SAFETY INFORMATION

This section explains the safety of wind tunnels.

This article aims to inform users about the different security features of tunnels and their relative importance.

Additionally, a discussion on security will be initiated in the industry to develop and improve existing standards. Wind tunnels have no incentive when deciding how much to invest in safety. We believe that if users understand the importance of their safety and act accordingly, sport as a whole will be safer and more sustainable.

If you are (and are not) a skydiver, you know that safety is important. Unfortunately, all security measures come with a price: They cost us time, money and effort. It's up to us to decide how much to invest in security. If we don't invest enough, we will get hurt. Actually, everything is that simple.

Likewise, drop zones and wind tunnels must decide how much to invest in the safety of staff and customers.

Wind tunnels have been around for nearly 40 years with constant improvement in technology and safety. Security wasn't really brought into focus until about 10 years ago. This is not surprising when you consider that from 1978 to 2005 there were only 7 wind tunnels in the world. Today there are more than 120 operational wind tunnels worldwide.

There are two major institutions promoting security today:

Mainly in the USAInternational Bodyflight Association
If in Europe Tunnel Instructor Organization

In recent years, tunnels have become more focused on providing customers with higher levels of comfort and reducing energy consumption to reduce operating costs. To better understand the development, we can divide the tunnels into 4 generations. The scope of this document is to analyze the security features available in 3rd and 4th generation tunnels.

Tunnel construction is defined by a tunnel meeting certain conditions and characteristics that define the tunnel it creates. We divided wind tunnel features into 7 main categories. In general, if a tunnel meets at least 6 of these, it can be characterized as a tunnel of this generation.

The tunnel type refers to whether the tunnel is recirculating, that is, whether the wind is continuously absorbed from outside the tunnel (open circuit) or reused in a closed circuit.

It refers to a wall-to-wall tunnel with a flight chamber. Originally the tunnels had no side walls but essentially had netting over large fans.

What kind of flight can be done in this tunnel, where the wind speed is separated according to modern standards? In most open tunnels, flying freely was nearly impossible due to slower wind speeds.

Security refers to the security features of the tunnel. The purpose of this whitepaper is to expand the general understanding of available safety features to better understand what makes a wind tunnel safe.

Wind quality refers to how turbulent or laminar the airflow in the wind tunnel is.

Energy efficiency refers to how much electricity wind tunnel motors need to reach a certain wind speed.

Comfort level refers to how comfortable and convenient the tunnel is for customers

When you choose a tunnel for qualification, you want it to be safe. Naturally, you want it to be as cheap as chips. But where is the balance? What makes a tunnel safe?

Here is an overview, in this article we will briefly explain what each measure means.

We have reached the point where almost all tunnels can provide a basic level of security. Most wind tunnels built today are 3rd or 4th generation tunnels, which means they are naturally safer than previous tunnels. The two most basic safety rules that are almost always followed in all tunnels are:

1. Always have a properly trained guard at the door.

2. A suitably trained driver is always present in the driving cab

These rules have few details and caveats, but we can accept them on their premises. You always want to have a certified, effective spotter at the gate and a certified, effective driver in the driver's cab. What does it mean? This means that the person may pay close attention to you. They should be able to focus comfortably on you without getting too tired or too distracted.

"Okay, that makes sense," you'll think, "all the tunnels I've flown in follow these rules. What else is out there?"

Let's explain this question

4th generation tunnels have higher security level features that are relatively new. It's a bit like when seat belts or airbags first came out. Initially, they were seen as a "weird" additional security feature that almost no one used. But it soon became a minimum requirement for any car to be considered safe.

In this article, we will introduce you to modern safety features aimed at reducing the likelihood of injury. These are: Diffuser Size, Safety Lines, Airflow Quality, Network Flexibility and Light sensor.

1. Diffuser Size

The diffuser is the part of a flight chamber that makes it slightly larger than the rest of the chamber. In the drawing below you can clearly see what a diffuser looks like and how it behaves. Diffusers are used to reduce wind speeds within the flight chamber. This is done to protect aircraft using the highest wind speeds. Some passes or recovery takes can result in a flat stance that will launch them across the entire room unless they regain their vertical position quickly.

