January 19th, 2021

Yellow light vs white light in fog

One general view about yellow vs white light in fog is based on the theory that scattering, by anything at all, is always greater at the short-wavelength end of the visible spectrum than at the long end. It must be true because the nineteenth-century British scientist Lord Rayleigh showed this in his paper of 1871 on the dispersion of electromagnetic radiation. This explained, amongst other things, why the sky is blue. This is because when the pure white light from the sun passes through the gases and extremely small particles in the atmosphere it’s scattered. Blue, and violet, light is dispersed the most because they travel as much shorter waves. So, the sky looks blue.

You’d assume therefore to get the greatest penetration of light through fog, you should use the longest wavelength possible. Red, being the longest, is obviously unsuitable however because it is used for traffic stoplights. So, you compromise and use yellow light instead.

This view is flawed though when it comes to light penetrating through fog. Rayleigh scattering – as it’s known – applies only to ‘scattering’ particles that are smaller than the wavelength of light and at wavelengths far from absorption. Fog droplets are huge compared with the wavelengths of visible light. This means that the scattering of light by fog is essentially wavelength independent. See Reference Articles 1 below.

We don’t need to consult scientific papers to understand this is true though. Just look at cars on the road at night. Designers of vehicle headlights have known for a long time that there is no magic colour that gives greater fog penetration. That’s why most headlights are white and why, for example, EU regulations require all new vehicles to have white lights. See Reference Articles 2 below.

So, for light penetration and perception in fog, the colour of light is unimportant. Yellow light. White light. There’s no difference.

Reference Articles 1

Bohren C. F, & Fraser A. (1985) – Colours of the Sky in The Physics Teacher pp 267-272. And Bohren, C. F. & Huffman, D. R. (1998) – Particles Small Compared with the Wavelength, in Absorption and Scattering of Light by Small Particles, Wiley-VCH Verlag GmbH, Weinheim, Germany.

Reference Articles 2

Nelson, J.H. (1938) – Optics of headlights in The Journal of Scientific Instruments Vol. XV, pp. 317-322. Also see the more recent Schreuder, D. A. (1976) – White or yellow light for vehicle head-lamps? In the Dutch Institute for Road Safety Research SWOV.

Commercial Director & Co-Founder

As an entrepreneur, Yuli has worked across sectors as diverse as Finance, Oil & Gas, Music, Real Estate and Electronics. His passion in business is challenging the status quo, disrupting markets, building first-class teams, and solving complex challenges with creative solutions.

Yuli trained in Finance and Economics in London, with postgraduate studies in Law (LLM) and Engineering (MEng) in Scotland and Australia. He’s also been appointed as an Export Champion by the UK Government’s Department of International Trade.

Recent Blog Posts

0

December 10th, 2020

Thinking Metal Halide? Think again, again, again, and again…

There are quite a few ‘cheap’ deals on the market for Metal Halide lighting at the moment. If you’re being tempted by them, we’d really recommend you think again.

You might be saying to yourself, ‘Midstream are world-leading pioneers in LED. So, they would say that. They’re biased.’ We are. But only because of the facts. Let’s explain just a few reasons why – without blinding you with any science because that’s not our way.

Energy savings

We won’t dwell on this one too much. Let’s face it though, LED lighting has been proved time after time to cut energy use – massively. In fact, you can make savings of 50% or sometimes even more.

Maintenance

Again, another area where LEDs have been shown to beat Metal Halides hands down.

Metal Halide lamps degrade much, much faster than LEDs. So they often need replacing, even before a lamp has failed totally. That’s not all. Because of the way they’re built, Metal Halide lamps can’t cope well over time with things like vibrations on cranes and high masts. This can lead to components breaking and the lamps dying. Not a problem at all with solid-state LED systems.

What does this all mean for you? You’ll have to pay several hundred Euros for each new lamp you need. You’ll also need to pay for someone to replace them. You might need to get in specialist equipment too like cherry pickers to reach them – yet another big cost. And we’ve not even mentioned yet the problems and costs caused by downtime, or an immediate failure, you could incur.

Efficiency and efficacy

At the start of its life, a Metal Halide lamp can deliver a high lumen output. Obviously, this lumen output is related to efficiency. However, give it six months or so and 20% of that lumen output will be lost as the bulb degrades. It’ll still be consuming the same amount of energy though, meaning it’s getting more and more inefficient. And by the time it’s reached its half lifetime it’ll need replacing because it won’t deliver the quantity and quality of light needed.

