{"id":594078,"date":"2026-09-08T16:46:38","date_gmt":"2026-09-08T16:46:38","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/594078\/"},"modified":"2026-09-08T16:46:38","modified_gmt":"2026-09-08T16:46:38","slug":"wind-turbines-are-built-for-gusts-near-120-miles-an-hour-so-the-10-steel-towers-a-radar-truck-watched-fold-across-three-iowa-wind-farms-were-carrying-almost-three-times-that","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/594078\/","title":{"rendered":"Wind turbines are built for gusts near 120 miles an hour, so the 10 steel towers a radar truck watched fold across three Iowa wind farms were carrying almost three times that"},"content":{"rendered":"

A wind turbine tower is a tube, not a post.<\/p>\n

It carries the machine on top by keeping its own wall in tension and compression, and that wall is thinner in proportion than the skin of a drinks can.<\/p>\n

Thin walls do not snap.<\/p>\n

They buckle, which means a dent forms on the compressed side and the whole section folds through it in\u00a0a fraction\u00a0of a second.<\/p>\n

That is what happened in Iowa.<\/p>\n

Rows of\u00a0steel towers\u00a0went over in one afternoon, and the tornado that did it was still\u00a0being measured\u00a0as it passed.<\/p>\n

Why a tornado is not simply faster wind<\/p>\n

A turbine is built for a direction.<\/p>\n

The rotor turns to face the wind, the blades feather to spill it, and every load path in the tower assumes the push arrives from one side at a time.<\/p>\n

A tornado removes that assumption.<\/p>\n

The flow rotates, so the direction of the push swings through\u00a0a full circle\u00a0in seconds and the tower is loaded from angles it never saw in testing.<\/p>\n

There is also lift.<\/p>\n

Air inside a tornado moves upward as well as around, which adds\u00a0a vertical component\u00a0to a structure designed almost entirely for\u00a0sideways force.<\/p>\n

What was standing on that ground<\/p>\n

The machines were not experimental.<\/p>\n

The damaged sites ran two megawatt units from a Danish manufacturer, a workhorse design installed by the thousand across the American Midwest.<\/p>\n

The rotor is the giveaway.<\/p>\n

Blades on that model sweep a circle about\u00a0361 feet\u00a0across, which is an enormous amount of surface for a moving air mass to catch hold of.<\/p>\n

The towers went down in a line.<\/p>\n

Survey crews found the flattened machines strung along a corridor of\u00a0seven to eight\u00a0miles, which traces the damage path rather than a series of unrelated failures.<\/p>\n

Design wind speed is the reference point.<\/p>\n

Machines of this class are built to ride out gusts near 120 miles per hour, and the engineer who refined the damage scale puts the toppling threshold at 140.<\/p>\n

Nothing about the sites was unusual.<\/p>\n

Two of them sit in Adair County on ordinary farm ground, in a state that ranks second in the country for installed\u00a0wind capacity.<\/p>\n

The numbers the storm left behind<\/p>\n

The official rating came from damage.<\/p>\n

Surveyors put the tornado at the fourth step of the intensity scale with winds around\u00a0185 miles\u00a0per hour, which is the standard method and a conservative one.<\/p>\n

A radar truck happened to be there.<\/p>\n

<\/p>\n

\"Drone<\/p>\n

Other top storyA drone flew a pilot rope half a mile across a gorge near Yass and dropped 650 feet on the way, while the conductor that followed it weighed more than the aircraft could have lifted at all<\/a><\/p>\n

A mobile Doppler unit scanning every seven seconds recorded between 308 and\u00a0318 miles\u00a0per hour at roughly one hundred feet above the ground.<\/p>\n

That reading is not the whole tornado.<\/p>\n

The peak sat in a narrow band on one side of the circulation and lasted under a second at any given point, which is long enough to start a buckle.<\/p>\n

The storm was on the ground for 48 minutes.<\/p>\n

It ran 42 miles from beginning to end and grew to nearly a mile wide at its broadest, which is how it managed to cross more than one wind farm.<\/p>\n

The turbines reported too, briefly.<\/p>\n

Sensors on several machines logged winds above 100 miles per hour and then\u00a0stopped transmitting, so that figure marks where the instruments quit rather than where the wind stopped.<\/p>\n

The count that keeps getting left out<\/p>\n

Six is one company\u2019s share.<\/p>\n

The same tornado also took down four more turbines at a third site in the next county, owned by a completely different operator.<\/p>\n

The real total is ten.<\/p>\n

Ten machines across\u00a0three wind farms\u00a0in two counties, which is\u00a0a larger event\u00a0than the figure most coverage settled on.<\/p>\n

The engineering account is harder to check.<\/p>\n

A journal study of these failures exists and\u00a0the paper<\/a>\u00a0sits behind a paywall, so nobody quoting its conclusions in public has shown the working.<\/p>\n

The field evidence points one way.<\/p>\n

The forensic engineer who walked the site said the blades came apart first and the tower held longer, which is the same order seen when\u00a0one blade<\/a>\u00a0fails on\u00a0a calm day.<\/p>\n

\"SolarOther top storyMalawi put 600 solar fridges into clinics with no reliable power, and each one freezes a thermal store during the day so vaccines hold between 36 and 46 degrees for three days without sun<\/a>
\nWhat six towers out of thousands means<\/p>\n

The operator called it unprecedented.<\/p>\n

That word is doing real work, because the company has run wind farms since 2004 and had lost exactly one turbine to a tornado before this.<\/p>\n

The denominator matters.<\/p>\n

Six losses came out of a fleet of more than\u00a03,400 turbines\u00a0across 34 counties, and\u00a0the operator<\/a>\u00a0keeps that number public.<\/p>\n

The failures are becoming useful.<\/p>\n

Damage surveyors are adding turbines to the intensity scale as a formal indicator, because a folded tower says more about the wind than\u00a0a blade<\/a>\u00a0that simply stops turning.<\/p>\n

None of it changes the design.<\/p>\n

A tower built to survive a direct tornado hit would cost far more than the losses it prevents, so the economics point at rebuilding instead.<\/p>\n

Which leaves the honest reading.<\/p>\n

Six\u00a0steel towers\u00a0folded because a rotating wind found a thin wall, and the machines that did not fold were\u00a0a mile away.<\/p>\n","protected":false},"excerpt":{"rendered":"A wind turbine tower is a tube, not a post. It carries the machine on top by keeping…\n","protected":false},"author":2,"featured_media":594079,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[273,111,139,69,147],"class_list":["post-594078","post","type-post","status-publish","format-standard","has-post-thumbnail","category-environment","tag-environment","tag-new-zealand","tag-newzealand","tag-nz","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/594078","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=594078"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/594078\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/594079"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=594078"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=594078"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=594078"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}