Comments From A Mechanical Engineer

[JEBar]

This wiki page is current to what is known, maybe that will help settle the question of 'best' configuration. http://en.wikipedia.org/wiki/Three-wheeler

Especially check the 'safety' section.

link appreciated .... it did note some of the issues with both configurations which have been covered on this forum .... I still believe that the intended use for a vehicle is of prime consideration but, that said, one can always find folks who use all types of equipment in ways that it wasn't designed for .... you can go from NC to LA on a moped but that doesn't mean that is what it was designed for .... in short, I completely agree with you that "A 2F1R expert almost always differs with a 1F2R expert. But like I said before, it's often the goals and intent that differ when we thought we were arguing physics"

Jim

 

[Ekh]

Your friend is wrong. Lifting a wheel is a good idea? Since when is reducing traction by one third a good idea? And driving the rear wheel would make it far more prone to dangerous oversteer in slick conditions. As an engineer, autocrosser, and road-racer, I think they picked the correct drive arrangement.

They had a longer video up before of the P3 doing a slalom, but you can still see it here in the intro montage and briefly in the video. Keep in mind this is also without the anti-sway bar the production model will have:

The trouble with this video is that they cut in the middle of turns ... you don't get to see how the car actually handles throughout the turn, nor do you get any idea of how fast it's going or how hard it's pressing through the turn. I think this is probably just pr people being "creative" in the editing, rather than malign intent, but I'd surely rather see 'em do a "Top Gear" course with the thing ... then we'd know.

 

[Ekh]

link appreciated .... it did note some of the issues with both configurations which have been covered on this forum .... I still believe that the intended use for a vehicle is of prime consideration but, that said, one can always find folks who use all types of equipment in ways that it wasn't designed for .... you can go from NC to LA on a moped but that doesn't mean that is what it was designed for .... in short, I completely agree with you that "A 2F1R expert almost always differs with a 1F2R expert. But like I say before, it's often the goals and intent that differ when we thought we were arguing physics"

Jim

I once went all the way around France on an elderly moped, and you are so right -- not what it was designed for! (this was in 1962, in case you're curious)

 

[goofyone]

The trouble with this video is that they cut in the middle of turns ... you don't get to see how the car actually handles throughout the turn, nor do you get any idea of how fast it's going or how hard it's pressing through the turn. I think this is probably just pr people being "creative" in the editing, rather than malign intent, but I'd surely rather see 'em do a "Top Gear" course with the thing ... then we'd know.

At the very beginning of the video, to the right of the Elio Motors logo, you can see the Elio handle a few cones.

 

[carzes]

Isn't this discussion completely academic? Itt's not as though there are no examples of this vehicular geometry in use today. Just find some examples of similar vehicles and find out how they handle. That will tell you if there is any validity to the concerns at least. But if one 2F1R vehicle has none of the feared characteristics, then you know it's at least POSSIBLE to make one without them. If ALL the ones in existence handle like crap, then there is probably something to be concerned about.

 

[ElioDigger]

looks like it did ok to me

 

[Johnapool]

One big difference between rear and front wheel drive is that the front wheel drive is PULLING the vehicle along, while the rear wheel drive is pushing. The wheels delivering the power, in FWD are always pointing in the direction of travel, versus the rear wheel drive, which may drift to the side under conditions that cause loss of traction.
I know lots of the younger folks on here have experienced only front wheel drive. The change over to FWD for those of us who drove 30+ years with RWD was a phenomenal experience. You could actually power through a curve the vehicle wanted to skid through, because those front wheels would pull you through.
I am not a mechanical engineer, but I have a hard time thinking one rear drive wheel would even come close to the stability of two front wheels under power, not to mention traction on slick road surfaces.
Yeah, Carze, it is all academic, but it will be academic until I have that little fob in my hand with an Elio key on it!!

 

[Snick]

I've been exchanging info about Elio Motors with a good friend who has degrees in both mechanical and electrical engineering .... he's also owned/driven motorcycles for well over 40 years, currently owns 2 nice Harley cruisers .... as a result of me asking him to look into it, he sent the following :

"IMHO it should have been designed to drive the rear wheel and keep the front end light enough to lift one of the front wheels in a hard turn. Put the trunk in the front engine over the rear wheel. With some caution (I could be wrong) I believe this design is going to drive like a square fronted boat. With three wheels something has to shift in a turn. With 4 wheels the weight shifts and the platform remains parallel to the ground. With three wheels the same weight shift causes a lean over the single wheel, you can't fix that so you have to go with it and allow something to roll over. Otherwise you need an acre and a half to make a flat turn without the roll.

Three wheel design = drive the single wheel and allow the front end to take up the roll required to make a turn. Morgan has this right."

I have gone back and looked at every YouTube Elio video that I can find and I haven't seen any which show it in a sharp turn .... in thinking about it, the Elio is designed to be a commuter vehicle which usually doesn't require traversing a slalom course .... that said, I have no doubt that some folks are bound to give it a try .... I'm looking forward to a test drive, hopefully that will be possible next year

Jim

Hi Jim,

Please give your friend this link: http://www.rqriley.com/3-wheel.htm and ask him to read the article "Dynamic Stability of Three-Wheeled Vehicles in Automotive-Type Applications."

It will explain it very well.

 

[Terrence]

One big difference between rear and front wheel drive is that the front wheel drive is PULLING the vehicle along, while the rear wheel drive is pushing. The wheels delivering the power, in FWD are always pointing in the direction of travel, versus the rear wheel drive, which may drift to the side under conditions that cause loss of traction.
I know lots of the younger folks on here have experienced only front wheel drive. The change over to FWD for those of us who drove 30+ years with RWD was a phenomenal experience. You could actually power through a curve the vehicle wanted to skid through, because those front wheels would pull you through.
I am not a mechanical engineer, but I have a hard time thinking one rear drive wheel would even come close to the stability of two front wheels under power, not to mention traction on slick road surfaces.
Yeah, Carze, it is all academic, but it will be academic until I have that little fob in my hand with an Elio key on it!!

Greetings-keep in mind that this is a tandem designed auto cycle. Tandem is narrow, the passenger sits behind the driver, not alongside the driver. With that narrow image, the rear wheel sits in the center of the back section. That rear wheel easily supports the rear of the auto cycle (and the rear wheel is free rolling). The front wheel drive Elio masterpiece with stability control will easily amaze you!
I could only wish to see your smile after you have driven your 2015 Elio
Terrence

 

[Terrence]

Hi Jim,

Please give your friend this link: http://www.rqriley.com/3-wheel.htm and ask him to read the article "Dynamic Stability of Three-Wheeled Vehicles in Automotive-Type Applications."

It will explain it very well.

Great answer you found there Snick! Good Assist! Get er done
Terrence