The way Metal Halides cast their light, compared to LEDs, can lead to further inefficiencies. Metal Halides throw light in all directions and to focus it on a target they need reflectors. These reflectors aren’t nearly as efficient as the optical systems, such as lenses, used in LEDs. So, straightaway with Metal Halides you’re looking at an effective light loss of 20 to 50% depending on the photometrics you want to achieve.

Just remember too… A well-built LED will achieve around 110 to 130 lumen per watt. Whereas with Metal Halides, after taking optical losses into consideration, you’re looking at only 70 lumen per watt. That’s costing you twice the installed power to achieve the same lighting levels! What’s there to think about?

Light quality and CRI

All the light emitted from LEDs is in the visible spectrum. But when it comes to Metal Halide lamps, as well as visible light, they emit both infrared (IR) and ultraviolet (UV) light. The IR emitted is one of the reasons Metal Halides are so inefficient compared to LEDs as you’re wasting energy on heat. The UV light emitted doesn’t waste much energy. Too much exposure to it in a confined space could cause skin damage and health issues, however.

Metal Halides don’t fare well compared to LEDs when it comes to their colour deviation and Colour Rendering Index (CRI) values. With a well built LED system both colour deviation and CRI changes don’t really come into play. As Metal Halide lamps age though, you’ll get colour deviation, and the CRI value won’t be stable. In fact, with Metal Halides you can only be sure of the CRI when it’s very first installed – it starts to change very soon after.

Controls

LEDs can be turned on and off thousands of times a second with no impact on lifetime or performance. Which makes them perfect for things like light shows in places like large sporting venues. It also means they can be used with controls such as motion sensors to dim or turn them on and off instantly when required – helping save money lighting areas when they’re not needed.

Because they’re electromechanical Metal Halide lamps need time to reach full power. And when they’re turned off, you’ll need to wait fifteen minutes or more for them to cool and restart before they can reach full power again. So in terms of controls, the best you can do is dim them with voltage regulators – which are very expensive. You’ll also have to invest in having a separate power line for them so they can be dimmed independently of any other systems.

So why are Metal Halide systems going cheap?

We’re not going to ‘pull any punches’ here. Basically, because of all the reasons above, the Metal Halide era is coming to or has already reached its end. And to clear their stocks, manufacturers are cutting their prices. An added issue that’s starting to emerge is that once those stocks are cleared, finding replacement parts is going to become impossible.

Paolo Corno, Technical Director & Co-Founder, Midstream Lighting

With over ten years of LED lighting industry experience, Paolo is an invaluable and highly regarded member of our core leadership team.
Coming on board as one of the company’s co-founders in 2013, Paolo’s responsible for overseeing our Lighting Design, Engineering, and R&D Teams. He personally leads the design and development of Midstream’s comprehensive product portfolio – including the Atlas, Titan and Modus Floodlight Series – which are installed in over 85 airports globally.

An experienced designer, who holds a degree from Bocconi University in Milan, Paolo has led the design of over 100 LED lighting solutions in the aviation, maritime, sports and horticultural markets. ensuring that all national, local, industry and customer requirements are met.

Recent Blogs

0

November 17th, 2020

Understanding colour shift… made easy

If you trawl the internet for ‘colour shift’ you’ll come up with hundreds of results. The problem is though, whilst they’re all talking about the same thing, they often approach it from different angles. In most cases, you’ll need a Ph.D. in Physics to understand what they’re saying too.

So, in true Midstream style, we’re going to keep this really simple. And if you’ve got any questions, or want to learn more, no problem. Just contact us.

What is colour shift?

Colour shift is a deviation from the originally selected colour which happens on the LED chip. Generally, this shift usually goes to the blue end of the spectrum – so you lose the spectrum outside of the blue emissions. However, this deviation can affect green and red emissions too. Different chips will deviate to a different colour depending on the characteristics of the phosphorus used in the LED chip.

Perhaps the easiest way to think of colour shift is that it’s effectively lumen depreciation in specific parts of the LED’s colour spectrum.

Why does it happen?

Colour shift can happen for a number of reasons.

One of the most common is caused by defects in the chip during the production of the LED. Another reason is due to a problem with the application of the chip’s phosphors coating. This coating converts the invisible, pure UV emissions into visible light and can change its characteristics over its lifetime.

The biggest cause though is nothing to do with the chip itself but is due to its misuse by the luminaire manufacturer. This can be because:

  • They’ve mounted the chip on the board incorrectly.
  • They’re driving the LED too hard beyond its effective design parameters.
  • Or, because of luminaire design issues, it isn’t being cooled sufficiently.
How do you recognise it?

