That is it for Aptera

[Arragonis]

Originally Posted by drmiller100

Your assistance is much appreciated, and we all need to remember to be good little sheeple and follow the lead of our socialist friends.

You tapped this twice - Not entirely sure where politics came into this, but I appreciate your gratitude Add a thanks to my post...

You need to read my other comments, I am happy for people to build these themselves - I really do look forward to seeing the results. Folks here are a very creative bunch. If you are building one, good luck. Enjoy. I remain unconvinced that this automatically a "better" approach than with 4 wheels - thats all. Not sure how that makes me Stalin or a "sheeple" in one post.


Baah.

Originally Posted by NeilBlanchard

And the G-Wiz accident is a straw man -- that is a death trap by almost everybody's opinion. It is a NEV, right? Isn't that how it avoided a crash test?

No design is inherently crash-worthy or not crash-worthy. The G-Wiz has 4 wheels, and it is not very good in a crash. The Aptera was designed to be crash-worthy, and it was crash tested, both in a computer, and for real. They did a 35mph front end crash; Steve Fambro will hopefully release the video of this.

I didn't intend it to be a straw man, it was an example of something which had avoided a crash test due to regulations and that had some consequences. GWizz has gone bust - again.

However you are now saying they (Aptera) did a crash test - which will be good to look at. If you have a link that would be appreciated.

However this was where I got the impression they avoided it:

Originally Posted by Ken Fry

The real disadvantage to four wheels is that you are then a car, and are playing in a market where a $billion to develop a single new model is standard, and Aptera's 24 million in funding is a rounding error. You can expect to spend millions in crash testing.

so you can see my confusion, I hope ?

3 wheelers can be fun and can handle well. A 3 wheel 1930s Morgan "Supersport" held the Outright lap record at a circuit in the North of England - light weight and being better round corners than motorcycles gave it the edge. I believe a four wheel Caterham eventually bettered it by having more power and the same weight.

I find this a little like the idea of a rear mounted engine - another favourite idea amongst some ecomodders. I can't help wondering if, like that idea, there isn't a reason why the majority of car makers who adopted that layout switched back to a front mounted engine or went under. Morgan dropped 3 wheelers in 1952 until the new 3 wheeler limited production run, Reliant went back to making sports cars in the 1980s and Bond went bust.

Like I tapped earlier, "comrades" I wish all those building one the best of luck - may all your winds be tail ones, and may your tyres roll with little resistance.

[Frank Lee]

Originally Posted by Arragonis

Being Frank for a moment, that is an incomplete answer. Why does it give you these advantages ? The devil is in the details.

It's easier to teardrop a body with one wheel on one end.

Maybe tires are not as sensitive to scrub as I imagine, but one wheel should not suffer side scrub by itself from imperfect alignment/track changes through suspension travel.

One spring/damper assy ought to be lighter than two.

Trikes aren't mainstream because they are more load sensitive. The lowest common denominator users out there can't be trusted with that. Add wheel #4, gain lots of safety margin.

[Arragonis]

Originally Posted by Old Mechanic

For me (and ME alone) 3 wheels allows me to use a single module in the rear wheel. Since the cost to built a module from scratch will probably exceed the cost of many used cars driven daily in the US, 3 wheels is the pathway to a practical vehicle.

It will provide a platform where I can try various engine or motor configurations for power generation. Electric, gas, or diesel, any one of which could provide power for the primary pump to charge the accumulator. It could even use different power modules for different length trips.

The chassis will be structurally as strong as most Race cars of tubular design, and will be built by a shop the builds race cars, with collision protection far exceeding pressed sheet metal uni body structures.

The interior will be using Extensive padding, racing quality seats, and a 5 point harness for driver and passenger. I would certainly rather get hit in that vehicle than in the bike I ride almost daily, and probably in the car I drive as well.

Once the design has been proven to offer real efficiency gains, then I will start to work on 4 wheeled configurations. The choice is solely based on total cost for a functional vehicle.

regards
Mech

Good luck with it, not sure about the idea of the single driven rear wheel - I assume motorcycle mechanics ? - and converting it to four wheels later. IF I was building one I would go for a transverse FWD design as its easier to get an engine / transmission unit (e.g. Metro etc.) and as has been tapped elsewhere bike engines are not always better for FE. Plus it means that the single rear wheel has less work to do ?

[Arragonis]

Originally Posted by Frank Lee

It's easier to teardrop a body with one wheel on one end.

Maybe tires are not as sensitive to scrub as I imagine, but one wheel should not suffer side scrub by itself from imperfect alignment/track changes through suspension travel.

One spring/damper assy ought to be lighter than two.

Trikes aren't mainstream because they are more load sensitive. The lowest common denominator users out there can't be trusted with that. Add wheel #4, gain lots of safety margin.

Teardrop -
The Citroen Coccinelle managed a neat teardrop (the original name was "A Drop of Water") with 4 wheels. It had stability problems though due to weight distribution (in this case due to the passengers and engine being too close to the front).



We've also seen some pretty neat teardrops here on EM - the Dolphin for example.

Geometry -
How do you keep the rear wheel upright to the road with body lean ? When the body leans it would ride on the edge of the tire instead of the face ? A wheel at each corner can have suspension geometry keeping it flat.

