Parallel Hybrids - Urbee
 

This is a small category of hybrids; as only the Honda IMA is a production parallel-only hybrid, and they are "mild" hybrids because they do not have electric-only modes.

But, we now have a new unique example of a "full" parallel hybrid, called the Urbee:

http://www.autotantra.com/img/urbee-hybrid.jpg
http://www.blogcdn.com/green.autoblo...1/04-urbee.jpg

SEMA 2010: Urbee Concept has just one word for us: "Plastics" — Autoblog Green

Urbee Hybrid Is World’s First 3D Printed Car - Green Car Reports

It is electric drive on the two front wheels, and has a very small (single cylinder?) ICE driving the single rear wheel -- that also steers! I'm not sure I like that... But, they have some interesting solutions.

The headroom looks pretty darn low, and the visibility out the windshield is quite limited; as you are looking through a 9-12" high "slot".

http://www.youtube.com/watch?v=IWGfx_XumhI

Oh, and there is the GM Precept, which is certainly a full parallel hybrid concept:

http://ecomodder.com/forum/showthrea...ame-14026.html

Here's the Urbee website:

http://www.urbee.net/home/

Unfortunately, it is a little thin on info. The pictures on the Autoblog Green site are by far the most helpful.

http://www.urbee.net/images/template/header.jpg
(click on image for link)

Actually, I think rear wheel steering may be a non-starter. Driving this at highway speeds could be scaryscaryscary.

I've driven forktrucks and rear wheel steering is required for these, but they take quite a while to get used to, and the faster you go, the harder they get to control.

But, maybe they have a progressive power steering that can handle this?

I like their (general) objectives:

These could apply to any car!

Fuzzy video of actual prototype:

[youtube]FzXXC_KUxr8[/youtube]

Gallery of pictures on Jalopnik

Speed-sensitive power steering, and limited steering angles at speed, I'd hope.

Depending on their weight distribution, 3wheelers are also quite easily flippable - as quite a few velomobile owners have found out.

The tadpole layout is much more stable than the Delta.
The big issue is with a rear drive tadpole, if you apply power when the inside wheel is lifting, it produces more lift on that wheel. Unload it completely and you have a motorcycle pointed towards the outside of the turn. Instint is to turn more. This causes the now sideways tire to roll under and grab. Apply more power to the rear wheel and over she goes.
Front drive tadpoles are harder to flip than a 4 wheeler.

Yeah, that rear steering scares the poop out of me too.

informed discussion of rear steering reverse trike
 

This is an interesting read about the Urbee and how it compares to the Dymaxion:

The Left-handed Cyclist: Bucky Fuller and the Urbee

What I knew as mild hybrids were vehicles which had the start-stop (often quoted as "micro-hybrid") and an auxiliary electric motor for accessory drive (power steering pump, A/C compressor, among others) only, not for traction purposes.

A thought comes to mind. Aside from clever steering geometry, since the front wheels are electrically driven, couldn't some form of active torque vectoring be used to both stabilize handling and improve turning? (not knowing how the motor is attached to the wheels...)

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Interestingly, since this thread started, we've seen one of the rare examples of a Delta layout that's extremely stable... the Nissan DeltaWing... of course, that involved positiong the (front) steering wheels faaaaaaar away from center mass.

If it has the differential in 'software', torque vectoring should be within easy reach. If the rear steering were speed sensitive, it could trade off with the front as speed increases. 3WD and 3WS.

Jet planes with swept forward wings are inherently unstable too, fly-by-wire makes them manageable and nimble.

The Urbee project is apparently still progressing:

3D Printed Cars Could Revolutionize The Automobile - Gas 2