Easily. You can see it with the human eye and measure it with the right equipment, such as a spectroradiometer. The extent to which you can recognise it – by sight or measurement – depends on how bad the colour shift is. This in turn can depend on how poor the product quality is, or how much the chip is being overheated. Either way, a rapid colour shift will usually result in the complete failure of the LED board in a very short time.

How can you prevent it?

A good place to start is chip selection. Using the right chip for the required application will help stop any colour shift. So, when you choose this crucial part of your luminaire you need to assess its lifetime depreciation by looking at its LM80 data. This will give you a good guide as to how a chip will age. You can find out more about LM80 here.

Also, make sure the PCB board manufacture has good quality assurance systems in place and follows the chip manufacturer’s mounting instructions to the letter.

The best way to prevent it however is by putting extra care into the heat management of the luminaire. A well cooled, quality LED, even if it’s being driven by high currents, will rarely suffer from colour shift. This is why when we’re developing a new product, we always put heat management at the top of our key considerations – unlike some companies we won’t mention.

How does it differ from lumen depreciation?

General lumen depreciation is where the total light emission decreases across the whole spectrum. And, as we’ve already said, colour shift is in a way is lumen depreciation that happens more in certain parts of the spectrum. For example, a shift to blue just means you’re losing more flux from the rest of the spectrum and not an increase in the blue area.

Does it affect all the luminaires in the same location in the same way?

It depends on the cause of the shift. If it’s due to a production defect, the luminaires may be affected in different ways in the same location.

If it’s a result of poor heat management or poor chip choice, then all the luminaires in the same location will be affected in the same way.

Does it only concern high-temperature climates?

No. But it is more likely to happen in them because the high working temperatures will cause it to happen faster. A light that may show colour shift in Finland will almost certainly suffer from it in Qatar. So high-temperature climates in a way are the ultimate test in terms of quality and heat management.

Paolo Corno, Technical Director & Co-Founder, Midstream Lighting

With over ten years of LED lighting industry experience, Paolo is an invaluable and highly regarded member of our core leadership team.
Coming on board as one of the company’s co-founders in 2013, Paolo’s responsible for overseeing our Lighting Design, Engineering, and R&D Teams. He personally leads the design and development of Midstream’s comprehensive product portfolio – including the Atlas, Titan and Modus Floodlight Series – which are installed in over 85 airports globally.
An experienced designer, who holds a degree from Bocconi University in Milan, Paolo has led the design of over 100 LED lighting solutions in the aviation, maritime, sports and horticultural markets. ensuring that all national, local, industry and customer requirements are met.

Recent Blog Posts

0

Sep 1st, 2020

Seven apron floodlighting lessons learned over the years

As LED lighting pioneers, we’ve been working with aviation clients, from major international hubs to regional airports to military facilities, for over a decade. And we’re masters at making LED lighting solutions for airport aprons.

Here are just some of the lessons we’ve learned over the last ten years.

Lesson One: Apron lighting must be a design-led solution

Most people working on the airfield side of an airport will be familiar with Airfield Ground Lighting (AGL). They’re very standard products. It doesn’t matter who you buy them from, things like their output, size and optics will be almost the same.

But with LED floodlighting that’s not the case. You can’t assume a 600W floodlight from one supplier will behave in the same way as a 600W floodlight from another. They can in fact perform very differently.

This means you can’t approach a potential supplier saying ‘We’ve had a design from a supplier using 123 pieces of 400W floodlights. Can you give us a quote for the same number so we can use that as your competitive bid?’.

Unfortunately, you can’t just do that as floodlights will vary depending on their photometry and efficacy – the efficiency of useful light on the ground. So, you could have a 400W floodlight, with the right optics, performing better much than a more ‘powerful’ 600W one.

Another important factor to consider is how well products will fare over time. LED lighting will degrade, just like sodium or metal halide lighting – at a much slower rate though. But you still need to know by how much and over what time period. Again, this will be different for each manufacture and will certainly depend on the environment in which they operate

So, a manufacturer’s design and quote for a project must be based on their actual products. If they’re not, you can’t make any meaningful comparison.

The lesson here, in summary, is don’t try to compare ‘apples with oranges’.

Lesson Two: Test, measure and verify

Let’s move on to the next phase of a project.

