1983

F-117 Stealth Fighter

Radar came into being during WWII and creates an all-seeing eye. Is it possible to make a military airplane that is invisible to this eye?

What are the options? Engineers can make an airplane smaller to cut the radar cross-section. Flying very close to the ground renders ground radar useless in most cases. By combining these two techniques, engineers created cruise missiles. But what about larger planes that need to fly high?

What happened next was a two-part process. To understand the first part, get into the mindset of evading radar. Think of an airplane as a mirror-coated cigar-shaped cylinder. Now shoot a laser at it. Because of the shape, some portion of the laser light reflects back to the source of the laser beam. Radar uses a beam of radio waves instead of a laser, but the concept is nearly identical. The plane’s tendency to reflect the radar beam back to the source creates the vulnerability.

What if, instead, the plane was shaped like a mirror-coated box—nothing but flat surfaces. Now when the beam hits, it reflects away from the source. This is the essence of stealth technology—radar energy hits the airplane but reflects away from the receiving antenna.

Once engineers had this insight, there was another problem—how do you make an airplane with nothing but flat surfaces? And how do you control such an airplane? The answers produced one of the strangest-looking airplanes to ever fly—the F-117 stealth fighter, launched by the United States Air Force in 1983.

The F-117 does not look very aerodynamic because we expect aerodynamic shapes to consist of smooth curves. It is so boxy and angular that it doesn’t look like it should fly at all. However, a combination of computer control and angular aerodynamics produces an airframe virtually invisible to radar that can actually fly.

To create stealth technology, engineers needed an insight, then a reconceptualiztion of what an airplane could look like, and then computer intervention between pilot and control surfaces to make it all work.

SEE ALSO Radar (1940), ENIAC—The First Digital Computer (1946).

The B-2 stealth bomber, pictured, completed its first flight at Edwards Air Force Base, CA, July 17, 1989.