Understanding Models

Understanding Models — page 1 — CHAPTER ONE Models Help Us Test New Designs Imagine spending years building a skyscraper forty floors high Finally the last window is set into place and the final piece of tile installed You plan a grand opening ceremony to unveil your creation to the eager public but before the big day arrives a storm blows in High winds course through the city and your skyscraper begins to sway in the ever-stronger winds Finally incredibly it comes crashing to the ground In Moscow Russia old factories were torn down to make room for the Moscow International Business Center The towers under construction will be 62 and 73 stories when completed 4

Understanding Models — page 2

Understanding Models — page 3 — Your fictional skyscraper was unable to withstand the effects of high wind but real skyscrapers can Long before building begins engineers test their designs in wind tunnels Airflow in and around the building is studied and analyzed for stability Engineers use a technique called Schlieren photography to study supersonic airflow around aircraft in wind tunnels 6

Understanding Models — page 4 — DID YOU KNOW NASA uses wind tunnels and water tunnels to test the aerodynamics of vehicles in flight In water tunnels blue red and green dyes in the water help scientists predict how air would flow over an aircraft In 1920 the first wind tunnel was built at Langley Research Center A screened air intake assured a steady flow of air 7

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