The Building Speed Blog

The Science of Fast

Daytona, Catchfences and Flying Cars

Track barriers originally were erected to keep cars separated from spectators. In addition to concrete walls to prevent the cars from driving off track, debris-spewing accidents necessitated fencing to contain airborne objects. Catchfences should have the same properties as walls, but they can't block the view. Chain link fence is a good compromise: It's cheap, plentiful, easy to put up and surprisingly strong given its high visibility. Chain-link fabric is an elastic metal mesh. It can give in two ways: gentle forces cause the mesh to deform. The diamonds stretch out of shape, but when the force is removed, the fabric springs back to its original shape. The fence can also deform by stretching the wires that make up the mesh. A large-enough force will break the wire entirely.

As some of you know, I was in New York for the weekend celebrating my anniversary, so I’m just now catching up on the weekend’s accident at Daytona. Note: Some basic information about catchfences is modified (and updated) from a blog originally posted on 11/14/11.

And I bet there are some typos, still.

A Brief History of Barriers

Track barriers originally were erected to keep cars separated from spectators.  In addition to concrete walls to prevent the cars from driving off track, debris-spewing accidents necessitated fencing to contain airborne objects.

ChainlinkFenceCatchfences should have the same properties as walls, but they can’t block the view.  Chain link fence is a good compromise: It’s cheap, plentiful, easy to put up and surprisingly strong given its high visibility.

Chain-link fabric is an elastic metal mesh. It can give in two ways: gentle forces cause the mesh to deform.  The diamonds stretch out of shape, but when the force is removed, the fabric springs back to its original shape. The fence can also deform by stretching the wires that make up the mesh. A large-enough force will break the wire entirely.

The mesh must must supported, usually by poles and cables. How much the mesh can stretch depends on how it is supported.  If the frame is too big – meaning that there’s a very large area of mesh between supports — the mesh can stretch too much. How the poles are attached to the mesh is critical, because the attachments allow the load to be shared between the fabric and the poles.  The larger the forces, the more robust the links between the poles and the mesh must be.
Catchfence_Daytona2Race track fencing is stouter in just about every way.  The mesh is made of larger-diameter wire with higher tensile strength.  The links between the poles and the fabric are stronger:  In the picture at right (Daytona), steel cables run horizontally through the mesh and are fixed to the vertical poles using some massive turnbuckle-like fixtures.

Different tracks have different installations.  Some have metal tubing running horizontally as reinforcement. Catchfence improvements have primarily been via stronger mesh, stronger or a greater number of poles, or better links between the poles and the mesh.  But it’s basically the same fundamental design.

The chain-link fence is a motorsports institution, with different sanctioning bodies requiring different standards for debris fencing.  In the FIA test, a 760-kg  (1675 lb) test mass is shot into a fence at a speed of 65 km/h (40 mph) at heights of 1.6 m and 2.5 m (5.25 and 8.2 feet respectively).  While 40 mph seems very slow, they’re taking just about the entire mass of an Indy car and concentrating it in a relatively small sphere.  A real car would impact over a much larger area and spread out the force.

Geobrugg_Debris_Fence

The photo at left shows a Geobrugg fence being tested:  The mesh deforms (a lot!) – but it does not break. Load is transferred to the poles, with the poles nearest the impact bending, but not breaking.  The emphasis, however, is pretty strictly on containment.

Geobrugg, one of the primary catchfence providers for motorsports (and many other things) made the video below that shows a car going into a standard vs. going into one of their fences.

The advances in catchfencing that have been made are huge; however, you are always going to have issues. As long as the fence is permeable, small pieces (and fluids) are going to get through the fence. Some of the people injured in the Carl Edwards crash in Talladega were burned by oil. Unless you use a solid fence, this is a hazard you will never eliminate.

Is Speed a Factor?

We’ve been hearing calls for slowing things down at Daytona. Is speed the issue? It is certainly true that speeds have been increasing.

BSPEED_DaytonaAccidents_DaytonaPoleSpeeds

Here’s the pole speeds at Daytona over its entire history. You have to be a little careful. The idea of group qualifying is very recent, and we know single car speeds are lower than those of cars in a pack, so it’s not quite fair to compare these one one one. But the pack qualifying pole speeds are a good 4mph below the peak single-car pole speed, which means we’re still probably 8-10 mph slower than the highest speeds that have been raced at Daytona.

So maybe it would be helpful to compare speeds at different tracks this year, since single-car speeds aren’t really all that different than race speeds at non-plate tracks.

BSPEED_DaytonaAccidents_2015PoleSpeeds

I put triangles above the plate tracks. You’ll notice that speeds there aren’t that much higher than many of the other tracks – and Michigan was faster than either Talladega or Daytona.

Which led me to wonder about whether this year was just an anomaly. So here’s this year and last year.

BSPEED_DaytonaAccidents_PoleSpeeds2015_2014

Michigan is consistently faster than either Daytona or Talladega. I also wanted to look at the speeds for the Sprint Cup versus the XFINITY series, because the last big accident we had at Daytona was Kyle Larson running in the then-Nationwide series.

BSPEED_DaytonaAccidents_SprintvsXFINITY

You can see that the lower-level series runs at significantly lower speeds (10-15 mph) – and still they’re getting in the air.

So I have a hard time believing that simple reducing speed is going to have a lot of effect on these types of crashes.

