Reflections on the potential of human power for transportation

Sunday, June 29, 2014

From the Piaggio MP3 to the Toyota i-Road: The Reemergence of the Man-wide Car

I work for a high-tech aerospace company. You would think with all the techie engineers in the place, there would be some interesting vehicles in the parking lot. Except for one vehicle, all the others are pretty mundane. The exception is a Piaggio MP3 three-wheel leaning scooter. It belongs to one of our technicians and, with more enthusiasm than he may feel is justified, I tell him he is riding the future.

The extra wheel significantly increases stopping performance and the ability to lean allows the MP3 to be controlled when the wheels break free on slippery surfaces. This is opposed  to the vehicle falling over if it had just two wheels. While road testing the new 500cc version of the MP3 LT, a Cycle World reviewer dropped (out-distanced) a rider on a BMW R1200GS on a snow-slicked section of curved Berlin highway, a clear indication of the performance potential of a leaning trike. The LT stands for large track, an acknowledgement of the front wheel spacing being over 650mm. In Europe and the UK, if a trike has a track wider than 650mm, it is consider a car and can be ridden without a cycle license or a helmet. Only an auto driver’s license is required.

By making the MP3-LT controllable on slippery surfaces, Piaggio has taken a huge step forward to producing an all-weather scooter.  And with top speed in excess of 80mph and a fuel economy of 60mpg, is offers an attractive commuting alternative to an auto. It just needs a body and it could be considered an all weather scooter, or in a broader sense, a man-wide vehicle or MWV.

In a University of Michigan sustainability study for 2010, vehicle occupancy was calculated to be 1.55 persons per vehicle. That means that for most of our trips and the majority of vehicles there just one occupant in the auto. It is clear that one person in a four-person vehicle is moving too much mass, pushing too much air, burning too much fuel  and taking up too much space.
Most trips could be accomplished using a vehicle tailored to one person or two persons in tandem, a man-wide car. Since the vehicle is lighter and more aerodynamic (less frontal area), fuel consumption could be significantly reduced. And the smaller vehicle size would allow more vehicles to occupy the same lane width as a normal-width vehicle.

The investigations into MWVs by large auto companies are not new. Honda had its EP-X which seated two.

Volkswagen had its L1 which also seated two.

And general motors had its Lean Machine which only sat one.
But only the Lean Machine approximated the width of a motor cycle, 850mm (33.5”), with its 915mm width. Narrow-track three and four-wheel vehicles risk overturning when cornering. Allowing the vehicle to lean like a motorcycle provides  for dynamic stability  and allows the width to remain narrow without the risk of overturning. The Lean Machine was narrower than these other attempts because it could lean.

Now both Toyota and Nissan have MWVs that utilize leaning to reduce the vehicle width. Both are completely electric powered.

The Nissan Land Glider uses four wheels that are articulated allowing the vehicle to lean. At 1100mm width, the Glider is wider than a motorcycle but still significantly narrower than a Smart Car’s 1550mm width. The glider seats two in tandem.

 The Toyota i-Road is also a dual occupant vehicle that is narrower than the Glider at 850mm, mostly due to the layout (like the Lean Machine) where the single wheel does the steering and thus doesn’t require the width that two-wheel steering does. What is unusual about the i-Road is the single-steered wheel is in the rear. If the instability issues associated with rear-wheel steering can be overcome, (see below),

this layout is ideal for packaging. Because the front wheels incorporate the electric-drive motors there is room between them for the driver while maintaining minimum vehicle width and the steered wheel fits easily in the width of the vehicle. 

I attempted to use this layout for the initial design approach of my EcoVia commuter trike, but could not come up with a mechanism for stable control of the steering and leaning that functioned at anything  but low speeds.

Fortunately, the i-Road can utilize active electronic control to insure stability. The i-Road’s top speed is less than 40mph so it is not suited for highway use. What is encouraging is that the project has graduated to the consumer test phase where 20 Japanese drivers will get to evaluate the i-Road under real-world driving conditions.

Probably the most unusual approach to developing a MWV is the C1 from Lit Motors. It uses two gyroscopes to balance the two wheel vehicle. Gyro-stabilized two-wheel vehicles have been around since the dawn of the automobile, but in this case, since the vehicle is all electric, power is available to keep the gyros running temporarily even when the drive motor is turned off. It also features twin retractable support legs that hold the vehicle up when permanently stopped. The amount of balance torque generated by the gyros is impressive and will insure the vehicle stays upright during collisions. It will seat two people. Since it has only two wheels, it will require a motorcycle license to drive.

