An article by Jochen Peschel

It won´t be long before the second Hydraulic Launch Coaster by Intamin in Europe will appear in front of us. From the main entrance only the summit of the Top Hat is visible, and on our way through the park tension rises with every step. We pass a small bridge and stop in front of a purple entanglement of track. Then the power of the hydraulic propulsion system causes a small earthquake. Liseberg´s Kanonen has once again fired off a train.

. Vekoma's Booster Bike at Toverland .

Liseberg like most Scandinavian downtown parks suffers from a chronic lack of space, and so the park parted with the scenic railway in 1987, last but not least because of the high maintenance cost. The citizens of Gothenburg complained vociferously about the loss of the wooden coaster at which a brakeman on board of every train controlled the speed manually, and so Balder was built in 2003 as a modern replacement that has easily won the coaster fans´ favor.

But this new ride also brought some changes in the park configuration, and so Vekoma´s Invertigo HangOver, a Boomerang with hanging trains, had to give way for a compensation area. But afterwards Liseberg had no looping coaster at their disposal, so the course for the next attraction was already set.

So the park managers solicited bids from well-known manufacturers like Gerstlauer, Intamin, S&S, Mack Rides, Maurer Söhne and the Italian manufacturer Zamperla to be able to put patrons upside-down again. "Due to the good experiences with Balder and the impressive catapult launch we decided to mandate Intamin again with the project", tells Lars-Erik Hedin, the Technical Director of the park.

Left: Jenny Gustafsson, Press Officer, and Lars-Erik Hedin, Technical Director at Liseberg are proud of the powerful novelty

Now the company from Liechtenstein could show that their powerful hydraulic coasters are not only good for ever new height and speed records, but also qualify for compact layouts on a limited footprint. The first Hydraulic Launch Coaster in Europe, Rita - Queen of Speed at Alton Towers (UK), which opened three weeks before Kanonen, already has a low and twisting track. The version for Liseberg not only has a "classic", just 24 meters high Top Hat, but also offers two inversions, tight curves, airtime bumps and extreme changes in direction.

"Due to the soft underground, which had already caused problems with HangOver, a concrete paving slab of 50*25 meters has been cast. It rests on 170 piles up to 25 meters deep. So the dynamic load can be better dispersed. This way we inhibit that the respective foundations sink in too deep at every ride, which would highly stress the structure of the ride each time", says Lars-Erik Hedin. Therefrom it was possible to shift the whole ride into the second floor and to underpin it, thus gaining space for the drive technology, workshops and storage rooms. The latter formerly occupied the area - shortage of space makes people ingenious.

From zero to 75km/h in less than two seconds

We now stand in the "basement", to be exact in the engine room of Kanonen, with Lars-Erik Hedin. Multiple red containers and aggregates are connected by a seemingly endless number of hoses thick as arms, containing the oil fluid. To the left in front of us there is a huge quadrangular tank that holds 4000 litres of hydraulic oil. Via a pump a pipeline leads to another reservoir that is formed by a pile of horizontal cylinders connected among each other. They hold the nitrogen, a compressible gas that buffers the energy that is necessary for the launch.

The volume of the cylinders is divided into two parts by a movable piston in the uppermost cylinder. One part contains the nitrogen, the hydraulic oil is pumped into the other one between the launches. The oil is hardly compressible, so it moves the piston and compresses the nitrogen on the other side at the same time. So there a pressure of up to 300 bar is generated. This is 300 times the air pressure in the atmosphere - an enormous energy. For the launch the hose to the pump is closed and the valves to the motors are opened. Now the oil is pressed through the eight hydraulic motors because of the pressure inside the nitrogen. Two seconds later the entire oil is back in the pressureless tank.

Insight into the engine room of the Intamin Rocket Coasters considering Kanonen as an example

The motors are arranged circularly around a huge toothed wheel that is connected to a winch. Through a hole in the ceiling they are hardly visible. On the winch, which has a diameter of about one meter, the ends of the steel cables that actuate the so-called Catch Car are wound up and off. This longish sliding carriage moves shortly underneath the launch track. To transfer the power of the hydraulic system to the train a pusher under the vehicle engages the Catch Car. At the end of the just 20 meters long launch track the Catch Car is decelerated by magnetic brakes in the track, the train automatically disengages from the pusher and rushes towards the coaster pleasure at full speed.

The hydraulic pump not only conveys the oil into the pressure tank, but also a small amount directly through the motors after the acceleration process. The motors thereby slowly rotate in opposition to the main direction to move the Catch Car back to the starting position.

. Track length 440 meters Height 25 meters Max. Height difference 20 meters Catapult launch From 0 to 75km/h in under 2 seconds Max. banking 80° Inversions 2: Vertical looping, In-Line-Twist Ride duration 40 seconds Trains 2 with 16 seats each Capacity 930 riders per hour Manufacturer Intamin, Liechtenstein Owner Liseberg, Gothenburg, Sweden Opening 14 April 2005 .

For the actual launch only very few liters of hydraulic oil are needed. But in the system, or rather in the tank, many times the amount is stored since the moved oil heats up to a maximum of 40 degrees due to friction effects. In the tank it can dispense most of its heat quantity to the "unused" oil, the oil temperature is additionally lowered by an active cooling.