You’ve chosen a supplier. Their design works – on paper. You know it meets or exceeds your needs. And it’s on budget. You give it the green light and it gets completed. You may think that’s it, job done.

But it’s not.

You’ve got to check that what was promised in the design phase is true to real life and it really complies with or exceeds what’s required by your local aviation authority.

Here’s an example why. Istanbul Airport asked 10 major lighting suppliers to pitch for an upgrade to the airport’s lighting. As part of the pitch process, they asked each supplier to set up two test poles to demonstrate they could reach the compliance levels shown in their designs. 80% didn’t pass the test. The Airport Authority was very relieved they ran the test!

And you need to go on testing and verifying your lighting regularly, with a documented testing methodology, to make sure it stays compliant.

As an example, Frankfurt Airport had a new system installed during the winter. After live testing, it was confirmed it matched the light levels needed. In fact, the lighting exceeded what was required, as a ‘buffer’ had been allowed for in the design. Six months later, in the summer, when they ran the tests again, the levels had fallen by 20%. They were still within the required levels though because of the ‘buffer’. The airport however was obviously concerned why they’d fallen and what would happen in the coming months and years. When they tested again in the winter, the lighting was back to its original levels. It was the ambient temperature change between the winter and the summer that was having an effect. By factoring this into their testing methodology they were able to make true comparisons going forwards, test after test.

The lesson here? Test, measure, and verify regularly to make sure you stay compliant with regulations. And going a bit above and beyond what’s required in the standards is never a bad idea…

Lesson Three: Optics rule

Glare is the enemy of all airports. It primarily affects pilots and can cause not just discomfort but also temporary blindness, which in turn can lead to accidents. So, from a health and safety standpoint reducing glare is exceedingly high on an airport’s agenda.

This is where the optics used come into play.

In virtually all the projects we’ve done, we’ve used our proprietary asymmetric optics. Why? Simply because they deliver a low glare output spread over a large angle compared to symmetric optics. We also make sure that they have a full cut-off above the horizontal plane to further reduce the chance of any glare issues.

The result is lower glare, not just for pilots but for ground staff too.

This lesson? Put your supplier under the spotlight when it comes to glare and get a guarantee it won’t be a problem for you.

Lesson Four: Pay cheap – pay twice

When it comes to virtually any project, engineers want to use premium products to give the best possible outcome. Finance departments, however, are usually focused on the price. And this can cause problems.

We’ve heard many ‘horror stories’ where the budget has been the primary reason for choosing a particular supplier’s solution.

In one case, because the luminaire’s heat dissipation wasn’t up to the job, the LEDs burnt themselves out so much, they actually fell off their circuit board.

In another, cheap floodlights were used and within six months nearly all of them had failed. They were replaced under warranty. But within another six months, they’d failed again. To solve the problem once and for all, the airport had to approve a new budget for a more expensive, more resilient solution.

So, remember these three things:

  • Apron floodlighting is part of your critical infrastructure. Don’t let budget be your controlling factor when it comes to it. The cost of having a cheaper system can be quickly outweighed by the costs of continued maintenance etc. And just imagine that you had an accident on an apron – if your lighting wasn’t up to prescribed standards you could end up facing huge legal costs.
  • Premium products will almost always outlast low-quality ones. And premium product providers usually will be around for a lot longer than their competitors. Go cheap and you may find that, when problems start to happen later down the line, the company you went for isn’t around to put things right.
  • Contractors are always looking to make as big a margin as they can. They try to reduce costs by taking what’s in the design specification and replacing certain products with cheaper ones. Reducing their cost increases your risk. Don’t let them. Make sure they stick to the specifications to meet your needs.

Compromising on quality can cost you a lot more, in the long run, is the lesson to take out here.

Lesson Five: Remote vs integrated drivers

This is a question we get asked a lot. ‘Is it better to have your drivers in the luminaires or a separate box?’

There are positives and negatives on both sides. Depending on where your airport is based can influence your choice too. In the UK, Italy, and Germany integrated drivers are more common. In France and the US remote drivers are mainly used.

So, make sure your supplier has both options available to meet what you want.

One thing to remember though is voltage spikes are killers when it comes to LED lighting. That’s why surge arrestors are so important. Make sure your supplier’s remote or integrated solution takes voltage spikes into consideration and can protect your lighting.

This lesson is simple, talk to your supplier about which will work best for you and how they’ll protect you from voltage spikes.

