Elio reverse trike aerodynamics
 

The Elio fully enclosed reverse trike is currently slated for production and delivery in summer of 2014.

[EDIT]
As of Jan-Feb 2014 Elio is showing the P4 prototype which has improved aerodynamics. More details at post #26 in this thread. Here's a photo:

http://www.eliomotors.com/wp-content...3.50.48-PM.png
[/EDIT]

Based on early photos I thought the body shell to be pretty slippery (not counting the outrigger front wheels). The newer photos here: Elio Motors: Ultra High Mileage Car
show good views of rear quarter and from above. Click tab "Photos" and scroll down.

http://www.eliomotors.com/_livesite/...range_Back.jpg
http://www.eliomotors.com/_livesite/...lack_Top-j.jpg

What do you think? Will the essentially flat rear deck lid cause turbulence?

How about the rounded back end? Is that worse than if they had continued the side taper to the same final total length, with a straight vertical back end?
[EDIT: Apparently Elio found they did hurt; the P4 version lost those drag-inducing features.]

Even so, I would not be surprised to learn this has a very low Cd and CdA.
I think one might build good tails for the front wheel fenders; I suspect they are the area with greatest trailing turbulence and drag.

I'm looking for comments from those here with a good education in fluid dynamics.

Bump.
I think this reverse trike deserves a look here.

I think that it's surface area is so small, that it could be shaped like a brick and still be more aerodynamic than 99% of all other road vehicles.

The outboard front wheels are the biggest source of drag, probably. The flat deck lid in the back will not be an issue, I don't think.

Neil,

Thanks. I agree re the front wheels. In their defense, I expect they contribute significantly to the trike's stability. I suspect their absence is a marketing decision; tailed fairings would have a more extreme appearance.

Too bad they are not included. OEM could likely build them at nearly the same cost as the fenders we see. Will be a challenge for modders to build unless the modder has fiberglassing skills, I think.

Elio
 

I would compare it to 'Sylph' which scored one of the lowest drag coefficients ever measured in Cal Tech's 'tunnel.

Thanks for posting this. I had not heard of them, but for $6,800 I would
buy one right now. I'll be very curious to see if they make it.
-dave

looks familiar..... (grins)

Looks great! I wouldn't worry about those front wheels. Remember, they need to turn. Fairings'd need to be supported. The additional weight and structural complexity seems like high fruit. I say they struck excellent balance. Kudos!

http://ecomodder.com/forum/member-fr...-prototype.png
There was a point where the aerodynamics went downhill (turned uphill?). They raised the cowl height, and consequently the frontal area, at least 10-20%. Compare the earlier rendering for the height of the headlight above the fendertop and note the semi-enclosed rear wheel.

You could totally duct tape coroplast onto those front fenders.

How about wedge-shaped pontoons that are flat on the inside in front and flat on the outside in back? That would pull air away from the body as it is widening, with some indeterminate effect abaft that.

And why aren't those ribs areas either side of the rear tire not all taillight? Like a big ribbed Mercedes one from the 90s?

How does raising the hood cowl increase the frontal area?

I'm highly suspicious that this vehicle will ever be produced. It's another pipe dream. Invest $100 and you get a t-shirt. Invest $1000 and you are virtually assured of getting one of the first bikes off the assembly line, and a t-shirt. That tells me if you invest $1000, you're going to get nothing except a t-shirt.

I think that you are correct.

Straight from their reservation agreement:

"The Reservation Payment is NON-REFUNDABLE and provides you with the benefits in Section 4 below depending on the level of your payment. This Agreement does not constitute an agreement for the sale of a vehicle and does not lock in pricing, a production slot, or an estimated delivery date. You are under no obligation to purchase a vehicle from us, and we are under no obligation to supply you with a vehicle."

^Gee, that sounds like a deal I can't refuse. :rolleyes:

Re: cowl height: looks like the entire thing gained height with the raised cowl. Doesn't really matter anyway because I suspect it's all vaporware.

Sorry for the delay.
http://ecomodder.com/forum/member-fr...io-comparo.png
Wheel height and overall length are approximately equal; The 'thickness' at the windshield is 20% greater.

The first was probably never more than a rendering, but that's where they set expectations. It appears to me they moved the whole nose forward and up (front engine needed clearance?). Compare the angle of the door opening and the windshield post. And then shortened the rear to maintain the overall length

Yes, that rendering is a bit longer proportionally and the beltline and door has changed, but I don't think the frontal area is significantly increased. A very small decrease in the Cd would drop the CdA a lot more than an inch or two of width.

