When wheels turn faster
On opposite sides of the world, humanity’s most important invention has been made better
HUMANITY’S most important tool has in recent times been made a little bit better on opposite sides of the world.
In Japan, two brothers made a bicycle axle so smooth it can add at least three kilometres per hour to a rider’s speed.
In England, a group is building wheels for the supersonic Bloodhound record car, while worrying about the weight of a bag of sugar.
From Japan, Jason Clenfield reports for Bloomberg Businessweek about a set of bicycle wheels that costs over R94 920 a pair.
The wheels turn on super-smooth axles, engineered by brothers Nobuo and Yutaka Kondo at Kondo Machine, a company that employs 30 engineers who make parts for Rolls-Royce jet engines and machines that make parts for Toyota cars.
They call ther wheel the Gokiso wheel and their tests prove it turns four times smoother than competing wheels. Spin a Gokiso wheels at 28 km/ h on a test track and it will take six minutes to come to rest, compared with about 90 seconds for a high-end, resistance-impaired competitor.
The Kondos told Clenfield they weren’t thinking much about sales when they started developing their bike wheels in 2009.
Younger brother Yutaka had just lost to his older brother in an endurance race and like all little brothers, he blamed the bike. But he was right, as the rear axle had been partly crushed during the four-hour ride. Yatuka took about six months to develop an axle that could remain completely straight, suspending it inside a protective sleeve that redistributes weight and absorbs shock.
They have since tested the axle at speeds of up to 300 km/h and have run it twice around the Earth at 100 km/h, (a test that took 10 hours a day for 100 days). After all that, Nobuo says, the wheels still spun like new.
The Gokiso has one-third less mechanical resistance than the next-smoothest wheel on the market, the brothers say, which means speeds of three kilometres per hour more for most riders and crucial seconds shaved off professional’s race times.
Even in Japan, paying close to R95 000 for a set of bicycle wheels is a lot, which is why only 30 sets of the tyres have sold in four years, and about 1 000 of the cheaper models that go for “only” R39 650 a pair.
In England, engineers at the company Bloodhound SCC are preparing a supersonic race car that will attempt to set a new land speed record at Hakskeenpan near the Namibia border.
Powered by a F1 racing engine and the jet engine from a Typhoon fighter, the Bloodhound can, in theory, blast across the pan quite a bit faster than the speed of sound. To handle such supersonic speeds requires wheels that can withstand stress and can turn without deforming from 10 200 rpm.
These revolutions are only the lower limit, because it is not certain how fast the Bloodhound will go and hence how fast the wheels will actually be turning at top speed. When going flat out, the wheels generate 50 000 radial g at the rim, which means that a one-kilogram bag of sugar set on the rim would weigh 50 tons or as much as a truck.
To handle that sort of stress, the wheel discs are made of a special aluminium alloy created for cutting-edge aerospace applications called 7037, which is forged into a perfectly balanced “cheese” using hot and cold presses.
The company forging the wheels, Bloodhound SSC, said the aim of both presses is to remove any voids and form a stronger, more compact matrix in the crystalline structure of the aluminium.
Even such strengthening, followed by precision machining by the Castle company and testing by Rolls Royce has its limits. Should the crew that has been sweeping the pan overlook a single stone, the results could be catastrophic.
A pebble hitting the wheel at supersonic speeds could cause it to lose its balance, which would quickly damage bearings and increase the wobble until the wheel tore itself apart in a manner normally only seen in an exploding jet turbine. Another danger is that the front wheel could fire a stone at the rear wheel or into the body of the car at supersonic speeds.
This could be extremely dangerous for the driver, Andy Green, despite the carbon composite cockpit. To protect against this, Morgan Advanced Materials is developing lightweight composite ballistic panels to guard the cockpit and other vital areas. The laminated panels will not stop the stone, but will tear to dissipate its supersonic momentum. • email@example.com
Nobuo Kondo (left) and Yutaka Kondo made a bicyle axle so smooth it can add at least three kilometres per hour to a rider’s speed.
Bloodhound SSC staff with one of the wheels that is designed to handle supersonic stresses over Hakskeenpan near the Namibia border.