Stealth is located at Thorpe Park in Surrey. The £12m thrill ride is the UK’s fastest roller coaster utilising a hydraulic launch to accelerate to 80 mph in 1.9 seconds before racing into a steep, vertical top hat element. The ride reaches a height of 205ft in under 2 seconds.
Stealth at Thorpe Park
Stealth is one of Europe’s fastest roller coasters and one of the UK’s tallest. The ride reaches a height of 205ft in under 2 seconds using the fastest acceleration of any coaster in the UK with riders being propelled from 0-80mph. The experience has the equivalent brake horsepower as two Formula 1 cars.
Top Speed – 130km/h 80mph
Cost – £12m
Length – 1312ft 400m
Height – 205ft 62m
Type – Steel Launched
Inversions – 0
Theme Park – Thorpe Park
Year Opened – 2006
Construction of Stealth
Stealth was designed and built by Intamin of Switzerland at a cost of £12 million. Once the site had been cleared, the foundations were laid in June 2005. By the end of 2005, the ride buildings and hydraulic launch mechanism had been completed and the pre-fabricated track sections were added ready for the rides opening in 2006. The thrill ride is so high that the Civil Aviation Authority had to be consulted on its construction. When the £12m ride first opened, it proved so popular that the park had to close its gates to the thrill-seeking masses on a number of occasions.
The rollercoaster’s interesting design, known as the ‘top hat’, is just part of what makes Stealth so unique. Riders on Stealth are in for a breathtaking few moments of either white-knuckle thrill or panic, depending on your view of frighteningly fast rollercoasters. The roller coaster train almost silently accelerates forward faster than a Formula One car, reaching 80mph in around two seconds. Before a breath can be taken, the car hurtles upwards at a 90-degree angle and catapults up to the top hat, 62 metres above the ground. There is little time to enjoy the views over the Surrey countryside. After a split-second’s pause, the train plummets back to earth and reaches the station, a mere 15 seconds after it was launched.
Stealth is one of a growing number of ‘hydraulic launch’ rollercoasters, also nicknamed rocket-coasters, a term that sheds some light on their popularity. The technology was developed by world-leading rollercoaster engineer Intamin from Switzerland and was first used in a series of giant rides built in US theme parks. The biggest being Kingda Ka, a 140m-high monster of a ride upon which Stealth’s design is based. According to Andreas Wild, an engineer at rollercoaster expert Ingenieur Buro Stengel, Stealth is really ‘the son of Kingda Ka’.
Ingenieur Buro Stengel designed the entire Stealth ride, including its layout, geometry, dynamics and acceleration. They are the design company set up by rollercoaster designer and innovator Werner Stengel. Over the past 40 years, Stengel has been the driving force behind many of the innovations in the rollercoaster industry and his work with fighter pilots helped set many of the standards on maximum acceleration forces for passengers used in the industry. The key to Stealth’s success and its unique acceleration is the hydraulic launch system, which works in a completely different way to conventional rollercoaster launch mechanisms.
The launch mechanism for Stealth begins with a two-metre high tank filled with 14,000 litres of hydraulic oil. Three massive hydraulic pumps force the oil through a valve into two banks of six nitrogen accumulator tanks, which pressurises the nitrogen inside to around 50,000psi.
When the gas is fully pressurised, the valve opens, releasing the fluid, which is flung by the gas into 24 powerful motors. These motors power a huge winch drum, which pulls the rope attached to a catch car (the shuttle-like device that pulls the train along). The winch pulls the catch-car along the 18m of launch track up to the ride station, where it hooks onto the bottom of the roller coaster train and propels it forward.
At the end of the launch track, the catch-car let’s go and acts like a slingshot, hurtling the roller coaster train along the track. Once the car has been released, the hydraulic fluid is pumped back into the tank and is then sent straight to the motors, which wind the winch back to its starting point ready for the next launch.
The roller coaster design relies entirely on the speed generated from the launch phase to get the train straight up and over the top hat. This doesn’t always happen, resulting in occasional ‘rollbacks’, when the ride loses momentum before it reaches the peak and rolls back down, in reverse, to the starting point.
Stealth has a power correction facility as part of its specially built substation so that on days when fewer visitors are expected engineers can switch the power down so the train can run more efficiently. But on busy days, when the ride is running two trains and there are 15,000 people in the park, the power can be turned up to full.
Stealth’s special magnetic brakes can bring the ride to a safe and comfortable halt. Permanent magnets are fitted beneath each train with an attractive force between them. To stop the train, copper fins in the track are moved into position into the magnetic field of the train, which creates a resistive force and slows the train down. The brakes are not powered, they work as pure magnets. It is a super efficient system.
The track was one of the most important considerations in the design of Stealth with a great deal of careful consideration given to controlling the forces that riders experience, particularly in terms of the maximum acceleration that they must endure. Riders on Stealth are said to experience anything up to around 4G, but only for a split second.
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