Anyways, the as-built version would make it easier to get in and out

I also think its a prime candidate for coroplast fairings. My idea is to angle the inner surface away from body in the rear. So when steering, the fairing clears the body. In front a rounded blunt surface would be fine, or maybe even leave the bare tire as OEM.

As for the grooved side panels at rear wheel, I think those side panels are removable for tire changes and access to brakes and rear suspension. Adding lighting would add complexity, cost, and would increase power consumption. Just my guess.

the first rendering is idealized.
when you go to actually build the thing, reality steps in.

The fundamental driver's height is a hard number. You cannot really drop below it and stay comfortable - I spent a lot of hours trying to cheat the height down, and you can't do it.

The driver's door is another hard and fast thing. there is a maximum length the door can be and still provide side impact at a reasonable weight. It is pretty standard in coupes made in the past 25 years.

The door post is set by the driver's seat. Which means the body line is between the windows is set by the driver's seat.
The width of the greenhouse is all going to be the same between cars, although I figured out how to "cheat" it narrower.

I wanted more length to the car for passenger comfort, so my car is longer. I wanted still a great turning radius - their car is going to have issues with turning radius I believe, and I think the front suspension will be 'ugly' out exposed, but we chose different design paths.

I am glad my car was the first of these - they are all going to look very similar as the design has to follow function.

drmiller100,

Can you post a link or photos of your car?

Elio reduced the greenhouse width by using tandem seating. I'm guessing you did that too?

I'm impressed.

Elio Motors
 

Looks like they have at least two driveables "mules", this grey one and another green one:
youtube com/watch?v=OVVah66X35s

I believe that I once compared the Elio to the template, but it would have been on a previous computer (I have so many!) and I cannot find it on here. I should have realized earlier, but when HHOTDI shared his pictures with the Elio, I realized that it does not have a back window. Aside from lacking attachment points, wouldn't that make a Kammback easier? You would not have a view to obstruct!
http://i39.tinypic.com/140gglk.jpg

Also, I asked in HHOTDI's thread if motocycles are required to have mirrors. According to http://drivinglaws.aaa.com/laws/motorcycle-equipment/:

State that requires both left and right mirrors: Alaska, Maryland, Nevada, Oklahoma, and Washington*.

States that require one mirror: Arizona, Arkansas, California, Kentucky, Maine, Minnesota, Missouri, New Hampshire, North Dakota, Ohio, Rhode Island, South Carolina, Tennessee, Utah, and West Virginia.

States that do not require mirrors: Alabama, Colorado, Connecticut, Delaware, DC, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Massachusetts, Michigan, Mississippi, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, South Dakota, Texas, Vermont, Virginia, Wisconsin, Wyoming, and Puerto Rico.

*25 years old and newer

In Canada, Quebec requires one on each side of the vehicle, but the other provinces do not.

So, many of us could remove at least one mirror, replace it with an interior one or camera, etc.

Latest (P4 prototype) drawings, Dec. 2013
 

http://eliomotors.files.wordpress.co.../elio4_end.jpg

This drawing and the other one below are from
Elio Motors | The next big thing in transportation, the blog edition!

Will the flip extension at the back end hurt aero? I thought it best to continue the slope and let it cut off. Or is it good because the little "fin" is basically horizontal, in line with the air's general rearward flow? What do you folks know?


http://eliomotors.files.wordpress.co...pg?w=324&h=105

They've considerably improved the front wheel fairings. Elio wrote, and I completely believe, that the older P3 and P2 design fairings were one of the aerodynamically dirtiest areas on the vehicle, if not the worst. Also P2/P3 had the coils and shocks between body and wheel fairing, generating more drag than the smaller items that are now in the open. Also the back end has more squared off vertical corners, for better separation.

http://www.eliomotors.com/wp-content...b2-723x382.jpg

Improved back end:
http://www.eliomotors.com/wp-content...b2-483x406.jpg

It does go in the snow (posted due to interest I've seen on the Elio boards on this question):

http://www.eliomotors.com/wp-content...00-723x406.jpg

That is just going to get in the way of our boat tails! :) I think that it looks good, but that is all that spoilers generally do. If it is supposed to make air reattach before passing the vehicle, then isn't the taper too fast?

http://eliomotors.files.wordpress.co.../elio4_end.jpg

Back seat only for this guy?

http://i146.photobucket.com/albums/r...psf95d521e.jpg

I hate to admit I think the downward taper may be too steep. However remember the sides taper also, gently. Rear face is only about 15"-18" wide judging from the photos.

