Tuesday, January 3, 2017

Stealth technology hits the wind power industry


I've long known that wind turbine blades can cause massive interference to radar systems, so much so that wind power generation is usually banned within a reasonable distance of things like airports.  Now there may be a novel solution.  The Telegraph reports:

Defence and technology group QinetiQ has built 'stealth’ wind turbines which barely show up on radar.

The company has applied knowledge built up over 40 years in military applications to make a French windfarm consisting of 35 turbines each 400ft high appear to radar systems as if they were just 4ft high each.

EDF, the French state-owned power giant, turned to FTSE 250-listed QinetiQ for help after being refused permission to build the country's most powerful wind farm at a site near Perpignan, southern France, because the giant towers and spinning blades of the turbines would interfere with radar systems used to predict weather.

. . .

Military stealth works to defeat radars using multiple frequencies while weather radar is narrow band so on the face of it producing a stealthy turbine should have been simpler than most military applications.

However, Mr Moore said it turned out to be extremely challenging.

“The aerodynamic shape of the turbines blades couldn’t be altered significantly because they would become inefficient and we couldn’t put a stealthy coating on because it would be thick and heavy, which would also make them inefficient,” he said.

In the end the company designed blades made out of composite materials which absorb radar waves and turn it into heat, while a special cladding was put on the towers and the generators themselves to make them disappear to radar.

There's more at the link.

I find this fascinating, for two reasons.  First, if turbine blades (and their supporting towers) can be made less visible to radar, will they pose a greater risk of collision to low-flying aircraft?  I can see military planes, flying nap-of-the-earth, running slap into one if they can't see it coming on their electronic systems.  Second, can the same technology be applied to helicopter rotors?  Rotors are one of the most visible parts of any helicopter on radar systems.  If they can be made radar-invisible, a full 'stealth helicopter' can't be far away - and that has huge implications for Special Forces infiltration and exfiltration operations.

Most interesting . . .

Peter

10 comments:

SiGraybeard said...

These guys are solving the wrong problem. The problem to the weather radars isn't that the turbines are 400' tall and look like they are. Any radar that's worth a damn can categorize a structure like a tower as clutter and ignore it. The problem is that the wind turbines produce turbulence that shows up on weather radar. And it really would be a problem if the aircraft flew into it. They didn't change the way the turbines ruin the downstream air flow, they just hid the rotating part.

And the analogy of making a 400' tall radar look like it's 4' tall is just incomprehensible. Radar doesn't really react to height, it reacts to reflecting area. Do the writers mean the turbines disappear behind the horizon when the radar is that much closer? I suspect they're trying to talk about radar cross section, which is measured like area (square feet or meters or centimeters, etc.)


Kristophr said...

The real problem is that wind turbines do not produce enough power to pay for themselves and their own maint. And the power they produce is dirty, and causes havoc with the AC power grid.

Liquid-salt nuclear plants are a better solution.

Anonymous said...

What Kristopher said. And they are death on migrating birds. And there appears to be no good way to dismantle and recycle them when they fail, so they are abandoned (see Hawaii's Big Island for an example). Those are the problems that need to be solved. Wind power is one of those things that just doesn't scale up well.

LittleRed1

Chris Sutch said...

and I'm curious - wouldn't the "Absorption" of the radio waves still disrupt weather radar? Wouldn't they create a dead zone in your sweep where you wouldn't see the weather behind the turbines?

Old NFO said...

Sig is correct, and that one doesn't get solved by making them stealth! Re running into them, that's what charts are for, along with keeping them current!!!

Post Alley Crackpot said...

Perpignan also happens to be home to an infamous French prison ...

It's likely that the French authorities thought that someone might grow massive stones and decide to spring someone out of "Le Trou", figuring that the radar signature of their stolen helicopter would be disguised by the radar footprint of the windmills.

All I want is to be able to see the YouTube video of the break-out. :-)

Richard Blaine said...

We have a whole world of problems that need to be solved, and they pick one that's solving itself thru attrition due to economic infeasibility.

Spend the money educating the public on new nuclear reactor designs like the traveling wave reactor.

More environmental stupidity - solar roads.

Spend the money on more efficient photovoltaic panels - useful for a home install. I think we're a long stretch from industrial capacity usage.


Thomas W said...

So do we weaponize it? Stealth high speed fans to knock aircraft / missiles out of the sky? Ought to be good for at least a short story.

Anonymous said...

Regarding avoiding collision with windmills. Flight Management Systems (FMS) produced by Garmin, UNS or Trimble have a 3D map in their database. The aircraft's GPS systems are constantly providing the exact latitude and longitude and altitude along with speed, course and vertical speed (climb or descent) to the FMS which is comparing the aircraft's position in the sky and the projected course with the 3D map to ensure you won't fly into a mountain, skyscraper, bridge or windmill. One of the views that the pilot can select on his screen is Synthetic Vision (that's Garmin's term) that displays the terrain and obstacles just like a flight simulator for your PC. Anything coloured red is what you're going to crash into if you don't change your course. I've looked over the pilot's shoulder the last time I was up in one of our G1000 equipped King Airs, it was pretty impressive. Google 'garmin synthetic vision' and watch the videos.

If you have FMS installed in your aircraft, you have to subscribe to the Obstacle Database which is updated every 4 weeks since people are constantly erecting things like windmills. The subscription is over $1,000 a year, IIRC, but if you don't subscribe your FMS will mulishly refuse to let you input your waypoints.

Al_in_Ottawa

urbane legend said...

. . . a full 'stealth helicopter' can't be far away . . .
What if you equipped one with a Gatling gun, maybe get Roy Scheider to fly it?