The Vomit Comet: the world's first zero gravity roller coaster - tabpi

ROLLER COASTERS
Scream,if you want to go faster
Thrilling, frightening and fascinating — roller coasters are the ultimate
adrenaline-fuelled experience. EC examines the unsung engineering skills
that create the rides and keep them running safely
You mutter a quick ‘good morning’ to the
receptionist on the front gate, slurp down
a quick cuppa and strap yourself into your
chair. Today is going to be frantic: clients to
see and deadlines to meet. So you settle
back and focus on getting things off to a flyer.
Bam! A ferocious blast of wind forces your eyeballs
back into your skull and your stomach plummets
towards the South Pole. Beating back the G forces,
you pull a grin and think to yourself: ‘I’m glad I became
a roller coaster engineer’.
This is not a hoax. You really can get paid to ride
roller coasters. Hundreds of UK engineers are
employed in the design, construction, safety testing
and maintenance of roller coasters and other theme
park rides. The rides may be all about fun, but with a
typical ride costing £15 million, they’re also big
business.
“It starts with a discussion with the theme park
operators,” explains Thorsten Koebele, a mechanical
engineer who develops roller coasters for Germanbased
manufacturer Mack Rides. “How big is it going
to be? What’s the throughput of people? And where
are you going to position the splash points?”
Typically, an engineer has around 10,000 sq metres
of park space to accelerate, brake and generally
frighten the life out of thrill-seekers. But before the white
knuckle stuff comes some basic mathematics.
Calculations start with Newton’s laws of motion, as
engineers work out the forces on the body caused by
every twist, turn and drop in the track. The resulting G
force can hit you two ways. First, there are the positive
Gs, which are experienced when you’re fired upwards
on the track, giving the sensation of being pinned back
in your seat.
Passengers can ‘pull’ anything up to 6G positive -
the equivalent to a Formula One car under heavy
braking. The duration a passenger is exposed to the
G force is as critical as the size of the force itself,
explains Thorsten. “In the standards we work to, you
can have a 5G vertical force for less than two seconds.
If you go beyond that, then you’re going to risk the
guests blacking out.”
Then there are the negative Gs. Riders will
experience these when a ride plummets over the crest
of a hill, causing a falling sensation and deep regret
over that pre-ride burger and chips. Track design
means mixing up your G forces. Too many, too often,
and your ride will be vetoed on safety grounds. Too few
and you’ll deliver something predictable and boring.
Engineers test designs on computer modeling
packages, explains Thorsten. The challenge
goes beyond how many corkscrews you
introduce, he adds. “Ride operators are
usually targeting around 1,300 people per
hour. As an engineer, that payload affects
how many carriages you have on the roller
coaster and the forces you’ll need to brake.”
The Vomit Comet: the world’s first zero gravity roller coaster
A rollercoaster so utterly terrifying that post-traumatic stress counsellors are going to be the norm in
theme parks of the future. The Vomit Comet will generate over eight seconds of zero gravity, as Joe public
experiences the same forces as astronauts for a fleeting few moments.
The Vomit Comet will achieve the feat by firing passengers along a horizontal track at 100mph, using a
linear induction motor system for power. Riders will then be thrown up towards the heavens on a vertical
section of track. The induction motors will slow the ride’s capsule just enough so the passengers come
slightly forward and away from their seat. The trajectory of passengers will be matched by the ride’s
capsule and computer controlled by the linear accelerators. With no view out of the capsule, passengers
will feel as if they are floating.
The speed will slow until the passengers stall at the top of the track and start to reverse back down. The
ride will actually accelerate in a power dive down the track, meaning the riders feel as if the capsule is
falling just ahead of them and they’re floating. Seconds later, linear accelerators will brake heavily, causing
the passengers to go from zero G to 2G and be pulled back into their seats.
The ride presents a complex engineering challenge and each launch group will have to be weighed to
calculate the right acceleration trajectories for zero gravity. The ride is the brainchild of BRC Imagination
Arts, a California-based design firm, and inspired by the NASA aircraft used to train astronauts. EC has just
come over all queasy - anyone fancy a spin on the teacups instead?
18 19

ROLLER COASTERS
GO!
1) Gravity
The same stuff that makes an apple fall from
the tree will cause a fully loaded coaster to
shoot down a track. The engineering challenge
is getting the roller coaster to a height where
gravity can do her thing. The most common
method is pulling carriages up an incline on a
chain. The climb is powered by an electric
motor, with chain dogs on the bottom of the
carriages connecting the coaster to the moving
chain. The mechanism makes the clip-clap
sound familiar to any seasoned roller coaster
rider. When the coaster reaches the cusp of the
hill, the chain disconnects and Sir Isaac
Newton’s friend does the rest.
Fear factor: 7
2) Hydraulic launch
Hill starts are a thing of the past with this
horizontal launch system. A catch car running
through a trackside trough tows
the train. The catch car is linked to a steel
cable, wound around a giant winch drum. High
Once you strike the right balance between
thrills and thrift, your design must pass a
stringent review by safety watchdog ADIPS.
Further inspections are carried out after
construction to check the ride reflects the
original design. And, finally, a safety inspector
straps in and tests out the ride for real. Only
after passing these criteria will the roller coaster
be granted a one-year operating licence.
This intensive safety screening highlights the
painstaking lengths the industry goes to to
avoid injuries. Your odds of dying on a roller
coaster are one in 300 million, compared to
one in 30 million on an aeroplane - a sector
often lauded for its intensive safety standards.
The rigour is forged by a gruelling maintenance
regime, carried out by engineers such as
Martin Booth of Alton Towers, who’s been
servicing rides for over 20 years.
Basic daily checks are made on brakes,
harnesses couplings and computer systems.
