Max Yamabiko: Nordschleife safety under scrutiny

The moves taken to reduce the speed of GT3 cars racing at the Nurburgring are a short term solution to what could be a long term problem.

Not many people had heard of the ADAC Westfalenfahrt before late March this year, now the opening round of the VLN championship will be remembered for only one thing, the death of a spectator. As with all VLN races the Westfalenfahrt was held on the full course - over 20km in length, this includes the famous Flugplatz section where most cars get some flight over a sharp crest.

It was here the tragedy happened, when the #23 Nissan NISMO GT-R, at the time driven by Jann Mardenborough, gained air over the crest, but instead of landing the upforce continued to lift the front of the car up until it was skating on its boot lid into the opposite barrier. The force of the ensuing impact would proceed to flip it over into the spectator area at force and striking onlookers. One person died from their injuries.

So what exactly causes a 1300kg GT3 car to take off with such devastating effect? Well, in some ways this was a crash waiting to happen, and a crash that is directly analogous to other aerial accidents seen at circuits such as Le Mans.

The most infamous of these crashes was the one that involved Peter Dumbreck's Mercedes CLR at Le Mans in 1999, when a 925kg car taking off over a crest spiralling off the track into the neighouring trees in a similar fashion to that of the heavier Nissan in Germany.

On paper, cars like these, which are designed for maximum downforce and adorned with aerodynamic devices that are meant to stick them to the ground, should not take off. However, the reality is that they are often on the edge of flight.

If you take a step back from any individual accident you find yourself presented with a simple set of facts that one of the investigators close to the 1999 crashes summed up by saying, "you have a vehicle that is about the same weight as a light aircraft, travelling faster than the take-off speed of a light aircraft with about the same or greater aerodynamic surface of a light aircraft, so of course it will take off!"

The Nissan GT-R like most GT3 cars has a flat floor and once a car like this reaches a certain nose up angle above a certain speed it is inevitable that a flight will happen.

However it is rare for those circumstances to occur. The exact angle and speed required for a car to fly are directly related to the size of the flat floor and the weight of the car, and I understand the floor of the Nissan GT-R is somewhat larger than other GT3 designs such as the BMW and Ferrari, even if the weight is similar.

The length of the front overhang is also a key factor. The GT-R does have a particularly long front overhang, though it is not substantially longer than some other GT3 models.

The biggest factor of all is the track. At Le Mans in 1999, all of the flights of what became known as 'Norbert Haug's Flying Circus' happened on noticeable crests in the road. As the cars came up over the crests, the road dropped away faster than the car could react and for a brief moment the nose pointed upward, nullifying most - if not all - of the those well-crafted wings and vanes designed to keep the car on the road.

At the ring in as many as five places the front of a fast car will lift off the ground and, most notably at Pflantzgarten and Flugplatz, the cars momentarily become airborne. This is not due to anything particular to aerodynamics rather it is due to the shape of the road and the speed of the car, a bit like driving your road car over a humpback bridge too fast. Your car is never going to fly but it may do a little hop, something seen often on rally stages.

However, when you add in a flat floor and very high speed, what is a little hop in most cars can become an aerodynamic event, and that's exactly what befell the no.23 Nissan.

So why did it happen to that car and why did it happen when it did? After all, the car had run a number of laps in practice, race and qualifying and it had not taken off and it wasn't even the fastest GT3 car running on the track at the time.

One of the major factors in the Mercedes crashes at Le Mans was that the cars that flew were running closely in the wake of another car, but the videos of the Nissan crash show clearly that the car was running in clean air so that has to be discounted as a factor.

Another similar crash which claimed the life of Michele Alboreto at Eurospeedway was caused be a rear puncture at high speed, something which lifted the nose of the Audi R8 LMP he was driving at the time enough for it to take off. It landed upside down on the barrier, causing terrible head injuries. When Anthony Davidson's Toyota TS030 took off at Le Mans its rear suspension was destroyed by a GT Ferrari.

Watching one of the two videos of the crash a small puff of what appears to be tyre smoke can be seen behind the #23 Nissan on the run up to Flugplatz. This does seem to come from the Porsche behind the Nissan, but it could have come from the leading car. Perhaps it is a sign of a tyre or suspension issue on the right rear of the car. If that was the case it might have been enough to make the car fly when it reached the crest of the hill barely a second later. It may not be a factor at all.

The Nissan may have been on a super-hot lap, cresting the hill faster than it had ever done before something that will be clear to see in the data, but that data is not public. Another issue may be the weight distribution of the GT-R, a quick search of pictures of other GT3 Nissans on that section of track show that the car has a tendency for the front to lift more than other cars.

Immediately following the crash DMSB banned the use of GT3 cars (and some others) in races held on the full Nurburgring. After preliminary investigation, it removed the ban and introduced a number of restrictions including an ECU governed speed restriction of 250kph at the relevant sections of the track and a 5% reduction in power of the full lap.

This should keep the cars below take off speed for now, though we do not yet know what the take-off speed is of the GT-R or indeed over GT3 models. That requires a lot of data analysis and wind tunnel testing.

So this essentially a band aid to fix a larger wound. However, with a new GT3 rule book coming in 2016 perhaps aerodynamic measures could be taken across the board to allow the cars to continue at the #Ring, but it seems unlikely that the FIA would sanction changes to the cars which are already completed simply so they can contest races on a single track.

What other measures could be taken? Well LMP and DP cars were fitted with openings over the wheel arches, and in the case of the former chamfered floors and fins to reduce the chances of a flight, but none of the measures has proven fully effective. After Le Mans in 1999 the length of front overhangs was restricted too.

The biggest change was to the tracks themselves: 8 meters was shaved off the hump on the straight at Le Mans and similar moves were made at other tracks too.

In GT3 perhaps a stepped floor with plank could be a good move, but overall the cars seem to be fine on all circuits apart from the 'Ring, which does not meet FIA track safety standards anyway.

Even so, the Nordschleife will return to the forefront of motorsport in 2015 having been granted a round of the World Touring Car Championship. Though those cars are unlikely to gain flight, it does bring the full circuit under a more watchful eye of the FIA when it comes to safety standards and quality.

The most succinct conclusion I can come to is that GT3 is now too fast for the 'Ring. To let them race there they would either need a very expensive aero kit or hugely expensive changes to the track. Neither I feel are realistic, and this could spell the end for GT3 racing at the 'Ring.

Max Yamabiko

Max Yamabiko will bring you a closer look at the technical side of F1 and motorsport in 2015, from the latest developments and solutions employed to keep you ahead of the game