If the top tapers to quickly then that's a mod the car can benefit from - an applied rear top section. No rear glass there anyway so no window to worry about.

Is adding the spoiler easier than adjusting the taper?

LOL. That is awesome Frank!!:D
Someone with photoshop skills should put a template on Franks avatar cat, rotated 90 deg clockwise. The cat would look, and fit great nestled up on the deck behind (or around the neck of) the guy with the convertible forehead.

A real ecomodder would solve this issue by installing an articulating (aerodynamic) dome that props up to accommodate the rarely frequented passenger seat.
I know I couldn't get an adult to ride with me in one of these (out of fear). My wife might not mind if she could sleep back there in comfort:). My kids would love it though.
I consider it a thoughtful commuter vehicle that by definition: almost always is occupied by a sole occupant. Everyone check this theory (number of passengers) on your way to work tomorrow.:)

Edit: Note: you can see the top of the guys head extending beyond the glass in the line drawing. Pop up car top, or pop down skull. Your choice.

I think the passenger sits further forward than was speculated in the drawing. Which of course is an aerodynamic phenomenon. [/Sarcasm]

These dimensions are from Elio's site, Elio Motors: Ultra High Mileage Car. (specs tab):

Headroom:
Driver 39.8
Passenger 36.4 in

Seat width:
Driver 20.6
Passenger 25.3 in

Interior Shoulder Width: 26.8 in
Front seat Legroom: 42.7 in
Rear seat Legroom: 33.1 in

Elio has been designed to fit 95% of all men. The tallest person we have had in the Elio is a 6’8″ former college basketball player, the largest is a 6’3″ 365 lb man, and the smallest is a 5’0″ woman (no, we didn’t ask the weight!).

Who has sat in the back seat? :)

The lip spoiler on the back might have a small affect on the aero drag, but the exposed suspension and exhaust system are more concerning. The Elio vehicle (name yet to be announced) is *far* better than almost anything on the road today - the shape is pretty darn good, and detail drag like the lip spoiler seems to be minimal.

One of the photos in this thread shows the current configuration of exposed suspension components: (here). Really, only driveshaft and various control arms. Back side of wheel fairings shows some exposed hardware. Earlier P3 version had exposed spring/strut.

True about the exposed exhaust. Current P4 still has the Geo Metro engine. New IAV engine is expected installed in June; then we may see an exhaust system that's closer to production design. Elio has specified 5.75" ground clearance so hopefully they will tuck the visible downpipe up into the bay a bit more.

I did in the P3 version they brought to Denver a few months ago. I'm a touch over 6'3", and I couldn't comfortably sit the back seat. I had to slouch to not have my head pushing into the ceiling. My 5'2" wife fit fine...
The front seat had plenty of head room and didn't feel confined at all. Great 1-person car.
We're "all in" and awaiting production. Like mentioned before, we both commute alone whether we like it or not, so might as well use less to do it.

A little rear bubble top would help him, ala P-38M night fighter.








http://www.youtube.com/watch?v=8JS1lO2V-f8

What about Kach22i's suggestion from http://ecomodder.com/forum/showthrea...ml#post372312?

Although I imagine that the back tapers more than most roofs would. I remember riding in the back of a friend's Neon. My head kept hitting the glass. Just hitting upholstery would be much less of a problem. We should petition them to tuft test and if that does not work, petition to let us tuft test!

If it tapers too quickly, then it reduces rear headroom a small amount for no reason.

Is anyone planning to actually put someone in the back seat?? I like the idea of this car but because of it's MPG, not its capability to transport the soccer team. I'd rather see this thing marketed as a 1 seat trike with a good jack and full size spare. Screw the little bit of added weight from the tools, I'm driving it 100miles a day and don't want to call a tow truck because I got a nail in tire. Make it the blend it's supposed to be: MPG and useful (useless?) as a motorcycle with the all weather capability of a car...

Elio recently posted that they are raising the rear roof line somewhat. This will give more rear headroom AND will allow a more gentle rear roof slope, probably will be closer to template with that change.

They are still working to achieve 84 mpg highway, not quite there yet. We could give them a few pointers.