THE HUMMINGBIRD AND THE SWAN: The Story of the E-Tracer
PIAXP X-Tracer Team Switzerland Story
The sight the Peraves’ E-Tracer® cornering at a 52-degree lean instills awe, if not trepidation.
But fear not, this electric-powered cabin motorcycle was engineered for safety as well as fun and efficiency. Accelerating to 60 mph in under five seconds, at top speed of over 150 mph and covering a distance of 150 miles on a single one-hour battery charge, the X-Tracer Team Switzerland’s entry in this year’s Progressive Insurance Automotive X PRIZE (PIAXP) competition is likely to zoom off with first prize in the alternative class.
Anyone tempted to dismiss the E-Tracer as either a puffed up motorcycle or a slimmed down car, however, is missing the point. When asked what inspired the E-Tracer design, the X-Tracer Team Switzerland is quick to respond: the hummingbird and the swan.
What can the hummingbird and the swan tell us about vehicle design? Plenty, according to X-Tracer team leader, Roger Riedener.
Riedener explains: “We are huge fans of well-engineered cars, whether they resemble sports cars like the Porsche 911 or eco-boxes like the famous but unfortunate Audi A2.” But, he laments, of the millions of cars built annually, the efficiency of the average (based on sales figures) automobile is dismal.
The automobile is a frozen tribute to the era that first produced it, when fossil fuel oozed plentifully and cheaply and landscapes unfurled like pristine pages waiting to be inscribed.
Today’s car transports an average of 1.4 people from point A to point B amid creature comforts, ample baggage storage and protection from weather and harm — all at the bargain price of 15,000–35,000 USD.
On the opposite end of the driving spectrum sits the sport motorcycle. “All of our team members have at least one of these fun machines in their garage,” Riedener eagerly asserts. With a price tag between 15,000–20,000 USD, the sport bike delivers real bang for the buck: “There isn’t anything quite like a power-to-weight ratio of 1:2 for the money!”
But pleasure and power collide head-on with grim mortality statistics for these bikes, targeting them for possible regulatory extinction. At the very least, they could soon carry the stigma of being “socially incorrect,” if singled out by the airbag generation and their safety-crazed governments who demonstrate zero tolerance for passenger injury.
Such concerns were not urgently voiced back in 1974, when jet pilot and aircraft designer Arnold Wagner founded Peraves Ltd. in Winterthur, Switzerland, to advance his vision of an alternative driving experience. Since 1985 Peraves Ltd. has been hand assembling the world’s only cabin motorcycle in production, the Ecomobile, adding the MonoTracer® in 2009.
The company’s built-to-order MonoTracer® is powered by a high-performance BMW internal combustion bike engine. Developed for speed rather than overall efficiency, its fuel economy is already an astounding 50–65 MPG.
All members of the X-Tracer team have been designing, building and playing with these extraordinary machines for 25 years. Emphasis should be placed on the word “play.” In 1996, ten Ecomobiles rode through 22 US states in what Riedener recalls as “one huge lap of America, doing no less than 7000 miles in three weeks. My best holiday ever!”
Anually since 1990, the growing Peraves community has convened at a racetrack to compete in their own “World Championship for Cabin Motorcycles.” The event enhances driving skills, feeds design improvements and fosters friendship among the over 100 owners of Peraves vehicles.
The new MonoTracer® out-performed all expectations from Day One.
Still, a huge leap forward in its development was possible with the availability of lithium ion (Li-Ion) cells.
Explains Riedener: “Upon the arrival of lithium cells in 2000, it was clear that the first purely electric high-performance road vehicle would be the ‘smallest available two-seater plane without wings’ — which is, incidentally, the MonoTracer!”
And it is at this crossroads where we, and the Peraves cabin motorcycle, encounter the hummingbird and the swan.
Core members of the X-Tracer team have also been electric model RC flying enthusiasts for two decades. This experience provided key input into their 2007 proof-of-concept prototype of the E-Tracer®, the first electric cabin motorcycle.
The comparatively small size and extremely low drag of the E-Tracer due to it’s single track and the tandem seating allows, by the laws of physics, scaling of the electrical drive comparable to a small airplane. This could never work in a normal-size car. The inner circles of airplane design refer to this phenomenon as the Hummingbird-Swan-Effect:
The hummingbird uses approximately two grams of its total muscle mass of eight grams to sustain hovering flight over a nectar stem.
A swan, with ten kilograms of mass, would require a wing muscle mass of over twenty kilograms to perform the same party trick, bringing its total proportional weight closer to 30 kilograms. In effect, this leads to a wing muscle that weighs in excess of 50 kilograms …
The picture becomes clear: The E-Tracer is the hummingbird.
Illustrated another way, a mid-size car with an electric drive typically consumes 400 Wh/mile. To attain a range of 200 miles, the equivalent 80-kW battery would weigh 1200 pounds and cost 40,000 USD.
The crowning achievement of every Peraves cabin motorcycle model is its “Peraves Body-Mass Index” BMI. The E-Tracer design reduces the mass of resources needed to build, operate and (at the end of its lifespan of 20–30 years) recycle the vehicle, in comparison to the average automobile or sports motorcycle:
|empty weight in pounds||3600||1200||600|
|number of people transported||1.4 average 5 maximum||1.5 average 2 maximum||1.005 average 2 maximum|
|Peraves “BMI”||3600:25:1.4 = 100 average to a possiblebest of 20.0||1200:300:1.5 =2,7 average to a possible best of 2.0||600:40:1.005=15 average to a possible best of 7.5|
|Performance||120 mph,0-60 in 9 seconds||150 mph,0-60 in under 5 seconds||150 mph,0-60 in 3 seconds|
It is the body-mass index that impedes or enhances any vehicle’s performance. Fuel efficiency directly correlates to a vehicle’s body-mass index.
