Metrology Careers Blog

Careers in measurement science.

Modern Marvels – Aerospace 03/08/2011

Filed under: Modern Marvels — admin @ 12:06 pm

plane doing trick 2

If you’ve ever gone to an airshow and experienced the thrill of pilots performing death-defying aerobatics with their airplanes, then you’ve seen machines and people pushed to their limits. This is Metrology at work. Indeed, the entire aerospace industry couldn’t exist without Metrology. From calculating how air moves over a wing to create the lift that allows an airplane to fly, to satellites relaying the signal from your cell phone around the world, they all depend on measurements being precise. Students of physics and aerodynamics are taught that airplanes fly as a result of Bernoulli’s principle, which says that if air speeds up, the pressure is lowered. Thus a wing generates lift because the air goes faster over the top, creating a region of low pressure, and thus lift.

When an airplane is on the ground not moving, there is not enough air flowing around it to create lift. Another force is needed to get the airplane moving through the air, so that the airflow can do its job of creating lift. This force is called thrust. Thrust propels an object in a particular direction. The arm of a baseball pitcher generates trust and applies it to a baseball (that is, throws it) towards a batter. Likewise, a jet engine generates thrust and, because it is attached to the wing of an airplane, its thrust will be applied to the airplane. So, as the engines thrust the airplane in the direction that they are pointed, air flows over and under the wings which creates the lift force. If enough lift is generated, the airplane will fly. The 747-100 has a maximum thrust capacity of 22,545 kg and a lift capacity of 333,400 kg.

Thrust, like any other force, is measured in either newtons or pounds. Jet engines are usually rated according to the amount of thrust they can produce. Although internal combustion engines also produce thrust by means of the propeller, those used on vehicles are usually described in terms of the amount of power they produce, expressed in horsepower.

Precise measurements and control technology are required for launching vehicles that can break gravity and enter space. It’s precision application combined with raw thrust power that allows rockets to obtain orbit. NASA’s space shuttles typical payload capacity is about 22,700 kilograms. The shuttle’s two solid rocket boosters each provide 12.5 million Newtons of thrust at liftoff, which is 83 % of the total thrust needed for liftoff.


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