According to new research from Duke University, the best helmet to protect soldiers from direct blasts may be more than 100 years old.

The researchers, from Duke's Pratt School of Engineering, tested four different military helmets to see how modern military equipment compares to older gear.

The team chose the Advanced Combat Helmet (ACH), the current US Army standard that has been in use since 2002, and tested it against three helmets from World War I.

Researchers at Duke University found the French Adrian helmet from World War I was better at absorbing blasts to the top of the head than the Advanced Combat Helmet currently used by the US Army

The World War I helmets included the French ‘Adrian’ helmet, the German Stahlhelm helmet, and the American Brodie helmet.

To test each helmet, the researchers placed them on a test dummy head and exposed them to a series of blunt force blasts.

They then took readings from sensors on the dummy’s head to measure how much of that force made it through the helmet's protective barrier.

The pressurized helium blasts were designed to deliver an equivalent amount of force to several different types of German artillery shells exploding a distance of three feet to 16 feet.

The blasts were generated by a ‘shock tube,’ a wide cylinder that had a membrane behind which helium gas would build up until it reached a high enough pressure to explode through the barrier.

The team measured the force conveyed by a forced blast of helium gas to test dummy heads wearing four different helmets, three from World War I and the current standard US Army helmet

The ACH performed slightly better than the German and American WWI helmets, but the French Adrian helmet outperformed the three others, relaying around half the amount of pressure of the more modern helmet.

The amount of pressure recorded by the sensors under the Adrian helmet were correlated with less than a one percent chance of internal bleeding in the brain, compared to around five percent chance for the other three helmets.

As a baseline measurement, the team also tested the amount of force on an unprotected helmet, which conveyed force enough to correlate with a 50 percent chance of brain bleeding.

The helmets tested, from left to right: the American Brodie helmet, the French Adrian helmet, the German Stahlhelm helmet, and the modern American Advanced Combat Helmet. The final panel is the bare test dummy head

‘The result is intriguing because the French helmet was manufactured using similar materials as its German and British counterparts, and even had a thinner wall,’ Duke’s Joost Op ‘t Eynde said in an interview with the university’s website.

‘The main difference is that the French helmet had a crest on top of its crown. While it was designed to deflect shrapnel, this feature might also be deflecting shock waves.’

Researchers believe the benefit came from the additional ridge built into the top of the Adrian helmet

The advantages of the Adrian helmet disappeared when the blast was applied to other parts of the head.

‘The difference a simple crest or a wider brim can make in blast protection, shows just how important this line of research could be,’ Op ‘t Eynde said.

‘With all of the modern materials and manufacturing capabilities we possess today, we should be able to make improvements in helmet design that protects from blast waves better than helmets today or 100 years ago.’