Diamond wheel configuration.

[sheepdog 44]

I was at work today and i came across a 4 high (a wheeled multiple shelf) only the wheels were off. Instead of the two front wheels being turnable and the back two fixed, it was in a diamond pattern with the front and back wheels turnable and the side wheels fixed. It made the 4 high more manueverable with comparable stability.

What are the possible automotive applications? Lets do a thought experiment on a possible future concept car.

I imagine a pure 3D teardrop sliced in half and laid over the frame. Aerodynamics would be beyond concept car territory.

......W......
..----------..
.------------.
w..........W
.------------.
..----------..
... --W--....
.....-----.....
......---......
.......-.......

(My thoughts lean more towards a light enclosed vehicle)
Obviously this would be the optimal 4 wheel layout for aerodyamics with the front and back wheel being fully enclosed (solving adjustable front wheel skirts on a normal design) and the two side stabilization outrigger wheels faired into the body. This also gives the widest wheel distance both side to side and front to back (for maximum roll stability) over a conventional design adapted to the teardrop shape (Where the conventional square wheel template infringes on the rounded curvature making the length of the car unreasonably long if it were to follow the streamling template perfectly). This solves the aerodynamic issues of the aptera by moving the front wheels to the side back into the optimal teardrop shape, while maintaining front and back balance. It also avoids the unstable retractable wheels of the Monotracer. And seating can be made for two or four people doubling the passenger capacity over both vehicles.

It can be mid-engine for the center of gravity, with direct drive to the enclosed "outrigger" side wheels to eliminate some transmission losses. Or it could be rear wheel drive like a converted motorcycle; or i think the more practical for design issues: rear and front wheel drive through electric hub motors with free wheeling side wheels. That would propel you into and out of turns at the same time for enhanced manueverability.

Steering is the biggest issue. I don't know the possible pitfalls of such a configuration. I think the front and back wheels could deflect at the same angle and that would be fine. Handling would be interesting if your turning around the center of gravity. With the driver ahead of the side wheels though i believe the experience would be the same as driving a motorcycle with a side car. Parking would be interesting.

Is such a design Possible?

[Frank Lee]

Possible, sure. Desireable... ?

Bede Pulse/Autocycle/Litestar would be a relatively easy starting point...

[sheepdog 44]

Originally Posted by Frank Lee

Possible, sure. Desireable... ?

Bede Pulse/Autocycle/Litestar would be a relatively easy starting point...

For concept car names? Edit: Holy crap that is awesome! I can see having four seats being practical on that. I think someone should start a high mpg motorcycle company. How easy would it be make and manufacture a purpose built high mpg motorcycle like the one featured here that can get 1L per 100 kilometers. Say for 5-6k maximum, but for a 230+mpg motorcycle who wouldn't buy it.

http://www.youtube.com/watch?v=gnJ2KH0uWDM

[Ryland]

Delta trikes are not stable because when you make a sharp turn the weight shifts to the outer front corner... where there is no wheel, that is why tadpole trikes are more popular, because of this I see an issue with handling, your rear wheel is going to be working as a support for the ballast weight to keep the thing from rolling over in sharp turns, but because of that the rear wheel isn't going to have much traction a lot of the time that you are not going in a nice straight line.
The other issue with trikes is that each wheel is making it's own path in rain and snow and the other wheels are in it's wake, being pushed around.
So if I was to have any wheels not inline like a standard 4 wheeled vehicle is, I would want a tadpole trike, because at least with that wheel layout you are really stable.

[Peter7307]

I really hate to pour cold water on this otherwise enthusiastic post... but it has been done already.

FIAT in the late 1950's commissioned Pinnifarina I think to do a study on this arrangement.

Bottom line:
No aero improvements,
Higher manufacturing costs,
Harder for drivers to negotiate obstacles (due to three wheel tracks),
Drive and transmission arrangements are more difficult to package,
Entry / exit arrangements are likewise,
and most importantly...

potential customers thought it was a joke and none wanted to buy one.

Strangely , vehicle handling was pretty much unaffected.

Peter.

[sheepdog 44]

@ Ryland

It would be neither a delta or tadpole trike, as the center of gravity would be directly on the middle axle of vehicle but adjusted back by 100 pounds. Delta and tadpole trikes have the center of gravity within the triangle of the three wheels so their handling would be different. This is like having a tadpole trike with 85% weight directly on the front two wheels, so much like it might pitch over if you brake too hard, than bolting a copy of the trike facing backwards onto the front of it.