The i-Road and the C1 are essentially all-weather motorcycles, but for the increased cost, buyers will require significantly more crash protection than your average motorcycle. Providing this will require some creative use of materials and structures to prevent significantly increasing size or weight.

If MWVs become numerous, they may cause changes in highway infrastructure. Single wide highway lanes could be turned into two narrow lanes, and therefore improve traffic throughput. This would require recognition that the smaller vehicles merit special consideration which may be a difficult sell to the general public.

I rented an original Honda Insight when my car was being serviced. Since the car was more narrow that what I had been used to, sitting in the car in my driveway I could imagine the vehicle was only one-seat wide. As long as I am warm and dry and can safely maintain highway speeds, I could live with a vehicle like that.

Hopefully, in the not too distant future, there may be mature MWVs parked in the lot where I work. Maybe one will be mine.


Tuesday, June 3, 2014

The Sinclair C5 to the Organic Transit Elf: Pedalectric Identity Crisis

The Sinclair C5

The Organic Transit Elf

One would think if George Georgeiv’s Varna Tempest could cover a distance of over 56miles in one hour, that it would be a straight forward process to design a commuter vehicle that could travel at half that speed, a vehicle that could keep up with urban traffic while only requiring about 200Watts of mechanical power. To date, this has proven to be more difficult than I would have expected, partly due to the increased requirements that go along with comfortable and safe commuting.

The first decision that designers must address is predominately where the vehicle will be ridden.
If it is mostly on bike paths, the vehicle can be considered an all-weather electric bicycle, or AWEB. (I use the term bicycle to embrace the most common embodiment of a pedaled vehicle. It will more likely be a tricycle.)

It takes more than adding a third wheel, a motor and a body to produce a fully functional AWEB.

 The main criteria is to keep the vehicle narrow enough to fit within bike lanes and keep it high enough to be visible to other cyclists and autos when it is ridden on shared roadways. For the bike lanes I use, the width needs to be less than about 33 inches.  (The width of a motorcycle is considered to be about 33 inches). If the vehicle is to be stable on slippery road surfaces it will require three wheels and if it is to have reasonable corning speeds without tipping over, it must be a leaning tricycle.

Most locations have speed limits for electric bicycles which limit their effectiveness in challenging cars for commuting purposes. In the US, the electric bicycle speed limit is 20mph.
If it is to be ridden where it shares the traffic lanes with autos it can be considered a pedal-electric car or PEC.  A PEC needs to be visible and able to keep up with traffic to not cause congestion. Where I live that means that it needs a top speed of 40mph.

In addition, for adequate traction on slippery road surfaces, more then 50% of the vehicle weight should be on the driving wheels.

The Drymer discussed in the post listed above comes very close to meeting all the requirements of an AWEB. The Cyclodyne discussed later came very close to meeting all the requirements of a PEC without an electric assist
In 1985 the British electronics industrialist Sir Clive Sinclair decided to mass produce one of the first pedalectric vehicles. More than just an electric bicycle, it had three wheels and a partial faring.  The pedals drove one rear wheel and an electric motor drove the other. Lotus Cars developed a flexible chassis in lieu of a suspension and Polymotor of Italy developed a motor with an integrated gear-reduction. To take advantage of riding the C5 without a license, the top speed was limited to 15mph.

 Automotive Engineering titled its May 1985 article “Motor Assisted Trike Presages Electric Cars.” For all the media hype and large financial investment in the project, 12million pounds, the result was an abysmal failure.

 Here is a list of the more obvious failings:
   1.        It had only one pedal speed.
   2.       The pedal cranks were much shorter than normal.
   3.       The pedal-seat distance couldn’t be adjusted.
   4.       It was too low to be visible in traffic.
   5.       It had poor weather protection.
   6.       It didn’t have enough electric power to get uphills.
   7.       The front wheel was too small.

Below is a picture of a tall rider, Automotive Engineering’s European Editor Scott, wedged into the vehicle.

