Instead of the canned beer typically available on airplanes, passengers of KLM Royal Dutch Airlines may soon be able to enjoy draft beer at high altitudes thanks to the company's partnership with Heinkein and a specialized keg design.Heineken’s product designer, Edwin Griffioen, had to come up with a keg design capable of fitting in the small space of an airline aisle without using the carbon dioxide cartridges often found home tap installations since they are prohibited on airplanes. The design also had to take into account the difference in pressure at high altitude, with lower air pressure on the airplane compared to sea level. Because of this, conventional beer taps would create too much foam if used on airplanes.

The key, according to Griffioen, is the balancing air pressure and the diameter of the tap.

“We managed to set the diameter of the tap and the air pressure to exactly the right combination, which delivers at 36,000 feet (11,000 m) exactly the same beer as you would get on the ground,” he said.The kegs also had to be compressed to fit into the airline catering trolley space, which meant sacrificing the cooling system.

To compensate for the lack of conventional refrigeration, the drinks trolley was redesigned to act like a thermos and keep the beer under 5°C. Heineken reports that the beer flavor is unchanged. Delivered cold to the Amsterdam Airport, four kegs can be loaded onto each flight.

“We are always looking for typical Dutch products to set us apart from other companies,” said KLM in-flight services vice president Miriam Kartman. “Heineken has been our beer partner for many years, and we both know that customers rate a beer from draught higher than out of a can.”

The good news for beer connoisseurs is that the on-tap beer is expected to be available within the next month. Launch of the tap service is pending until the airline obtains safety certificates from civil aviation authorities.

For a very different approach to in-flight beer, check out this two-stage beer keg rocket.

First published on engineering.com July 26, 2016