With symmetrical front rear weight distribution a hard turn would shift the center of gravity directly towards the out rigger wheels. Accelerating or braking would shift the CG front or back during a turn. I imagine a hard braking accident avoidance manuever would shift it the most and be more common and practical than seeing hard acceleration for an economy minded vehicle. You could change the diamond wheel config into a kite config and leave center of gravity alone. This would still give you the minimal yaw required to turn while maximizing accident avoidance. Like a 40 delta/60 tadpole trike. Yes, an inline car does have its turning wheels farther out right and left, but is it necessarily better or worse?

Say X is center of gravity and D is the direction of CG shift in a hard braking turn. The CG will shift directly to the the right wheel W maintaining balance. Take a conventional car withe the center of gravity farther forward with a front engine. The center of gravity represented as Z will shift toward the the right wheel C in the direction of the CG shift H.



.....................H
C....W....C......D
..----------..
W---Z---W
------X------
.------------.
..----------..
C. --W--.C.
.....-----.....
......---......
.......-.......

With the Center of gravity directly in the middle or optimally 60-65% to the rear both front and rear tires will have the same load or the rear tire will carry more for better acceleration and handling. Outrigger wheels will be designed to carry far less load as they neither propel nor steer but only stabilize. They will have brakes though.

Rain and snow drag for a trike i can deal with If the overall mpg in the other more common weather conditions is higher.

@ Peter

I would see aero improvements because it is better designed for the teardrop streamlining template. An example would be the VLC with its conventional inline drive requiring its four wheels to protrude outside of the teardrop frame and into oncoming wind.
I understand manufacturing and drivetrain cost issues especially for front and back wheel drive. But designing more around a motorcycle could mitigate that. Front and rear wheel electric drive would be awesome though and the platform could carry more batteries far better than a motorcycle can.
Entry and exit can be as awesome as the jetfighter like Pulse.

My biggest issue is simultaneous Front and rear wheel steering. I know its possible but would it end up making it catastrophically undriveable? I know the gyroscopically balanced motorcycle company has said they could have front and rear wheel steering if they wanted to. With outriggers maybe there could be increased tire wear if the outriggers don't naturally want to turn with the rest of the vehicle.

I actually want feedback that tells me i could be wrong or i missed something. Ecomodding is a science. If it will not scientifically improve mpg it must be discarded and new theories formed!

I searched for the study but couldn't find it. Id really like to see what they did.

[Peter7307]

The Pinnifarina vehicle was named the X Concept.

A couple of references:

LeMay Museum > Motor Mouth Blog > Gordon v. Gorgoni

Pininfarina X | Strange Vehicles

to it an another vehicle using a similar layout.

Peter.

[gone-ot]

...motorcycle/bicycle configuration with "fixed" outrigger/training wheels!

[sheepdog 44]

That is so awesome. I can see how front and rearwheel steering can be twitchy though and i do see problems with regaining control on ice. I think the Autocycle is the best way to get around steering issues; with only three wheels on the ground at any one time it avoids having to use the rear wheel to steer. You could use front wheel steering only if you have outrigger wheels like a shopping carts though.

I read in the Pulse Autocycle website that an enclosed motorcycle can be as much as 10 times more aerodynamic than an open cycle and its driver. I see some people on here are approaching 100mpg with fairings on open bikes, but i think so much more can be gained in aerodynamics. Ive had some thoughts on how you could overcome the issues of enclosed motorcycles in DIY low tech ways (of which the diamond wheel pattern was one). The major issues i see are the increased area in sidewinds and stabilization of the motorcycle at stops.

Correct me where i'm wrong.
To counteract sidewinds would lengthening the wheel base help? I think the problem with the motorcycles and scooters that are being modded is that they weren't designed for the amount of force sidewinds can impart on a streamlined bike. Especially in scooters, they are much to squirrelly, when what you want is a longer cruising bike where side winds would impart less force to steering.

For stabilization at stops i would start with a standard vetter bike with a faired in nose and a boat tail, but extend a canopy from the hips on up so you have a fully streamlined top half instead of the big gaps in the current design. Constructed of foam with a plastic finish and a cockpit like windscreen. It would hinge from the front like a hatch to enter and be designed to break away on impact. The leg area would have front and rear fairings. I think the top half is causing the most drag loss because the human back is impractical to partially fair in. In a motorcycle posture where the human back changes angles, the tail presents a spoiling blunt front end.

Or a fully enclosed motorcycle with a "wing" sidecar like stabilization wheel. Kind of like an aerodynamic football shape that acts like a sidecar but is small and weighted and carries limited cargo.

I wish i could draw some pictures to show you exactly what i mean.