Long before the B-2 Spirit stealth bomber took to the skies, the Nazis built a similar plane.
The Horten Ho 2-29 — often called "Hitler's Stealth Fighter" — closely resembles the B-2. It's a single wing aircraft, with smooth round edges, and no vertical stabilizers.
But, one single element doesn't make an aircraft "stealth" to radar; several features have to be applied. And, the 2-29 made use of many of these principles in its design.
"These guys knew about this stuff," said aviation historian David Myhra in an interview for National Geographic News. "When I talked with Walter Horten in the 1980s and '90s he always referred to his aircraft as low-observable."
To test the stealthiness of the 2-29, Northrop Grumman built a full-scale replica made out of materials and techniques of the time and tested the aircraft with World War II-style radar.
Tom Dobrenz — a Northrop Grumman stealth expert — told National Geographic, "This design gave them just about a 20 percent reduction in radar range detection over a conventional fighter of the day."
While the Nazis understood the principles of stealth, they were a long way off from building a maneuverable flying wing aircraft. But had the Nazis achieved the technology during World War II, it would have been a game changer.
This video shows the complexity of stealth and why the Nazis were too ahead of their time to achieve it.