How the planks under F1 cars became firework displays – and weapons

As F1 fans, we get used to hearing about hi-tech developments and ground-breaking innovations that would have been hard to imagine, far less put into production, a generation ago.

But some innovations can use very old technology indeed – and still have a huge effect on the sport.

One of these is the humble plank (highlighted), which has long affected how F1 cars drive and look.

F1’s bright sparks

In the 1980s and early 1990s, there were huge developments in F1 aerodynamics and suspension.

The rear of cars could be raised and lowered to alter the amount of downforce being generated and teams were running less and less clearance between the car floor and the ground – the smaller the gap, the more downforce a car would generate.

This was the era when sparking F1 cars made their debut. Titanium skid plates were introduced to protect the cars as they regularly bottomed out on any bump on a circuit.

These skid plates had only one function – they were sacrificial offerings to the gods of friction, to stop the undersides of cars being worn away and destroyed.

F1’s lowest point

This was as low as the underside of F1 cars would ever run. Everything changed thanks to a very different sort of low point – the weekend of the 1994 San Marino Grand Prix, which would see Ayrton Senna (pictured in the Lotus) and Roland Ratzenberger die in separate accidents.

In the wake of these tragedies, the FIA took action to slow cars – a simple plank was to be fixed to the bottom of every F1 car, and it would be measured to ensure it wasn’t being worn away by being rubbed along the ground.

These planks have very specific dimensions; in particular, they must be 10mm thick, +/– 1mm. In practice, this means they can be carefully manufactured to be almost 11mm, and must be 9mm thick at the end of a race.

Of course, it wasn’t long before F1 introduced changes…

Planks for the memories

In the early days, the planks were wood-based – they were a bit more complex than a bit of 2x4 from Homebase but they weren’t particularly hi-tech.

The most common plank material was Jabroc, a hard-wearing beech laminate.

Beech veneers were kiln dried, coated with phenolic resin (the stuff that’s used to help make Bakelite) then packed together and squeezed at high temperature, until they formed laminated boards.

This material still crops up in other motorsports. It’s much stronger, stiffer and more stable than hardwood and, although it is half as strong as steel, it weighs only a fifth as much.

Still, in F1 It wasn’t long before the innovators turned up and a slightly more exotic material appeared to manufacture planks from – and it was so good that it’s still in use today.

It is called Permaglass and is also a laminate, but it is glass-reinforced.

It’s light, strong and non-flammable – and also good at resisting wear, which is important when it’s stuck on the bottom of a car travelling at 200mph.

So that ‘wooden’ plank on an F1 car that people joke about … well, it’s not really a wooden plank at all.

It’s a weapon?

While it’s easy to assume all the innovation in F1 happens on the technical side, that’s not the case.

In the 1980s and 90s, before titanium skid plates were originally outlawed, sparks literally flew between drivers – and it wasn’t always accidental.

Some drivers adapted their driving style to the titanium fireworks, including 1992 champion Nigel Mansell (pictured with Senna).

He was a huge fan of the sparks, particularly because they were such a distraction to any driver behind him.

In free practice sessions, Mansell would seek out bumps in the track, even if they were slightly off the racing line, so that he could shower competitors with pyrotechnics if they got too close.

He said: ‘The lines would not slow me but I knew they’d give a big shower of sparks to the guy behind.

‘Hopefully, they’d pock-mark their visor too – they really did make burns on your visor.’

The reason visors got burned was because those sparks were not just a light show.

Californian scientists experimented with titanium golf clubs (which travel considerably slower than an F1 car… average swing speeds are less than 100mph and even the very best will struggle to hit 150mph).

When the clubs struck a stone, the resulting sparks were about 3,000C. You wouldn’t want one of Mansell’s spark showers anywhere near your face.

In fact, Ayrton Senna had a mark on his face that was attributed to a stray titanium spark that somehow made it past his visor.

The return of the fireworks

Although titanium skid plates vanished from F1 for several years, they made a return in 2015 and are still lighting up the sport, particularly at night races.

Although the aesthetics of F1 were partly responsible for this – sparking cars were thought to be a good way of attracting audiences – there was more to the decision.

Innovation in F1 is often as much about safety as speed, and that is why titanium made its return to the underside of cars.

The FIA measures the thickness of F1 planks around a series of holes in the material. Skids are placed to offer maximum protection to these holes, not surprisingly.

Until 2015, teams used heavy metals such as tungsten, to guarantee maximum protection.

The problem was that these metals resisted wear too well – when they did break, rather than a fairly harmless spark, they could release a lump of tungsten that was big enough to cause a puncture or, worse still, hit a driver or marshal.

In Spa in 2014, two punctures were blamed on such incidents. So bringing back titanium minimised the risk of this re-occurring.

In addition, according to F1 Race Director Charlie Whiting, the titanium wears away about 2-2.5 times more quickly, offering less protection.

As a result, cars have to run a little higher above the ground and lose some aerodynamic advantage – they go slower in corners, which is less risky.

The F1 plank, then, is an incredibly simple bit of kit but, thanks to the sport’s innovative minds, it has been used to make cars go faster, to slow them down and even to attack drivers behind with titanium flares. Not bad for a part that was originally a glorified slab of wood.