Equally amazing is the low power consumption of the drive system - the immense power of the catapult launch lets one to assume differently. Only the almost continuously working hydraulic pump stresses the power supply system. It has a power consumption of just 150 kilowatts (150.000 watts) - less than most electric motors of larger chain lifts -, but this is enough to increase the pressure inside the nitrogen to 300 bar within about one minute. The energy stored that way is transformed in just two seconds during the catapult launch - the hydraulic motors provide about 3 megawatts (3 million watts) during this period - enough to accelerate the 8 ton train from stand to 75km/h.

Lars-Erik Hedin tells us about another feature: The nitrogen in the stacked cylinders is preloaded with 250 bar. So even the last drop of hydraulic oil is pressed out of the pressure tank strongly enough the keep the acceleration of the train almost constant. With a little more than one G, more than their own weight, the riders are constantly pressed into the seats during the launch.

After the Top Hat follows an impressive airtime hill with an integrated twist to the left

Well, that was the technology part, but what counts at last is the ride experience. At Kanonen this begins with an about four meters high ascent to the waitung area on the concrete paving slab that skillfully runs below the track. From here the whole layout can be seen, what makes the waiting time literally fly by. The distance between the track and the waiting crowd is very small at some points, especially a tight curve close to the ground, with a banking of 80 degrees taken at high speed, does look really impressive (not only) from a short distance. Only a finely woven fence separates the queue from the train flying by.

The design of the waiting area is quite minimalistic: The white supports are screwed onto the concrete without any further decoration, so this area makes a rather incomplete impression. Finally we have reached the station, just a few more rides separate us from the experience as a living cannonball. About every minute one of the two 16 seat trains is shot from the station onto the track towards the Top Hat.

Just like at the adjacent wooden coaster Balder there is a red and a blue train, but at Kanonen they can only be distinguished by the color of some plastic appliqué. The recently developed over the shoulder restraints, which are constructed redundant by an additional latch, keep the passengers safe in their seats. Then the operators give the all-clear. The about 68 safety brake fins on the launch track lower themselves, a slight hitch catches the train, then the launch catapults us from the relatively dark station into the bright daylight.

In less than 2 seconds the train has reached its maximum speed on the launch track which is only 20 meters long. Since the acceleration at the end of the launch track is still almost one G because of the preloaded nitrogen, the moment the train leaves the catch car automatically at a speed of 75 kilometers per hour and the acceleration suddenly ends is subjectively sensed as a jerky braking. The four-limbed train then shoots along an inclined section directly above a watercourse and then straight up the 24 meters high Top Hat. To the riders´ surprise This element is taken at agonizing low speed - the height difference of 20 meters slows the train down to about 10 kilometers per hour. Then the vertical fall follows - but the full visual effect only unfolds in the front row.

Seen from up above, Kanonen looks almost minimalistic, but the ride surprises with impressive changes of acceleration

After a small but effective airtime bump with a simultaneous, very surprising sharp bend to the left the first inversion in terms of a 20 meters high vertical loop follows. Due to the low speed of the train at the top dead center the riders noticeably hang in their restraints. In contrast, the following torsion is taken quite fast. The vehicle shoots from a right hand bend up an eight meters high hill and simultaneously turns into a left hand bend. On a distance of only very few meters the track undergoes a change in banking of 160°. As impressively intense the experience at this point may be, as obviously it becomes apparent that the restraints aren´t perfect yet. A massive pelvis bracket holds the riders in their seats, two small arches over the shoulder area keep the upper part of the body in place. Depending on size, the sidewise arches of the restraints can cause noticeable blows to the jugular area. At least some padding or an elastic design would be desirable here.

The train shoots into a turn banked with 80 degrees at high speed. Almost lying on the side, the riders rush through the tight curve, pressed into their seats with almost four times their weight. Next is a small hill of about eight meters and a vast right hand bend that leads the train into the finishing In-Line-Twist. The riders are turned 360 degrees around their longitudinal axis while the element leads through the loop as an additional gimmick. This inversion, too, is negotiated rather slowly, which gives those waiting underneath a good look at the riders hanging upside-down.

Finally the train is slowed down smoothly by magnetic brakes. Without the lifthill of most other coasters the actual ride experience takes less than 30 seconds. Accordingly fast the train is back in the station, giving less than 50 seconds to the operators for loading and unloading. Riders with belongings they can´t take with them often cause delays since they have to deposit their stuff themselves in compartments on the exit side of the station.

Kanonen really offers a dazzling clew of track

Kanonen has obvious strengths and shortcomings. The first thing to mention is the hangtime in both inversions that might not be to everyone´s liking. There is a direct interrelation with the slow speed at the Top Hat. This may increase the thrill at high coasters like Top Thrill Dragster or Kingda Ka - but the more than 100 meters (!) lower versions like Kanonen make you wish for higher speeds and the accompanying airtime at the top. A higher launch speed, even if it may cause the need for additional trim brakes at the exit of the first inversion to keep the already extreme forces in the second part of the Kanonen adventure ridable, was surely worth a try.

Official website of Liseberg

So much for the critic, let´s get to the positive impressions. At first, Kanonen offers an impressive launch that is intensified by the fact that - unlike at Booster Bike at Toverland or the Vekoma LSM coasters - it starts right in the station. The compact layout offers no reprieve to the riders: With a mixture of fast, highly banked curves and airtime bumps the track delivers all the forces that make up a roller coaster ride. Kanonen isn´t perfect, but it competently fills one of the very few gaps in Liseberg´s ride range. Last but not least, it is adopted very positively by the patrons.

Pictures: Alton Towers (1), Coastersandmore, Liseberg (1)