More detailed work is carried out weekly,
monthly and then, every year, a ride will have to
undergo a full strip-down, explains Martin. “We
do non-destructive testing (NDT) of all the
components. We’re stripping the ride back to
the bare bones.” The NDT uses magnetic
particle analysis, ultrasound and X ray to spot
any cracks in axils, couplings or wheels.
Brakes are, for obvious reasons, a key
Three different ways to
power the roller coaster
horsepower pumps on each side of the winch
fire a piston under hydraulic pressure, which
catapults the carriages to 120mph in a few
seconds. Hydraulic powered roller coasters
have pimped gravity’s ride and can achieve
higher speeds over shorter areas of track than
standard coasters.
Fear factor: 10
3) Linear induction Motors
Linear Induction Motors (LIMs) use electricity
to propel the carriages along the track, much
like an electrified railway system. LIMs are
positioned in areas where the roller coaster
needs to be accelerated. The LIMs produce an
electric current that triggers fins on the bottom
of the cars to produce an opposite electric field.
The two currents repel each other and
generate forward movement. LIMs can
accelerate passengers from 0-60mph in 3-4
seconds.
Fear factor: 7
The roller coaster
Established
1650: Russia launches the ice slide, where
thrill-seekers hurl themselves down giant
ice towers on wooden sleds.
Typical cost
£15million or more
Maximum G force
+6G
Top speed
120mph
Key features
Braking zones: Computer-controlled
magnetic/pneumatic brakes.
Overload engineering: Rides are built to
withstand weights far in excess of the
maximum advertised ride capacity.
Materials: Steel dominates, due to its high
tensile strength and durability. Fibre glass
is used to theme the track design and foam
and plastic in the carriages and harnesses.
Computer control: Software measures
speed along different parts of the track and
then calculates braking intensity.
It takes two: Safety backups are a must. if
the first set fails, reserve brakes kick in.
UPS: Back-up battery devices kick in when
a power cut strikes returning the roller
coaster to a safe point on the track.
Wheels, axils, track: all components are
stripped down and take non destructive
tests every year. Engineers use ultrasound
to spot cracks.
concern. Roller coasters employ a mixture of
pneumatic and more recently magnetic brakes.
Martin explains: “It’s got to be failsafe. So there
will be duplicate brakes. One will be enough to
do the job, but there is always a second, just in
case you need it.” Pneumatic brakes are
computer controlled, but include a back-up,
spring-loaded mechanism, which will fire in the
event of a power cut and halt the train.
Rides also feature uninterruptible power
supply back-ups that will take a roller coaster
safely back to the station or brake zones,
positioned in quieter areas of the track. It’s a
triumph of carefully designed computer
systems, which act like guardian angels over
passenger safety, he says. “Computer
systems are constantly talking to each other
as the roller coaster goes around the track,
checking where the cars are on the track.
There are two independent systems and they
have to agree on the data or the ride will stop.”
No doubt supported by a trusty back-up team
of engineers like Martin, who prove that there
are some jobs where Monday really can’t come
fast enough. “Most of our guys start the day up
by taking a ride. It’s great fun, but I’m doing it
for a reason: to look out for certain aspects of
the ride. We’re engineers creating things for
people to have fun, but our number one role is
safety.”
Get on board: Three jobs to jump at with
roller coasters
1) The job: Maintenance engineer
What will I do: Carry out essential TLC on the ride, from
replacing worn wheels to X raying track for deadly
cracks. Maintenance engineers perform daily, weekly
and annual servicing to ensure rides pass stringent
safety standards. Much of the heavy-duty work is carried
out in the winter period when the theme park’s
shutdown.
Who will I work for: UK or international theme park
operators or directly for a manufacturer. Alton Towers
employs around 50 full-time maintenance engineers and
has previously recruited engineering apprentices.
Job prospects: Very good. There’s a shortage of talent in
the pipeline, according to Martin. “It’s getting more and
more difficult to recruit experienced engineers in our
industry.”
Will I get to go on any rides: Yes, daily rides of the roller
coaster are actively encouraged. Purely for business and
safety reasons, of course.
2) The job: Engineer at ride manufacturer
What will I do: Engineers work in a variety of roles at ride
manufacturers, from directing production to sales and
marketing. You could be involved in non-destructive
testing of component parts or convincing the theme
parks that you can deliver the ultimate roller coaster
experience.
Who will I work for: Most of the big roller coaster
manufacturing takes place abroad. The US, Germany and
Italy are hubs for headline rides. The UK still has a
presence but it’s generally for smaller rides and
components.
Job prospects: Strong. Roller coasters have been
enthralling us since they debuted as ice slides at Russian
fairs in the 1700s. PlayStations and online gaming may
have sprung up since, but people still travel far and wide
to experience the exhilaration of being catapulted around
a track at breakneck speed.
Will I get to go on any rides: Yes, what better way to
assess your build quality than climbing on board when
the ride is complete.
3) The job: Safety inspector
What will I do: Scrutinise the rides to ensure they comply
with strict safety guidelines. Mechanical, civil and
electrical engineers are employed by inspection bodies.
Inspectors will be involved at the design phase to crosscheck
calculations. They’ll also perform extensive annual
safety reports, looking for wear and tear on components
and measuring G force exposure.
Who will I work for: You could be employed by an ADIPS
accredited consultancy, performing safety inspections on
behalf of the regulator and advising operators on
improving standards.
Job prospects: There are a limited number of places for
inspectors in the UK. But, if you can find a way in, then
your skill set is likely to keep you in demand with theme
park operators for a long time to come.
Will I get to go on any rides: Yes, lots, and all in the line of
duty. Remember to hold on to that clipboard really tight,
as you loop the loop.
20 www.engcareers.co.uk winter 2012