Can X-planes solve the sonic boom problem?
Rocket-powered and shrouded in secrecy, X-planes helped pave the way for the US space programme: Now they have another mission – taking the boom out of supersonic travel.
In 1973, the US government banned commercial supersonic flights over land in the United States. With that ban – and others like it – went the business case for aircraft like Concorde. That might be about to change if years of research into how to create a quiet sonic boom come to fruition; Nasa and the secretive "Skunk Works" of aircraft manufacturer Lockheed are trying to build an aircraft that creates it.
You can read more on this story in this BBC Future article.
Presented and produced by Riyadh Khalaf
Camera: Chris Griffiths
Edit: Dan John
Animation: Pomona Pictures
Additional Footage and Images: Nasa, Lockheed Martin, BBC News, Getty Images