A Future Without Flats
Tweels are airless. They consist of a semi deformable central wheel, which behaves some what like a conventional car wheel. Branching off from the wheel are flexible spokes that act as shock absorbers. Around the ring of spokes is the actual tread of the tire on a thin band. The tweels are all one piece and provide many advantages over classic radials. First and foremost is their lack of a pressure system. The spokes of the tweel do the job that a pneumatic cushion would, without the dangers of a flat or blow out. Secondly, because of the nature of the tweel, engineers now have have the freedom to focus on both comfort and performance.
With a typical tire, there are two types of rigidity. To increase the handling of a car, you want a tire that is stiff laterally. But for a comfortable ride, you want a vertically stiff tire. With a conventional radial tire that relies on air pressure, there is a limit to the amount of one that you can have without sacrificing the other. But with the tweel, you can optimize both the lateral and vertical stiffness of the spokes and hub independently. Thus without loosing the slightest bit of comfort, you can drastically improve a cars handling. This is the real reason why engineers at Michelin are giving the tweel a spin. In the long run, it stands to completely out perform radials.
For now the tweel is still in the design and testing phases. Michelin has approved the tweel for use in low weight low speed vehicles, such as Dean Kamen's tall standing stair climbing wheelchair, the iBot. They are also experimenting with military applications. Vehicles equipped with tweels are much less likely to be immobilized by explosives or other damage than vehicles with pneumatic tires. Further down the list are heavy equipment and construction vehicles that could benefit from improved performance. But the endgame sees the tweel much closer to home.
Michelin has outfitted an Audi A4 with prototype tweels. Eventualy, they would like to see tweels on passenger vehicles and beyond. But there are issues that must be overcome. At high speeds, tweels suffer from both excess vibration and unacceptable noise. Michelin engineers have been working diligently to solve those problems in the year since the tweel's debut. Already the tweel has been noted "one of the most amazing inventions of 2005" by Time magazine, and "Best of Whats New" in Automotive Technology by Popular Science. Earlier this year the tweel earned a gold medal for innovation at Intermat 2006 in Paris.
Have a look at this promotional video of tweeled vehicles in action. Once these airless wonders are ready for prime time, I can see them catching on quickly. No doubt they'll cost a premium for their performance, at first being the domain of auto enthusiasts. But eventually a robust tweel technology could become the new standard, leaving radial tires in the dust. Either way, true innovation is a rare gem in the automotive industry. We have been doing a lot of the same things the same way since the time of our grandparents. It's good to see that in a field dominated by convention and the status quo, some one has the wherewithal to reinvent the wheel. [via WallStreetFighter]
"One sees them all about—men who do not know that yesterday is past, and who woke up this morning with their last years ideas [...] there is a subtle danger in a man thinking that he is ‘fixed’ for life. It indicates that the next jolt of the wheel of progress is going to fling him off." - Henry Ford