Jet engines are responsible for carrying roughly one billion people from Point A to Point B every year. They power everything from the 737s that shuttle passengers around the world to B-52s and modern military planes. However, these remarkable inventions have a somewhat muddled history when it comes to who created them.

Who came first?

Based on patent information and contemporary accounts, it’s unclear who is the true inventor of the jet engine. Many sources say that the person responsible for the modern jet engine was Frank Whittle while others claim that Hans von Ohain was the true inventor, having created the first operational model. The two worked on their patents and designs around the same time, leading to some confusion over who deserved credit for the invention. Whittle filed his patent before von Ohain, and though von Ohain supposedly never read it, critics including Whittle’s son believe that he did.

The Engineer

When it comes to working models of jet engines, Whittle was the first to produce a prototype, though it had its flaws. Namely, the first prototype would not turn off at the flip of a switch. To the test crew’s horror, the engine accelerated once the fuel line was shut off. Later, it was determined that there had been a leak that produced pools of gas which continued to burn even after the link to the source had been severed. These ground tests were performed on April 12, 1937, but Whittle wouldn’t be able to produce a flight-capable model for another four years.

Taking to the skies

Credit for the world’s first jet-powered aircraft flight undisputedly goes to von Ohain when his He 178 became airborne in late August of 1939. That same year, Whittle’s W.1X engine was flight tested by the British Air Ministry, and while it did become airborne, it was only capable of performing short, straight hops during taxiing tests. Two years later, on May 15, 1941, Whittle’s jet engine made its first official flight, earning him a contract with General Electric and the glory of powering the Bell XP-59A Airacomet beginning in October of 1942.