Lesson Six: Control and intelligence

Everyone thinks they need controls. But do you really need them? Before you add a control system to your project specification you need to:

  • Decide who will be in charge of the control systems. Will they need to be trained to handle them? Will you need to have 24/7 cover in case something goes wrong?
  • Look at what intelligence they can give you. Is it really that useful to your operation?

Control systems come at a cost. There’s no point in having them if they’re just going to turn your lighting on and off.

The lesson here? If you’re not going to see any additional benefits from having them, don’t be convinced by your supplier to buy them.

Lesson Seven: Yellow vs white? Which is best.

Another question we get asked quite often is, ‘For fog dissipation is yellow or white light the best?’.

Most people think yellow light is. But in truth, they perform exactly the same as each other.

Why? Fog droplets are on average, much smaller than cloud droplets. But they are still huge compared to the wavelengths of visible light. So the scattering of such light by fog is essentially wavelength independent. Car manufactures have known this for years and that’s why they don’t use yellow fog lights any longer.

This last lesson learned is a simple one. Don’t worry about it.

That’s it your seven lessons learned! Fill in your details below to watch the 7 Lesson Learned webinar recording

Yuli Grig, Commercial Director & Co-Founder, Midstream Lighting

As an entrepreneur, Yuli has worked across sectors as diverse as Finance, Oil & Gas, Music, Real Estate and Electronics. His passion in business is challenging the status quo, disrupting markets, building first-class teams, and solving complex challenges with creative solutions.

Yuli trained in Finance and Economics in London, with postgraduate studies in Law (LLM) and Engineering (MEng) in Scotland and Australia. He’s also been appointed as an Export Champion by the UK Government’s Department of International Trade.

Recent Aviation Blogs
+1

Sep 22nd, 2020

Football Pitch Lighting: England, Scotland, Wales, and UEFA

Depending on where a club is based and what level it plays at the rules governing the quality of pitch lighting needed can vary greatly.

The Football Association (FA) has its own rules. As do the Scottish Football Association (SFA), and the Football Association of Wales (FAW). And all clubs in each of these associations playing at a premier level are governed by the Union of European Associations (UEFA) regulations.

So, to help you understand what regulations your club has to comply with we’ve created this simple guide. It covers the regulations for each association in turn. Each one has its own classification system. So, we’ve put a note below each chart to let you know how they are ordered.

We’ve also pulled together a quick ‘at-a-glance’ chart to make comparing them as easy as possible.

Two terms you need to know

The two metrics used to grade lighting used here are lux and uniformity. Here’s what they mean in layman’s terms:

  • Lux – A measure of the intensity of light that hits a surface. The higher the lux, the brighter the light.
  • Uniformity – The uniformity of illuminance in terms of how evenly light is distributed over a given surface. The higher the figure, the more evenly light is spread.
Help is at hand

We’ve tried to keep this guide as simple as possible. If there’s anything you don’t understand, or you have any questions, we’re here to help. Just call us on +020 8038 7432 and one of our Sports Lighting specialists will be happy to help.

The FA Regulations
Football Pitch Lighting: England, Scotland, Wales, and UEFA

N.B. In this chart Grade G is the lowest level and Grade A the highest. League and Premier League clubs are covered by UEFA Regulations.

This Chart is from Page 5 of the FA Guide to Floodlighting Regs: see the full guide here.

The SFA Regulations
Football Pitch Lighting: England, Scotland, Wales, and UEFA

Chart is from page 29 of the Scottish FA Club licensing manual.

Clubs are required to have a floodlight system at the ground. To meet the Platinum standard not shown in the above chart, the club will be able to provide a back-up power supply which will provide two-thirds of normal power.

In the case of a Platinum, the floodlighting lux level is required to be: Average – 1200 lux and 0.45 uniformity

N.B. In this chart Bronze is the lowest level and Platinum the highest. Scottish Premier League clubs are covered by UEFA Regulations.

FAW Regulations
CategoryLuxUniformity
Tier 1500 luxN/A
Tier 2250 luxN/A
Tier 3250 luxN/A

N.B. In this chart Tier 3 is the lowest level and Tier 5 the highest. Cymru Premier League clubs are covered by UEFA Regulations.

UEFA Regulations
Football Pitch Lighting: England, Scotland, Wales, and UEFA

Chart is from Page 12 of the UEFA Stadium Infrastructure Regulations Guide: see the full guide here.

N.B. In this chart Grade 1 is the lowest level and Grade 4 the highest.

An ‘at-a-glance’ comparison

This chart compares the lux and uniformity levels of each regulatory body.