In fact, fossil fuel remains a highly “efficient” energy source. One kilogram of premium fossil fuel packs more than 12,000 Wh of thermal energy whereas the same amount of the best lithium ion cells has just attained 200 Wh of usable storage. The sad truth is that 90% of the planet’s fossil fuel resources have been squandered on cars that run on 10% energy efficiency. By contrast, the E-Tracer carries 120 kg of Li-Ion cells on board, but maximizes its energy efficiency to 90%. Thus 120 kg of Li-Ion cells, equal to just 2 kilos of gasoline, at 90% efficiency powers the E-Tracer at a rate of 300 MPG.
The PIAXP requirement of 100 MPGe pushes the physical limits of what we all recognize as a car — however reduced its bulk, weight, or friction, and whatever its drive: turbo-diesel, hybrid, or pure electric.
On the other hand, the physical limits of a 1200-pound, fully-enclosed tandem two-seater with a one-track main running architecture and an additional extendable three-track maneuvering system lie somewhere between 350–400 MPGe. This leaves a lot of room for fun in the E-Tracer, which easily achieves 200 MPGe during sporty driving. The X-Tracer Team elaborates on just a few points:
- We don’t have to use thin wheels and pump them up to 50 psi.
- We don’t have to use rear-facing cameras as mirrors.
- We do not shave off every ounce of weight and can therefore invest in some luxury.
- Aerodynamics don’t have to compromise daily usability, as is the case in many of today’s cars.
- We don’t have to worry about passing the slow 18-wheeler in front of us on a two-lane road, we just do it.
- We can overpower the E-Tracer with a 204-hp electric engine, resulting in a very sporty 10-lb/hp weight-to-power-ratio fully loaded with two occupants. This is clearly Porsche Territory.
- With over 1100 Nm always available at the rear wheel, there is plenty of safe acceleration on tap to cope with the ever-decreasing gaps in today’s traffic. This is more like Ferrari or Lamborghini Territory.
- All this with a 150-mile range and a 250-pound battery for 10’000 US$ at this time of writing. Prices per kWh will eventually come down by 30-50%, but not like with DVD Players, cellphones or flat-screens by 90% in ten years. Batteries are mainly made out of resources, and not of engineering or marketing costs.
In short, the E-Tracer keeps it nice and sexy; or, “green and sexy,” as Mrs. Micheline Calmy-Rey, the Swiss Foreign Minister, accurately described the future of individual transportation at the 2008 Geneva Car Show.
Each year perhaps 10,000 sports car owners who also have a love affair with the sports bike would be captivated by the E-Tracer’s ability to combine the talents of the two. These owners would enjoy a welcome bonus: peace of mind. For, depending on the source of electricity, they are able to reduce their carbon footprint to virtually zero. For example, 15-m^2 of photovoltaic solar panels on a garage roof produce ample current to power the E-Tracer for 10,000 miles per year.
And, the E-Tracer looks as good in the city as it does on the open road. In tomorrow’s mega-cities (following trends already established in London, Tokyo, Singapore and Hong-Kong), it will be crucial to limit traffic to electric-powered vehicles within certain boundaries. Not only does the E-Tracer qualify, it is entitled to use less congested bus lanes due to its classification as a motorbike. Already in Singapore, it is impossible to purchase a car without proof of a parking space! Because a bike can be parked virtually anywhere, the E-Tracer owner is able to bypass this rule. The E-Tracer is able to sneak through traffic thanks to its very narrow (less than 4-foot wide) form, which also reduces the risk of head-on collision to nearly nil. This latter fact is proven by 25 years of safe driving records maintained by Ecomobile and E-Tracer customers across 20 million miles.
Peraves has designed the world’s most efficient high-performance electric vehicle, the E-Tracer. However, even the X-Tracer team is realistic about the transition required before we find an E-Tracer in every garage.
Their intermediate solution? A better internal combustion engine, namely, the Superball-Engine®, another Peraves invention.
Riedener elucidates: “We have burned all that fine black gold with a lousy 10% total efficiency. If inventions like our own Superball-Engine could improve that rate to 30% or even better, it would be very rational to use fuel for another 20 years, until electric batteries have reached a sufficient performance level to power “normal” cars.”
With the Superball-Engine, Peraves has engineered an ICE that consists of only three (yes, three!) moving parts, able to perform the same thermo-dynamic functions as a four-cylinder-inline-four-stroker with supercharging. Such a conventional engine needs at least 36 rotating or oscillating parts to tackle the same tasks. The resulting higher efficiency through the lower friction, cheaper production, tighter packaging and better power-to-weight-ratio of the Superball-Engine is therefore obvious.
Check out the video of the virtual engine running here:
It is easy to see that these solutions, fueled by longtime Peraves passions and play, are more than suddenly relevant. They are elegant. The hummingbird and the swan have taught these innovators well, and the planet will only benefit in the short and the long run.
And along the road, the X-Tracer Team Switzerland may bring home the Progressive Insurance Automotive X PRIZE.