Hydraulic-launched roller coasters provide riders with high acceleration combined with improved smoothness, over electromagnetic and catapult launch mechanisms. To date, many high-speed accelerator roller coasters, also known as launch coasters, use hydraulics to provide the initial rapid get away. It’s a similar mechanism to the steam catapults used to launch fighter jets on large military aircraft carriers.
Hydraulic Launch Systems
Hydraulic launch systems, work in a completely different way to conventional roller coaster launch mechanisms. The most widely used launch mechanism uses linear induction motors (LIM), which provide linear force instead of rotational torque, and are similar to the systems that power Maglev trains. Hydraulic launch, on the other hand, is quite different. One of the main benefits of hydraulic launch over LIM launch is that the hydraulic launch uses far less power. In the US, power for rides isn’t a problem, but in the UK manufacturers have to be more aware of the maximum power available.
Hydraulic launch systems are considered capable of giving a far greater and smoother acceleration than current electromagnetic propulsion styles. The acceleration from a hydraulic launch remains nearly constant throughout the entirety of the launch, whereas the acceleration from a LIM/LSM launch is greatest at the beginning and dies off rapidly towards the end of the launch.
Hydraulic launch systems have the highest power and are compact but the number of moving parts makes Hydraulic Launch Systems generally less reliable than electromagnetic systems that contain no moving parts.
Hydraulic launch roller coasters utilise a catch-car, (called a sled) which is a shuttle-like device that pulls the roller coaster train along. The catch-car latches on to a mechanism on the underside of the roller coaster train, housed in a groove which runs along the entire length of the launch section of track. The hydraulic launch motors are located in a small building underneath the track at the end of the launch section. Approximately 2/3’s of the launch section of track is utilised to launch the roller coaster train, with the remaining 1/3 used to stop the catch-car after it disengages. This type of propulsion is capable of catapulting a roller coaster train to very high speeds, like a giant fishing rod reeling it in super-fast before releasing it.
How the Hydraulic Launch Works
Powerful hydraulic pumps (each capable of producing around 500 horsepower) are used to force hydraulic oil through a valve into several accumulator tanks (energy storing devices) comprising of two compartments separated by a piston. As the incompressible hydraulic oil is pumped into one compartment, nitrogen gas in the second compartment is compressed and pressurised to around 50,000psi. The example photo shows some of the equipment used to launch Stealth at Thorpe Park.
Whilst the roller coaster train takes up its starting position, the catch-car moves along the launch track from the hydraulic launch motor towards the train. Once the catch-car connects, it is only a short time before the anti-rollback braking system drops beneath the track, giving the train the green light to be launched.
When the nitrogen gas is fully pressurised, the valve opens, releasing the fluid, which is flung by the gas into a number of powerful motors (Stealth at Thorpe Park has 24). The power from all of the motors is transferred to a huge winch drum by a planetary gearbox. The winch drum spins rapidly winding in the cable connected to the underside of the roller coaster train via the catch-car. In a matter of seconds, at the end of the launch section, the catch-car let’s go and acts like a slingshot, hurtling the roller coaster train along the track.
Hydraulic Launched Roller Coasters
Stealth at Thorpe Park 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 used for Stealth 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. It was Intamin who also installed Rita at Alton Towers in 2005.
Manufactured by Vekoma, Velocity at Flamingo Land Resort in North Yorkshire is the UK’s first and only motorbike launch coaster. The ride uses a hydraulic launch to Accelerate riders from 0-60mph in just 2.8 seconds giving riders the sensation of racing on high-performance motorcycles over a low twisted layout. The ride also features a unique restraint system design created specifically for Flamingo Land Resort, leaving your upper body to move freely.