Regulatory bodyTheir classification groupingLux levelUniformity
FAGrade A (Step 1) Conference2500.25
Grade B (Step 2) Conference1800.25
Grade C (Step 3) Conference120 (180)0.25
Grade D (Step 4) Conference120 (180)0.25
Grade E (Step 4-5) Conference120 (180)0.25
Grade F (Step 5) Conference120 (180)0.25
Grade G (Step 3) Conference120 (180)0.25

N.B. Where the lux levels are given as ‘120 (180)’, the 120 figures show the minimum for any existing lighting systems. 180 figures show the lux levels that will need to be achieved if there is a lighting upgrade at any point.

Regulatory bodyTheir classification groupingLux levelUniformity
SFAPlatinum2500.25
Gold1800.25
Silver120 (180)0.25
Bronze120 (180)0.25
Entry120 (180)0.25
WFATier 1500N/A
Tier 2250N/A
Tier 3250N/A
UEFACategory 41,4000.5
Category 31,2000.4
Category 28000.4
Category 1N/AN/a

N.B. Category 1 clubs lux levels don’t apply. However, they should be high enough for matches to be broadcast.

Get in touch if you want to know more

This is just a quick, introductory guide on football pitch lighting. If you’d like to know more – from the benefits to the pitfalls to avoid – our Sports Lighting specialists are here to help.

0

June 22, 2020

Understanding windage

When it comes to designing industrial lighting solutions, windage is something you ignore at your peril. So, we’ve asked our mechanical engineering guru, Andrea Peratello, to explain what it means and why it’s so important.

What is Windage?

Windage can mean different things to different people. In ballistics, for example, it’s the adjustment that needs to be made to keep a missile on target after taking the wind into account.

However, in our industry, we need to consider its engineering definition. This is where windage refers to the area or shape of an object that makes it susceptible to pressure.

Let me put that into an everyday, easy to understand context. If you’re walking down the road on a windy day you get pushed by the pressure of the wind. That pressure pushing you is called drag or drag force.

If you’re walking head on into a constant wind, you’ll find it harder to walk than if you were walking sideways into it – because the drag is greater. The wind speed is the same, it’s just the amount of your body you’re exposing it to – the windage – that’s changed. And if the wind speed and/or your windage goes up – the drag force goes up and you get blown over.

Why is it important and when does it need to be considered?

When you’re building something, like a large mast holding lots of lights, you want it to stay where it is – not sway around or even worse topple over. This explains why engineers have to think carefully about windage when they’re building something. They also need to take into consideration other things that can add to this drag force e.g. the weight and positioning of the mast and lights.

How do you calculate windage?

In general terms, engineers are less concerned with calculating windage itself – but more with the drag force, it can contribute to. It’s this drag force that can cause damage.

Drag force is easily calculated with this formula:

DRAG= ½ X V2 X ρ X EPA

Where:
V – is the air velocity.
ρ – is the air density.
EPA – is the Effective Projected Area.

And EPA is calculated with this formula:

EPA = Cd X FPA

What’s the difference between EPA and FPA?

Let me try to put this into everyday terms again. Imagine an oblong box with different dimensions on each side. The top, front, and end of the brick each have a different surface area, which is effectively the FPA for that side. And the greater the FPA, the greater the drag. That’s why we need to consider the largest FPA of an object as our worst-case scenario in any calculations we make.

However, we need to consider an object’s aerodynamics also to calculate it’s EPA.

Now imagine a ball and a cylinder of the same diameter. If the wind were blowing directly on the ball and the end of the cylinder, they’d have the same FPA. But because the ball is more aerodynamic the drag force against it is less than the cylinder and it has a lower EPA. That’s why we need to use an object’s drag coefficient and its FPA to get to its EPA, so we can calculate the actual drag.

So, floodlight manufacturers usually characterise the aerodynamics of their products with the maximum EPA value under the Windage tag of the datasheet as a worst-case scenario.

Andrea Peratello, Product manager, Midstream Lighting.

A mechanical engineer, production manager, project leader, and inventor Andrea’s career has been broad and varied. He’s worked in the chemical, mechanical, and electromechanical sectors – where he’s been responsible for the design of products and production equipment.

Andrea holds a Master’s Degree in Mechanical Engineering from the Politecnico di Torino.

With over 10 years of experience in LED lighting design and delivery, Andrea has boosted the development of all Midstream products inside our Engineering and R&D teams. He’s also responsible for overseeing the product manufacturing process of all our products.

+1
Do NOT follow this link or you will be banned from the site!