Pack Racing

So what’s the big different between Michigan – the fastest track – and Daytona/Talladega? It’s the restrictor plates. Restrictor plates produce a very different type of racing. If you watch the throttle/brake indicators during non-restrictor plate races, you’ll see the drivers easing off the throttle going into the turns, or even braking. The pole speed is an average speed, which means they’re generally traveling faster down the straightaways and slower in the turns.

Not at a plate track. The throttle is full open at all times. The cars are maxed out in terms of their engines.

Remember that, at 204 mph, a car goes a football field a second. Think about that. You’ve seen cars scatter to avoid accidents on other tracks. You can’t do that on a plate track because there is nowhere to go. You’re blocked in on all side.

An accident on a plate track is more likely to involve multiple cars. The last line here is the total number of cars involved in accidents

Michigan 2014 Daytona 2015 July Daytona 2015 Feb Las Vegas 2015 Atlanta 2015
6 1-car accidents
1 9-car accident
5 1-car accidents
1 7-car accident
1 9-car accident
1 11-car accident
2 1-car accidents
2 2-car accidents
2 7-car accidents
3 1-car accidents 2 1-car accidents
1 4-car accidents
1 6-car accidents
15 32* 20 3 12

*Racing-reference.info didn’t mention how many were involved in the end-of-race crash because it wasn’t technically a caution, so the number is much larger.

The numbers are small, so it’s hard to prove this, but my intuition, based on observations and the data we do have, is that more cars involved in an accident at close quarters mean

  • more likelihood of a car spinning (and cars are more likely to become airborne if they are not going straight)
  • more likelihood of a car launching off another car and getting airborne

When all this happens in conjunction with high speeds, you have all the elements for a catastrophic accident.

I am not suggesting we remove restrictor plates – that would be just plain stupid for both the drivers and the fans.

So Let’s Just Make Pack Racing Safer!

Everyone seems to assume that NASCAR will come up with a solution that will allow pack racing to continue the way we’re used to it happening. They’ve done an admirable job of dealing with past issues…

BUT

There are limits. I mean, if we could do anything, we’d have cured cancer and found a way to make sure everyone in the world has access to clean drinking water.

 

If there were an obvious solution to make pack racing safer, NASCAR would have already done it. It is possible that there isn’t a solution and that pack racing will always be inherently more dangerous than other types of racing.

Cars travel just as fast at other tracks and they don’t leave the ground nearly as often as they do at Talladega and Daytona.  Putting on a smaller restrictor plate to decrease speeds will not help. It’s not the speed. It’s the combination of the speed and the pack racing.

Perhaps the best that can be done is to protect spectators and let drivers take their chances. (If you’re wondering whether a Lexan ‘hockey-type wall’ would work, I addressed that elsewhere. (TL;DR: expensive and difficult, especially since you not only have to stop the car and parts from getting into the stands, you have to make sure that you don’t make it more dangerous for the drivers.)

Perhaps you have to make a radical change to the engine so that the drivers have to brake and accelerate around the track and you don’t get pack racing. This would make a lot of fans upset. There is nothing as breathtaking as standing in the infield watching the entire field take the turn.

There is also nothing as breathtaking as that gasp of fear, your heart skipping a beat and the feeling in the pit of your stomach as you whisper a prayer that the driver in the crunched up shell of a car just coming to a stop will climb out and wave and live to race another day.

2 thoughts on “Daytona, Catchfences and Flying Cars

  1. I think motorsports, in general, has shot itself in the foot, from a safety standpoint.

    The general idea has always been to go faster than the next guy, in order to win, and, if the next guy wins too often or by too much, rules have been made to equalize the opportunity.

    Sixty years ago, tracks were being designed with nothing in mind but speed.(High banks, long straights, or virtual circles.)

    Remember, the NASCAR guys were racing full steel-bodied sedans, with very little done to change the “stockness” of the car, still running on street tires. The AAA/USAC (I refuse to use the term Indycar, because the turd that it has become is so far removed from the sport that it once was) folks were running tube frame, open-wheeled, non-caged cars, with a 400-425 HP engine, lapping IMS at 135MPH, in T-shirts. Formula 1 was a bunch of European guys in a small garage, putting a small engine into a structure not much larger than a go-kart.
    (And if this smells like “the good ole days”, remember, each of these leagues was losing AT LEAST 1 man/year)

    My Dad & I went to a Sprint Car race in Wichita, Ks., I think in about ’65 or ’66, roll cages were not allowed. Some of those cars had spoke wheels, just like a Model ‘A’….three men died that night, after they got upside down.

    Now, we see ALMOST perfect technology that enables ALMOST everything to be perfect. (Equally fast cars, competing on the fastest circuits available, and, (thankfully) the safety technology is ALMOST as perfect as the rest.

    Many are whining about “pack” racing…isn’t this racing at its best? Do we wish to go back to the days when one guy, or maybe two finishes 2-3 laps ahead? Some of the drivers need to pay homage to AJ Foyt, David Pearson, and Cale Yarborough….racing is no home for whiners!

    Considering the use of a space-age panel similar to a hockey rink I think is a bad idea…hockey is played indoors…

    I wish I could offer a brilliant solution….driver-safety is great, fan protection is 40 years behind…

    For NASCAR, would additional flaps on the car (namely on the rear deck) help?

    Thanks !

  2. The best option is to eliminate pack racing “so that the drivers have to brake and accelerate around the track.” The easiest way to do that is with hard-compound, treaded tires.

    Driver skill should be measured by one’s ability to know when to lift, not the spotter’s ability to determine when the high line is faster. The spectacle may be lost, but the 32 non-plate races seem fine without it.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Copyright © All rights reserved. | Newsphere by AF themes.