Aviation & Wind farms

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Aviation & Wind farms

Unread post by jean » Thu Jul 09, 2020 5:37 pm

It is coming our way ...

... "Among the issues are the turbulence wind farms can create, how their operation can affect radar and how they can simply “be in the way”, a representative of aviation consultancy TO70 wrote in a blog post.
“Wind turbines can cause radar interference whereby the blades appear as ‘clutter’ on radar screens and can be mistaken for aircraft,” says Balsdon. Accepting this is not the most suitable solution, he says the relied-upon mitigation has traditionally been “blanking” – covering the part of the radar screen where the turbine is. “That’s clearly not an ideal or long-term solution,” he accepts. “We have also looked at changing airspace design, but again that’s not always possible.”

Full text https://airport.nridigital.com/air_jul2 ... d_turbines
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Re: Aviation & Wind farms

Unread post by Rooster » Fri Jul 10, 2020 8:18 am

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Re: Aviation & Wind farms

Unread post by MemyselfandI » Fri Jul 10, 2020 8:43 am

Well that bloke clearly doesn't know how radar works. There is a thingamajig called moving target indicator (MTI) and it is set on the radar to ignore anything below a certain speed. As these wind farms are stationary, they will not be 'painted' on a radar screen as a target. As they are not squawking either there is no way to see them. Only an old primary radar MAY see them if they are close enough without setting the MTI.
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Re: Aviation & Wind farms

Unread post by heisan » Fri Jul 10, 2020 11:40 am

MemyselfandI wrote:
Fri Jul 10, 2020 8:43 am
Well that bloke clearly doesn't know how radar works. There is a thingamajig called moving target indicator (MTI) and it is set on the radar to ignore anything below a certain speed. As these wind farms are stationary, they will not be 'painted' on a radar screen as a target. As they are not squawking either there is no way to see them. Only an old primary radar MAY see them if they are close enough without setting the MTI.
The blade tips are going at well over 100kts, and are radar reflective...
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Re: Aviation & Wind farms

Unread post by opsmike » Fri Jul 10, 2020 11:59 am

heisan wrote:
Fri Jul 10, 2020 11:40 am
MemyselfandI wrote:
Fri Jul 10, 2020 8:43 am
Well that bloke clearly doesn't know how radar works. There is a thingamajig called moving target indicator (MTI) and it is set on the radar to ignore anything below a certain speed. As these wind farms are stationary, they will not be 'painted' on a radar screen as a target. As they are not squawking either there is no way to see them. Only an old primary radar MAY see them if they are close enough without setting the MTI.
The blade tips are going at well over 100kts, and are radar reflective...
To raw radar they are not moving relative to their position on the ground and therefore will only be picked up as ground clutter if close enough to the radar head
Airports are where it happens
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Re: Aviation & Wind farms

Unread post by MemyselfandI » Fri Jul 10, 2020 12:14 pm

Heisan.... if a helicopter stands on the ground, rotors turning...does radar see it ?
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Re: Aviation & Wind farms

Unread post by heisan » Fri Jul 10, 2020 12:44 pm

MemyselfandI wrote:
Fri Jul 10, 2020 12:14 pm
Heisan.... if a helicopter stands on the ground, rotors turning...does radar see it ?
Probably not - but then the radar cross section of a helicopter rotor is insignificant.

Wind farms give you a whole field of radar returns, all with significant radar cross sections, and all with a Doppler shift in the range of typical targets.

While modern radar software will generally figure out that these are actually static structures, the moving pattern of returns often trigger false positives. And real targets in the vicinity of wind farms are also frequently lost in the cluster of returns from the area.

It really is a significant problem, and there is a lot of research going into it. Both on the radar algorithm side, and in manufacturing 'stealth' turbine blades with a lower radar cross section.
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Re: Aviation & Wind farms

Unread post by MemyselfandI » Fri Jul 10, 2020 1:40 pm

For radar to see something stationary it has to be a significant size to produce a decent reflection. A pole with a rotating blade is not going to be seen by radar. Radar's don't generally look horizontally, they are angled slightly above the horizon, so it stands to reason that unless the wind farm is right next to the radar head , the energy beam will go over the top of these wind generators. No, they can't be an issue to radars and as most countries require SSR, they are of no consequence them.
As for turbulence , well they don't turn by themselves, the wind turns them ie, they are not producing thrust...so the turbulence effect is merely that of wind blowing through an obstacle. The weaker the wind the less the effect. I doubt you will find anybody flying that low in strong winds anyway, so again...much ado about nothing IMHO. :?
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Re: Aviation & Wind farms

Unread post by NewGroundPounder » Fri Jul 10, 2020 6:51 pm

Wind farms are generally at ground level, or sea level in Europa, radar installations normally ignore ground clutter.
Somebody had too much time to think, and too little knowledge.....
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Re: Aviation & Wind farms

Unread post by heisan » Fri Jul 10, 2020 7:27 pm

https://defensesystems.com/articles/201 ... rence.aspx
A case study in the December 2012 Air Force Law Review notes that the problem cropped up at Travis Air Force Base, Calif., when a radar system was upgraded from analog to a more precise digital system. Controllers began seeing “persistent but non-existent weather cells” and aircraft they were tracking disappear and reappear on their screens. The problem was coming from a farm of more than 700 wind turbines southeast of the base.
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Re: Aviation & Wind farms

Unread post by MemyselfandI » Fri Jul 10, 2020 8:19 pm

They don't mention how far 'southeast' of the base. Like I said, if it's close, it is the only possible time it MAY return a reflection of energy and 700 turbines in close proximity will probably provide enough background to reflect some energy. Maybe you can find out how close the radar head is and if the radar is beaming horizontally or not?
They offer a solution in the article anyway. It boggles my mind that a nation so advanced (supposedly) would still have issues with raw primary radar,ie,not sorted the static from the dynamic.
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Re: Aviation & Wind farms

Unread post by biffvj » Fri Jul 10, 2020 8:29 pm

Interference from large wind turbines depends on the RADAR being used. Weather RADAR is one that can be adversely affected by them.
Besides interference they are not bird friendly and they are noisy.
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Re: Aviation & Wind farms

Unread post by heisan » Fri Jul 10, 2020 8:41 pm

I don't think you understand the scale of these wind turbines. The radar cross section of each individual blade is bigger than the typical light aircraft (actually some are bigger than medium aircraft too). The tops of the blades are nearly 400' AGL on some of the biggest turbines. Add the fact that the tip speed gives a similar Doppler shift to light aircraft targets, and you have some real issues for radar systems.
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Re: Aviation & Wind farms

Unread post by stheeman » Sat Jul 11, 2020 7:40 am

... and radar is not the only one affected...
heisan wrote:
Fri Jul 10, 2020 8:41 pm
...the scale of these wind turbines... ...tops of the blades are nearly 400' AGL on some of the biggest turbines...
Think about the wake turbulence these tips produce at 400ft, in addition to the fact that this wake (physical location i.r.o. the turbine) is dependent on the wind direction! Not sure how far downwind this wake can still be dangerous to low flying light aircraft? I'll be giving these things a wide berth...

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Re: Aviation & Wind farms

Unread post by DustFlyer » Sat Jul 11, 2020 8:47 am

Here are two screen shots of a quick Google search. It gives a better picture... :D
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