A Glimpse Into World's Biggest Wind Tunnel

The massive propellers, weighing a tonne each, are 24 metres in diameter and can get up to speeds of 230 rotations a minute

Rare Glimpse Into World's Biggest Wind Tunnel That Blows Gusts Twelve Times The Speed Of Sound -- The Daily Mail

Shrouded in total secrecy, massive wind tunnels that test the resistance of European aircraft have been opened up and photographed.

Journalists were offered the rare glimpse of the 24 metre diametre steel tubes at the National Centre for Aeropsace Research (Onera), where propellers, weighing over a tonne each, power the huge gusts of wind.

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My Comment: That's one big wind tunnel.