is called a beaver tail. If the proportions of the frontal area are taller and narrower (like the Elio), then the side tapers will intersect before the top and bottom, and so they will form a fish tail.

[brucepick]

Ok I see your point there.
It's a good explanation of why the Elio's back has the shape it does.

I think the design at this point has a pretty good Cd overall. I had thought you were finding some degree of fault with the shape but I think that was a misunderstanding on my part.

I want to point out here, I'm pretty sure the recommended rates of taper are maximums and not prescribed rates. A passenger jet fuselage has a much gentler taper rate than nearly any road vehicle, and of course has a very low Cd. So a designer isn't forced to taper faster than they want to. At least not by the laws of aerodynamics.