Clearly there was no input from cyclists on the pedal drive or there would have been multiple gears and an adjustable seat-to-pedal distance. The pedal portion of the vehicle was merely window dressing.
The height issue was addressed by adding a tubular loop in the rear that could hold flags or reflectors.

The inadequate weather protection was addressed by adding a rain suit and waterproof side covers. (Anyone that has ridden a recumbent in the rain will see that this rider will develop a puddle in his lap!)

There were a few features that were to be commended. The overall design had an attractive, streamlined esthetic, in some part due to the delta configuration (one-front wheel, two rear wheels), which allowed the steered front wheel to comfortably enclosed by the nose of the vehicle. And having the handlebars beneath the seat proved a comfortable location.

In the end there were 17000 vehicles sold, but many owners abandoned the pedals and used electric power only. Although it aspired to be an AWEB, the C5 ended up being little more than a recumbent electric scooter.

Skip ahead 19 years to the Elf from Organic Transit of Durham, N.C. The Elf is a semi-enclosed electric tricycle using the tadpole configuration (two front wheels, one rear wheel). The pedals and the electric motor drive the rear wheel. It is a noticeable improvement over the C5. It has much better weather protection. The seat-to-pedal distance can be adjusted and it has multiple speeds. Below is a picture of an Elf chassis being assembled. The seat slides on the two-horizontal rails between the front and rear wheels.

Everything looks promising until we check the vehicle width, which at 48 inches is too wide to fit within most bike lanes. In addition, the rear wheel appears to support less than 1/3rd of the vehicle’s weight, so traction in snow will be a problem. (The Organic Transit site shows a pretty picture of an Elf in on a snowy road.) So the vehicle width prevents it from being a viable candidate for an AWEB. On the other hand, since the speed is limited to 20mph, it is not a candidate for a PEC either.

The people at Organic Transit are working on the next generation of the Elf. So one suggestion for a simple improvement is to go from the 26 inch dia. wheels to the more standard (for human-powered vehicles) 20 inch dia. wheels. These are more electric-motor friendly since they rotate faster. They also take up less space, so volumes for turning and fenders can be smaller, leading to a more streamlined design. Another simple improvement is to have only one door (like the Pedicar). This provides for a more continuous structure for the body and better weather protection.

If they are interested in adding leaning to their design, it would benefit them to take a closer look at how the Drymer people incorporated leaning into their trike design.

Because the Drymer leans, the c.g. of the vehicle can be shifted toward the rear wheel without concern for tipping during cornering. As a result, traction for the driving wheel is improved and suspension on only the rear wheel is very effective.

The Organic Transit people also have a utility trike on the drawing board called the Truckit. The Truckit uses a delta configuration for the wheel locations with pedals driving the front wheel.

 A more compact and streamlined concept for a delta-configuration velo truck, based on the EcoVia leaning-trike, is shown below.

The pedals drive a central driveshaft and the two leaning wheels are chain driven off that shaft.

The truck is 108 inches long, 33 inches wide, 57 inches high and has a cargo capacity of over 25 cubic feet. The leaning can be locked up for loading and low speed operation. The pedals drive both rear wheels and the motor drives both rear wheels through twin ratchets that act like a posi-traction differential. This produces excellent performance on slippery surfaces.
Had the Cyclodyne from the 1980’s incorporated an electric drive to supplement the pedal drive, it would have been the first successful PEC.

Even though it had a pedal-powered cruise speed of 30mph, it wasn’t quite fast enough to keep up with traffic, which it needed to do because it was almost as wide as an Elf. The addition of electric assist could have easily increased its top speed to over 40mph.

The Cyclodyne drove and steered both front wheels providing excellent all-weather traction. It would have been straightforward to integrate an electric motor into that drive.

So in conclusion, I believe that AWEBs, operating on most bikeways will have to use the leaning-trike configuration.

Bridgestone seems to reinforce this point by joining  the ranks of the AWEB's with their own version of a Drymer-like leaning trike.

For the less common PECs, leaning is not a requirement, since they will be able to keep up with cars and can therefore be wider. That being said, being able to lean makes the vehicle narrower and more aerodynamic. And this makes it more efficient. 

Automakers are again looking at tandem-seating two-passenger vehicles for fuel economy and they are also incorporating leaning to reduce the vehicle width. More on these man-wide vehicles in the next post.