The absence of diffuser (A) means that there is no intentional wind speed drop across the flight chamber. This means that if you are flying at high speed in any tunnel (at upside down speeds) and performing complex maneuvers, you may accidentally end up on your belly or back longer than intended and then shoot into the room. In an extreme case, it is possible for an aircraft to touch or even crash into overhead rotating wings. The wings themselves are not particularly dangerous. But crashing into a metal wall, no matter how smooth, isn't something you do in your spare time.

In some cases the tunnels do not have a diffuser per se, but change from a circular shape to a square shape (B). This is better than not having a diffuser because the corner of the square is "won". The larger the space the air has to fill, the lower the velocities.

The optimal solution is a cone type diffuser (C), which continuously expands the room, increasing the surface area and gradually reducing the wind speed. Aircraft that reduce wind speed to half their speed will find it impossible to fly higher and thus remain at a safe altitude, with the possibility of hitting overhead vents or even flying at more dangerous altitudes.

Ideally, after the maximum effective width, there should be at least a few more feet of room above it to undo any inertia the flyer has. This means that if a flyer is at high speed in the net and enters the belly position, he fires aggressively, but begins to slow down as soon as the diffuser starts. Even if the wind speed drops by 50%, the plane still needs a few more meters to stop the upward movement.

2. Security Lines

This new concept was introduced by Tunnel Instructor Org in 2016 and is now being adopted in American tunnels. It basically consists of 3 safety signs at increasing altitudes of a flight chamber. These lines represent the maximum safe flying altitude based on the flyers' abilities.

Most accidents occur due to the vertical fall of the flyer, not the horizontal thrust. The lower a flyer is, the smaller the drop, the softer the strike. In short: flying low is safer. Naturally, as with all rules, there are some special cases where a flyer will want to be a little higher than normal.

This helps patrons control themselves and ensure they stay low, and also enforces a simple rule for spotters to fly below a certain line. Without these lines, it was very difficult to define how much height was safe enough. Moreover, some wind tunnels impose a financial penalty on anyone who crosses the red line. Unfortunately, it could be argued that the only time all flyers take security seriously is when it hurts their wallets.

3. Airflow Quality

Airflow quality refers to how turbulent the wind is in a wind tunnel. This is the essence of the wind tunnel. All wind tunnel manufacturers are constantly trying to improve and perfect wind flow. In the image below you can see the different airflow qualities, from worst (A) to best (C).

When air quality is poor (A), flying feels like crossing a bumpy road. We don't get a constant, uniform wind resistance that forces our bodies to move in ways we don't want, forcing us to constantly compensate. This results in a much less precise and more tiring flight, which is counterproductive for any flyer. This not only causes more dangerous situations by depleting flyers, but also causes a particularly dangerous situation when an aircraft makes a mistake and cannot find intense airflow to help it compensate for its mistake, resulting in a more severe crash or even a more severe crash.

Think of it as accidentally flying over a formation in the sky. When a flyer accidentally flies over a formation, it is too late to correct his mistake, as he then mutters the flyers below and cannot avoid falling into them. The same thing happens when there are wind tunnel-induced fluctuations.

Most 4th generation tunnels have pretty good airflow, which tends to be a little weaker near the walls and/or door (B). This means that as long as coaches try to keep a half-eye during their training so that the student and themselves are well positioned, it should be a good session.

The ideal is to have a very "clean" laminar flow throughout the entire chamber (C). This means that no matter what wind speed or flight modality, the aircraft must find a direct response from the wind. This makes sessions as smooth and effortless as possible. Flyers always cause explosions, and if a flyer remains motionless in one position for a long enough time, it can affect the quality of airflow around it, but the better the quality of airflow, the harder it will be to cause explosions. flyers to make matters worse.

4. Soil Flexibility

Networking is an often overlooked feature. When a flyer falls, the fall is stopped by something: the web. Net flexibility will often determine the severity of any injury. Would you rather take a two-meter drop from a balloon to a castle or onto a concrete floor?

How resilient a network is depends on many factors, all controlled by the manufacturer. Most networks suffer from two basic problems. Firstly, they will lose their elasticity over time (months), and secondly, they are not equally elastic across the entire surface (some closer to the sides).