The VW Scooter had this issue



This could be more of an issue if you plan on using RWD (maybe motorbike as Mech may be planning ?) then you need a tyre wide enough to cope with the extra weight over a bike, and also giving reasonable traction in the wet. A peaky MC engine, singe rear wheel and a hill start in the rain will be fun

Weight -
Lomax made 3 and 4 wheelers (both FWD based on the Citroen 2CV) in the 1980s





I don't think the difference in weight was that much - just one suspension arm and lever to connect it to the central spring in between the suspension units - and the 4 wheeler has the advantage of having some luggage space between the rear wheels.

As you tap though anything this light is going to have issues when loaded. I would suggest that extra wheel (and weight required) would minimise that but I'm sure someone has a neater solution to make it work.

And yes, none of these went through crash testing as they were sold as kit cars.

[Frank Lee]

Pac Car II isn't a quad. Why?

[Arragonis]

This suggests it is because they wanted to limit frontal area and rolling resistance to an extreme level, even limiting the effect of the steered wheels.

PAC-Car II is equipped with 3 wheels; the single rear wheel is powered and steered, and the front wheels have a camber angle of -8°.

This solution allows the reduction of the frontal surface area because the room needed to steer the wheels is not needed. Some experiments on a test bench have shown that this camber angle does not provide too much rolling resistance.

So they put the steered wheel at the rear where it would be shielded by the bodyshape, and the two at the front in a fixed position to minimise RR. It did its record breaking at 18 MPH though.

[kach22i]

Originally Posted by Arragonis

Teardrop -
The Citroen Coccinelle............

Very nice example, I've never seen this one before.

Thanks to this thread I've learned that rolling resistance is due to weight, not the number of wheels. I have always wondered about that.

I once had the chance (1982-83 when he spoke at MSU) to show Buckminster Fuller my wedged shaped VW Beetle based trike. All he said to me was; The two wheels should be in front, you have it backwards.

I drew and clay modeled single front wheeled cars for another 20 years before giving in to the reverse trike layout. I'm a slow learner I guess.

[botsapper]

Optimizing aero profiles (narrow) + driver visibility (tall & upright) + stability concerns, has been addressed by tilting/leaning. Tilting type is active. The active suspension geometry decides the lean angles for optimum balance for both three or four wheel platforms.

http://www.youtube.com/watch?v=OjOEihfIk5s

http://www.youtube.com/watch?v=ryDG-vHf5OA

Survivable 'motorcycle' head-on crash test video.

http://www.youtube.com/watch?v=S3ywadBp3wc

http://www.youtube.com/watch?v=qyDoa...feature=relmfu

[Ken Fry]

Originally Posted by botsapper

Optimizing aero profiles (narrow) + driver visibility (tall & upright) + stability concerns, has been addressed by tilting/leaning.

Its odd how few of these actually take advantage of aero potential. Many are cutesy bricks.

There are a zillion of these tilters, and some could be fun, with the Persu being the furthest along, having licensed the Carver tech. However, the only modern tilting vehicle that takes a serious look at side impact protection is the Lit C1.



All the rest will flip when hit from the side. The C1, ostensibly, (with 1300 lb-ft righting moment) remains vertical in a side impact (with the stabilizing torque able to overcome tire traction).

Most of the tilters, however, at least offer better protection than the typical motorcycle.

The only tilting three wheeler that has done OK so far is the MP3 by Piaggio... but it has sold well only in France, and has flopped in most other places. The enclosed ones at least offer weather protection.

The open versions (like the Piaggio) offer very subtle advantages (don't have to put your feet down??) and major disadvantages in weight and complexity. Although Piaggio in their early promos showed the MP3 doing stoppies (standing on the front wheel) (unwise advertising, in my view -- because the newbies who would buy a motor scooter fear such things, correctly) stopping ability is not an issue for motorcycles. Not once in racing did I say, "... gosh, if I just had one more wheel in the front, then I could unload the rear and destabilize handling even more."

I've flown with autopilots in control, but was always able to go to the backup: flying by hand. Active control in a motorcycle-like vehicle would make me nervous, because there are not adequate backups in place. To cause the vehicle to bank, the wheels must be steered out from under the CG, the logic for which can certainly be computer-controlled. But once the driver has learned the computer-controlled technique (turn right to go right) then the manual technique (turn right to bank left) is not likely to be mentally and kinesthetically accessible quickly enough in a computer failure.

The manual control versions seem to make more sense from this perspective. (But they become unmanageable if heavy.) The Persu, (which is computer-controlled) has warning lights for too-high tilt angle, but when you need the warning most is when you are unlikely to have many options (evasive maneuvers, being already banked to 45 degrees and seeing that the turn tightens up, etc.) While an overbanked motorcycle (grounding pieces and rear wheel unweighted) will drop to the inside of a turn, a Persu going too fast into a turn appears to run the risk of high-siding, if the tires are sticky -- an unpleasant experience, if ever there was one. On a manually controlled version (open air or with enough cabin space) you can hang off the side to "cheat" the lean angle. (This technique is seen in online videos of the Ducati-powered tilter.)

[Arragonis]

Originally Posted by kach22i

Very nice example, I've never seen this one before.

Thanks to this thread I've learned that rolling resistance is due to weight, not the number of wheels. I have always wondered about that.

I once had the chance (1982-83 when he spoke at MSU) to show Buckminster Fuller my wedged shaped VW Beetle based trike. All he said to me was; The two wheels should be in front, you have it backwards.

I drew and clay modeled single front wheeled cars for another 20 years before giving in to the reverse trike layout. I'm a slow learner I guess.

My example is from this book



which is worth a read for the development stories of the 2CV, the Traction Avant and the DS - all of which still seem to make modern cars feel quite basic.