High-speed wind tunnel tests for the Boeing 777X started last week at the company’s transonic wind tunnel in Seattle, Boeing announced Wednesday. Last month, engineers started wind tunnel tests at QinetiQ's facility in Farnborough, UK, where testing of the low-speed performance of the airplane continues.

“This is another important step forward in the development of the 777X,” said Terry Beezhold, vice president and chief project engineer of the 777X program. “Data from these tests will allow us to validate our airplane cruise performance models in support of our ongoing design efforts.”

The data will help engineers with the configuration development of the airplane, validate computational fluid dynamics (CFD) predictions and support preliminary loads cycle development.

Plans call for subsequent rounds of low-speed and high-speed testing to provide further design refinement and validation of overall airplane performance predictions. Boeing has also scheduled wind tunnel tests for noise, icing and propulsion in the coming years.

Boeing expects the 777X program to reach its firm configuration milestone in 2015. The 777X has drawn orders and commitments for 280 airplanes from five customers.