The worst type of mesh is a completely rigid mesh (A). This net does not bounce and is equivalent to hitting a hard surface. There are actually no 3rd and 4th generation type tunnels with this type of network as it is considered a very high risk situation.

The most common type of mesh is a partially elastic mesh (B). Although this network is truly resilient, it suffers from both common problems we mentioned earlier. First, it loses its flexibility over time. This means that every year the network becomes less flexible. This can be corrected by having a more complex and expensive network and a more meticulous maintenance procedure. Second, resilience is not always evenly distributed throughout the network. Again, a more complex and expensive structure can achieve this by maintaining a high degree of elasticity across the entire surface, ensuring that a fall on a particular point of the web will not encounter a harder mesh.

The most elastic mesh type (C) is the ideal one, with the strongest possible technology, providing a high level of elasticity throughout the entire surface and lifetime. This naturally requires a larger investment, but significantly limits the severity of any hit on the network.

5. Light Sensors

Naturally, having large pickets and security lines can only accomplish so much. Flyers should never fly above the red line for their own safety. If they see it, the spotter should remind them of the safety hazard and force them to fly lower. However, since the spotter is always several meters below it, it is difficult to say for certain that an aircraft has crossed the red line. Also, when multiple flyers are flying, a spotter must sometimes decide where to focus his attention and may not realize one is flying too high. The perfect solution for this is to use automatic infrared sensors.

When a pilot crosses the red line, the sensors are activated and the entire tunnel flashes red, making it clear to everyone that the flyer is engaging in dangerous flying. This is similar to the "beer line" concept in skydiving. Some tunnels even imposed expensive fines on customers who crossed the red line, removing 5 minutes of flight time from their accounts or outright banning them from flying after a warning or two.

This concept should be applied to all security lines, but it is much more critical on the top line. Automatic light sensors ensure that the wind tunnel operator can recognize if a flyer is dangerous and fix the problem immediately.

Figure 6

There are two types of tunnel pilots. Those who hit the wall and those who hit the wall. And when you hit the wall, you want to slide it, rather than hitting it full force at a 90-degree angle, or even into a corner. The science behind it is simple. Imagine falling down a slide or landing on a flat surface. Aren't the sliding noises much less painful? Because he.

Injuries are much less likely in circular chambers than in polygonal chambers. Moreover, training is much more comfortable in a circular tunnel for more reasons. Wall shifting means a plane can continue to perform its exercise fluently. However, tucking one foot into a corner often results in relief from the exercise at hand. For example, consider learning how to carve a flyer face. If his legs hit the corners several times, it is very likely that the coach will force his whole body into a turn, putting too much effort into bringing him in and thus disrupting the exercise. This can also happen in team exercises where space is scarce. Teams of 4 are often forced to drag legs along walls, which is much simpler in a circular tunnel, especially if you have grip with another member

A very common flight chamber shape, especially in old tunnels, is the octagon (A). Over time the tunnels evolved into using a decagon chamber (B), which is much closer to a circle and has less severe corners. However, the ideal flight room design is the circle (C) for all the issues mentioned above.

The main reason why manufacturers don't always make circular tunnels is that they are much more expensive and complicated to build. Not only are they complicated, but they also make other room-related issues more complicated. Adding a diffuser to a circular room is much more complicated than to a polygonal room. Maintaining good airflow in a circular baffle is much more complicated than a polygonal baffle.

Security is important. Always. Being safer, improving equipment, research, development and training are expensive. The most effective way for companies to improve security is to show customers that they appreciate and value security.

Modern 4th generation tunnels tend to be very secure tunnels. Comfort stuff comes into play at this level. There is often an overlap between comfort and safety. A good example of this is having water fountains in the front compartment. Having these eliminates the risk of loose water bottles floating around the room, as well as the possibility of a coach or students becoming dehydrated during camp. This is a comfort feature that shares common ground with safety. However, we will gladly write more articles about modern comfort features in future issues.

Fortunately, we live in an age where tunnels are becoming increasingly accessible. Consumers now generally have a choice. Tunnels are selected primarily based on price and time availability. We want to encourage you to start thinking about security, too.

How expensive is it to fly in a secure tunnel? How much are you willing to spend for your own security? Is it worth it ? We are working on it...