Guy Martin’s Wall of Death (Part 2)

This Easter Monday Guy Martin will ride around the largest Wall of Death ever built, aiming for a top speed of 60mph and a Guinness Word Record, all live on TV. Here’s everything you need to know before the big event… 

The Wall

Like no other Wall of Death on earth. Built from 48 up-ended shipping containers, it stands six meters high and is the biggest in the world

Expert view – Christopher Mattews, Associate Structural Engineer, Altelier One

‘We’ve built it. It’s down to Guy now’ 

Chris is a structural engineer tasked with designing the wall – he specialises in unusual projects.

The tricky thing about designing this is that there is nothing to go off. I visited Ken’s wall, but it is a lot smaller and his riders travel at a slower speed so the design doesn’t translate to our wall. That makes it interesting because we had to start from scratch. Here’s how we did it…

We were given the maximum weight of the bike and rider (320kg) before anything else. So once we had that figure we could design the wall and specify everything to match. But first we would have to work out the maximum wheel load using that total weight figure.

The bike stays on the wall due to centrifugal acceleration (mass x velocity, squared, divided by radius), which gives us the G-force Guy will feel. We’ve upped it to 8.5G to give plenty of room. Using that figure we can get the wheel load by multiplying the G by the weight of the bike and the rider, which equals 2.72 tonnes. Two thirds of that gives the max weight of one wheel, 1.8 tonnes. And then we’ve rounded that up to 2.3 tonnes to be well on the safe side. So now we have the maximum G-force, weight of bike and rider and wheel load. So all we have to do is make sure every single point on the wall can cope with that pressure. We tested that out by using a telehandler fitted with load sensors to push against random parts of the wall and make sure they can all cope with 2.3 tonnes of pressure.

We know we can design a wall that can take the forces. We tested the wall, it’s good to go. The big question is what happens when Guy tries to ride it. It’s down to him now.

Doors

The key thing when designing the doors was that we have to be able to get Guy out within 40 seconds. So we have people training to open them as fast as possible. The doors are designed in such a way that as you ride over them they close tighter, so they’re shaped like cheese wedges. The bolts stop the doors swinging upwards while the bike pushes them downwards.

The shell

We wanted something large and bulky that already existed for the shell as we didn’t want to have to build a giant frame for one show. I was helping my dad move stuff into a shipping container when I realised that all we had to do was turn one on its end. So we used 48 containers with two containers with doors at either end for the shell. The front face is welded top and bottom and the back is tied together with container locks and studded bar.

The Ramps

Our wall has a ramp with two angles; one at 30 degrees and one at 60. By having two angles Guy is able to build up his speed more gradually. The rest of the wall is absolutely vertical.

The wood

Structural grade C24 soft wood. It’s strong timber used in house construction. Imagine those cradles you stick underneath wine barrels to stop them rolling away; we have a whole series of those that fit on to the base of the containers to give them the curved form. Each plank is screwed down to them and to the containers. There are no sharp edges.

Viewing area

The more people standing on the structure, the more stable it is.

What makes Guy’s wall so different?

If you go to Ken Fox’s traditional wall you will feel it shaking because it’s lightweight and portable. This one is a lot more stable thanks to the shipping containers tied together in one big ring, making it incredibly strong for the higher speeds Guy needs to reach.

• Ken’s wall is 9.75m in diameter while Guy’s has a 37.35m diameter, making it nearly four times the size.

• Most importantly, Guy’s wall can support much higher loads. The forces on the wall will be double the forces placed on Ken’s portable wall.

• Guy has two angles on the base. Ken’s has one 45 degree angle, which is fine if you don’t have to change speed often, but Guy will have to reach 55mph before sticking to the vertical wall so will need to build up speed more slowly.

Wall of Death facts

• It took 30 designers, builders and engineers to construct the wall

• 1.5 miles of wooden planks were used

• 48 shipping containers stand on their ends to make up the shell

• Add up all the metal and it’s just shy of 100 tonnes, plus the wood…

• All the timber will be reused for housing after the event, the containers are rented and will be returned afterwards

• It’s 3.8 times bigger than the standard Wall of Death used by Ken Fox

How will Guy stick to the wall?

Expert view – Professor Hugh Hunt, Cambridge University

A traditional Wall of Death would place around 2 to 2.5G on the rider, and that’s the minimum needed to stay on the wall. Guy needs to reach 60mph, which equals 3.5G. But he’s been training hard so it wouldn’t surprise me if he pushed it and went for 80mph. That would then equal around 6.4Gs. Now, to reach either of those speeds on a conventional sized wall with a 10m diameter the rider would be facing 14Gs, which is impossible – the heart wouldn’t be able to pump blood to the brain. So that’s why we’ve had to build a bigger wall, with a 40m diameter to bring the G down to a level his body can handle. Let’s say he does 80mph, which we know equals 6.4G. That means that he will feel 6.4 times his actual weight. So, assuming he weighs 80kg, he’d feel like he weighs 512kg and if the bike is 300kg on the ground then it will be 1.9 tonnes of metal flying around the wall.

Photos: Ryan Mcnamara/Channel 4